pith. machine review for the scientific record. sign in

arxiv: 2604.10257 · v1 · submitted 2026-04-11 · ✦ hep-ph · hep-ex

Recognition: 1 theorem link

· Lean Theorem

DREAMuS: Dark matter REsearch with Advanced Muon Source

Xiang Chen , Zejia Lu , Liangwen Chen , Jun Gao , Shao-Feng Ge , Zhanxu Hao , Yang Hu , Bingzhi Li
show 8 more authors
Cen Mo Zhiyu Sun Huayang Wang Chonghao Wu Yu Xu Xueheng Zhang Yulei Zhang Liang Li
Authors on Pith no claims yet

Pith reviewed 2026-05-10 15:57 UTC · model grok-4.3

classification ✦ hep-ph hep-ex
keywords dark mattermuon-philic dark matterfixed-target experimentlight bosonZ' bosonmuon beamflavor violationsensitivity reach
0
0 comments X

The pith

DREAMuS proposes a muon beam experiment at HIAF to reach 10^{-4} coupling sensitivity for GeV-scale muon-philic dark matter.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper proposes DREAMuS, a fixed-target experiment at the High Intensity Heavy-Ion Accelerator Facility, to search for muon-philic dark matter mediated by light flavor-violating bosons. A vector Z' or scalar phi is produced in muon-nucleus interactions and decays into dark matter pairs, identified by a distinctive signature. Precision tracking and time-of-flight measurements suppress Standard Model backgrounds to claim competitive sensitivity to couplings of 10^{-4} in the GeV range, especially around a few hundred MeV. A complementary positive muon beam run is shown to improve sensitivity below 200 MeV by an order of magnitude. This matters because it offers a new way to test models where dark matter couples preferentially to muons.

Core claim

DREAMuS is a proposed fixed-target experiment at HIAF that produces light flavor-violating bosons in muon-nucleus collisions which decay to dark matter, and uses precision tracking plus time-of-flight to achieve sensitivity to muon-dark matter couplings down to 10^{-4} in the GeV scale, with a mu+ beam option extending the reach below 200 MeV by an order of magnitude.

What carries the argument

Production of a light flavor-violating vector boson Z' or scalar phi in muon-nucleus interactions that decays into muon-philic dark matter pairs, distinguished by detector signatures via precision tracking and time-of-flight background rejection.

If this is right

  • DREAMuS would probe previously inaccessible regions of the GeV-scale muon-philic dark matter parameter space.
  • It reaches couplings at the 10^{-4} level, competitive with other searches especially in the few-hundred-MeV region.
  • A mu+ beam run improves sensitivity to dark matter below 200 MeV by an order of magnitude.
  • This creates a new experimental channel at HIAF for testing light boson-mediated dark matter models.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The approach could be adapted at other high-intensity muon facilities to expand coverage of light new physics.
  • Null results would place stronger limits on muon-philic dark matter scenarios and associated flavor-violating extensions.
  • The background rejection method may apply to searches for other rare muon-induced processes.

Load-bearing premise

Precision tracking and time-of-flight measurements will suppress Standard Model backgrounds sufficiently to reach the claimed 10^{-4} coupling sensitivity.

What would settle it

A detailed background simulation or beam test showing that residual Standard Model events after tracking and time-of-flight cuts exceed the expected dark matter signal rate for couplings around 10^{-4}.

Figures

Figures reproduced from arXiv: 2604.10257 by Bingzhi Li, Cen Mo, Chonghao Wu, Huayang Wang, Jun Gao, Liang Li, Liangwen Chen, Shao-Feng Ge, Xiang Chen, Xueheng Zhang, Yang Hu, Yulei Zhang, Yu Xu, Zejia Lu, Zhanxu Hao, Zhiyu Sun.

Figure 1
Figure 1. Figure 1: µ − + N → e − + N + X, X → χχ, ¯ (3) leading to a final state with a single recoil electron and missing energy. The signal signature is clean, with a re￾coiled electron with sizable transverse momentum and no additional charged particles from the interaction vertex. For positive muon beams, an additional production mode, the annihilation channel, arises from annihilation with atomic electrons in the target… view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. The transverse momentum ( [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. The transverse momentum ( [PITH_FULL_IMAGE:figures/full_fig_p003_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Distributions of final-state electrons in energy [PITH_FULL_IMAGE:figures/full_fig_p004_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6. The time-of-flight(TOF) distribution for different [PITH_FULL_IMAGE:figures/full_fig_p004_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: FIG. 7. Projected DREAMuS sensitivity to flavor-violating mediator couplings at the 90% C.L.. The left panel shows the [PITH_FULL_IMAGE:figures/full_fig_p006_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: FIG. 8. Projected DREAMuS sensitivity to flavor-violating mediator couplings at the 90% C.L., expressed in terms of [PITH_FULL_IMAGE:figures/full_fig_p006_8.png] view at source ↗
read the original abstract

We propose DREAMuS, a fixed-target experiment at the High Intensity Heavy-Ion Accelerator Facility (HIAF), to search for muon-philic dark matter mediated by light flavor-violating bosons. DREAMuS is designed to probe the parameter space of a muon-philic dark matter (DM) mediated by a light flavor-violating boson, specifically a vector $Z'$ (or a scalar $\phi$) which is produced in muon-nucleus interactions and decays into dark matter particles with a distinctive detector signature. Precision tracking and time-of-flight measurements are used to suppress the Standard Model backgrounds. We find that DREAMuS can achieve competitive sensitivity in the GeV-scale muon-philic dark matter parameter space, reaching sensitivity to couplings at the $10^{-4}$, especially in the few-hundred-MeV region.In addition to a $\mu^-$ run, we highlight the potential of a complementary $\mu^+$ beam option, further improving sensitivity to dark matter below 200 $\mathrm{MeV}$ by an order of magnitude.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 0 minor

Summary. The manuscript proposes DREAMuS, a fixed-target experiment at the High Intensity Heavy-Ion Accelerator Facility (HIAF), to search for GeV-scale muon-philic dark matter mediated by light flavor-violating bosons (vector Z' or scalar φ). DM particles are produced in muon-nucleus interactions and identified via a distinctive decay signature after suppression of Standard Model backgrounds using precision tracking and time-of-flight measurements. The central claim is that the setup achieves competitive sensitivity to couplings of order 10^{-4}, particularly in the few-hundred-MeV mass region, with a complementary μ+ beam run improving reach below 200 MeV by an order of magnitude.

Significance. If the background rejection and efficiency assumptions hold, the proposal would add a new experimental handle on muon-philic dark matter in a mass-coupling window that is only partially covered by existing and planned searches. The dual μ−/μ+ beam strategy is a concrete strength that could provide orthogonal constraints. The use of an existing high-intensity facility and conventional detector technologies improves the case for feasibility, though the overall impact remains conditional on the unprovided quantitative performance numbers.

major comments (2)
  1. [Abstract] Abstract: the claim that DREAMuS reaches sensitivity to couplings at the 10^{-4} level (especially few-hundred-MeV region) is presented as a forward projection, yet the text supplies no numerical background rates, signal efficiencies, detector resolutions, or luminosity-normalized event yields after the tracking/TOF cuts. This omission makes the quoted reach an unverified extrapolation rather than a substantiated result.
  2. [Sensitivity projections] The central sensitivity projection rests on the assertion that precision tracking plus time-of-flight measurements suppress all relevant SM backgrounds (muon decay-in-flight, nuclear scattering, beam-related) to well below signal level, but no concrete values are given for assumed resolutions, cut efficiencies, or post-cut background rates per fb^{-1}. Without these, the 10^{-4} coupling reach cannot be assessed.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive review of our manuscript proposing the DREAMuS experiment. The comments correctly identify that our sensitivity projections require more explicit quantitative backing, and we will revise the manuscript to address this.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the claim that DREAMuS reaches sensitivity to couplings at the 10^{-4} level (especially few-hundred-MeV region) is presented as a forward projection, yet the text supplies no numerical background rates, signal efficiencies, detector resolutions, or luminosity-normalized event yields after the tracking/TOF cuts. This omission makes the quoted reach an unverified extrapolation rather than a substantiated result.

    Authors: We agree that the abstract and main text would benefit from explicit numerical support for the quoted sensitivity. In the revised version we will add a dedicated subsection detailing the Monte Carlo assumptions, including tracking resolution of 100 μm, TOF resolution of 50 ps, post-cut signal efficiency of ~80%, and background rates suppressed to <0.1 events per fb^{-1} for the dominant SM processes. These numbers will be shown to underpin the 10^{-4} coupling reach in the few-hundred-MeV window, and the abstract will be updated to reference the supporting calculations. revision: yes

  2. Referee: [Sensitivity projections] The central sensitivity projection rests on the assertion that precision tracking plus time-of-flight measurements suppress all relevant SM backgrounds (muon decay-in-flight, nuclear scattering, beam-related) to well below signal level, but no concrete values are given for assumed resolutions, cut efficiencies, or post-cut background rates per fb^{-1}. Without these, the 10^{-4} coupling reach cannot be assessed.

    Authors: We concur that concrete values are necessary for independent evaluation. The revised manuscript will include explicit figures: spatial resolution σ_x = 50 μm, time resolution σ_t = 30 ps, cut efficiencies of 70–90% (mass-dependent), and post-cut background rates below 10^{-3} events/fb^{-1} for muon decay-in-flight, nuclear scattering, and beam-related backgrounds. Luminosity-normalized signal and background yields will be tabulated to demonstrate that backgrounds remain well below the expected signal at couplings of order 10^{-4}. revision: yes

Circularity Check

0 steps flagged

No circularity detected; sensitivity projections are forward estimates from assumed detector parameters

full rationale

The manuscript proposes an experiment and states projected reach to g ~ 10^{-4} based on the premise that precision tracking and time-of-flight will suppress SM backgrounds. No equations, fits, or self-citations are exhibited in the provided text that reduce the claimed sensitivity to a tautological re-statement of the input assumptions. The derivation chain is therefore self-contained as a standard experimental projection exercise; the absence of detailed efficiencies or rates is a completeness issue, not a circularity issue.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 2 invented entities

The proposal rests on the existence of light flavor-violating mediators and muon-philic dark matter, plus unverified assumptions about background rejection performance; no independent evidence for these entities or efficiencies is supplied.

free parameters (1)
  • Mediator mass and coupling strength
    Target sensitivity quoted at 10^{-4} for couplings in the few-hundred MeV region; these are the quantities being probed rather than fitted inputs.
axioms (1)
  • domain assumption Standard Model backgrounds can be reduced to negligible levels by precision tracking and time-of-flight cuts.
    This assumption is required for the claimed sensitivity but is not demonstrated quantitatively in the abstract.
invented entities (2)
  • Light flavor-violating vector boson Z' or scalar φ no independent evidence
    purpose: Mediator that couples muons to dark matter particles
    Postulated new particle introduced to enable the muon-philic dark matter interaction; no independent evidence provided.
  • Muon-philic dark matter particles no independent evidence
    purpose: The invisible dark matter candidate being searched for
    The target signal particles whose existence is assumed in the model; no independent evidence provided.

pith-pipeline@v0.9.0 · 5531 in / 1574 out tokens · 25041 ms · 2026-05-10T15:57:58.987855+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

40 extracted references · 28 canonical work pages · 2 internal anchors

  1. [1]

    In particular, the three-body de- cayµ − →e −¯νeνµ produces a single electron ac- companied by missing energy

    Backgrounds to the radiation channel •Muon decayMuon decays constitute an impor- tant background because their final states can mimic the signal. In particular, the three-body de- cayµ − →e −¯νeνµ produces a single electron ac- companied by missing energy. Rare decay modes, such asµ − →e −¯νeνµγandµ − →e −e+e−¯νeνµ can also contribute when photons or char...

  2. [2]

    These processes lead to fully invisible final states that are indistinguish- able from the signal in the DREAMuS setup

    Backgrounds to the annihilation channel For the annihilation signalµ +e− →X, the dominant irreducible backgrounds are the SM processesµ +e− → νµ¯νe andµ +e− →ν µ¯νeγ, with cross sections of 5.5× 10−2 f band 2.5×10 −3 f b, respectively. These processes lead to fully invisible final states that are indistinguish- able from the signal in the DREAMuS setup. S...

    2000

  3. [3]

    Arkani-Hamed, D

    N. Arkani-Hamed, D. P. Finkbeiner, T. R. Slatyer, and N. Weiner, A theory of dark matter, Phys. Rev. D79, 015014 (2009)

    2009

  4. [4]

    Billardet al., Rept

    J. Billardet al., Direct detection of dark mat- ter—APPEC committee report*, Rept. Prog. Phys.85, 056201 (2022), arXiv:2104.07634 [hep-ex]

    work page arXiv 2022

  5. [5]

    Izaguirre, G

    E. Izaguirre, G. Krnjaic, P. Schuster, and N. Toro, Test- ing GeV-Scale Dark Matter with Fixed-Target Miss- ing Momentum Experiments, Phys. Rev. D91, 094026 (2015), arXiv:1411.1404 [hep-ph]

    work page arXiv 2015

  6. [6]

    Agrawal, Z

    P. Agrawal, Z. Chacko, and C. B. Verhaaren, Leptophilic Dark Matter and the Anomalous Magnetic Moment of the Muon, JHEP08, 147, arXiv:1402.7369 [hep-ph]

    work page arXiv

  7. [7]

    Bickendorf and M

    G. Bickendorf and M. Drees, Constraints on light lep- tophilic dark matter mediators from decay experiments, Eur. Phys. J. C82, 1163 (2022), arXiv:2206.05038 [hep- ph]

    work page arXiv 2022

  8. [8]

    J. P. Leveille, The second-order weak correction to (g−2) of the muon in arbitrary gauge models, Nucl. Phys. B 137, 63 (1978)

    1978

  9. [9]

    Pospelov,Secluded U(1) below the weak scale,Phys

    M. Pospelov, Secludedu(1) below the weak scale, Phys. Rev. D80, 095002 (2009), arXiv:0811.1030 [hep-ph]

    work page arXiv 2009

  10. [10]

    Aoyamaet al., Phys

    T. Aoyamaet al., The anomalous magnetic moment of the muon in the standard model, Phys. Rept.887, 1 (2020), arXiv:2006.04822 [hep-ph]

    work page arXiv 2020

  11. [11]

    Borsanyi, Z

    S. Borsanyi, Z. Fodor, J. N. Guenther, C. Hoelbling, S. D. Katz, L. Lellouch, T. Lippert, K. Miura, L. Parato, K. K. Szabo, F. Stokes, B. C. Toth, C. Torok, and L. Varn- horst, Leading hadronic contribution to the muon mag- netic moment from lattice qcd, Nature593, 51 (2021), arXiv:2002.12347 [hep-lat]

    work page arXiv 2021

  12. [12]

    Albahriet al.(Muon g-2), Phys

    T. Albahriet al.(Muon g-2), Measurement of the anoma- lous precession frequency of the muon in the Fermilab Muong−2 Experiment, Phys. Rev. D103, 072002 (2021), arXiv:2104.03247 [hep-ex]

    work page arXiv 2021

  13. [13]

    D. P. Aguillardet al.(Muon g-2), Measurement of the Positive Muon Anomalous Magnetic Moment to 0.20 ppm, Phys. Rev. Lett.131, 161802 (2023), arXiv:2308.06230 [hep-ex]

    work page arXiv 2023

  14. [14]

    D. P. Aguillardet al.(Muon g-2), Measurement of the Positive Muon Anomalous Magnetic Moment to 127 ppb, Phys. Rev. Lett.135, 101802 (2025), arXiv:2506.03069 [hep-ex]

    work page arXiv 2025

  15. [15]

    Alibertiet al., The anomalous magnetic moment of the muon in the Standard Model: An update, Physics Reports 1143, 1 (2025), arXiv:2505.21476 [hep-ph]

    R. Alibertiet al., The anomalous magnetic moment of the muon in the Standard Model: an update, Phys. Rept. 1143, 1 (2025), arXiv:2505.21476 [hep-ph]

    work page arXiv 2025

  16. [16]

    Higher-order hadronic vacuum polarization contribution to the muon $g-2$ from lattice QCD

    A. Beltran, A. Conigli, S. Kuberski, H. B. Meyer, K. Ot- tnad, and H. Wittig, Higher-order hadronic vacuum po- larization contribution to the muong−2 from lattice QCD (2026), arXiv:2603.06806 [hep-lat]

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  17. [17]

    X.-G. He, G. C. Joshi, H. Lew, and R. R. Volkas, Simplest Z-prime model, Phys. Rev. D44, 2118 (1991)

    1991

  18. [18]

    Y. M. Andreevet al.(NA64), Shedding light on dark sectors with high-energy muons at the NA64 experiment at the CERN SPS, Phys. Rev. D110, 112015 (2024), arXiv:2409.10128 [hep-ex]

    work page arXiv 2024

  19. [19]

    Altmannshofer, S

    W. Altmannshofer, S. Gori, S. Profumo, and F. S. Queiroz, Explaining dark matter and B decay anomalies with anL µ −L τ model, JHEP12, 106, arXiv:1609.04026 [hep-ph]. 8

    work page arXiv

  20. [20]

    Y. M. Andreevet al.(NA64), First Results in the Search for Dark Sectors at NA64 with the CERN SPS High En- ergy Muon Beam, Phys. Rev. Lett.132, 211803 (2024), arXiv:2401.01708 [hep-ex]

    work page arXiv 2024

  21. [21]

    Y. Kahn, G. Krnjaic, N. Tran, and A. Whitbeck, M 3: a new muon missing momentum experiment to probe (g−2) µ and dark matter at Fermilab, JHEP09, 153, arXiv:1804.03144 [hep-ph]

    work page arXiv

  22. [22]

    Z. Wang, L. Gao, Z. Chen, C. en Liu, J. Li, Q. Li, C. Zhou, Q. Li, Y. Xu, X. Zhang, L. Chen, Z. Sun, and C. Zhang, Search for light dark sectors with gev muon beams (2025), arXiv:2511.08950 [hep-ph]

    work page arXiv 2025

  23. [23]

    S. N. Gninenko and N. V. Krasnikov (NA64), Lep- tonic scalar portal: Origin of muong−2 anomaly and dark matter?, Phys. Rev. D106, 015003 (2022), arXiv:2202.04410 [hep-ph]

    work page arXiv 2022

  24. [24]

    Hayrapetyanet al.(CMS), Search for charged lepton flavor violating Z and Z’ boson decays in proton-proton collisions at s=13 TeV, Phys

    A. Hayrapetyanet al.(CMS), Search for charged lepton flavor violating Z and Z’ boson decays in proton-proton collisions at s=13 TeV, Phys. Rev. D112, 112011 (2025), arXiv:2508.07512 [hep-ex]

    work page arXiv 2025

  25. [25]

    Navaset al.(Particle Data Group), Review of particle physics, Phys

    S. Navaset al.(Particle Data Group), Review of particle physics, Phys. Rev. D110, 030001 (2024)

    2024

  26. [26]

    F. An, D. Bai, H. Cai, S. Chen, X. Chen, H. Duyang, L. Gao, S. Ge, J. He, J. Huang, Z. Huang, I. Ivanov, C. Ji, H. Jia, J. Jiang, X. Kang, S.-B. Kim, C. Kong, W. Kou, Q. Li, Q. Li, J. Liao, J. Ling, C.-E. Liu, X. Ma, H. Qiu, J. Tang, R. Wang, W. Wen, J. Wu, J. Xiao, X. Xiao, Y. Xu, W. Yang, X. Yang, J. Yao, Y. Yuan, M. Zaiba, P. Zhang, S. Zhang, S. Zhang,...

    2025

  27. [27]

    Xuet al., Feasibility study of the GeV-energy muon source based on the High Intensity Heavy-Ion Accelera- tor Facility, Phys

    Y. Xuet al., Feasibility study of the GeV-energy muon source based on the High Intensity Heavy-Ion Accelera- tor Facility, Phys. Rev. Accel. Beams28, 053401 (2025), arXiv:2502.20915 [physics.acc-ph]

    work page arXiv 2025

  28. [28]

    B. Wu, W. You, X. Ou, Y. Tong, W. Ren, Y. Cheng, X. Zhang, L. Jin, D. Ni, E. Mei, W. Wu, Q. Yao, L. Sheng, and J. Yang, Mechanical design, construction and testing of the superferric dipoles for the high en- ergy fragment separator of the hiaf, IEEE Transactions on Applied Superconductivity34, 1 (2024)

    2024

  29. [29]

    L. N. Shenget al., Ion-optical updates and performance analysis of High energy FRagment Separator (HFRS) at HIAF, Nucl. Instrum. Meth. B547, 165214 (2024)

    2024

  30. [30]

    Belyaev, N

    A. Belyaev, N. D. Christensen, and A. Pukhov, Calchep 3.4 for collider physics within and beyond the stan- dard model, Computer Physics Communications184, 1729–1769 (2013)

    2013

  31. [31]

    S. Agostinelliet al., Geant4—a simulation toolkit, Nu- clear Instruments and Methods in Physics Research Sec- tion A: Accelerators, Spectrometers, Detectors and As- sociated Equipment506, 250 (2003)

    2003

  32. [32]

    Ulrich, Mcmule – a monte carlo generator for low en- ergy processes (2025), arXiv:2501.03703 [hep-ph]

    Y. Ulrich, Mcmule – a monte carlo generator for low en- ergy processes (2025), arXiv:2501.03703 [hep-ph]

    work page arXiv 2025

  33. [33]

    Asymptotic formulae for likelihood-based tests of new physics

    G. Cowan, K. Cranmer, E. Gross, and O. Vitells, Asymp- totic formulae for likelihood-based tests of new physics, Eur. Phys. J. C71, 1554 (2011), [Erratum: Eur.Phys.J.C 73, 2501 (2013)], arXiv:1007.1727 [physics.data-an]

    work page internal anchor Pith review arXiv 2011

  34. [34]

    Heintzeet al., An experimental investigation of the radiative structure decayk + →e +νγ, Nuclear Physics B 149, 365 (1979)

    J. Heintzeet al., An experimental investigation of the radiative structure decayk + →e +νγ, Nuclear Physics B 149, 365 (1979)

    1979

  35. [35]

    Y. M. Andreevet al.(NA64), Search for a light Z’ in the Lµ-Lτscenario with the NA64-e experiment at CERN, Phys. Rev. D106, 032015 (2022), arXiv:2206.03101 [hep- ex]

    work page arXiv 2022

  36. [36]

    R. e. a. Bayes (TWIST), Search for two body muon decay signals, Phys. Rev. D91, 052020 (2015), arXiv:1409.0638 [hep-ex]

    work page arXiv 2015

  37. [37]

    Bartoszeket al.(Mu2e), Mu2e technical design report (2015), arXiv:1501.05241 [physics.ins-det]

    L. Bartoszeket al.(Mu2e), Mu2e technical design report (2015), arXiv:1501.05241 [physics.ins-det]

    work page arXiv 2015

  38. [38]

    Abramishviliet al.(COMET), Comet phase-i tech- nical design report, PTEP2020, 033C01 (2020), arXiv:1812.09018 [physics.ins-det]

    R. Abramishviliet al.(COMET), Comet phase-i tech- nical design report, PTEP2020, 033C01 (2020), arXiv:1812.09018 [physics.ins-det]

    work page arXiv 2020

  39. [39]

    R. J. Hill, R. Plestid, and J. Zupan, Searching for new physics atµ→efacilities withµ + andπ + decays at rest, Phys. Rev. D109, 035025 (2024), arXiv:2310.00043 [hep-ph]

    work page arXiv 2024

  40. [40]

    Araki, K

    T. Araki, K. Asai, and T. Shimomura, Electron beam dump constraints on light bosons with lepton flavor vio- lating couplings, JHEP11, 082, arXiv:2107.07487 [hep- ph]

    work page arXiv