hep-th — Pith

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hep-th 2026-05-13 2 theorems

Anomalies arise from broken currents in neural network parameter space

Anomalies in Neural Network Field Theory

Ward identities in NN-FT depend on a conserved parameter-space current that detects symmetry breaking and recovers standard results for the

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Neural network field theory (NN-FT) formulates field theory in terms of a network architecture and a density on its parameters. We derive Schwinger--Dyson equations and Ward identities in NN-FT and utilize them to study anomalies. The equations depend on a conserved parameter space current that characterizes symmetries and how they break. It is relevant even in non-local NN-FTs, but can recover local currents in the case of a local Lagrangian by an appropriate fiber-wise average. In machine learning, this formalism is applied to feedforward networks and the attention mechanism. In physics, we use this machinery to study $U(1)$ symmetry for a complex scalar, the scale anomaly in $4d$ massless $\phi^4$ theory, the Weyl anomaly for the bosonic string (including a new computation of the critical dimension), and examples involving discrete topological data, such as winding numbers and T-duality. Since the results are obtained in network parameter space rather than the standard field space, they represent a new way to understand symmetries in quantum field theories.

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hep-th 2026-05-13 Recognition

Cutting rules link two-loop QED corrections to trident rates

Cutting rules in strong field QED with application to trident pair production

In strong laser fields the imaginary part of higher-order electron scattering amplitudes determines electron-positron pair creation rates.

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Following Veltman's approach, we formulate and discuss a general cutting equation for QED in a plane-wave background. We apply the corresponding cutting rules to justify the connection between the two-loop radiative corrections to elastic electron scattering and the rate of the trident process in a constant crossed field. As a byproduct, we compare the previously published results for the trident process in a constant crossed field and present a complete analytical expression for direct and exchange contributions to its rate, which is resolved in the spin of the initial electron. Our findings establish that although total rates can be reliably extracted from higher-loop by applying the cutting rules, reconstruction of differential rates requires additional care. The cutting rules apply to any loop order and may be extended to nonperturbative regimes.

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hep-th 2026-05-13 Recognition

Refined Chern-Simons universality holds only for simply laced groups

A note on universality in refined Chern-Simons theory

Original Vogel form works for any simple Lie group; refinement narrows it to groups with symmetric root systems.

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We discuss various forms of refinements of Vogel's universality in Chern-Simons theory. While the original universality applies to arbitrary simple Lie groups, its counterpart in refined Chyrn-Simons theory is restricted to simply laced Lie groups.

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hep-th 2026-05-13 2 theorems

High-T asymptotics derived for non-stationary gravity effective action

Non-vacuum gravitational effective action

A generalized vector field allows the one-loop action on periodic non-static spacetimes to yield simplified nonlocal coefficients at high有效

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Curvature expansion for the heat kernel trace and the one-loop effective action is built for the wave operator of the theory in the quasi-thermal setup of a nonvacuum quantum state. This setup implies a non-static and non-stationary Euclidean gravitational background with periodic boundary conditions of the period $\beta=1/T$, where $T$ plays the role of effective global temperature to be locally rescaled by the metric gravitational potential. The results are obtained in the approximation quadratic in metric perturbations on top of flat Euclidean space and covariantized in terms of spacetime curvature. Covariantization includes a special vector field $\xi^\mu(x)$ which generalizes the Killing vector of static geometries with time translation isometry to the case of a generic arbitrarily inhomogeneous metric subject to timelike periodicity condition. This vector field is obtained as a covariant metric functional to quadratic order in metric perturbations and gives rise to the local function $T/\sqrt{\xi^2(x)}$, $\xi^2(x)=g_{\mu\nu}(x)\xi^\mu(x)\xi^\nu(x)$, reducing to Tolman temperature $T/\sqrt{g_{00}(x)}$ on stationary manifolds with Killing symmetry. High ``temperature'' asymptotic behavior of the nonlocal formfactors -- operator coefficients of the curvature tensor structures in the heat kernel and effective action -- are obtained and possible cosmological applications of these results are discussed.

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hep-th 2026-05-13 2 theorems

Null strings propagate D-3 modes

On the Consistency of Null Strings Literature: The Tale of an Overlooked Symmetry

An overlooked local symmetry in the action reduces the physical degree count and exposes inconsistencies throughout the existing null-string

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We observe that the null string action possesses a previously overlooked local symmetry. By correctly accounting for this symmetry, we show that the number of physical propagating degrees of freedom of null strings in $D$ dimensional target space is $D-3$, in contrast to $D-2$ that one finds in the literature. Overlooking this symmetry has led to an unphysical over-counting of states, rendering the null string analyses inconsistent. Thus, our observation calls for a thorough revision of all statements and results in the null string literature.

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hep-th 2026-05-13 2 theorems

Supergeometry uncovers new geometric Chern-Weil symmetries

Super-Higher-Form Symmetries

Supersymmetric theories gain extra topological supercurrents and charged defects whose charges follow from super-linking numbers in three-dm

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We review the construction of higher-form symmetries for supersymmetric theories using a supergeometry framework. This reveals an enlarged set of topological conserved supercurrents, including Chern-Weil symmetries and new geometric Chern-Weil symmetries built from invariant supermanifold forms. In N=1 super-Maxwell theory in three dimensions, we construct the corresponding operators and charged defects, with charges determined by a super-linking number between their supporting hypersurfaces. At the end we provide as an original unpublished contribution some hints on how to construct super-symTFT for Chern-Weil and geometric Chern-Weil symmetries directly from supergravity.

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hep-th 2026-05-13 2 theorems

Isometry elements classify double copies in AdS gravity

Classifying double copies and multicopies in AdS

so(2,3) orbits correspond one-to-one to metrics of black holes, branes and others via Penrose-type transform

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In this paper, we draw a parallel between solutions of pure three-dimensional gravity with a negative cosmological constant and classical double copies in four dimensions. In the former case, topological solutions, such as the BTZ black hole, deficit angles, and naked singularities, emerge from identifying points in AdS using elements from its isometry algebra $so(2,2)$. The type of solution corresponds one-to-one with the orbits of $so(2,2)$. We demonstrate how various double copies of four-dimensional AdS gravity similarly arise from the $so(2,3)$ isometry elements, which also correspond one-to-one with their orbits through a Penrose-type transform. We classify all such elements and generate the corresponding double copies, which include AdS black holes, black branes, and many others. The double-copy isometries originate from the centralizer of a given AdS isometry, allowing us to define canonical coordinates associated with its Abelian part. Additionally, the two Casimir invariants of $so(2,3)$ feature in the metrics. Our classification naturally extends to higher spins, providing nonequivalent multicopies at the linearized level.

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hep-th 2026-05-13 Recognition

High boosts make zero-momentum stability enough for causality in hydro

Necessary conditions for causality from linearized stability at ultra-high boosts

Gamma suppression lets homogeneous stability criteria identify the full causal parameter space at near-luminal velocities.

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In this work, we provide a novel method to constrain the causal parameter space of a relativistic hydrodynamic system exclusively from its linear stability analysis at non-zero momenta. Our approach exploits the Lorentz-invariant stability property of causal theories. In boosted frames, the dispersion relation exhibits a feature that we call ``$\gamma$-suppression,'' whereby the higher-order terms in the wavenumber expansion are increasingly suppressed beyond leading order at large boosts. As a consequence, at near-luminal values of Lorentz boost, stability criteria at the spatially homogeneous limit are sufficient to identify the region of the parameter space that satisfies the necessary conditions of causality, even at non-zero momenta. After presenting the general hydrodynamic framework, we test the method in conformal M\"uller-Israel-Stewart theory and show that it provides an efficient way of deriving the necessary conditions of causality while remaining within the low-energy regime of hydrodynamic validity.

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hep-th 2026-05-13 2 theorems

Static contributions to black hole angular momentum flux reduce to one-loop integrals

A Runway to Dissipation of Angular Momentum via Worldline Quantum Field Theory

The organization yields explicit O(G^3) results that match known values and extends to electromagnetism while vanishing above four spacetime

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We extend the worldline quantum field theory formalism to include a direct diagrammatic method of computing the total flux of angular momentum from a black hole scattering event in the post-Minkowskian regime. Remarkably, except for subtle zero-frequency gravitons, the diagrammatic and integrational challenge is in a one-to-one correspondence with the analogous calculation of the black hole impulses -- and the well-developed WQFT methodologies for the impulse may thus be directly imported to this problem. Zero-frequency gravitons appear in this calculation as a "static" integration region in addition to the "dynamical" region usually encountered for the impulse. We show that a large class of static contributions can be organized systematically by introducing $n$-point functions referred to as "static correlators". They reduce to a simple one-loop integral family which we compute explicitly using integration-by-parts relations and the method of differential equations. In passing, our analysis shows that static contributions disappear in space-time dimensions $D>4$. As a concrete application of our new method, we compute explicitly the $\mathcal{O}(G^3)$ total flux of angular momentum reproducing known results. Further, we apply the same method to electromagnetism where we compute the analogous $\mathcal{O}(\alpha^3)$ result.

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hep-th 2026-05-13 2 theorems

Podolsky electrodynamics alters Stefan-Boltzmann law

Thermal and spatial confinement effects in Podolsky electrodynamics

Higher-derivative terms change thermal radiation density and vacuum forces when temperature and boundaries are imposed via Thermo Field Dyan

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In this work, Podolsky theory, a second-order, Lorentz- and gauge-invariant extension of classical electrodynamics, is considered. The effects of Podolsky's modification on fundamental phenomena such as the Stefan-Boltzmann law and the Casimir effect for the electromagnetic field are investigated. The Thermo Field Dynamics (TFD) formalism is employed to describe quantum fields at finite temperature and under spatial confinement through its topological structure.

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hep-th 2026-05-13 2 theorems

Gauge dressing produces T-duality rules for heterotic strings

Gauge-Dressed Complex Geometry and T-duality in Heterotic String Theories

Shifted metric and quasi complex structure yield Buscher-like rules plus hypercomplex Born geometry in gauge backgrounds.

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We study T-duality of $(p,q)$-hermitian geometries in backgrounds with non-Abelian gauge fields $A$ in heterotic string theories. We introduce a gauge-dressed complex geometry characterized by a shifted metric $\bar{g} = g + \frac{1}{2} \mathrm{Tr}(A^2)$, the closed 2-form $\omega$ and a quasi complex structure satisfying $\bar{J}^2 < 0$, but not necessarily $\bar{J}^2 = -1$. Utilizing the positive and negative chirality half generalized complex-like structures constructed by $(\bar{g}, \bar{J})$, we derive a heterotic Buscher-like rule for geometric quantities. We also demonstrate that the gauge-dressed structures can be used to construct an extended Born geometry that satisfies algebras of hypercomplex numbers.

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hep-th 2026-05-13 2 theorems

Scalar form factor reaches non-trivial fixed point in quantum gravity

Scaling Solutions of Matter Form Factors in Asymptotically Safe Quantum Gravity

The kinetic term flows to a solution that deviates from the classical form but becomes local at infinite cutoff, with a discrete spectrum of

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We investigate the renormalization group flow of a gravity--matter system in which a scalar field is minimally coupled to Einstein gravity and its kinetic term is given by a scale-dependent form factor $f_\Lambda(-\Box)$. Employing the Wilsonian proper-time flow equation, we derive a closed integro-differential equation that encodes the dependence of the form factor on the UV cutoff $\Lambda$. We solve the resulting fixed-point problem with a pseudospectral discretization and find a non-trivial fixed point for which $f_\ast(-\Box)$ departs from the canonical $-\Box$ behavior. Linearizing the flow about this solution yields a discrete spectrum of perturbations and a corresponding set of critical exponents, indicating a non-trivial scaling structure in this non-local sector compatible with asymptotic safety. We also observe that the form factor becomes local once the UV cutoff is removed, suggesting that the bare action associated with this fixed point is local in the scalar two-point sector.

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hep-th 2026-05-13 2 theorems

Monte Carlo study gives 3D dipolar critical exponents

A Monte Carlo Study of the Dipolar Universality Class in Three Dimensions

Constrained lattice simulations show continuous transition and restored isotropy at the critical point.

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The dipolar universality class describes the phase transition in 3D ferromagnets with strong dipolar interactions, as first discussed by Aharony and Fisher in the 1970s. While this universality class has been studied theoretically using renormalization group methods, as well as experimentally, little is known about it from Monte Carlo simulations. In this paper we aim to bridge this gap. We introduce a lattice model that faithfully implements the transverse constraint on the order parameter. We introduce a Markov Chain Monte Carlo algorithm which involves a combination of local Metropolis updates preserving the constraint, and a global update of the zero mode. We perform simulations on cubic lattices up to volume $48\times 48 \times 48$. We observe a continuous phase transition between the disordered and ordered phases. We obtain estimates of universal quantities such as the main critical exponents and the Binder ratio, and compare them with results from other techniques. We also investigate the emergence of rotation invariance at the critical point.

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hep-th 2026-05-13 2 theorems

Dirac oscillator energies depend on cloud-of-strings curvature

The Dirac oscillator in the curved spacetime of a cloud of strings

Exact solutions via tetrads reduce the Dirac equation to the Whittaker equation, yielding a spectrum quantized in n and κ that varies with ω

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In this paper, we determine the relativistic bound-state solutions for the Dirac oscillator (DO) in the curved spacetime of a cloud of strings in $(3+1)$-dimensions, where such solutions are given by the four-component normalized Dirac spinor and by the relativistic energy spectrum. However, unlike in literature, here, we work with the spacetime in two different forms/configurations, that is, both in its original form and in its modified form. To achieve our objective, we work with the curved DO in spherical coordinates, where we use the tetrad formalism. So, by defining a stationary ansatz for the spinor, we obtain two coupled first-order differential equations, and by substituting one equation into the other, we obtain a second-order differential equation. To analytically and exactly solve this differential equation, we use a change of function and of variable. From this, we obtain the well-known Whittaker equation, whose solution is the Whittaker function. Consequently, we obtain the energy spectrum, which is quantized in terms of the radial quantum number $n$ and the angular quantum number $\kappa$, and explicitly depends on the angular frequency $\omega$ (describes the DO), curvature parameter $a$ (describes the cloud of strings), and on the effective rest mass $m_{\text{eff}}$ (describes the rest mass modified by the curvature of spacetime). Besides, we graphically analyze the behavior of the spectrum as a function of $\omega$ and $a$ for three different values of $n$ and $\kappa$, as well as the behavior of the radial probability density for four different values of $\kappa$, $\omega$, and $a$ (with $n=0$).

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hep-th 2026-05-13 2 theorems

Supersymmetric model induces Aharonov-Casher effect from Lorentz violation

Aharonov--Casher effect from a supersymmetric N=1 D=4 model with Kalb--Ramond Lorentz-violating background: a SUSY-preserving mechanism via the Fayet--Iliopoulos term

A Kalb-Ramond background generates the neutral-fermion dipole term dynamically without breaking supersymmetry.

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The Aharonov--Casher (AC) effect describes the geometric phase acquired by a neutral particle carrying a magnetic dipole moment moving in an external electric field. In supersymmetric gauge theories it is often argued that exact supersymmetry enforces the vanishing of anomalous magnetic dipole moments, suggesting that the AC interaction may be incompatible with unbroken supersymmetry in four dimensions. In this work we show that this conclusion is model-dependent. We construct an $N=1$, $D=4$ supersymmetric gauge model in which a Lorentz-violating Kalb--Ramond background induces dynamically the dipole interaction responsible for the AC effect while leaving the supersymmetry algebra intact. The model couples a chiral superfield to an Abelian gauge superfield through a Chern--Simons--type interaction supplemented by a Fayet--Iliopoulos term. A duality identification between the symmetric combination $S+S^\dagger$ of the chiral superfield and the Kalb--Ramond superfield strength allows the antisymmetric tensor background to enter the supersymmetric dynamics without breaking supersymmetry. Integrating out the auxiliary $D$ field generates dynamically an effective dipole interaction of the form $\bar{\psi}\sigma^{\mu\nu}F_{\mu\nu}\psi$. In the nonrelativistic limit the resulting equation of motion reproduces the Aharonov--Casher Hamiltonian for a neutral fermion. The effective magnetic dipole moment is expressed in terms of the parameters of the model and can be mapped onto tensor coefficients of the fermion sector of the Standard Model Extension. Our results therefore provide an explicit realization of a four-dimensional supersymmetric theory in which the Aharonov--Casher interaction emerges dynamically while supersymmetry remains exact in the presence of Lorentz violation.

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hep-th 2026-05-12 2 theorems

Renormalization group yields generalized Fokker-Planck for inflation

Stochastic inflation from a non-equilibrium renormalization group

A Polchinski-type flow on the density matrix generates dissipative and diffusive corrections beyond the standard stochastic equation.

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Understanding stochastic inflation, and in particular the systematic computation of controlled corrections from first principles, remains an important open problem. In this work, we address this problem from two complementary perspectives. First, we derive the effective field theory governing long-wavelength modes from the reduced density matrix of a coarse-grained description. In this framework, locality in time follows from the thin-shell approximation, while locality in space is recovered dynamically in the super-Hubble regime. The resulting open effective field theory contains both dissipative and diffusive operators, with diffusion dominating as the coarse-graining scale is pushed into the infrared. This construction reproduces the usual Fokker-Planck equation at leading order and allows us to compute its corrections, including subleading contributions to the stochastic dynamics. Second, we study the evolution of the density matrix under changes of the coarse-graining scale. We show that this flow is governed by a Polchinski-type renormalisation group equation formulated directly for the density matrix. Dissipative and diffusive operators are generated dynamically along the flow, and the resulting effective action matches the Schwinger-Keldysh description. We derive a generalised Fokker-Planck equation directly from the renormalisation group flow, systematically incorporating subleading corrections and recovering the results obtained in the open effective field theory approach.

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hep-th 2026-05-12 Recognition

Veneziano amplitude is fixed uniquely by bootstrap moments

Analytic Bootstrap of the Veneziano Amplitude

Dispersive sum rules plus monodromy or hidden-zero conditions leave no other dual solution at any order.

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We analytically prove, to all orders, that the Veneziano amplitude is the unique outcome of a dual bootstrap based on dispersive sum rules, unitarity, and a small amount of additional stringy input. This stringy input can be either the string monodromy condition or the recently uncovered splitting and hidden-zero conditions. A key ingredient in our proofs is to interpret the dispersive sum rules as sequences of moments. Equally important is the precise incorporation of the extra stringy input into the amplitude ansatz, which makes the analytic bootstrap sufficiently rigid to fix the amplitude uniquely.

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hep-th 2026-05-12 Recognition

Compact spaces trigger homogeneous false vacuum decay below critical volume

Compact space catalysis of false vacuum decay and Schwinger effect

New bounce replaces Coleman bubble for small volumes, nucleating uniform fields and boosting decay rates exponentially.

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We study zero-temperature false vacuum decay in $D$ compact spatial dimensions and show that for volumes below a critical value a new bounce solution, different from Coleman's celebrated $O(D)$ bubble, mediates the decay process, and typically leads to an exponentially enhanced decay rate. The bounce, when analytically continued to Lorentzian signature, nucleates a homogeneous field configuration for spatial volumes below a critical value, and quasi-homogeneous configurations for slightly larger volumes, and is not of the form of a thin or thick-walled bubble embedded in a false vacuum background. We explicitly show that the new bounce has the necessary features associated with false vacuum decay, following from its eigenvalue spectrum of fluctuations. The cross-over from homogeneous to quasi-homogeneous solutions as the spatial volume is increased is discussed, as is a real-time interpretation of the bounce. We apply this bounce to the study of a scalar field model, as well as a close cousin of the Schwinger effect that applies to $(1+1)d$ axion electrodynamics in compact space.

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hep-th 2026-05-12 2 theorems

Spin-3/2 EFTs confined to tiny supergravity neighborhood at low mass

Positivity in Massive Spin-3/2 EFTs and the Planck-Suppressed Neighbourhood of Supergravity

Allowed coupling volume shrinks as m^6 over M_Pl^6, vanishing in the massless limit

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It is well known that a strictly massless spin-$3/2$ particle can interact consistently only within supergravity. Recently, positivity arguments have shown that an effective field theory of a massive Majorana spin-$3/2$ particle admits a smooth $m \to 0$ limit only if a graviton is present and the four-fermion contact interactions are tuned to the values dictated by $\mathcal{N}=1$ supergravity. In this work, we investigate how this limit is approached at finite mass. Assuming that the graviton $t$-channel pole can be discarded, we derive non-forward, tree-level dispersive bounds on massive spin-3/2 contact operators and determine the region of effective couplings consistent with unitarity and analyticity. For sufficiently small $m$, we find that the allowed parameter space forms a bounded, Planck-suppressed neighbourhood of the supergravity point, defined by the supergravity values of the four-fermion couplings. The supergravity point lies on the boundary of this region. In the regime $m \ll M_{\rm Pl}$, the volume of the allowed region scales parametrically as \[ \mathrm{Vol} \sim \frac{m^{6}}{M_{\rm Pl}^{6}} \, , \] and shrinks to zero as $m \to 0$, smoothly reproducing the massless-limit results. The allowed region becomes unbounded when mass approaches the Planck scale. We further analyze the effect of including additional light scalar and pseudo-scalar degrees of freedom, motivated by the Polonyi model, and find that their couplings are also bounded in a way similar to the contact couplings and that it doesn't enlarge the allowed contact coupling space.

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hep-th 2026-05-12 2 theorems

This paper suggests that Hořava-Witten theory can realize the dark dimension scenario by…

Towards the Realization of the Dark Dimension Scenario in Hov{r}ava-Witten Theory

Hořava-Witten theory offers a potential string embedding of the dark dimension by localizing the Standard Model on the 11th interval, with…

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It has been suggested that Ho\v{r}ava-Witten theory could provide a concrete realization of the Dark Dimension Scenario. In this context, the observable Standard Model sector is naturally localized in the micron-sized large dimension, which is the interval in the eleventh direction. Considering Calabi-Yau manifolds supporting generic vector bundles including also abelian factors, we point out that symmetric tadpole cancellation on the $E_8$ walls has the potential to ameliorate some of the issues of such a realization, including too fast proton decay. By taking not only the hierarchically small value of the dark energy but also the size of the Standard Model gauge couplings into account, one is driven to a special infinite distance limit, which is the Ho\v{r}ava-Witten analogue of a limit recently at the focus of the M-theoretic Emergence Proposal. Extrapolating results obtained for BPS-saturated amplitudes, we speculate about the possibility of obtaining the moduli dependence of the scalar potential, the gauge couplings and the Planck scale by simple one-loop Schwinger integrals over towers of states.

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hep-th 2026-05-12 2 theorems

CMB polarization rotates at dark vacuum interfaces

CMB Birefringence from Vacuum Interfaces

A fixed geometric phase from wall Chern-Simons terms produces the rotation without light axions and stays constant with distance and energy.

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Hints of cosmic microwave background polarization rotation ($\Delta\vartheta \sim 10^{-3}$ rad) are commonly attributed to late-time dynamics of ultralight axions. We show that such ultralight degrees of freedom are not required. Polarization rotation naturally arises as a geometric interface phase acquired when photons cross interfaces between topologically distinct dark sector vacua. The effect is a discrete phase shift fixed by the normalization of a wall-supported electromagnetic Chern--Simons interaction and protected by an emergent $1$-form symmetry of the low energy effective theory. This mechanism reproduces the familiar adiabatic rotation induced by light axion domain walls, but persists for arbitrarily thin walls where the axion is heavy or absent. In this regime the rotation manifests as a Pancharatnam phase localized at vacuum interfaces, independent of redshift and photon frequency below a natural ultraviolet cutoff. Cosmic birefringence thus emerges as a probe of vacuum structure in the dark sector, rather than of light-field dynamics.

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hep-th 2026-05-12 Recognition

Monster CFT parafermionization produces so(3)_p symmetries

Parafermionizing the Monster

Defect McKay-Thompson series for the resulting symmetries prove invariant under Gamma_1(p+2) for odd primes p.

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We study the parafermionization of the Monster CFT with respect to its $\mathbb{Z}_{pA}$ subgroups, with $p$ an odd prime. Under certain assumptions, we show that the parafermionization is equal to a non-invertible gauging of $\mathcal{P}(p) \times \mathcal{P}(p)^\vee$, where $\mathcal{P}(p)$ is the theory of $\mathbb{Z}_p$-parafermions and $\mathcal{P}(p)^\vee$ is an appropriate dual theory, with global symmetry characterized by the centralizer of $\mathbb{Z}_{pA}$. By tracking the symmetries of $\mathcal{P}(p) \times \mathcal{P}(p)^\vee$ through the non-invertible gauging, we argue that the diagonal Monster CFT has $\mathrm{Rep}(\mathfrak{so}(3)_p) \boxtimes \mathrm{Rep}(\mathfrak{so}(3)_p)^\mathrm{op}$ symmetry, and hence that the holomorphic Monster theory has symmetry $\mathrm{Rep}(\mathfrak{so}(3)_p)$. We then compute the defect McKay-Thompson series associated to these symmetries, and prove that their invariance subgroups are $\Gamma_1(p+2)$.

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hep-th 2026-05-12 2 theorems

Analytical setup yields Lanczos coefficients for BMN Krylov complexity

Krylov state complexity for BMN matrix model

Reduction to the pulsating fuzzy sphere model gives exact expressions in both large- and small-deformation limits.

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We explore Krylov complexity in the BMN matrix model following a systematic reduction of it, known as the pulsating fuzzy sphere model. We present an analytical setup that allows us to calculate Lanczos coefficients in both large and small deformation limits of the matrix model.

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hep-th 2026-05-12 3 theorems

String theory paths to moduli boundaries accelerate the universe

Axion-Scalar Dynamics: from the Distance Conjecture to Cosmic Acceleration

Dynamical trajectories prove infinite at finite-distance singularities and produce late-time expansion, extending the distance conjecture.

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We discuss the cosmology of axion-scalar systems in asymptotic limits of type IIB/F-theory flux compactifications. These results allow us to test a putative extension of the Distance Conjecture in a dynamical setting, which posits that towers of states should become exponentially light in the distance measured along the trajectory (as well as in the geodesic one). In the case of infinite distance limits, we review a known classification of late-time asymptotic solutions, which always verify the extension of the conjecture whenever all relevant effects are taken into account. We also extend the analysis to the case of finite distance limits, where the analogous statement would require trajectories approaching the singularity to have a finite length. Surprisingly, we find this is not the case for the class of models under consideration. Moreover, the new solutions we find exhibit asymptotic accelerated expansion when approaching the boundary of moduli space.

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hep-th 2026-05-12 Recognition

Finite master-field regularization computes large-N matrix models

Regularized Master-Field Approximation for Large-N Reduced Matrix Models

Method reproduces exact Euclidean solutions and perturbative Minkowski results with no sign problem

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We propose a numerical method based on the master field for large-$N$ reduced matrix models. While the master field is originally an infinite-dimensional matrix, in this method it is regularized to a finite dimension, with the requirement that it satisfies the loop equations as much as possible. This formulation can be directly implemented for numerical computation, and since there is no sign problem at the fundamental level, the method can be applied regardless of whether the model is of Euclidean or Minkowski type. In numerical calculations for one- and two-matrix models, the exact solution is well reproduced in the Euclidean case, while perturbative results are well reproduced in the Minkowski case. This demonstrates the effectiveness of the method and supports the idea that the matrix models studied in this paper admit a regularized master-field description.

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hep-th 2026-05-12 2 theorems

Dynamical edge mode plate yields same Casimir force as magnetic conductor

On the Casimir effect with mixed dynamical edge mode and perfect electromagnetic conducting boundary conditions

The force matches the perfect magnetic conductor case when the second plate is a perfect electromagnetic conductor.

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We study the Casimir effect for a parallel plate setup with one plate with dynamical edge mode (DEM) boundary conditions, and one plate with perfect electromagnetic conductor (PEMC) boundary conditions. In order to restore BRST invariance, new edge fields are introduced on the DEM plate. We then lift the boundary conditions into the action using Lagrange multiplier fields, and integrate out the bulk fields to obtain a non-local effective boundary theory from which we compute the Casimir energy. The resulting Casimir force is identical to a PMC-PEMC setup, implying that, from the point of view of the Casimir effect, a DEM plate is equivalent to a PMC plate. We also include a detailed derivation of the general functional method used to compute the Casimir energy from the partition function.

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hep-th 2026-05-12 1 theorem

Wineglass wormholes birth inflating universes from flat space

Birth of Inflationary Universes via Wineglass Wormholes and their No-Boundary Relatives

Numerical solutions reveal they split into no-boundary instantons when charge is small, allowing expansion after tunneling from existing sp

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We study Euclidean wineglass wormholes, which mediate the nucleation of inflationary spacetimes from an existing spacetime with asymptotically flat or Anti-de Sitter regions. These wormholes are distinguished by the presence of a local maximum of the scale factor, which allows the analytically continued Lorentzian spacetime to expand after materialization. We present explicit numerical wormhole solutions supported either by an axionic field or a magnetic gauge field, in both cases in conjunction with a self-interacting scalar field. More exotic solutions, with multiple extrema of the scale factor, are also described. As we discovered recently, in the limit of small axionic or magnetic charge, wineglass wormhole solutions split into two separate geometries, one being the background spacetime and the other a disconnected no-boundary instanton. We study the associated topology changing transition in detail and provide an extensive discussion of both the properties and puzzles exhibited by this common family of wineglass/no-boundary instantons.

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hep-th 2026-05-12 2 theorems

Analogue black holes fail to match known dilaton models

On the dilaton gravity of analogue black holes

Superconducting circuit setups show no correspondence for state-independent temperature cases, so labs should instead engineer conditions to

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We investigate which dilaton gravity models can reproduce the typical two dimensional analogue black holes realized in platforms such as superconducting quantum circuits. We identify the most reasonable assumptions these models must satisfy, and determine the dilaton models for which the state-dependence of the Hawking temperature, T, can be switched on and off, a feature that is absent in four dimensional black holes. When the analogue black hole exhibits state-independent temperature, as in the cases considered here, the kinematics governing T decouples from the dynamics underlying S. Our numerical analysis reveals that the given analogue black holes do not correspond to known dilaton gravity models, limiting their usefulness for extracting theoretical insights. We then show that the logic can be easily reversed: starting from established well known dilaton models, one can derive the conditions that laboratory implementations must satisfy. This shifts the challenge from the theoretical perspective to the experimental realization.

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hep-th 2026-05-12 2 theorems

Chiral gauge theories produce diverse infrared spectra

Infrared spectra of some strongly--coupled chiral gauge theories

Anomaly matching fixes light particle content and RG flows for simple models with chosen gauge groups and scale ratios.

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Several simple asymptotically-free chiral gauge theories are studied. The only ``free parameters'' of our models are the choice of the gauge group and the matter Weyl fermion representations, and the relative magnitudes of the renormalization-group-invariant scales $\Lambda_i$ associated with each gauge group. None of our models has nontrivial nonabelian global symmetries (``family''--like fermion representations). We rely on some recent theoretical developments on the dynamics of strongly--coupled chiral gauge theories, based on the generalized symmetries and associated new types of anomaly-matching consideration, but also on the solid knowledge on vectorlike gauge theories such as QCD and supersymmetric Yang-Mills theories. The structures of the infrared effective theories, the RG flows, and the light spectra found in these models are surprisingly rich and intriguing.

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hep-th 2026-05-12 2 theorems

Complex Hopf fibration classifies FQH bulk-edge effects

Bulk-Edge Correspondence via Higher Gauge Theory

It also reconstructs the chiral edge currents via higher gauge theory engineered on M2/M5-branes in 11D supergravity.

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More profound than bulk topological order of quantum materials is only its unwinding via gapless excitations along boundaries of the sample. We recast this bulk-edge correspondence -- for the experimentally relevant case of fractional quantum Hall (FQH) systems -- in terms of effective relative higher gauge theory, controlled by choices of classifying fibrations. For FQH systems, we identify the complex Hopf fibration as classifying the bulk/boundary topological effects, and find that it yields a non-Lagrangian reconstruction of Floreanini-Jackiw/Wess-Zumino-Witten chiral edge currents. Remarkably, the resulting effective FQH higher gauge theory turns out to be "geometrically engineered" on M2/M5-branes probing A-type orbi-singularities in 11D supergravity, globally completed by flux-quantization in twisted equivariant differential (TED) Cohomotopy: Here the M-string ends of M2-branes on M5-branes engineer the FQH liquid's boundary. This geometric engineering on M-branes might naturally elucidate the curious combination of $W_\infty$-symmetry and of super-symmetry that is known to govern the collective excitations of FQH liquids at long wavelengths.

0

hep-th 2026-05-12 2 theorems

Free particle, oscillator and inverted oscillator share one conformal module

The Free Particle--Oscillator--Inverted Oscillator Triangle: Conformal Bridges, Metaplectic Rotations and mathfrak{osp}(1|2) Structure

Bridge transformations connect their states with different spectra while preserving the shared algebraic structure

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We study the free particle (FP), the harmonic oscillator (HO) and the inverted harmonic oscillator (IHO) as parabolic, elliptic and hyperbolic realizations of one conformal/metaplectic structure, naturally extended to the superconformal algebra $\mathfrak{osp}(1|2)$. Since the corresponding self-adjoint Hamiltonians have different spectra, the relations between them are not ordinary unitary equivalences. They are instead bridge transformations between different realizations of the same conformal module. We show that the zero-energy Jordan states of the FP are mapped to HO bound states and to the two IHO Gamow families, while FP plane waves are mapped to HO coherent states and, after light-cone Mellin decomposition, to the IHO scattering data. The direct FP--IHO bridge is a real metaplectic quarter-rotation, in contrast with the stationary FP--HO conformal bridge, which is nonunitary in the Schr\"odinger representation but becomes unitary as a change of polarization to the Fock--Bargmann representation. The IHO transmission and reflection amplitudes are obtained as Fourier--Mellin connection coefficients, equivalently as Weber/Stokes connection data. We also describe the hyperbolic Cayley--Niederer map for the time-dependent Schr\"odinger equation, the Wigner/separatrix picture, and the coherent-state and Bogoliubov-transformation aspects of the construction. Some physical applications of the hyperbolic sector are briefly discussed, including quantum Hall saddle scattering, Schwinger-type production, Rindler/Unruh and near-horizon Hawking settings, and Berry--Keating/inverse-square structures.

0

hep-th 2026-05-12 2 theorems

G-theory compactifications require End of the World branes to cancel cohomology

Double fibration in G-theory and the cobordism conjecture

Bordism group analysis shows that extra non-perturbative objects are also needed in Type IIB models with varying fluxes and dilaton.

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We investigate Type IIB compactifications with spatially varying fluxes and dilaton profiles in the setting of dynamical cobordism. In particular, we analyze a G-theory motivated compactification in which the fluxes and the dilaton depend on coordinates of a complex two-dimensional plane. From the equations of motion, we deduce the existence of End of the World branes. In a cohomological interpretation, these branes appear precisely in order to trivialize the relevant cohomology class. Furthermore, we compute the associated bordism group and show that additional non-perturbative objects are needed to cancel the class, while retaining the cohomological contribution as a subgroup. This suggests a mathematical structure that connects energy scales with the emergence of perturbative and non-perturbative physics.

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hep-th 2026-05-11 2 theorems

Eigenvector joint distributions in random tensors reduce to one geometry function

Joint distributions of eigenvectors of symmetric random tensors

Large-dimension asymptotics yield a common function of tensor shape, extending earlier universality from single to joint distributions.

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We compute the joint distributions of arbitrary numbers of eigenvectors of real and complex symmetric random tensors by the quantum field theoretical methods which were previously used to compute the mean distributions. We obtain the random matrix representations and the large-dimension asymptotics of the joint distributions. The latter can be expressed by a common function of tensor geometries, extending the universality found for the mean distributions to the joint distributions. Several crosschecks of our results are carried out by Monte Carlo computations.

0

hep-th 2026-05-11 2 theorems

Borel-autonomous method matches stochastic de Sitter evolution better

Taming the infrared in de Sitter space: autonomous equations, stochastic approach, and Borel resummation

Applying autonomous equations to Borel-Le Roy transforms yields closer agreement with the stochastic time evolution for scalar fields in deS

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We investigate the divergent perturbative series of correlation functions for a massless, self-interacting scalar field in de Sitter space. First, we use our previously proposed method of autonomous equations to obtain finite time-dependent functions, and show that these functions approximate the time evolution of the correlation functions of the stochastic theory reasonably well. Second, we apply the technique of autonomous equations to the Borel-Le Roy transforms of correlation functions, and use solutions of these equations to perform Borel resummation. The results match the time evolution obtained in the stochastic picture substantially better. In addition, we propose an alternative method for extracting perturbative coefficients and provide a new derivation of our autonomous equation by truncating a system of Schwinger-Dyson-type differential equations.

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hep-th 2026-05-11 Recognition

Modified gravity alters non-Abelian monopoles at strong Higgs coupling

Non-Abelian monopoles in modified gravity

Numerical solutions show sizable structural differences from Einstein gravity when Higgs self-interaction grows large.

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Within modified gravity, we study static spherically and axially symmetric self-gravitating non-Abelian monopoles in $SU(2)$ Yang-Mills-Higgs theory. By comparing these monopoles with those obtained in Einstein-Yang-Mills-Higgs theory, we identify the differences introduced by the modification of gravity and show that they can be quite significant for systems with strong Higgs self-coupling.

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hep-th 2026-05-11 Recognition

Mixed Chern-Simons models allow arbitrary vortex-antivortex numbers

Bogomol'nyi Equations in Mixed Product Chern-Simons Theories Governing Charged Vortices and Antivortices

But bound their difference on periodic domains, leading to unbounded energy spectra unlike vortex-only cases.

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We extend product Chern-Simons theory to develop several mixed $U(1)\times U(1)$ models where one gauge field is governed by a Chern-Simons term and the other by a Maxwell or Born-Infeld term. We show that, by choosing suitable potentials, the energy functional admits a topological lower bound saturated by first-order self-dual equations. The resulting dyonic systems can be divided into vortex-vortex and vortex-antivortex configurations, and the coexistence of vortices and antivortices in the latter extends the vortex-only result known in product Chern-Simons model. On a doubly periodic domain, we establish Bradlow-type bounds with distinct physical implications: for vortex-only systems, the vortex numbers stay below this bound and cannot be arbitrarily large; for vortex-antivortex systems, the bound is imposed on the difference between the vortex and antivortex numbers, while the individual numbers are arbitrary. This distinction results in a bounded energy spectrum for the former and an unbounded energy spectrum for the latter.

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hep-th 2026-05-11 Recognition

Fuzzball models often lack entanglement islands

Entanglement islands, fuzzballs and stretched horizons

Boundary conditions and horizon position control whether islands form, with solutions vanishing across wide parameter ranges and uncertainly

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We study the implementation of the island prescription in fuzzball-inspired models of black holes. As a simplified setup, we model a fuzzball by replacing the event horizon with a reflecting boundary (stretched horizon). In the framework of two-dimensional model with such boundary, we analyze the dynamics of entanglement entropy. We find that the presence of the boundary modifies the behavior of the island saddle, and for a range of parameter values we observe the effect of blinking island found in arXiv:2311.16244 which inevitably leads to the analogue of information paradox. We then extend the analysis to higher dimensions, incorporating both bulk and boundary contributions to the generalized entropy. The existence of island solutions is found to depend sensitively on the boundary conditions and the position of the stretched horizon, naturally leading to the absence of entanglement islands for a wide range of parameters. Finally, we consider more "realistic" stringy fuzzball geometries, including superstrata and bubbling solutions, and estimate whether island solutions can arise in these backgrounds. The results indicate that the existence of islands depends on the behavior of the geometric area near the cap, and is not guaranteed in general.

0

hep-th 2026-05-11 2 theorems

Holographic model yields DC and Hall conductivities in magnetized QGP

Charge Transport in Magnetized Holographic mathcal{M}-QGP

Probe brane calculation isolates regimes where pair production overtakes charge carrier transport under magnetic fields.

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We investigate DC transport in a top-down construction of thermal QGP-like theories using a holographic M-theoretic background, incorporating quartic curvature corrections. The DC and Hall conductivities are computed from the Dirac-Born-Infeld (DBI) action of the corresponding type-IIA probe D6 flavor branes via the reality condition method proposed in arXiv:0708.1994 and arXiv:0705.3870. We further analyze pair-production contributions in the presence and absence of an external magnetic field and work out regimes where pair production dominates over charge carrier transport. These findings extend earlier AdS/CFT results to non-conformal, higher-derivative settings relevant to thermal QGP-like theories.

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hep-th 2026-05-11 2 theorems

Inner-horizon saddle supplies minus sign in near-extremal entropy

Inner Horizon Saddles and a Spectral KSW Criterion

A complex geometry with negative boundary length cancels the outer-horizon contribution and enforces vanishing state density as horizons col

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The Bekenstein-Hawking entropy formula $\rho = e^{A/4G}$ receives significant corrections for charged black holes near extremality. Using standard results in JT gravity, the correction term can semiclassically be expressed as minus the exponential of the inner horizon area, $e^{A_{\text{inner}}/4G}$, and the cancellation between these two exponentials enforces a vanishing density of states towards extremality, when the two horizons collide. Building on arXiv:2402.10162, we argue that the correction term corresponds to a complex saddle geometry of the bulk gravitational path integral. The proposed geometry has a negative boundary length and caps off at the inner horizon; we refer to it as the inner horizon saddle. We discuss how the saddle, and its accompanying minus sign, contribute to the density of states through a Picard-Lefschetz analysis of the inverse Laplace contour, together with a stability analysis of the saddle. We also address the inner horizon saddle's violation of the Kontsevich-Segal-Witten (KSW) allowability criterion for the inclusion of complex metrics. Despite this violation, which is believed to cause unphysical divergences in path integral computations, one can describe one-loop effects on the inner horizon saddle by carefully treating wrong-sign modes. Motivated by this observation, we propose a weaker version of the KSW criterion, which we call the spectral KSW criterion. Its purpose is to characterize when one-loop corrections around complex gravitational saddles are well defined.

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hep-th 2026-05-11 Recognition

1/4-BPS index in N=4 SYM independent of rank N

Fermionic trace relations and supersymmetric indices at finite N

Exact cancellations of bosonic and fermionic trace relations make the index the same at every finite N in this model.

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We study invariants of bosonic and fermionic (Grassmann-valued) matrices under the adjoint action of $U(N)$, weighted by the fermion number. Such models naturally appear as the supersymmetric indices of supersymmetric gauge theories and are captured by $U(N)$ matrix models. We discuss two features of the fermionic models that are qualitatively different from bosonic models. Firstly, the $2N^\text{th}$ power of a Grassmann matrix vanishes, which gives rise to many new trace relations. Secondly, trace relations in models involving fermions could cause an increase in the supersymmetric index as $N$ decreases, in contrast with purely bosonic models. We focus on a simple model involving one fermion and one derivative that corresponds to a $\frac14$-BPS supersymmetric index in $\mathcal{N}=4$ SYM theory, in which we find that the index is independent of $N$. We prove this rank-independence analytically, and experimentally study the cancellations between bosonic and fermionic trace relations that lead to it. Based on these observations, we make some conjectures on resulting algebraic structures, including the analogue of the polarized Cayley-Hamilton identities and the Second Fundamental Theorem of invariants in the presence of Grassmann matrices. Finally, we present various (smooth and singular) limits of the most general supersymmetric index in $\mathcal{N}=4$ SYM theory, and study some patterns in their behavior as a function of $N$.

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hep-th 2026-05-11 2 theorems

3D gravity favors undulating torus boundaries in AdS

Undulating Conformal Boundaries in 3D Gravity

Inhomogeneous solutions have lower free energy than uniform ones for negative Lambda and K in a narrow range.

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We consider three-dimensional Einstein gravity in Euclidean signature with a finite boundary of torus topology endowed with an induced metric of fixed conformal class and a constant trace of extrinsic curvature $K$. For vanishing, positive, and negative cosmological constant $\Lambda$, we analytically determine boundaries enclosing different patches of locally flat, de Sitter (dS$_3$), and Anti-de Sitter (AdS$_3$) spaces. We find solutions that depend non-trivially on either cycle of the torus, noting that some of them exhibit self-intersections. Adapting the Gibbons-Hawking prescription of interpreting the Euclidean gravitational path integral as a thermal partition function, we explore the rich semi-classical thermodynamic phase space of the problem. While most saddles are found to be either thermally unstable or metastable compared to those with uniform boundaries, we find inhomogeneous solutions that are thermodynamically favourable in the case of $\Lambda < 0$ and $2<K|\Lambda|^{-1/2}<3/\sqrt{2}$. Moreover, for all values of $\Lambda$, there exist patches of space with a non-contractible thermal circle and a macroscopic entropy. We further analyse the problem in both the AdS$_3$ boundary limit and the stretched dS$_3$ horizon limit, and comment on a recasting of the problem in terms of classical strings.

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hep-th 2026-05-11 Recognition

Two-flavor Schwinger model has no confinement at theta pi

The two-flavor Schwinger model at 50: Solving Coleman's puzzles

Equal masses yield spontaneous charge conjugation breaking for any coupling and an exponentially small mass gap at strong coupling.

abstract click to expand

In his 1976 paper "More about the massive Schwinger model", Coleman introduced $1+1$-dimensional Quantum Electrodynamics coupled to two charged massive fermions. By applying Abelian bosonization, he elucidated much of the physics of this two-flavor Schwinger model, but he listed three puzzles at the end of his paper. We present new analytical and numerical calculations to solve Coleman's three puzzles and thereby deepen our understanding of this model. These puzzles pertain to the theory with equal fermion masses at $\theta = 0$ and at $\theta = \pi$, as well as the size of isospin-breaking effects when the fermion masses are unequal. For the puzzle at $\theta = \pi$, the solution is related to the structure of the zero-temperature phase diagram arXiv:2305.04437: for equal fermion masses $m$, the model exhibits spontaneous breaking of charge conjugation symmetry and absence of confinement for any value of the gauge coupling $g$, so that there is a smooth interpolation from weak to strong coupling. Using two-loop Renormalization Group and integrability methods, we show that the mass gap behaves as $\sim m e^{-0.111 g^2/m^2}$ in the strong coupling regime $m\ll g$. Our numerical results using the lattice Hamiltonian are in good agreement with this behavior. For the puzzle at $\theta = 0$, the solution is related to a level crossing between two isosinglet particles with different discrete quantum numbers; we demonstrate the necessity of such a crossing by comparing integrability and weak coupling calculations, and we also exhibit the crossing numerically. Finally, we provide a new estimate for the size of isospin-breaking effects caused by different fermion masses at strong coupling.

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hep-th 2026-05-11 2 theorems

Schwinger effect blocked topologically in Salpeter equation

Topological Blocking of the Schwinger Effect in the Salpeter Equation: A Lefschetz Thimble Analysis

Lefschetz thimble analysis reveals geometric reason for its absence unlike in Dirac and Klein-Gordon cases.

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We present a comprehensive Lefschetz thimble analysis of the one-dimensional Salpeter equation under a strong electric field. By treating the non-local square-root operator within the framework of algebraic analysis, we construct the full solution space, which includes relativistic generalizations of the Airy Ai and Bi functions and their negative-energy counterparts. Through a direct comparison with the Dirac and Klein-Gordon equations, we provide a geometric explanation for the absence of Klein paradox and the Schwinger effect in the Salpeter equation. Furthermore, our findings establish a unified geometric interpretation of the Schwinger effect across different relativistic wave equations.

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hep-th 2026-05-11 2 theorems

Monodromy with Virasoro flow rebuilds full log module in chiral TMG

From monodromy to SL(2,mathbb{R}): reconstructing the logarithmic sector of chiral TMG from virasoro flow

The Jordan structure of the logarithmic graviton persists through all descendants when radial continuation is imposed as a consistency.

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We construct and analyze the logarithmic sector of chiral Topologically Massive Gravity (TMG) at the critical point $\mu \ell = 1$ from the perspective of Virasoro evolution and radial monodromy in $\mathrm{AdS}_3$. We show that the logarithmic graviton arises naturally as a generalized eigenstate of $L_0$, with its Jordan structure persisting uniformly across the full $SL(2,\mathbb{R})_L$ descendant tower generated by $L_{-1}$. A central result is that the logarithmic mixing of primary and descendant states can be equivalently interpreted as unipotent monodromy under analytic continuation of the radial coordinate $r \to e^{2\pi i} r$. This establishes a direct identification between the LCFT Jordan cell structure and a geometric monodromy operator acting in the bulk. We demonstrate that requiring monodromy-compatible Virasoro flow uniquely reconstructs the full indecomposable logarithmic module, including all descendant levels, and show explicit equivalence with the logarithmic graviton module previously obtained in the linearized analysis of chiral TMG. This provides a unified representation-theoretic and geometric characterization of logarithmic gravity in $\mathrm{AdS}_3$.

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hep-th 2026-05-11 Recognition

Soft graviton theorems give closed-form map on wedge subalgebras

Higher-spin algebras from soft theorems I: the wedge condition

Sub^n-soft theorems produce explicit Top that represents higher-spin algebras precisely when restricted to wedge domains in Yang-Mills and 4

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In this article we use the sub$^n$-soft graviton theorems to construct the map $\Top$ from the spin-graded set of holomorphic functions on local celestial sphere patches to differential operators acting on the asymptotic data for massless particles at $\scrip$, in analogy with previous results in the literature for the sub$^n$-soft photon theorems. The result is an explicit closed-form formula. We show that the wedge subalgebras for both Yang-Mills and gravity are the natural domain on which $\Top$ becomes a representation.

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hep-th 2026-05-11 Recognition

Duality links massless RG flows to gapped phases breaking noninvertible symmetries

Characterizing bulk properties of gapped phases by smeared boundary conformal field theories: Role of duality in unusual ordering

Smeared boundary CFTs characterize bulk properties using states outside standard boundary modules.

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We study the classification of the gapped phases or massive renormalization group (RG) flows dual to the massless RG flows under changing the sign of the coupling constants. Whereas our formalism is based on combining Higgs- or Nambu-Goldstone-type arguments with Cardy's smeared boundary conformal field theories (SBCFTs), several puzzling structures arise. More specifically, the established Higgs or Nambu-Goldstone type arguments on the duality imply that the natural basis for the gapped states should be constructed from a set of smeared Ishibashi states, which are unphysical in boundary critical phenomena. Hence, the module of the gapped phases can be outside of that of boundary critical phenomena, whereas one can still calculate characterizing quantities by applying SBCFTs to the models. For example, we demonstrate that the massive RG flow dual to the massless RG flow from the tricritical Ising model to the Ising model, one of the simplest massless RG flows, has this unusual structure. This can be regarded as a quantum field-theoretic analogue of order-disorder coexistence in lattice models. More generally, the resultant gapped phases usually spontaneously break non-group-like symmetry (or noninvertible symmetry). Our work provides systematic quantum field theoretic descriptions of such unusual phases with spontaneous symmetry breaking of non-group-like (or noninvertible) symmetries.

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hep-th 2026-05-11 2 theorems

Double covers explain genus drops across curve types

Genus drop involving non-hyperelliptic curves in Feynman integrals

Unramified double coverings unify the mechanism for both hyperelliptic and non-hyperelliptic to hyperelliptic transitions in three-loop Feyn

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For both theoretical and phenomenological studies, it is important to analyze the function types of Feynman integrals. The phenomenon of genus drop between different representations of hyperelliptic Feynman integrals was discussed in \cite{Marzucca2024Genusdrop}. In this paper, we reformulate the extra-involution mechanism of \cite{Marzucca2024Genusdrop} as a special case of an unramified double covering between algebraic curves, and show that this covering mechanism also explains genus drops accompanied by a curve-type change from non-hyperelliptic to hyperelliptic for a class of three-loop Feynman diagrams. We also demonstrate that within a specific framework, the origin of the discrete spacetime symmetry that leads to the genus drop in hyperelliptic cases is manifest. This work also points out that there exist non-hyperelliptic Feynman integrals that exhibit no apparent genus drop.

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hep-th 2026-05-11 Recognition

Chiral theories with scalars achieve complete asymptotic freedom

Completely asymptotically free chiral theories with scalars

For tuned numbers of colors and fermion family multiplicities, both fundamental and adjoint scalar cases allow gauge, Yukawa and quartic Cou

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We provide the conditions for complete asymptotic freedom for chiral gauge theories including scalars, as motivated by grand unified models. These are generalised Georgi-Glashow and Bars-Yankielowicz theories that feature a scalar field transforming either in the fundamental or in the adjoint of the gauge group. In both scenarios, we consider the addition of multiple chiral fermion families. We systematically analyse the interplay between gauge, Yukawa, and quartic couplings required for all interactions to remain asymptotically free at short distances. We find that for both scalar representations, complete asymptotic free models can be obtained for a specific number of colours and multiplicity of vector-like and chiral families.

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hep-th 2026-05-11 Recognition

Holographic duals forbid O-planes on distinct homology cycles

Broken and restored: a holographic constraint for AdS vacua with orbifolds

Abelian orbifold violations are fixed by non-abelian extensions that project out extremal scalars, restricting compactification geometry.

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It has been suggested that families of weakly-coupled AdS vacua with a large-$N$ holographic dual must satisfy non-trivial consistency requirements, which amount to the vanishing of certain cubic couplings, corresponding to (super-)extremal arrangements of scalar operators. While this constraint is known to hold in the simplest incarnation of the DGKT scenario in massive type IIA string theory, i.e. on the $\mathbb{Z}_3\times \mathbb{Z}_3$ orbifold, we find that it is generically violated for type II AdS$_3$ and AdS$_4$ vacua arising from $\mathbb{Z}_2 \times \mathbb{Z}_2 \times \mathbb{Z}_2$ and $\mathbb{Z}_2 \times \mathbb{Z}_2$ orbifolds respectively, including scale-separated solutions and DGKT-CFI-type models. In most cases, however, this can be cured by enlarging the orbifold group to a suitable (non-abelian) extension that projects out precisely those scalar operators that would otherwise participate in the constrained cubic couplings. Our results suggest that consistency of the putative holographic dual imposes a non-trivial restriction on the compactification geometry, indicating in particular that O-planes cannot wrap cycles in distinct homology classes.

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hep-th 2026-05-08 2 theorems

Deformations show algebraic string models need non-algebraic extension

Beyond Algebraic Superstring Compactification: Part II

Even toric and complete intersection constructions indicate a generalization that fits mirror duality between algebraic and symplectic sides

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The most impressively prolific exploration of superstring models (aiming for our physical reality) has been focused on worldsheet-supersymmetric gauged linear sigma models and the closely associated complex-algebraic toric geometry. Mirror duality relates this to the inherently real symplectic geometry of Calabi-Yau factors in spacetime, implying a need for a more general, heterotic framework of analysis. In turn, a closer look at possible deformations even amongst the complex-algebraic complete intersections and toric geometry models themselves indicates an a priori non-algebraic type of generalization that however perfectly aligns with requirements of mirror duality.

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hep-th 2026-05-08 Recognition

Fuzzy sphere matrix model obeys chaos bound at all temperatures

Real-Time Quantum Dynamics on the Fuzzy Sphere: Chaos and Entanglement

The largest Lyapunov exponent vanishes at a finite temperature while entanglement entropy grows linearly, confirming fast scrambling.

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We study the real time quantum dynamics of a matrix model consisting two bosonic fields on the fuzzy sphere using the Gaussian state approximation. Starting from the Hamiltonian formulation and using Wick's theorem, we derive a closed set of coupled nonlinear differential equations governing the time evolution of the one- and two-point correlation functions. Thermal equation of state is found by maximizing the von Neumann entropy over Gaussian states and solving algebraic self-consistency equation(s) leading to a complete determination of the symplectic spectrum of the covariance matrix. We identify near thermal initial conditions and use them to solve the equations of motion and employ our findings to probe chaos by calculating the largest Lyapunov exponent at various temperatures. Our results demonstrate that the latter tends to zero at a finite temperature indicating that the quantum dynamics respect the Maldacena,Shenker,Stanford bound across all temperatures, while approaching toward the classically chaotic regime at high temperatures. Finally, we examine the entanglement dynamics of the model in real-time by considering a sequence of bipartitions of the Hilbert space and computing the entanglement entropy and clearly exhibit the fast scrambling features that emerge in due detail.

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hep-th 2026-05-08 2 theorems

Null-surface gravity gives finite graviton scattering

Quantum graviton scattering with definite helicities in the null surface formulation

All intermediate states stay on-shell and Gaussian-smeared wave packets make every energy integral converge without renormalization.

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We develop the second-order quantum perturbation theory of gravity in the Null Surface Formulation (NSF) of asymptotically flat spacetimes. In this framework all dynamical degrees of freedom are radiative data defined at null infinity; no bulk fields or off-shell propagators enter the construction. Working directly at null infinity, we derive the helicity-resolved Bondi shear and the corresponding out-operators governing nonlinear graviton processes. The formalism naturally generates a gravitational tail amplitude requiring opposite incoming helicities, and a graviton scattering amplitude that factorizes into two tail vertices connected by an on-shell intermediate graviton. Imposing the Poincare limit reproduces the s-channel contribution of the Weinberg tree-level amplitude, while the crossed channels are shown to arise at higher perturbative order. The theory is perturbatively finite for two independent reasons: all intermediate gravitons are strictly on-shell, so no loop integrals over virtual bulk momenta are generated; and the perturbative regime requires Gaussian-smeared graviton states (small Bondi mass relative to the Planck scale), whose suppression propagates recursively through the hierarchy, rendering all energy integrals absolutely convergent at every order without renormalization or counterterms. This finiteness is structurally distinct from the ultraviolet problem of covariant perturbative gravity, where divergences originate in off-shell bulk propagators and asymptotic states are defined only indirectly via an i{\epsilon} bulk prescription. The natural observables of the NSF are spectral-angular distributions on the celestial sphere, which encode BMS supermomentum flux rather than ordinary Poincare momentum conservation. Gravitational memory, MHV helicity selection rules, and the coherent-state classical limit arise naturally within the same framework.

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hep-th 2026-05-08 2 theorems

Symplectic bi-Grassmannian encodes CFT4 correlators

The Conformal Grassmannian: A Symplectic Bi-Grassmannian for CFT_ 4 Correlators

Integrals over mutually orthogonal n-planes in 2n-dimensional space reproduce ⟨JJJ⟩ and ⟨TTT⟩ structures and expose their double copy.

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We introduce a formalism for conformal field theory in four dimensions: a symplectic bi-Grassmannian representation of CFT$_4$ Wightman correlators. Working in Klein space with off-shell spinor-helicity variables, we show that correlators of $\Delta = 2$ scalars and symmetric-traceless conserved currents are encoded by integrals over a pair of $n$-planes in a $2n$-dimensional symplectic vector space. These planes are constrained to be mutually symplectically orthogonal and aligned with the external kinematics. Conformal invariance, momentum conservation, and little-group covariance all follow geometrically from this structure. We derive all two- and three-point functions involving scalars, fermions, conserved currents, and stress tensors. As a non-trivial test, we show that the construction reproduces the full set of independent conformally invariant structures of $\langle JJJ\rangle$ and $\langle TTT\rangle$ in CFT$_4$. The resulting expressions are considerably more compact than their momentum-space counterparts. They also make manifest the double copy between Yang--Mills $\langle JJJ \rangle$ and Einstein-gravity $\langle TTT \rangle$. We further present a helicity-basis reformulation that makes the GL(1,R) and SL(2,R) weights of individual helicity components explicit. This basis also provides a natural starting point for a twistor-space formulation of the correlators.

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hep-th 2026-05-08 2 theorems

G2 manifolds unify all five string theories in 3D N=1 theories

G₂ flux compactifications

The effective theories include complete scalar potentials, axions, gauge fields and fluxes organized by a real superpotential.

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We derive the three-dimensional $\mathcal{N}=1$ effective theories obtained by compactifying all five ten-dimensional string theories on generic seven-dimensional manifolds with $G_2$ structure. The resulting flux compactifications are worked out explicitly, including the full moduli dependence of the scalar potential, kinetic terms, axionic sectors, gauge fields, St\"uckelberg couplings, and the allowed geometric and form-flux data. Our results extend previous analyses by incorporating fields and fluxes that are generically present in $G_2$ reductions, and provide a unified framework for comparing type IIA, type IIB, type I and heterotic compactifications to three dimensions. In particular, the effective theories organize naturally in terms of the real superpotential formulation of three-dimensional $\mathcal{N}=1$ supergravity, making the relation between fluxes, torsion, Chern--Simons data, and moduli potentials manifest.

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hep-th 2026-05-08 Recognition

Theory structure fixes allowed range for spacetime-ending singularities

Sharpened Dynamical Cobordism

Sharpened dynamical cobordism uses the range of a critical exponent to separate true transitions-to-nothing from those blocked by global cob

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We propose a sharpened version of Dynamical Cobordism, where the physical structure $\xi$ of the theory in question determines an allowed range $R^\xi$ for the critical exponent $\delta$. We interpret a singularity with $\delta \in R^\xi$ as a true transition-to-nothing, i.e., a configuration ending spacetime, while a singularity with $\delta \notin R^\xi$ indicates some obstruction to such a transition, i.e., the presence of a non-trivial cobordism global charge, which is incompatible with a theory of quantum gravity. In the spirit of the original Cobordism Conjecture, this apparent inconsistency of the theory can be alleviated via the modification of the structure, for instance by introducing new degrees of freedom and associated defects. Inspired by the Gubser criterion for good singularities, we propose a way to determine $R^\xi$. As a proof-of-concept we show explicitly how the introduction of a higher-form gauge field changes the allowed range of $\delta$ compared to an EFT with only scalars. We test this sharpened version of Dynamical Cobordism against several examples, such as massive IIA string theory, where it is notably compatible with the presence of O8-planes; the Janis-Newman-Winicour and Garfinkle-Horowitz-Strominger black hole solutions; and certain singular distributions of D-branes. In all these cases, the Sharpened Dynamical Cobordism Conjecture leads to results consistent with our expectations.

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hep-th 2026-05-08 2 theorems

Brane collisions derive Carrollian fluid equations from first principles

Kinetic Theory of Carroll Hydrodynamics

Adapting Boltzmann statistics to space-filling branes grounds the equations previously obtained only as a relativistic limit.

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We develop the foundations of Carrollian statistical mechanics by considering a system of interacting instantonic space-filling branes on a flat background, thereby providing the closest Carrollian analogue to the Galilean gas of interacting particles that underpins Boltzmann's collision theory. By adapting Boltzmann's statistical approach within this framework, we provide a first-principles microscopic derivation of the so-called Carrollian fluid equations, which were previously obtained as the vanishing-speed-of-light limit of relativistic conservation laws. We then use this analysis as a basis for formulating the first elements of Carrollian thermodynamics.

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hep-th 2026-05-08 Recognition

Brane gas yields microscopic Carrollian hydrodynamics

Kinetic Theory of Carroll Hydrodynamics

Adapting Boltzmann's collision theory to instantonic space-filling branes derives the Carrollian fluid equations from first principles.

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We develop the foundations of Carrollian statistical mechanics by considering a system of interacting instantonic space-filling branes on a flat background, thereby providing the closest Carrollian analogue to the Galilean gas of interacting particles that underpins Boltzmann's collision theory. By adapting Boltzmann's statistical approach within this framework, we provide a first-principles microscopic derivation of the so-called Carrollian fluid equations, which were previously obtained as the vanishing-speed-of-light limit of relativistic conservation laws. We then use this analysis as a basis for formulating the first elements of Carrollian thermodynamics.

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hep-th 2026-05-08 2 theorems

N=2 USp Chern-Simons SQCD dual to planar Abelian quivers

Universal Planar Abelian Duals for 3d mathcal{N}=2 Symplectic CS-SQCD

Real mass deformations of N=4 mirrors yield matching partition functions, indices, and operator spectra.

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We propose a new class of infrared dualities relating three-dimensional $\mathcal{N}=2$ $USp(2N)$ Chern--Simons SQCD to planar Abelian quiver gauge theories. These dual descriptions are constructed via real mass deformations of established $\mathcal N=4$ mirror dualities between $\mathcal{N}=4$ $USp(2N)$ SQCD and unitary $D$-type quiver gauge theories. The resulting $\mathcal N=2$ dual pairs exhibit the characteristic exchange of topological and flavor symmetries. We provide nontrivial evidence for these dualities by matching $\mathbf{S}^3_b$ partition functions, superconformal indices, and gauge-invariant operator spectra. Furthermore, we systematically incorporate additional real mass deformations on both sides of the duality, allowing us to extend the construction to $\mathcal{N}=2$ symplectic SQCD with generic ranks, flavors, and Chern--Simons levels.

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hep-th 2026-05-08 2 theorems

Bounded-area surfaces diagnose holographic emergence failures

A Semiclassical Diagnostic for Spacetime Emergence

Evanescent quantum extremal surfaces keep generalized entropy large while bounding area, revealing when semiclassical spacetimes cannot come

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Recent developments have shown that some semiclassical spacetimes cannot emerge from a traditional application of the rules of holography, prompting proposals for restoring their emergence with "observer rules". In this paper, we propose a general semiclassical diagnostic of such failures of emergence, and of the extent to which observer rules can fix them. Our diagnostic is the presence of certain "evanescent" quantum extremal surfaces, which are distinguished by an upper bound on their area rather than their generalized entropy. In particular, the generalized entropy of an evanescent QES may be large: even though its area term must be small, its bulk entanglement term is unconstrained. This feature is explained by an operational distinction between classical and quantum connectivity in semiclassical gravity, or equivalently between the two summands of the generalized entropy.

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hep-th 2026-05-08 1 theorem

Symmetry fixes unique dressings reproducing memory in QED and gravity

Finite-time memory detectors and fully constraining Faddeev-Kulish dressings in QED and gravity

Finite-time Faddeev-Kulish choices recover both leading gravitational memory and higher-order Christodoulou terms in inclusive calculations.

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We show that for both QED and perturbative quantum gravity, finite-time Faddeev-Kulish dressings can be fully constrained by symmetry, and that this gives the unique choice which reproduces the classical memory effect. For gravity, we show that using this dressing to construct finite-time Fock spaces, as well as a carefully defined finite-time memory detector allows us to recover both the first order gravitational memory, as well as higher order Christodoulou contributions from the gravitational field. We explain how these higher order perturbative corrections arise in inclusive in-in calculations.

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hep-th 2026-05-08

Topological boundary averaging explains holographic ensembles

From Baby Universes to Narain Moduli: Topological Boundary Averaging in SymTFTs

Fixed SymTFT slabs with varying topological ends recover Poisson moments and Narain moduli measures without new dynamical input.

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We propose a SymTFT interpretation of ensemble averaging in low-dimensional holography. The central operation is to keep fixed both the SymTFT and the physical boundary condition, while averaging over topological boundary conditions at the other end of the SymTFT slab. Each such boundary condition gives an absolute completion of the same relative theory, so the ensemble is interpreted as an average over topological completions rather than over arbitrary local dynamics. We formulate this construction in terms of cap functionals and their natural groupoid or Haar-type measures, and illustrate it in two examples. In the closed-string sector of the Marolf--Maxfield model, topological boundary conditions are labelled by finite sets, and the groupoid sum reproduces the Poisson/Bell-polynomial moments. In the Narain case, compact topological boundary conditions of an $\mathbb{R}$-valued BF SymTFT are identified with maximal isotropic subgroups, so that topological-boundary averaging becomes the usual Narain moduli average with Zamolodchikov measure. We also discuss possible extensions to JT gravity, random matrix theory, Virasoro T(Q)FT, and 3D gravity.

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hep-th 2026-05-08

Scalar S-matrix boundary splits into universal phases

The Phases of the Scalar S-Matrix Island

Each edge shares the same high-energy behavior tied to a distinct way a massive scalar emerges from the ultraviolet.

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The two-to-two four-dimensional scattering amplitude of identical scalars obeys rigorous two-sided non-perturbative bounds derived via the modern numerical S-matrix bootstrap. These bounds carve out an allowed region with a rich boundary structure, featuring edges and vertices. In this work we further tighten this region and uncover the physics of its boundary by analyzing the asymptotic Regge behavior of the amplitude and the spectrum of resonances and virtual states. We find that the S-matrices along a given edge exhibit universal behavior, sharply contrasting with that on other edges. This reveals a classification of the boundary into distinct phases, corresponding to different UV mechanisms by which a gapped scalar arises.

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hep-th 2026-05-08

Hadron spectrum in N=2 SQCD matches 2D black hole string spectrum

Hadrons in mathcal{N}=2 supersymmetric QCD from non-Abelian string on 2D black hole

In N=2 SQCD with N_f=2N the four-dimensional particles arise as excitations of a vortex string on a two-dimensional black hole, with phases

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We continue the study of non-Abelian vortex string in 4D $\mathcal{N}=2$ supersymmetric QCD as critical superstring, and extend this analysis to $U(N)$ gauge theory with arbitrary even $N$ and $N_f=2N$ number of quarks. We introduce a special mass deformation and show that the SQCD hadron spectrum is still given by the string spectrum on the 2D $\mathcal{N}=2$ supersymmetric black hole. We perform a cross-check by computing the multiplicity of hadronic states of the high-energy part of the spectrum both from string and field theory pictures. We also clarify the spontaneous breaking of the global flavor symmetry by VEV of the massless baryon. We finally claim, that phase diagram of $\mathcal{N}=2$ SQCD with $N_f=2N$ consists of the Higgs phase at weak coupling and string/hadronic phase at strong coupling, separated by phase transition, and is seen as a conifold transition from string theory point of view.

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hep-th 2026-05-08

de Sitter chain graphs equal quadrangular polylogarithms

de Sitter Wavefunction from Quadrangular Polylogarithms: Chain Graphs

Explicit n-site formula follows from matching differential equations to cluster-algebra coproducts.

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We present an explicit formula for the $n$-site chain graph contribution to the cosmological wavefunction for conformally coupled $\phi^3$ theory in de Sitter space. Our result relies on the recent finding that the symbol of this function satisfies total compatibility with respect to the $A_{2n-2}$ cluster algebra, and that Rudenko's quadrangular polylogarithms provide, by construction, a complete basis for such functions. We prove our formula by directly relating a recursive set of differential equations satisfied by these wavefunction coefficients to a recursive coproduct formula for quadrangular polylogarithms.

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hep-th 2026-05-08

Hagedorn regime slows string temperature response via fluctuations

The Hagedorn Temperature as a Nonequilibrium Dynamical Bottleneck in String Thermodynamics

Higher-order moments of energy fluctuations create a dynamical bottleneck that reservoir coupling can induce in open systems.

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The Hagedorn regime of string theory is usually understood as an equilibrium limiting phenomenon: the exponential growth of the density of states makes the canonical partition function singular at the Hagedorn temperature, while in the microcanonical description additional energy is absorbed predominantly by highly excited long-string configurations. In this work we revisit this regime from a nonequilibrium perspective using Steepest-Entropy-Ascent Quantum Thermodynamics (SEAQT), where thermodynamic evolution is formulated directly on the state manifold and does not require a globally well-defined canonical ensemble. The inverse temperature is treated as an instantaneous, state-dependent quantity, and we derive its exact scalar evolution equation. In the commuting limit, this dynamics is controlled by higher-order fluctuation moments, showing that the Hagedorn regime may act as a dynamical bottleneck for the response of the effective intensive variable. We then extend the construction to an open-system setting through a system--reservoir splitting of the SEAQT metric and show that reservoir coupling can drive the subsystem toward effective Hagedorn slowing-down. A diagonal Hagedorn evaluation further shows that the strength of this bottleneck depends not only on the exponential density of states, but also on its algebraic prefactor. These results provide a nonequilibrium interpretation of Hagedorn behavior and suggest a connection between long-string dominance, thermodynamic slowing-down, and the breakdown of effective descriptions in quantum gravity.

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hep-th 2026-05-08

Non-planar corrections lift degeneracies and show chaos in orbifold

Non-planar corrections in the symmetric orbifold

Quarter BPS spectrum in Sym^N(T^4) splits at finite N and follows random matrix statistics, so integrability is confined to the planar limit

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We calculate the non-planar corrections to the anomalous dimensions of certain quarter BPS states in the symmetric product orbifold $\text{Sym}^N \big({\mathbb{T}^4}\big)$. We find that some of the degeneracies in the spectrum for large twist $w$ and large $N$ are lifted by these contributions. We furthermore find signatures of quantum chaos, namely level repulsion and random matrix statistics. This suggests that integrability is only present in the symmetric orbifold in the planar (i.e. large $N$) limit.

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hep-th 2026-05-08

Algebraic rings turn Yang-Mills equations into exact color waves and dyonic tubes

Systematic Extraction of Exact Yang-Mills Solutions via Algebraic Tensor Ring Decomposition

Promoting static gauge backgrounds to dynamical variables lets quotient rings and bifurcation analysis classify three families of solutions.

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The non-linear nature of Yang-Mills theory presents a challenge for extracting exact classical solutions, which are useful for understanding non-perturbative vacuum structures. In this paper, an algebraic tensor ring decomposition framework is introduced to systematically map the non-linear partial differential equations (PDEs) of Yang-Mills theory into tractable differential-algebraic systems. By promoting static pure-gauge backgrounds to dynamical variables, the reference state acts as a geometric template whose Maurer-Cartan forms generate the algebraic cross-terms necessary to stabilize non-linear self-interactions. To analytically resolve the resulting differential ideals, specific differential-algebraic quotient rings are employed as evaluation tools, and the solution space is organized by an algebraic bifurcation analysis. Applying this framework, three distinct classes of exact solutions are extracted: (i) relativistic $SU(2)$ color waves evaluated over an elliptic quotient ring, where the differential ideal bifurcates into a Decoupled Branch and two Coupled Branches, the latter exhibiting mass gap generation; (ii) dynamical dyonic flux tubes obtained from a time-dependent helical template, where the Gauss law ideal bifurcates the system into Coulomb, Dyonic, and symmetric Meissner branches. In the Meissner branch, an Artinian asymptotic truncation yields Bessel-type exponential screening, stabilized by a temporal dominance condition; and (iii) dynamical $SU(3)$ configurations where the Gauss law ideal bifurcates the solution space into four distinct phases. The non-trivial branches enforce a kinetic cancellation mechanism that maps the amplitude dynamics onto a generalized $x^2y^2$ chaotic oscillator. Across these settings, the framework provides a methodical approach to characterize the classical solution space of strongly coupled gauge theories.

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hep-th 2026-05-08

Half-spacetime gauging of 2-group symmetry yields non-invertible duality defects

Half-Spacetime Gauging of 2-Group Symmetry in 3d

In (2+1)d theories with cyclic anomalies, gauging different symmetry factors produces dual theories linked by defects whose fusion rules are

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We construct a class of non-invertible duality defects, in (2+1)d quantum field theories, arising from half-spacetime gauging of a 2-group symmetry. Starting from a parent theory with two discrete and Abelian 0-form symmetries and a prescribed mixed anomaly, we show that gauging one factor produces a theory with a 2-group symmetry, while gauging the other yields a theory with a non-invertible 0-form symmetry, whose fusion rules we derive explicitly. When the parent theory possesses three such symmetries with a cyclic anomaly structure, gauging different factors can produce mutually dual theories and the half-spacetime gauging of the 2-group is implemented by a non-invertible duality defect, whose fusion rules we obtain. We illustrate the construction with explicit examples, including a $U(1)\times U(1)\times U(1)$ gauge theory and a general class of product theories. We also include a self-contained pedagogical introduction to the cohomological tools employed throughout the article.

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hep-th 2026-05-08

Majorana field approaches Tsirelson bound for Bell inequality

Modular wedge localization, Majorana fields and the Tsirelson limit of the Bell-CHSH inequality

Explicit modular localization reduces vacuum correlator to spectral weight that concentrates to near-maximal violation.

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The massive Majorana field in $1+1$ dimension is employed to investigate the violation of the Bell-CHSH inequality in relativistic Quantum Field Theory. We give an explicit rapidity-space realization of the Summers-Werner modular-localization construction and reduce the vacuum Bell-CHSH correlator to a single spectral weight $h^2(\omega)$ for the modular operator. The resulting analytic families approach the Tsirelson bound in the vacuum state as their spectral weight concentrates near $\omega\approx0$, corresponding to the eigenvalue $\lambda^2 \approx 1$ of the modular operator.

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hep-th 2026-05-08

Born-Infeld seed produces causal self-dual electrodynamics

Causal self-dual nonlinear electrodynamics from the Born-Infeld theory

Auxiliary field plus arbitrary potential yields a family of duality-invariant theories that remain causal.

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Recently we have proposed a new auxiliary-field formulation for self-dual nonlinear electrodynamics (NLED) which makes use of two building blocks: (i) a seed self-dual theory $L(F_{\mu\nu};g)$, where $F_{\mu \nu}$ is the electromagnetic field strength and $g$ a duality-invariant coupling constant; and (ii) a scalar potential $W(\psi)$. Our formulation is based on the Lagrangian $ \mathfrak{L}(F_{\mu\nu};\psi) = L(F_{\mu\nu};\psi) + W(\psi)$, where $\psi$ is an auxiliary scalar field. Integrating out $\psi$, using its equation of motion, one obtains a $\mathsf{U}(1)$ duality-invariant NLED. Different self-dual NLEDs are derived by choosing different potentials $W(\psi)$. In the case that the seed Lagrangian defines the Born-Infeld theory, in this paper we demonstrate that the resulting models for self-dual NLED are causal and provide a general solution of the self-duality equation. We also elaborate on the procedure to relate our formulation to that developed by Russo and Townsend.

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hep-th 2026-05-08

Symmetry breaking turns gauge-field cohomology into matter-like cohomology

Non-abelian field cohomology, its relation with spontaneous symmetry breaking and Morse's Theorem

In SU(2) theories a field combination escapes the Gribov ambiguity, so Morse-based unitary gauge fixing satisfies the condition on-shell.

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We show that, for an $SU(2)$ gauge field (the reasoning extends trivially to $SU(N)$), spontaneous symmetry breaking changes the field cohomology. This defines a new field with cohomological properties characteristic of matter fields. Consequently, the construction of a renormalizable unitary gauge fixing, following Morse's problem of functional extremization, leads to the Gribov condition being automatically solved on-shell. This result occurs because a specific combination of fields is cohomologically matter-like and therefore free of the Gribov problem.

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hep-th 2026-05-08

Null-surface approach keeps quantum gravity finite order by order

Ultraviolet-Finite Perturbative Expansion of Quantum Gravity at Null Infinity

By building operators only from on-shell data on the celestial sphere, the perturbative series avoids renormalization up to fourth order.

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We present a perturbative formulation of quantum gravity for asymptotically flat vacuum spacetimes based on the Null Surface Formulation (NSF), in which the expansion is ultraviolet-finite term by term up to the orders computed, without the need for renormalization. The outgoing Bondi shear operators are constructed explicitly up to fourth order, with interaction kernels determined recursively from on-shell gravitational data at null infinity. Ultraviolet finiteness at each order follows from the on-shell structure of the construction and the restriction of all integrations to the compact celestial sphere, eliminating off-shell propagators. The map between the in and out states admits a perturbative construction, and unitarity is verified explicitly up to fourth order. The outgoing operators satisfy the same commutation relations as the incoming ones, indicating that the transformation is canonical and consistent with the unitary implementation. Collinear configurations give rise to infrared singularities, as expected in massless quantum field theories, but do not affect the ultraviolet behavior established here. In coherent states, the expectation value of the shear reproduces the known finite classical graviton scattering at lowest nontrivial order. These results provide a perturbative framework for quantum gravity with improved ultraviolet behavior relative to the covariant approach.

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hep-th 2026-05-08

Graviton fluctuations smear light cones and regularize UV divergences

Squeezed Gravitons and One-Loop Self-Energy under Light-Cone Smearing

Treating corrections to the world function as operators tames short-distance singularities in scalar loops, yielding a 10^{-10} correction

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We investigate light-cone smearing induced by quantum fluctuations of gravitons and its implications for the ultraviolet structure of quantum field theory. By treating the first-order correction to Synge's world function as an operator, we show that the retarded Green's function is smeared by the variance of graviton fluctuations. The smearing width depends on the quantum state of gravitons: vacuum fluctuations generate a Gaussian smearing of the light cone, coherent states shift the light-cone position, and squeezed states modify the smearing width itself. We then apply the smeared Feynman propagator to one-loop self-energies in interacting scalar field theories. In both the $\phi^3$ bubble diagram and the $\phi^4$ tadpole diagram, the short-distance singularities responsible for the usual ultraviolet divergences are regularized by a nonzero smearing width. We also estimate the contribution from primordial gravitons generated during inflation and show that it induces a finite correction of order $10^{-10}$ to the one-loop self-energy. Our results suggest that the quantum state of gravitons can leave a finite imprint on the causal and short-distance structure of quantum field theory.

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hep-th 2026-05-08

The paper compares quantum corrections to Newton's gravitational potential from conformal…

Trace anomaly, effective approach, and gravitational potential

Anomaly-induced corrections to the Newtonian potential in the Boulware vacuum disagree with effective quantum gravity results unless the…

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We explore and discuss corrections to the Newton potential from the quantum effects of conformal matter fields. In this special case, one can compare different approaches, including that of effective quantum gravity and another, based on the conformal (trace) anomaly. The comparison of these two methods is the main focus in the present work. Using the anomaly-induced effective action of gravity requires fixing the quantum vacuum state, similar to what is done in the description of black hole evaporation. In the Boulware vacuum state, we compute the anomaly-induced stress tensor and the first-order correction to the classical gravitational law. The quantum correction to the Newton's potential derived in this way, differs from the result calculated in a way analogous to the effective approach to quantum gravity. The only way to reconcile the two approaches for deriving the leading semiclassical corrections to Newtonian potential is to modify the asymptotic behavior of the average of the energy-momentum tensor in the Boulware vacuum state, as has been recently discussed in the literature.

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hep-th 2026-05-07

Spacetime must evolve stochastically to stay consistent with quantum matter

Stochastic modes in postquantum classical gravity

Linearized analysis identifies diffusive spin-2 and spin-0 modes whose fluctuations are bounded by existing noise and decoherence data.

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We study fluctuations of the metric in the postquantum theory of classical gravity, a covariant theory which couples a classical spacetime with quantum matter fields. Mathematical consistency requires spacetime to evolve stochastically. Starting from the classical-quantum path integral, we linearize around Minkowski space and perform a scalar-vector-tensor decomposition, identifying the stochastic modes: a classical spin-2 field and spin-0 scalar, both diffusing around their respective wave equations. There is also a non-dynamical vector and scalar field. These are related to the degrees of freedom found in quadratic gravity, but here interpreted as stochastic contributions to spacetime. We show that the action is positive semi-definite (PSD) on all dynamical modes, which is a necessary condition for the theory to consistently treat spacetime classically. We compute the two-point function and power spectral density corresponding to fluctuations of the Newtonian potential, and compare it to the excess noise found in LISA Pathfinder. This sets a bound on one combination of the two dimensionless coupling constants of the theory, while bounds on the stochastic gravitational wave energy density in a FLRW background constrain another combination. We derive the effective action for matter distributions, and find that bounds from decoherence experiments are constrained by fluctuations in the Newtonian potential $\Phi$ and the curvature perturbation $\psi$. Finally, we show consistency between different formulations of the pure gravity theory, the Onsager-Machlup form of the action, the Martin-Siggia-Rose form, and that given by stochastic differential equations.

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hep-th 2026-05-07

Free fields realize celestial dual for conformal gravity MHV

Celestial dual of conformal gravity MHV amplitudes: an OPE analysis

OPEs from vertex operators for gravitons and scalars match those from bulk amplitudes exactly.

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In an earlier paper [arXiv:2511.03669] we extracted the OPE of celestial CFT operator duals of positive helicity graviton and scalar particles from the Mellin transformed relevant MHV amplitudes of conformal gravity, realised as the bosonic subsector of the Berkovits-Witten theory. A soft theorem analysis of bulk MHV amplitudes established that this conformal gravity exhibits a chiral $\mathfrak{bms}_4$ symmetry on the celestial sphere with the associated $\mathfrak{sl}(2,\mathbb{R})$ current algebra, which acquires a non-trivial central extension, unlike the Einstein gravity. Here we construct a $2d$ chiral CFT free-field realisation of the relevant chiral $\mathfrak{bms}_4$ algebra in terms of three free scalars ($\phi_i$) and three $(\beta_i,\gamma_i)$ ghost pairs, and propose vertex operators for the positive-helicity graviton primary $G^{++}_{\Delta}(z,\bar{z})$ as well as the scalar primary $\Phi_{\Delta}(z,\bar{z})$, and compute their OPEs. These OPEs reproduce exactly those obtained from the bulk conformal gravity MHV amplitudes, providing a concrete celestial dual description of its MHV sector.

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hep-th 2026-05-07

Most Calabi-Yau fourfolds allow vacuum energies spaced at 10^{-120}

Small Vacuum Energy and Tunneling in a Modified Bousso-Polchinski Model

99.95 percent of the Schöller-Skarke database shows tiny spacing, with all satisfying the universe age bound on topology.

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We propose a simplified model for the cosmological constant in string theory flux vacua motivated by type IIB and F-theory compactifications. Relative to the Bousso-Polchinski model, small vacuum energy spacing occurs in thin wafers rather than thin shells. The model is applied to the entire Sch\"oller-Skarke database of Calabi-Yau fourfolds, which exhibit $532,600,483$ distinct sets of Hodge numbers. The overwhelming majority of those ($99.95\%$ percent for some choices of parameters) exhibit a vacuum energy spacing of~$10^{-120}$ in Planck units or smaller. Brown-Teitelboim membrane nucleation transitions can populate this landscape of flux vacua. In the thin-wall approximation, and ignoring gravitational corrections, we find that the bubble transitions are always dominated by giant leaps in flux space. The age of the universe places a bound on Calabi-Yau topology that is satisfied for the entire Sch\"oller-Skarke database.

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hep-th 2026-05-07

Perturbative celestial transforms mismatch full amplitudes in Sinh-Gordon

Challenges to Understanding Celestial Holography from the Bottom Up

The term-by-term prescription disagrees with the exact result at leading order, complicating direct tests of celestial dualities.

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In the bottom-up approach to celestial holography, it is tempting to define celestial amplitudes by transforming momentum-space amplitudes order by order in perturbation theory. We test this prescription in the exactly solvable two-dimensional Sinh-Gordon model. Because the full non-perturbative S-matrix is known, we can compare two operations directly: first transform and then expand, or first expand and then transform. They do not agree, already at leading nontrivial order in the coupling. More broadly, this suggests that naive term-by-term celestial transforms should not be assumed valid in generic quantum field theories with asymptotic weak-coupling expansions. This has an immediate consequence for proposed CCFT duals: if one tries to test them by taking celestial transforms of perturbative bulk amplitudes term-by-term, a mismatch need not falsify the proposal. This makes bottom-up tests of celestial dualities far more subtle than one might have expected.

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hep-th 2026-05-07

Wormholes bound imaginary values of coupling constants

Wormholes and the imaginary distance bound

Wormhole solutions with imaginary scalars limit analytic continuation in gravity theories, with string effects enforcing the cutoff at the b

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Some of the simplest wormhole solutions involve massless scalar fields that take imaginary values. Massless fields can be interpreted as coupling constants in asymptotically flat or asymptotically AdS gravity theories. We argue that wormhole effects imply an imaginary distance bound, an upper limit for the analytic continuation of the theory to imaginary values of these couplings. In string theory examples, we find explicit effects that render the low-energy theory invalid either before or precisely at this wormhole limit. We argue that the existence of such effects enforcing the distance bound is a general feature of string theories containing wormholes. In some cases, the bounds we discuss coincide with the weak gravity conjecture, and with the Kontsevich-Segal-Witten condition on complex metrics.

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hep-th 2026-05-07

Single Dirac action produces both electric and magnetic Carroll fermions

Carroll fermions from null reduction: A case of good and bad fermions

Light-cone split into good and bad modes unifies the two Carroll limits in any dimension via null reduction.

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We derive Carrollian fermionic actions using the null reduction method from Bargmann spacetimes. In the Lorentzian light-cone formulation, the Dirac spinor naturally decomposes into dynamical and constrained degrees of freedom $-$ the so-called `good' and `bad' fermions $\Psi_{(\pm)}$. These light-cone projections are intrinsically adapted to the null frame and, unlike the chiral decomposition into left- and right-handed spinors $\Psi_{L(R)}$, are valid in arbitrary spacetime dimensions, both even and odd. As in the case of bosons, the magnetic Carroll sector for fermions is governed by the dynamical modes of the parent theory, while the electric sector arises from the constrained modes. Upon deforming to a Bargmann spacetime, these constraints are removed, promoting the `bad' fermions to dynamical modes that describe the electric Carroll fermions. We construct the Clifford algebra on the Carroll manifold through its embedding in the ambient Bargmann manifold, and obtain both electric and magnetic Carroll fermion actions from a \textit{single} Bargmann-invariant Dirac action. We analyze the canonical structure of both theories, establish their invariance under Carroll transformations, and compute the corresponding two-point functions, which exhibit the expected behavior in both sectors. We conclude with some comments on the quantization of these Carrollian theories.

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