A frequentist analysis of three right-handed neutrinos with GAMBIT

Christoph Weniger; Julia Harz; Marcin Chrzaszcz; Marco Drewes; Suraj Krishnamurthy; Tomas E. Gonzalo

REVIEW 3 major objections 6 minor 4 cited by

A frequentist analysis of three right-handed neutrinos with GAMBIT

T0 review · 3 major / 6 minor · reviewed 2026-08-14 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read The first full frequentist fit of the three-right-handed-neutrino extension maps every allowed mass and mixing from 60 MeV to 500 GeV, and finds only mild hints of new physics.

desk verdict The first full frequentist global fit of the three-right-handed-neutrino seesaw below the TeV scale—solid, careful, and reproducible, with a few disclosed statistical approximations and one unquantified DELPHI caveat that deserves tightening. read the letter →

arxiv 1908.02302 v2 pith:RREYBUVP submitted 2019-08-06 hep-ph hep-ex

Marcin Chrzaszcz , Marco Drewes , Tomas E. Gonzalo , Julia Harz , Suraj Krishnamurthy , Christoph Weniger This is my paper · ORCID

classification hep-phhep-ex

keywords right-handedneutrinosseesawmechanismCasas-IbarraparametrisationprofilelikelihoodglobalfitleptonflavourviolationCKMunitarityBigBangnucleosynthesis

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

Three right-handed neutrinos, the minimal extension that can give mass to all three known neutrinos, remain plausible up to surprisingly large mixings because seesaw cancellations can hide their effects. This paper performs the first full frequentist scan of that model for heavy-neutrino masses between 60 MeV and 500 GeV, combining active-neutrino oscillation data with electroweak precision observables, lepton-flavour and lepton-universality tests, CKM unitarity, neutrinoless double-$\beta$ decay, nucleosynthesis, and every direct search that currently binds in this range. The central result is a set of profile-likelihood maps giving the strongest combined upper limits on the mixings $U^2_{\alpha I}$ and on flavour products $U_{\alpha I}U_{\beta I}$, together with the allowed flavour-mixing pattern as a function of the lightest active neutrino mass. The combined data also show a modest preference, just above $2\sigma$, for sizable tau-neutrino mixing, traceable to the $Z$ invisible width, CKM unitarity, and kaon lepton-universality measurements; the authors read these as hints rather than discovery.

What carries the argument

The machinery is the Casas-Ibarra parametrisation, a complex orthogonal rotation $R$ that constructs the active-sterile mixing matrix $\Theta$ from the measured light-neutrino masses and PMNS matrix, with one-loop corrections, so every scanned point respects neutrino-oscillation data by construction. Around this, the analysis profiles a composite likelihood: direct searches enter as Poissonian or one-sided-Gaussian likelihoods calibrated to published confidence limits, indirect observables as Gaussian likelihoods, BBN as a lifetime cut, and the results are presented with a capped profile likelihood to separate exclusion from the excess regions. A differential-evolution scan over the 18-dimensional parameter space, with targeted scans saturating each experimental bound, supplies the sampled likelihood surface.

What would settle it

Recalculate the profile likelihood after replacing the simplified-likelihood recasting of the DELPHI and LHC searches with a detector-level simulation for benchmark mass–mixing points; if a point excluded at 95% here becomes allowed, the central claim fails. A future NA62 or SHiP observation inside a 95% excluded region would settle it directly.

Watch

Extended reading notes

Core claim

The paper claims that the three-right-handed-neutrino (seesaw) parameter space below the TeV scale is now globally constrained in a statistically consistent way, and that the resulting 90% and 95% contours replace the overlay of individual exclusions. Because three heavy neutrinos allow symmetry-protected cancellations, the seesaw relation itself imposes almost no upper bound on the mixings; the bounds come from experiment: electron and muon mixings are set by fixed-target and collider searches, while tau mixing is limited mainly by electroweak precision and indirect observables. Below roughly 0.3 GeV, Big Bang nucleosynthesis demands that the total mixing $U_I^2$ be large enough for the heavy states to decay before nucleosynthesis, while oscillation data plus direct limits squeeze the flavour composition, forcing a minimum tau mixing. For the first time the flavour-mixing pattern of the three heavy neutrinos is mapped against the lightest active neutrino mass, showing that as $m_{\nu 0}$ drops below about 0.01 meV the allowed pattern tightens and reproduces the two-heavy-neutrino limit.

Load-bearing premise

The load-bearing premise is that each experiment's published limit can be converted into a simple count-based likelihood calibrated to that limit, including the simplified production assumptions of collider searches, with enough accuracy for the profiling.

Editorial extensions

If this is right

Any future heavy-neutrino signal claimed in this mass range must lie inside the 95% allowed contours; points outside are excluded simultaneously by all data, not just by one experiment.
The current best targets for next-generation searches are the high-mass region above 80 GeV, where couplings up to $10^{-2}$–$10^{-3}$ remain allowed, and the tau-mixing window near $0.3$–$0.5$ GeV.
If the $2\sigma$ hints persist, more precise measurements of the $Z$ invisible width, of $V_{us}$, and of $R^e_\mu$ will sharpen a specific prediction: a heavy neutrino with $U^2_{\tau 1}\sim 10^{-3}$–$10^{-2}$.
The recovery of the two-heavy-neutrino flavour pattern at very small lightest-neutrino mass means that flavour-ratio measurements could distinguish $n=3$ from $n=2$ scenarios without observing all three heavy states.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

Beyond the paper: the same dataset implies that if a discovery were made in the naive-seesaw 'forbidden' region, the most economical explanation would be an approximate $B-L$ symmetry rather than accidental tuning; the scan's symmetry-protected points show that region is populated.
Beyond the paper: the three excesses ($\Gamma_{\rm inv}$, CKM, $R^e_\mu$) all arise from the same non-unitarity of the lepton mixing matrix, so they are not independent; a future measurement that moves one should move the inferred tau-mixing island coherently.
Beyond the paper: a testable extension would be to rerun this global fit with the updated PIENU, ATLAS, and CMS results the authors note were released after their scans, and with detector-level recasting, to check whether the contours in the $0.1$–$0.3$ GeV and $>500$ GeV regions shift.

Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Bottom line: this is the most complete frequentist global fit of the three-right-handed-neutrino seesaw below the TeV scale, and it mostly delivers on its claims. The new content is real: active neutrino likelihoods included directly in the scan, a broad set of LFV and lepton-universality observables, an improved CKM unitarity treatment, and the first flavour-mixing-pattern constraints as a function of the lightest neutrino mass, including an explicit recovery of the n=2 limit. The GAMBIT implementation and the Zenodo dataset make the results reproducible, which is worth taking seriously.

The paper is generally careful. The main caveats are all disclosed by the authors. Likelihoods for direct searches are approximate recasts of published limits, using Poisson or half-Gaussian forms calibrated to quoted confidence levels. There is no full sampling-based goodness-of-fit, and the contour levels come from Wilks' theorem. Given the high dimensionality and the use of profile likelihoods, those are reasonable choices, but they are approximations and the paper says so.

The one place I would push back is the DELPHI treatment for U_tau. The paper applies the flavour-independent DELPHI limit to U_tau even though DELPHI itself says the bound weakens below about 4 GeV, and the tau-mass suppression is not quantified. Since DELPHI is the dominant direct constraint on U_tau between roughly 0.5 and 80 GeV, this could shift the quoted upper bound in the sub-4 GeV region. The authors flag this in Sec. 3.3.6 but do not estimate the effect. That is a genuine soft spot, and it should be fixed in revision by modelling the tau kinematic factor or adding an uncertainty band. It does not overturn the central result—the map is still the best available—but the U_tau contours in that range should be read with a grain of salt.

The excesses near 2 sigma in Gamma_inv, CKM, and R_K are handled honestly and are not oversold.

Who is this for: phenomenologists planning NA62, DUNE, SHiP, or FCC-ee searches, and anyone who needs a baseline for interpreting future heavy-neutrino results. It deserves peer review. Recommended actions: ask the authors to quantify the DELPHI U_tau suppression, provide an uncertainty estimate for the likelihood recasting, and ideally validate with a second scanner or a coverage check. These are revision-level issues, not grounds for rejection.

Referee Report

3 major / 6 minor

Summary. The paper presents a global frequentist analysis of the Standard Model extended by three right-handed Majorana neutrinos with masses between 60 MeV and 500 GeV, using the GAMBIT framework. The parameter space is scanned with the Casas-Ibarra parametrisation, and the authors combine likelihoods for active neutrino oscillations, electroweak precision observables, lepton flavour violation, lepton universality, CKM unitarity, neutrinoless double-beta decay, BBN, and a large set of direct search experiments. The results are presented as profile likelihood maps in the mass-mixing planes for electron, muon, and tau flavour couplings, cross-flavour products, and flavour-mixing triangles as a function of the lightest neutrino mass. The paper also identifies small (around 2 sigma) excesses driven by Gamma_inv, CKM, and R_K, and claims to provide the most comprehensive assessment of this model below the TeV scale so far.

Significance. If the results are correct, the profile likelihood maps in Figs. 1-7 and the flavour-mixing constraints in Figs. 11-13 constitute the most complete global constraints on the three-right-handed-neutrino model in this mass range. The analysis is a substantial technical effort: it uses an open-source framework, provides a new GAMBIT module, publishes the scan data on Zenodo, and explicitly combines many constraints that previous studies treated separately. The paper is commendably transparent about its approximations, including the use of approximate likelihoods calibrated to published limits, the absence of a full sampling-based goodness-of-fit test, and the reliance on Wilks' theorem for contour estimation. The Casas-Ibarra parametrisation builds in neutrino oscillation data as a modelling choice rather than as an external test, which is appropriate for a scan-oriented global fit. The main weakness is that some quantitative upper limits, especially for the tau coupling, rest on a small number of unvalidated recasting assumptions.

major comments (3)

[Sec. 3.3.6, Figs. 3, 6, 7] The DELPHI tau-flavour limit is applied without quantifying the kinematic suppression from the tau mass below about 4 GeV. The paper itself states that the quoted bounds become weaker in this region, but it then uses the flavour-independent limit as-is for U_tau. Since DELPHI is the dominant direct constraint on U_tau for roughly 0.5-80 GeV, an overestimate of its sensitivity would directly shift the upper bounds on U_tau^2 in Fig. 3 and the cross-flavour products in Figs. 6 and 7. The authors should either implement a conservative tau-mass suppression factor, rerun the fit with a weakened DELPHI likelihood, or quantify the resulting shift in the quoted upper limits.
[Sec. 4 and 5.1, Figs. 1-7] The 1 sigma and 2 sigma contours in the profile likelihood plots are estimated using Wilks' theorem with two degrees of freedom, but the likelihood is a composite of approximate Poisson and half-Gaussian likelihoods calibrated to published limits, and the contours are drawn on a capped likelihood. Wilks' theorem may be inaccurate for zero-event Poisson likelihoods, for parameters with physical boundaries at zero coupling, and for composite likelihoods that are not genuine likelihoods of the data. The authors do not provide any Monte Carlo validation or calibration of the profile likelihood ratio. Since the quantitative confidence levels are a central output of the paper, this approximation should be either validated or explicitly softened in the interpretation of the contours.
[Sec. 3.2.6, Figs. 3 and 4] The BBN likelihood is implemented as a step function requiring each RHN lifetime to be less than 0.1 s, and this bound is applied over the whole scanned range, including m_nu0 values as low as 1e-7 eV. The paper acknowledges in Sec. 3.2.6 that the BBN bound can be weakened for m_nu0 below about 1e-3 eV because the RHNs may not thermalise. This could overstate the lower bounds on U_tau^2 shown in Fig. 3 and on U_I^2 in Fig. 4 for small m_nu0. The impact of this caveat on the plotted lower limits should be quantified, or the affected regions should be identified in the figures.

minor comments (6)

[Abstract and Conclusions] The phrase 'three right-handed neutrinos model' appears twice and should read 'three right-handed neutrino model'.
[Sec. 3.3.10] There is a typo: 'indculde' should be 'include'.
[Sec. 6] There are typos: 'folliders' should be 'colliders' and 'measurments' should be 'measurements'.
[Sec. 2.6] The text contains 'in strictive' which should be 'instructive'.
[Sec. 1.2] The statement that the paper performs 'the first full frequentist analysis' is somewhat in tension with the later statement that no full sampling-based goodness-of-fit analysis is performed; rewording to 'first full frequentist profile-likelihood analysis' would be more precise.
[Sec. 4.2, Table 6] The parameter denoted delta_M21 would be clearer as Delta M21, consistent with the text in Sec. A.1, to avoid confusion with the active neutrino mass splitting Delta m^2_21.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the global fit is driven by external experimental likelihoods, and the Casas-Ibarra parametrisation is a scanning coordinate, not a fitted prediction.

full rationale

The paper's central objects are profile-likelihood constraints on the RHN parameter space built from external experimental likelihoods (NuFIT, EWPO, LFV, lepton universality, CKM, 0νββ, BBN, and direct searches). The Casas-Ibarra parametrisation (Sec. 2.4, Eq. 29) is a reparametrisation of the seesaw relation that automatically satisfies active-neutrino oscillation data; using it as a scanning basis while also profiling against NuFIT likelihoods is a coordinate choice, not a derivation whose output equals its input. The direct-search likelihoods in Sec. 3.3 are explicitly calibrated to published limits ('the factor of proportionality is set to reproduce the results from the experimental papers'), but the paper does not present those limits as predictions; the new content is the simultaneous combination and the cross-constraint interplay (e.g., BBN lower bound plus e/µ direct upper bounds giving a lower bound on U^2_τI, Sec. 5.1), which is not identical to any single input. Self-citations such as Ref. [42] for the analytic lower bound U^2_I ≳ m_ν0/M_I and Refs. [27,188] for the n=2 flavour triangles are used as cross-checks or comparisons; they are not fitted inputs that determine the plotted contours. The approximation U_N=I is justified by a theorem in [42], but the paper argues the experimentally relevant quantities are sums U^2_α, so this is not load-bearing for the main constraints. The acknowledged DELPHI tau-mass caveat (Sec. 3.3.6) is a correctness and robustness concern, not a circularity. No step in the derivation reduces by construction to its own input.

Assumptions & free parameters 6 free parameters · 7 assumptions · 0 invented entities

The ledger is dominated by scanned model parameters and stated domain assumptions. No new particles or interactions are invented. The most fragile inputs are the ad hoc simplification UN=I and the recasting of experimental limits into approximate likelihoods; both are disclosed but not quantified.

free parameters (6)

RHN masses M1, M2, M3 (log priors over [0.06, 500] GeV; differential model uses delta_M21) = no single fitted value; profiled over range
Masses are scanned model parameters and the central constraints are functions of them. They are not derived from first principles.
Complex Casas-Ibarra angles omega_ij (Re in [0,2pi], Im in [-15,15]) = profiled; no best-fit quoted
These angles control the active-sterile mixing U^2_alphaI. The scan treats them as free because the model has no predictive prior on them.
Lightest active neutrino mass m_nu0 (log prior in [1e-7, 0.23] eV) = profiled; cuts at 0.05, 1e-2, 1e-3, 1e-4 eV used in flavour-mixing figures
m_nu0 sets the lower bound on U^2_I and is otherwise unconstrained by oscillation data beyond cosmology.
Active neutrino oscillation parameters theta12, theta23, theta13, dm2_21, dm2_3l, delta_CP, alpha1, alpha2 = scanned over NuFIT 3-sigma ranges
These are profiled with likelihoods rather than fixed to best-fit values, which is one of the paper's improvements over earlier work.
Higgs mass m_H as nuisance parameter = Gaussian prior around world average, range [124.1, 127.3] GeV
Affects the one-loop correction in the Casas-Ibarra parametrization and is profiled over.
Rorder discrete permutation parameter = uniform over [1,6]
Introduced to cover all orderings of R_ij in the Casas-Ibarra parametrization; no physics meaning.

assumptions (7)

domain assumption The type-I seesaw Lagrangian with three right-handed Majorana neutrinos is the correct low-energy description.
Eq. (1) in Sec. 2.1 defines the model; the entire analysis rests on this extension.
domain assumption The seesaw relation m_nu = -theta M_M theta^T, plus one-loop corrections, holds.
Eqs. (12)-(14) in Sec. 2.2 are the basis of the Casas-Ibarra parametrization and the lower bound on mixing.
domain assumption The Casas-Ibarra parametrization with all R-order permutations covers the physical parameter space.
Sec. 2.4 and Sec. 4.1: the paper found the standard C-I parametrization did not fully cover the space and added Rorder to fix this.
ad hoc to paper UN can be approximated by unity in the numerical scan.
Sec. 2.3: this is a computational simplification that is justified for generic parameters but can fail for accidentally degenerate heavy neutrinos, affecting lepton-number-violating observables.
domain assumption The BBN constraint can be imposed as a step function requiring each RHN lifetime below 0.1 s.
Sec. 3.2.6: the paper notes this can be weakened for very small lightest neutrino mass and leaves refined BBN likelihoods for future work.
domain assumption Wilks' theorem applies to profile likelihood ratios for confidence contours.
Sec. 4.4: used to assign 1-sigma and 2-sigma contours; the paper does not validate this with Monte Carlo.
ad hoc to paper Published experimental limits can be recast as simplified Poisson or half-Gaussian likelihoods.
Sec. 3.3: the central method for direct search constraints; the paper acknowledges the true limits may be slightly weaker.

how reviews work

0 comments

Cite this review

Pith. "Pith review of A frequentist analysis of three right-handed neutrinos with GAMBIT." pith.science (2026). https://pith.science/paper/RREYBUVP

@misc{pith2026190802302,
  author       = {Pith},
  title        = {Pith review of: A frequentist analysis of three right-handed neutrinos with GAMBIT},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/RREYBUVP}},
  note         = {Machine review of arXiv:1908.02302}
}

read the original abstract

The extension of the Standard Model by right-handed neutrinos can not only explain the active neutrino masses via the seesaw mechanism, it is also able solve a number of long standing problems in cosmology. Especially, masses below the TeV scale are of particular interest as they can lead to a plethora of signatures in experimental searches. We present the first full frequentist analysis of the extension of the Standard Model by three right-handed neutrinos, with masses between 60 MeV and 500 GeV, using the Global and Modular BSM (beyond the Standard Model) Inference Tool GAMBIT. Our analysis is based on the Casas-Ibarra parametrisation and includes a large range of experimental constraints: active neutrino mixing, indirect constraints from, e.g., electroweak precision observables and lepton universality, and numerous direct searches for right-handed neutrinos. To study their overall effect, we derive combined profile likelihood results for the phenomenologically most relevant parameter projections. Furthermore, we discuss the role of (marginally) statistically preferred regions in the parameter space. Finally, we explore the flavour mixing pattern of the three right-handed neutrinos for different values of the lightest neutrino mass. Our results comprise the most comprehensive assessment of the model with three right-handed neutrinos model below the TeV scale so far, and provide a robust ground for exploring the impact of future constraints or detections.

Figures

Figures reproduced from arXiv: 1908.02302 by the authors.

**Figure 1.** Profile likelihood in MI vs U 2 eI plane for normal (left) and inverted hierarchy (right). Tables with the 90% and 95% CLs for both hierarchies can be found in Zenodo [184]. GAMBIT 1.4.0 G A M B I T 10−9 10−8 10−7 10−6 10−5 10−4 10−3 10−2 10−1 |UµI | 2 Profile likelihood ratio Λ = L/Lmax 1 10 102 MI [GeV] 0.2 0.4 0.6 0.8 1.0 GAMBIT 1.4.0 G A M B I T 10−9 10−8 10−7 10−6 10−5 10−4 10−3 10−2 10−1 |UµI | 2 Profile likel… view at source ↗

**Figure 2.** Profile likelihood in MI vs U 2 µI plane for normal (left) and inverted hierarchy (right). Tables with the 90% and 95% CLs for both hierarchies can be found in Zenodo [184]. pion decay experiments at even lower masses. In this regime the global constraints on U 2 eI and U 2 µI are in good approximation given by the direct search constraints, as discussed in Sec. 5.2 and Figs. 8-10. This is in contrast to the model w… view at source ↗

**Figure 3.** Profile likelihood in MI vs U 2 τ I plane for normal (left) and inverted hierarchy (right). Tables with the 90% and 95% CLs for both hierarchies can be found in Zenodo [184]. GAMBIT 1.4.0 G 10 A M B I T −14 10−13 10−12 10−11 10−10 10−9 10−8 10−7 10−6 10−5 10−4 10−3 10−2 10−1 |UI | 2 Profile likelihood ratio Λ = L/Lmax 1 10 102 MI [GeV] 0.2 0.4 0.6 0.8 1.0 mν0 = 0.05 eV mν0 = 10−2 eV mν0 = 10−3 eV mν0 = 10−4 eV GAMBI… view at source ↗

Figures from the paper (27 more)

**Figure 4.** Figure 4: Profile likelihood in MI vs U 2 I plane for normal (left) and inverted hierarchy (right). Overlaid are the lowest limits for various values of mν0 [42]. Tables with the 90% and 95% CLs for both hierarchies can be found in Zenodo [184]. The upper bound on the total mixi…

**Figure 5.** Figure 5: Profile likelihood in MI vs |UeIUµI | plane for normal (left) and inverted hierarchy (right). Tables with the 90% and 95% CLs for both hierarchies can be found in Zenodo [184]. GAMBIT 1.4.0 G A M B I T 10−9 10−8 10−7 10−6 10−5 10−4 10−3 10−2 10−1 |UeI Uτ I | Profile li…

**Figure 6.** Figure 6: Profile likelihood in MI vs |UeIUτ I | plane for normal (left) and inverted hierarchy (right). Tables with the 90% and 95% CLs for both hierarchies can be found in Zenodo [184]. appear that the E949 bound is in fact not saturated as the experimental limit falls below t…

**Figure 7.** Figure 7: Profile likelihood in MI vs |UµIUτ I | plane for normal (left) and inverted hierarchy (right). Tables with the 90% and 95% CLs for both hierarchies can be found in Zenodo [184]. GAMBIT 1.4.0 G A M B I T PS191 (e channel) CHARM (e channel) DELPHI (long-lived RHN) DELPHI…

**Figure 8.** Figure 8: Profile likelihood in MI vs U 2 eI plane with MI < 10 GeV and overlaid direct detection limits, for normal (left) and inverted hierarchy (right). the light neutrino oscillation parameters within their experimentally allowed range has a considerable impact on the predic…

**Figure 9.** Figure 9: Profile likelihood in MI vs U 2 µI plane with MI < 10 GeV and overlaid direct detection limits, for normal (left) and inverted hierarchy (right). GAMBIT 1.4.0 G A M B I T E949 PS191 (µ channel) NuTeV 10−9 10−8 10−7 10−6 10−5 |UµI | 2 Profile likelihood ratio Λ = L/Lmax…

**Figure 10.** Figure 10: Profile likelihood in MI vs U 2 µI plane with MI < 0.4 GeV and overlaid direct detection limits, for normal (left) and inverted hierarchy (right). The effect of BBN can be seen in the lower limits of [PITH_FULL_IMAGE:figures/full_fig_p024_10.png]

**Figure 11.** Figure 11: U 2 αI /U2 I (in percent) for different upper limits of mν0 (see legend). Solid (dashed) lines delineate the 1σ (2σ) contours, for normal (left) and inverted hierarchy (right). As discussed in footnote 12, these constraints apply to those heavy neutrinos that can be f…

**Figure 12.** Figure 12: Upper limits on the coupling ratios U 2 αI /U2 I within 2σ as a function of the lightest active neutrino mass mν0 , for normal (left) and inverted hierarchy (right). As discussed in footnote 12, these constraints apply to those heavy neutrinos that can be found experi…

**Figure 13.** Figure 13: Profile likelihood for U 2 αI /U2 I (in percent) in the limit of n = 2 in the symmetry protected region for normal (left) and inverted (right) hierarchy. For the detailed cuts we refer to the text. GAMBIT 1.4.0 G A M B I T 10−3 10−2 10−1 |Uτ1| 2 Profile likelihood rat…

**Figure 14.** Figure 14: Profile likelihood in MI vs U 2 τ I plane without likelihood cap showing the excesses due to the Γinv, CKM and Rτ constraints, for normal (left) and inverted hierarchy (right). mixing, as described in Section 3.2.1. For very high τ couplings, U 2 τ I > 10−3 , the pred…

**Figure 15.** Figure 15: One-dimensional profile likelihood for U 2 τ1 , Ltotal, and partial likelihoods for ΓZ , CKM and combination of the rest of constraints, L0, in the low mass region, M1 < 1 GeV, for normal (left) and inverted hierarchy (right). 68.3%CL 95.4%CL GAMBIT 1.4.0 G A M B I T …

**Figure 16.** Figure 16: One-dimensional profile likelihood for U 2 τ1 , Ltotal, and partial likelihoods for ΓZ , CKM , Rτ and combination of the rest of constraints, L0, in the high mass region, M1 > 60 GeV, for normal (left) and inverted hierarchy (right). The excesses shown in Figures 14–1…

**Figure 17.** Figure 17: Profile likelihood in M1 vs U 2 e1 plane without likelihood cap showing the excesses due to the RK constraint, for normal (left) and inverted hierarchy (right). 68.3%CL 95.4%CL GAMBIT 1.4.0 G A M B I T −2.5 −2.0 −1.5 −1.0 −0.5 0.0 Profile log likelihood Λ = lnL − ln L…

**Figure 18.** Figure 18: One-dimensional profile likelihood for U 2 e1 , Ltotal, and partial likelihoods for RK, CHARM and combination of the rest of constraints, L0, in the low mass region, M1 < 1 GeV, for normal (left) and inverted hierarchy (right). 6 Conclusions & Outlook We presented her…

**Figure 20.** Figure 20: Partial likelihood from direct searches with CHARM, e-channel, in the MI − |UeI | 2 plane. 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 log10(MI [GeV]) 10 9 8 7 6 5 4 3 2 1 lo g 1 0(|U eI|2 ) 12 10 8 6 4 2 0 [PITH_FULL_IMAGE:figures/full_fig_p045_20.png]

**Figure 21.** Figure 21: Partial likelihood from the long-lived particle searches with DELPHI, in the MI − |UeI | 2 plane. 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 log10(MI [GeV]) 10 9 8 7 6 5 4 3 2 1 lo g 1 0(|U eI|2 ) 12 10 8 6 4 2 0 [PITH_FULL_IMAGE:figures/full_fig_p045_21.png]

**Figure 19.** Figure 19: Partial likelihood from direct searches with PS191, e-channel, in the MI − |UeI | 2 plane. Figures 19 - 24 show the most constraining likelihoods on the |UeI | 2 coupling. The likelihood values are normalised to the best fit value for each partial likelihood. Consis…

**Figure 23.** Figure 23: Partial likelihood from direct searches with CMS, e-channel, in the MI − |UeI | 2 plane. 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 log10(MI [GeV]) 10 9 8 7 6 5 4 3 2 1 lo g 1 0(|U eI|2 ) 12 10 8 6 4 2 0 [PITH_FULL_IMAGE:figures/full_fig_p046_23.png]

**Figure 24.** Figure 24: Partial likelihood from sin θW , in the MI − |UeI | 2 plane. 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 log10(MI [GeV]) 10 9 8 7 6 5 4 3 2 1 lo g 1 0(|U I|2 ) 12 10 8 6 4 2 0 [PITH_FULL_IMAGE:figures/full_fig_p046_24.png]

**Figure 25.** Figure 25: Partial likelihood from direct searches with E949, µ-channel, in the MI − |UµI | 2 plane. Similar to the case above, the coupling |UµI | 2 is constrained from above by several direct and precision searches. Figures 25-31 show the effect of the individual likelihoods o…

**Figure 29.** Figure 29: Partial likelihood from the long-lived particle searches with DELPHI, in the MI − |UµI | 2 plane. 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 log10(MI [GeV]) 10 9 8 7 6 5 4 3 2 1 lo g 1 0(|U I|2 ) 12 10 8 6 4 2 0 [PITH_FULL_IMAGE:figures/full_fig_p047_29.png]

**Figure 30.** Figure 30: Partial likelihood from the prompt searches with DELPHI, in the MI − |UµI | 2 plane. 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 log10(MI [GeV]) 10 9 8 7 6 5 4 3 2 1 lo g 1 0(|U I|2 ) 12 10 8 6 4 2 0 [PITH_FULL_IMAGE:figures/full_fig_p047_30.png]

**Figure 31.** Figure 31: Partial likelihood from direct searches with CMS, µ-channel, in the MI − |UµI | 2 plane. Larger masses are not constrained by direct searches, but rather by a combination of precision limits. Contrary to |UeI | 2 , where only sin θW dominated at large masses, upper va…

**Figure 35.** Figure 35: Partial likelihood from the lepton flavour violating µ − e conversion, in the MI − |UeIUµI | plane. 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 log10(MI [GeV]) 10 9 8 7 6 5 4 3 2 1 lo g 1 0(|U I|2 ) 12 10 8 6 4 2 0 [PITH_FULL_IMAGE:figures/full_fig_p048_35.png]

**Figure 39.** Figure 39: Partial likelihood from direct searches with PS191, e-channel, in the MI − |Uτ I | 2 plane. 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 log10(MI [GeV]) 10 9 8 7 6 5 4 3 2 1 lo g 1 0(|U I|2 ) 12 10 8 6 4 2 0 [PITH_FULL_IMAGE:figures/full_fig_p048_39.png]

**Figure 40.** Figure 40: Partial likelihood from the invisible decay width of the Z-boson, in the MI − |Uτ I | 2 plane. In the mass range MI ∼ (0.3, 0.5) GeV, as well as for large masses MI & 80 GeV, direct searches do not constrain |Uτ I | 2 . Hence in these ranges, the strongest constraints…

Discussion (0). Continue with ORCID to comment.

Forward citations

Cited by 4 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

Muon Bremsstrahlung as a New Probe of Dark Sector at Neutrino Experiments
hep-ph 2026-07 conditional novelty 7.0 of 10

Muon bremsstrahlung from the focused muon beam at neutrino facilities can produce heavy neutral leptons up to ~1 GeV, opening new search territory for SBND and DUNE Near Detector.
Probing Solar Heavy Neutrinos with Heliospheric Electrons
astro-ph.HE 2024-12 conditional novelty 6.0 of 10

Using Ulysses and SOHO MeV electron data, the authors set the strongest direct upper bound U_e^2 ~ 10^-6 on solar-produced heavy neutral leptons, reaching that value at a mass near 10 MeV.
Low-scale seesaw with flavour and CP symmetries $\unicode{x2013}$ from colliders to leptogenesis
hep-ph 2024-12 conditional novelty 6.0 of 10

For four flavour-symmetry cases, this paper maps heavy-neutrino lifetimes, decay flavour ratios, and the parameter space where leptogenesis works and colliders can test it.
Archimedean Seesaw: Small Neutrino Masses and Large Lepton-number Violation
hep-ph 2026-08 conditional novelty 5.0 of 10

A texture-zero seesaw model allows large lepton-number violation together with naturally small neutrino masses by protecting the light neutrino with an accidental symmetry.

Reference graph

Works this paper leans on

223 extracted references · 7 canonical work pages · cited by 4 Pith papers

[1]

Minkowski,µ→eγat a Rate of One Out of 109 Muon Decays?, Phys

P. Minkowski,µ→eγat a Rate of One Out of 109 Muon Decays?, Phys. Lett. B67 (1977) 421–428

1977
[2]

R. N. Mohapatra and G. Senjanovic,Neutrino Mass and Spontaneous Parity Violation, Phys. Rev. Lett.44 (1980) 912. [,231(1979)]

1980
[3]

R. N. Mohapatra and G. Senjanovic,Neutrino Masses and Mixings in Gauge Models with Spontaneous Parity Violation, Phys. Rev. D23 (1981) 165

1981
[4]

Gell-Mann, P

M. Gell-Mann, P. Ramond, and R. Slansky, Complex Spinors and Uniﬁed Theories, Conf. Proc. C790927 (1979) 315–321, [arXiv:1306.4669]

arXiv 1979
[5]

Yanagida,Horizontal Symmetry and Masses of Neutrinos, Prog

T. Yanagida,Horizontal Symmetry and Masses of Neutrinos, Prog. Theor. Phys.64 (1980) 1103

1980
[6]

de Gouvea,See-saw energy scale and the LSND anomaly, Phys

A. de Gouvea,See-saw energy scale and the LSND anomaly, Phys. Rev.D72 (2005) 033005, [hep-ph/0501039]

arXiv 2005
[7]

Asaka and T

T. Asaka and T. Tsuyuki,Perturbativity in the seesaw mechanism, Phys. Lett. B753 (2016) 147–149, [arXiv:1509.02678]

arXiv 2016
[8]

Fukugita and T

M. Fukugita and T. Yanagida,Baryogenesis Without Grand Uniﬁcation, Phys. Lett. B174 (1986) 45–47

1986

Show all 223 references

[9]

E. K. Akhmedov, V. A. Rubakov, and A. Yu. Smirnov, Baryogenesis via neutrino oscillations, Phys. Rev. Lett.81 (1998) 1359–1362, [hep-ph/9803255]

1998 arXiv
[10]

Asaka and M

T. Asaka and M. Shaposhnikov,The nuMSM, dark matter and baryon asymmetry of the universe, Phys. Lett. B620 (2005) 17–26, [hep-ph/0505013]

2005 arXiv
[11]

Dodelson and L

S. Dodelson and L. M. Widrow,Sterile-neutrinos as dark matter, Phys. Rev. Lett.72 (1994) 17–20, [hep-ph/9303287]

1994 arXiv
[12]

Shi and G

X.-D. Shi and G. M. Fuller,A New dark matter candidate: Nonthermal sterile neutrinos, Phys. Rev. Lett.82 (1999) 2832–2835, [astro-ph/9810076]

1999 arXiv
[13]

Drewes,The Phenomenology of Right Handed Neutrinos, Int

M. Drewes,The Phenomenology of Right Handed Neutrinos, Int. J. Mod. Phys. E22 (2013) 1330019, [arXiv:1303.6912]

2013 arXiv
[14]

A. Atre, T. Han, S. Pascoli, and B. Zhang,The Search for Heavy Majorana Neutrinos, JHEP 05 (2009) 030, [arXiv:0901.3589]

2009 arXiv
[15]

Boyarsky, O

A. Boyarsky, O. Ruchayskiy, and M. Shaposhnikov,The Role of sterile neutrinos in cosmology and astrophysics, Ann. Rev. Nucl. Part. Sci. 59 (2009) 191–214, [arXiv:0901.0011]

2009 arXiv
[16]

F. F. Deppisch, P. S. Bhupal Dev, and A. Pilaftsis,Neutrinos and Collider Physics, New J. Phys.17 (2015) 075019, [arXiv:1502.06541]

2015 arXiv
[17]

Y. Cai, T. Han, T. Li, and R. Ruiz,Lepton Number Violation: Seesaw Models and Their Collider Tests, Front.in Phys.6 (2018) 40, [arXiv:1711.02180]

2018 arXiv
[18]

Antusch, E

S. Antusch, E. Cazzato, and O. Fischer,Sterile neutrino searches at futuree−e+, pp, ande−p colliders, Int. J. Mod. Phys.A32 (2017) 1750078, [arXiv:1612.02728]

2017 arXiv
[19]

Beachamet

J. Beachamet. al., Physics Beyond Colliders at CERN: Beyond the Standard Model Working Group Report, arXiv:1901.09966

1901 arXiv
[20]

Alimenaet

J. Alimenaet. al., Searching for long-lived particles beyond the Standard Model at the Large Hadron Collider, arXiv:1903.04497

1903
[21]

de Gouvêa and A

A. de Gouvêa and A. Kobach,Global Constraints on a Heavy Neutrino, Phys. Rev. D93 (2016) 033005, [arXiv:1511.00683]

2016 arXiv
[22]

Boyarsky, A

A. Boyarsky, A. Neronov, O. Ruchayskiy, and M. Shaposhnikov,The Masses of active neutrinos in the nuMSM from X-ray astronomy, JETP Lett. 83 (2006) 133–135, [hep-ph/0601098]

2006 arXiv
[23]

Adhikariet

R. Adhikariet. al., A White Paper on keV Sterile Neutrino Dark Matter, JCAP 1701 (2017) 025, [arXiv:1602.04816]

2017 arXiv
[24]

Boyarsky, M

A. Boyarsky, M. Drewes, T. Lasserre, S. Mertens, and O. Ruchayskiy,Sterile Neutrino Dark Matter, Prog. Part. Nucl. Phys.104 (2019) 1–45, [arXiv:1807.07938]

2019 arXiv
[25]

Antusch and O

S. Antusch and O. Fischer,Non-unitarity of the leptonic mixing matrix: Present bounds and future sensitivities, JHEP 10 (2014) 094, [arXiv:1407.6607]

2014 arXiv
[26]

Fernandez-Martinez, J

E. Fernandez-Martinez, J. Hernandez-Garcia, J. Lopez-Pavon, and M. Lucente,Loop level constraints on Seesaw neutrino mixing, JHEP 10 (2015) 130, [arXiv:1508.03051]

2015 arXiv
[27]

Drewes, B

M. Drewes, B. Garbrecht, D. Gueter, and J. Klaric,Testing the low scale seesaw and leptogenesis, JHEP 08 (2017) 018, [arXiv:1609.09069]

2017 arXiv
[28]

F. J. Escrihuela, D. V. Forero, O. G. Miranda, M. Tortola, and J. W. F. Valle,On the description of nonunitary neutrino mixing, Phys. Rev.D92 (2015) 053009, [arXiv:1503.08879]. [Erratum: Phys. Rev.D93,no.11,119905(2016)]

2015 arXiv
[29]

Fernandez-Martinez, J

E. Fernandez-Martinez, J. Hernandez-Garcia, and J. Lopez-Pavon,Global constraints on heavy neutrino mixing, JHEP 08 (2016) 033, [arXiv:1605.08774]

2016 arXiv
[30]

Drewes and B

M. Drewes and B. Garbrecht,Combining experimental and cosmological constraints on heavy neutrinos, Nucl. Phys. B921 (2017) 50 250–315, [arXiv:1502.00477]

2017 arXiv
[31]

Gorbunov and I

D. Gorbunov and I. Timiryasov,TestingνMSM with indirect searches, Phys. Lett. B745 (2015) 29–34, [arXiv:1412.7751]

2015 arXiv
[32]

Esteban, M

I. Esteban, M. C. Gonzalez-Garcia, M. Maltoni, I. Martinez-Soler, and T. Schwetz,Updated ﬁt to three neutrino mixing: exploring the accelerator-reactor complementarity, JHEP 01 (2017) 087, [arXiv:1611.01514]

2017 arXiv
[33]

Ferroglia and A

A. Ferroglia and A. Sirlin,Comparison of the standard theory predictions ofMW and sin2θlept eff with their experimental values, Phys. Rev. D87 (2013) 037501, [arXiv:1211.1864]

2013 arXiv
[34]

Y. Amhiset. al., Averages ofb-hadron,c-hadron, and τ-lepton properties as of summer 2016, arXiv:1612.07233

2016 arXiv
[35]

LHCb Collaboration: R. Aaijet. al., Test of lepton universality usingB+→K+𝓁+𝓁−decays, Phys. Rev. Lett.113 (2014) 151601, [arXiv:1406.6482]

2014 arXiv
[36]

LHCb Collaboration: R. Aaijet. al., Measurement of the ratio of branching fractions B( ¯B0→D∗+τ−¯ντ)/B( ¯B0→D∗+µ−¯νµ), Phys. Rev. Lett.115 (2015) 111803, [arXiv:1506.08614]. [Addendum: Phys. Rev. Lett. 115, no.15, 159901 (2015)]

2015
[37]

LHCb Collaboration: R. Aaijet. al., Test of lepton universality withB0→K∗0𝓁+𝓁−decays, JHEP 08 (2017) 055, [arXiv:1705.05802]

2017 arXiv
[38]

Ruchayskiy and A

O. Ruchayskiy and A. Ivashko,Experimental bounds on sterile neutrino mixing angles, JHEP 06 (2012) 100, [arXiv:1112.3319]

2012 arXiv
[39]

Athron, C

GAMBIT Collaboration: P. Athron, C. Balázs, et. al., GAMBIT: The Global and Modular Beyond-the-Standard-Model Inference Tool, Eur. Phys. J. C77 (2017) 784, [arXiv:1705.07908]

2017 arXiv
[40]

GAMBIT Scanner Workgroup: G. D. Martinez, J. McKay,et. al., Comparison of statistical sampling methods with ScannerBit, the GAMBIT scanning module, Eur. Phys. J. C77 (2017) 761, [arXiv:1705.07959]

2017 arXiv
[41]

Pilaftsis,Radiatively induced neutrino masses and large Higgs neutrino couplings in the standard model with Majorana ﬁelds, Z

A. Pilaftsis,Radiatively induced neutrino masses and large Higgs neutrino couplings in the standard model with Majorana ﬁelds, Z. Phys. C55 (1992) 275–282, [hep-ph/9901206]

1992 arXiv
[42]

Drewes,On the Minimal Mixing of Heavy Neutrinos, arXiv:1904.11959

M. Drewes,On the Minimal Mixing of Heavy Neutrinos, arXiv:1904.11959

1904 arXiv
[43]

Drewes, J

M. Drewes, J. Klarić, and P. Klose,On Lepton Number Violation in Heavy Neutrino Decays at Colliders, arXiv:1907.13034

1907 arXiv
[44]

J. A. Casas and A. Ibarra,Oscillating neutrinos and muon —> e, gamma, Nucl. Phys. B618 (2001) 171–204, [hep-ph/0103065]

2001 arXiv
[45]

Lopez-Pavon, E

J. Lopez-Pavon, E. Molinaro, and S. T. Petcov, Radiative Corrections to Light Neutrino Masses in Low Scale Type I Seesaw Scenarios and Neutrinoless Double Beta Decay, JHEP 11 (2015) 030, [arXiv:1506.05296]

2015 arXiv
[46]

Fukugita and T

M. Fukugita and T. Yanagida,Physics of neutrinos and applications to astrophysics. 2003

2003
[47]

Croon, T

D. Croon, T. E. Gonzalo, L. Graf, N. Košnik, and G. White,GUT Physics in the era of the LHC, Front.in Phys.7 (2019) 76, [arXiv:1903.04977]

2019 arXiv
[48]

Vissani,Do experiments suggest a hierarchy problem?, Phys

F. Vissani,Do experiments suggest a hierarchy problem?, Phys. Rev. D57 (1998) 7027–7030, [hep-ph/9709409]

1998 arXiv
[49]

G. F. Giudice,Naturally Speaking: The Naturalness Criterion and Physics at the LHC, arXiv:0801.2562

arXiv
[50]

C. D. Froggatt and H. B. Nielsen,Hierarchy of Quark Masses, Cabibbo Angles and CP Violation, Nucl. Phys.B147 (1979) 277–298

1979
[51]

’t Hooft,Naturalness, chiral symmetry, and spontaneous chiral symmetry breaking, NATO Sci

G. ’t Hooft,Naturalness, chiral symmetry, and spontaneous chiral symmetry breaking, NATO Sci. Ser. B59 (1980) 135–157

1980
[52]

Shaposhnikov,A Possible symmetry of the nuMSM, Nucl

M. Shaposhnikov,A Possible symmetry of the nuMSM, Nucl. Phys. B763 (2007) 49–59, [hep-ph/0605047]

2007 arXiv
[53]

Kersten and A

J. Kersten and A. Yu. Smirnov,Right-Handed Neutrinos at CERN LHC and the Mechanism of Neutrino Mass Generation, Phys. Rev. D76 (2007) 073005, [arXiv:0705.3221]

2007 arXiv
[54]

Gluza,On teraelectronvolt Majorana neutrinos, Acta Phys

J. Gluza,On teraelectronvolt Majorana neutrinos, Acta Phys. Polon.B33 (2002) 1735–1746, [hep-ph/0201002]

2002 arXiv
[55]

Moﬀat, S

K. Moﬀat, S. Pascoli, and C. Weiland,Equivalence between massless neutrinos and lepton number conservation in fermionic singlet extensions of the Standard Model, arXiv:1712.07611

arXiv
[56]

Abada, C

A. Abada, C. Biggio, F. Bonnet, M. B. Gavela, and T. Hambye,Low energy eﬀects of neutrino masses, JHEP 12 (2007) 061, [arXiv:0707.4058]

2007 arXiv
[57]

Abada, G

A. Abada, G. Arcadi,et. al., Low-scale leptogenesis with three heavy neutrinos, JHEP 01 (2019) 164, [arXiv:1810.12463]

2019 arXiv
[58]

Boyanovsky,Nearly degenerate heavy sterile neutrinos in cascade decay: mixing and oscillations, Phys

D. Boyanovsky,Nearly degenerate heavy sterile neutrinos in cascade decay: mixing and oscillations, Phys. Rev.D90 (2014) 105024, [arXiv:1409.4265]

2014 arXiv
[59]

Cvetic, C

G. Cvetic, C. S. Kim, R. Kogerler, and J. Zamora-Saa,Oscillation of heavy sterile neutrino in decay ofB→µeπ, Phys. Rev.D92 (2015) 013015, [arXiv:1505.04749]

2015 arXiv
[60]

Anamiati, M

G. Anamiati, M. Hirsch, and E. Nardi, Quasi-Dirac neutrinos at the LHC, JHEP 10 51 (2016) 010, [arXiv:1607.05641]

2016 arXiv
[61]

C. O. Dib, C. S. Kim, K. Wang, and J. Zhang, Distinguishing Dirac/Majorana Sterile Neutrinos at the LHC, Phys. Rev.D94 (2016) 013005, [arXiv:1605.01123]

2016 arXiv
[62]

A. Das, P. S. B. Dev, and R. N. Mohapatra,Same Sign versus Opposite Sign Dileptons as a Probe of Low Scale Seesaw Mechanisms, Phys. Rev.D97 (2018) 015018, [arXiv:1709.06553]

2018 arXiv
[63]

Antusch, E

S. Antusch, E. Cazzato, and O. Fischer,Heavy neutrino-antineutrino oscillations at colliders, arXiv:1709.03797

arXiv
[64]

Antusch, E

S. Antusch, E. Cazzato,et. al., Probing Leptogenesis at Future Colliders, JHEP 09 (2018) 124, [arXiv:1710.03744]

2018 arXiv
[65]

Cvetič, A

G. Cvetič, A. Das, and J. Zamora-Saá,Probing heavy neutrino oscillations in rareW boson decays, J. Phys.G46 (2019) 075002, [arXiv:1805.00070]

2019 arXiv
[66]

Hernández, J

P. Hernández, J. Jones-Pérez, and O. Suarez-Navarro,Majorana vs Pseudo-Dirac Neutrinos at the ILC, Eur. Phys. J.C79 (2019) 220, [arXiv:1810.07210]

2019 arXiv
[67]

Cvetič, A

G. Cvetič, A. Das, S. Tapia, and J. Zamora-Saá, Measuring the heavy neutrino oscillations in rare W boson decays at the Large Hadron Collider, arXiv:1905.03097

1905 arXiv
[68]

Wyler and L

D. Wyler and L. Wolfenstein,Massless Neutrinos in Left-Right Symmetric Models, Nucl. Phys. B 218 (1983) 205–214

1983
[69]

R. N. Mohapatra,Mechanism for Understanding Small Neutrino Mass in Superstring Theories, Phys. Rev. Lett.56 (1986) 561–563

1986
[70]

R. N. Mohapatra and J. W. F. Valle,Neutrino Mass and Baryon Number Nonconservation in Superstring Models, Phys. Rev. D34 (1986) 1642. [,235(1986)]

1986
[71]

Bernabeu, A

J. Bernabeu, A. Santamaria, J. Vidal, A. Mendez, and J. W. F. Valle,Lepton Flavor Nonconservation at High-Energies in a Superstring Inspired Standard Model, Phys. Lett. B 187 (1987) 303–308

1987
[72]

E. K. Akhmedov, M. Lindner, E. Schnapka, and J. W. F. Valle,Left-right symmetry breaking in NJL approach, Phys. Lett. B368 (1996) 270–280, [hep-ph/9507275]

1996 arXiv
[73]

E. K. Akhmedov, M. Lindner, E. Schnapka, and J. W. F. Valle,Dynamical left-right symmetry breaking, Phys. Rev. D53 (1996) 2752–2780, [hep-ph/9509255]

1996 arXiv
[74]

V. V. Khoze and G. Ro,Leptogenesis and Neutrino Oscillations in the Classically Conformal Standard Model with the Higgs Portal, JHEP 10 (2013) 075, [arXiv:1307.3764]

2013 arXiv
[75]

Appelquist and R

T. Appelquist and R. Shrock,Neutrino masses in theories with dynamical electroweak symmetry breaking, Phys. Lett. B548 (2002) 204–214, [hep-ph/0204141]

2002 arXiv
[76]

Appelquist and R

T. Appelquist and R. Shrock,Dynamical symmetry breaking of extended gauge symmetries, Phys. Rev. Lett.90 (2003) 201801, [hep-ph/0301108]

2003 arXiv
[77]

NuFit 3.2 (2018)

I. Esteban, M. C. Gonzalez-Garcia, M. Maltoni, I. Martinez-Soler, and T. Schwetz, “NuFit 3.2 (2018).”

2018
[78]

B. T. Cleveland, T. Daily,et. al., Measurement of the solar electron neutrino ﬂux with the Homestake chlorine detector, ApJ 496 (1998) 505–526

1998
[79]

Kaether, W

F. Kaether, W. Hampel, G. Heusser, J. Kiko, and T. Kirsten,Reanalysis of the GALLEX solar neutrino ﬂux and source experiments, Phys. Lett. B 685 (2010) 47–54, [arXiv:1001.2731]

2010 arXiv
[80]

SAGE: J. N. Abdurashitovet. al., Measurement of the solar neutrino capture rate with gallium metal. III: Results for the 2002–2007 data-taking period, Phys. Rev. C80 (2009) 015807, [arXiv:0901.2200]

2009 arXiv
[81]

Aharmimet

SNO: B. Aharmimet. al., Combined Analysis of all Three Phases of Solar Neutrino Data from the Sudbury Neutrino Observatory, Phys. Rev. C88 (2013) 025501, [arXiv:1109.0763]

2013 arXiv
[82]

Hosakaet

Super-Kamiokande: J. Hosakaet. al., Solar neutrino measurements in super-Kamiokande-I, Phys. Rev. D73 (2006) 112001, [hep-ex/0508053]

2006 arXiv
[83]

Super-Kamiokande: J. P. Cravenset. al., Solar neutrino measurements in Super-Kamiokande-II, Phys. Rev. D78 (2008) 032002, [arXiv:0803.4312]

2008 arXiv
[84]

Super-Kamiokande: K. Abeet. al., Solar neutrino results in Super-Kamiokande-III, Phys. Rev. D83 (2011) 052010, [arXiv:1010.0118]

2011 arXiv
[85]

Belliniet

G. Belliniet. al., Precision measurement of the 7Be solar neutrino interaction rate in Borexino, Phys. Rev. Lett.107 (2011) 141302, [arXiv:1104.1816]

2011 arXiv
[86]

Belliniet

Borexino: G. Belliniet. al., Measurement of the solar 8B neutrino rate with a liquid scintillator target and 3 MeV energy threshold in the Borexino detector, Phys. Rev. D82 (2010) 033006, [arXiv:0808.2868]

2010 arXiv
[87]

Belliniet

BOREXINO: G. Belliniet. al., Neutrinos from the primary proton–proton fusion process in the Sun, Nature512 (2014) 383–386. 52

2014
[88]

IceCube: M. G. Aartsenet. al., Determining neutrino oscillation parameters from atmospheric muon neutrino disappearance with three years of IceCube DeepCore data, Phys. Rev. D91 (2015) 072004, [arXiv:1410.7227]

2015 arXiv
[89]

KamLAND: A. Gandoet. al., Reactor On-Oﬀ Antineutrino Measurement with KamLAND, Phys. Rev. D88 (2013) 033001, [arXiv:1303.4667]

2013 arXiv
[90]

Daya Bay: F. P. Anet. al., Improved Measurement of the Reactor Antineutrino Flux and Spectrum at Daya Bay, Chin. Phys.C41 (2017) 013002, [arXiv:1607.05378]

2017 arXiv
[91]

Daya Bay: F. P. Anet. al., Measurement of electron antineutrino oscillation based on 1230 days of operation of the Daya Bay experiment, Phys. Rev. D95 (2017) 072006, [arXiv:1610.04802]

2017 arXiv
[92]

New Results from RENO. - 2017. Talk given at the EPS Conference on High Energy Physics, Venice, Italy, July 5-12

H. Seo, “New Results from RENO. - 2017. Talk given at the EPS Conference on High Energy Physics, Venice, Italy, July 5-12.”

2017
[93]

Adamsonet

MINOS: P. Adamsonet. al., Measurement of Neutrino and Antineutrino Oscillations Using Beam and Atmospheric Data in MINOS, Phys. Rev. Lett.110 (2013) 251801, [arXiv:1304.6335]

2013 arXiv
[94]

Adamsonet

MINOS: P. Adamsonet. al., Electron neutrino and antineutrino appearance in the full MINOS data sample, Phys. Rev. Lett.110 (2013) 171801, [arXiv:1301.4581]

2013 arXiv
[95]

T2K Neutrino Experiment. Recent Results and Plans. - 2017. Talk given at the Flavour Physics Conference, Quy Nhon, Vietnam, August 13-19

A. Izmaylov, “T2K Neutrino Experiment. Recent Results and Plans. - 2017. Talk given at the Flavour Physics Conference, Quy Nhon, Vietnam, August 13-19..”

2017
[96]

Latest oscillation results from NOvA. - 2018. Fermilab. Joint Experimental-Theoretical Physics Seminar USA, January 12

A. Radovic, “Latest oscillation results from NOvA. - 2018. Fermilab. Joint Experimental-Theoretical Physics Seminar USA, January 12..”

2018
[97]

Planck Collaboration: P. A. R. Adeet. al., Planck 2015 results. XIII. Cosmological parameters, Astropart. Phys.594 (2016) A13, [arXiv:1502.01589]

2016 arXiv
[98]

Antusch and O

S. Antusch and O. Fischer,Testing sterile neutrino extensions of the Standard Model at future lepton colliders, JHEP 05 (2015) 053, [arXiv:1502.05915]

2015 arXiv
[99]

Abada, A

A. Abada, A. M. Teixeira, A. Vicente, and C. Weiland,Sterile neutrinos in leptonic and semileptonic decays, JHEP 02 (2014) 091, [arXiv:1311.2830]

2014 arXiv
[100]

Dubovyk, A

I. Dubovyk, A. Freitas, J. Gluza, T. Riemann, and J. Usovitsch,Complete electroweak two-loop corrections to Z boson production and decay, Phys. Lett. B783 (2018) 86–94, [arXiv:1804.10236]

2018 arXiv
[101]

Particle Data Group: K. A. Oliveet. al., Review of Particle Physics, update to Ref. [? ] (2017)

2017
[102]

S. L. Glashow, J. Iliopoulos, and L. Maiani,Weak Interactions with Lepton-Hadron Symmetry, Phys. Rev. D2 (1970) 1285–1292

1970
[103]

MEG: A. M. Baldiniet. al., Search for the lepton ﬂavour violating decayµ+→e+γwith the full dataset of the MEG experiment, Eur. Phys. J. C 76 (2016) 434, [arXiv:1605.05081]

2016 arXiv
[104]

Aubertet

BaBar: B. Aubertet. al., Searches for Lepton Flavor Violation in the Decays tau+- —> e+- gamma and tau+- —> mu+- gamma, Phys. Rev. Lett.104 (2010) 021802, [arXiv:0908.2381]

2010 arXiv
[105]

Hayasakaet

Belle: K. Hayasakaet. al., New Search for tau -> mu gamma and tau -> e gamma Decays at Belle, Phys. Lett. B666 (2008) 16–22, [arXiv:0705.0650]

2008 arXiv
[106]

Bellgardtet

SINDRUM: U. Bellgardtet. al., Search for the Decay mu+ —> e+ e+ e-, Nucl. Phys. B299 (1988) 1–6

1988
[107]

BaBar: J. P. Leeset. al., Limits on tau Lepton-Flavor Violating Decays in three charged leptons, Phys. Rev. D81 (2010) 111101, [arXiv:1002.4550]

2010 arXiv
[108]

Hayasakaet

K. Hayasakaet. al., Search for Lepton Flavor Violating Tau Decays into Three Leptons with 719 Million Produced Tau+Tau- Pairs, Phys. Lett. B 687 (2010) 139–143, [arXiv:1001.3221]

2010 arXiv
[109]

ATLAS Collaboration: G. Aadet. al., Probing lepton ﬂavour violation via neutrinolessτ−→3µ decays with the ATLAS detector, Eur. Phys. J. C 76 (2016) 232, [arXiv:1601.03567]

2016 arXiv
[110]

LHCb Collaboration: R. Aaijet. al., Search for the lepton ﬂavour violating decayτ−→µ−µ+µ−, JHEP 02 (2015) 121, [arXiv:1409.8548]

2015 arXiv
[111]

Dohmenet

SINDRUM II: C. Dohmenet. al., Test of lepton ﬂavor conservation in mu —> e conversion on titanium, Phys. Lett.B317 (1993) 631–636

1993
[112]

SINDRUM II: W. H. Bertlet. al., A Search for muon to electron conversion in muonic gold, Eur. Phys. J.C47 (2006) 337–346

2006
[113]

Honeckeret

SINDRUM II: W. Honeckeret. al., Improved limit on the branching ratio of mu —> e conversion on lead, Phys. Rev. Lett.76 (1996) 200–203

1996
[114]

Ilakovac and A

A. Ilakovac and A. Pilaftsis,Flavor violating charged lepton decays in seesaw-type models, Nucl. Phys. B437 (1995) 491, [hep-ph/9403398]

1995 arXiv
[115]

S. M. Boucenna, J. W. F. Valle, and A. Vicente, Are the B decay anomalies related to neutrino oscillations?, Phys. Lett. B750 (2015) 367–371, [arXiv:1503.07099]

2015 arXiv
[116]

D. A. Bryman and R. Shrock,Improved Constraints on Sterile Neutrinos in the MeV to 53 GeV Mass Range, arXiv:1904.06787

1904 arXiv
[117]

R. E. Shrock,General Theory of Weak Leptonic and Semileptonic Decays. 1. Leptonic Pseudoscalar Meson Decays, with Associated Tests For, and Bounds on, Neutrino Masses and Lepton Mixing, Phys. Rev. D24 (1981) 1232

1981
[118]

Cirigliano and I

V. Cirigliano and I. Rosell,Two-loop eﬀective theory analysis ofπ(K)→e ¯νe[γ] branching ratios, Phys. Rev. Lett.99 (2007) 231801, [arXiv:0707.3439]

2007 arXiv
[119]

Ghosh, M

D. Ghosh, M. Nardecchia, and S. A. Renner,Hint of Lepton Flavour Non-Universality inB Meson Decays, JHEP 12 (2014) 131, [arXiv:1408.4097]

2014 arXiv
[120]

He and G

X.-G. He and G. Valencia,Are the B-anomalies evidence for heavy neutrinos?, arXiv:1706.07570

arXiv
[121]

Altmannshofer, P

W. Altmannshofer, P. Ball,et. al., Symmetries and Asymmetries ofB→K∗µ+µ−Decays in the Standard Model and Beyond, JHEP 01 (2009) 019, [arXiv:0811.1214]

2009 arXiv
[122]

Choudhury, A

D. Choudhury, A. Kundu, R. Mandal, and R. Sinha,RK(∗) and R(D(∗)) anomalies resolved with lepton mixing, arXiv:1712.01593

arXiv
[123]

A. Pich, I. Boyko, D. Dedovich, and I. I. Bigi,Tau decays, Int. J. Mod. Phys. A24S1 (2009) 715–737

2009
[124]

Tanabashiet

Particle Data Group: M. Tanabashiet. al., Review of Particle Physics, Phys. Rev.D98 (2018) 030001

2018
[125]

Lazzeroniet

NA62 Collaboration: C. Lazzeroniet. al., Precision Measurement of the Ratio of the Charged Kaon Leptonic Decay Rates, Phys. Lett. B 719 (2013) 326–336, [arXiv:1212.4012]

2013 arXiv
[126]

LHCb Collaboration: R. Aaijet. al., Measurement of forwardW→eνproduction inpp collisions at√s = 8TeV, JHEP 10 (2016) 030, [arXiv:1608.01484]

2016 arXiv
[127]

Schaelet

DELPHI, OPAL, LEP Electroweak, ALEPH, L3: S. Schaelet. al., Electroweak Measurements in Electron-Positron Collisions at W-Boson-Pair Energies at LEP, Phys. Rep.532 (2013) 119–244, [arXiv:1302.3415]

2013 arXiv
[128]

D. I. Brittonet. al., Measurement of the pi+ —> e+ neutrino branching ratio, Phys. Rev. Lett.68 (1992) 3000–3003

1992
[129]

Czapeket

G. Czapeket. al., Branching ratio for the rare pion decay into positron and neutrino, Phys. Rev. Lett.70 (1993) 17–20

1993
[130]

Aguilar-Arevaloet

PiENu: A. Aguilar-Arevaloet. al., Improved Measurement of theπ→eνBranching Ratio, Phys. Rev. Lett.115 (2015) 071801, [arXiv:1506.05845]

2015 arXiv
[131]

Antonelliet

FlaviaNet Working Group on Kaon Decays: M. Antonelliet. al., An Evaluation of|Vus|and precise tests of the Standard Model from world data on leptonic and semileptonic kaon decays, Eur. Phys. J. C69 (2010) 399–424, [arXiv:1005.2323]

2010 arXiv
[132]

Follana, C

HPQCD, UKQCD: E. Follana, C. T. H. Davies, G. P. Lepage, and J. Shigemitsu,High Precision determination of the pi, K, D and D(s) decay constants from lattice QCD, Phys. Rev. Lett.100 (2008) 062002, [arXiv:0706.1726]

2008 arXiv
[133]

Heavy Flavor Averaging Group: Y. Amhiset. al., Averages of B-Hadron, C-Hadron, and tau-lepton properties as of early 2012, arXiv:1207.1158

2012 arXiv
[134]

Patrignaniet

Particle Data Group: C. Patrignaniet. al., Review of Particle Physics, Chin. Phys. C40 (2016) 100001

2016
[135]

S. Aokiet. al., Review of lattice results concerning low-energy particle physics, Eur. Phys. J. C77 (2017) 112, [arXiv:1607.00299]

2017 arXiv
[136]

Agostiniet

M. Agostiniet. al., Background-free search for neutrinoless double-βdecay of76Ge with GERDA, arXiv:1703.00570. [Nature544,47(2017)]

2017 arXiv
[137]

KamLAND-Zen: A. Gandoet. al., Search for Majorana Neutrinos near the Inverted Mass Hierarchy Region with KamLAND-Zen, Phys. Rev. Lett.117 (2016) 082503, [arXiv:1605.02889]. [Addendum: Phys. Rev. Lett.117,no.10,109903(2016)]

2016 arXiv
[138]

Drewes and S

M. Drewes and S. Eijima,Neutrinoless doubleβ decay and low scale leptogenesis, Phys. Lett. B 763 (2016) 72–79, [arXiv:1606.06221]

2016 arXiv
[139]

Faessler, M

A. Faessler, M. González, S. Kovalenko, and F. ’imkovic,Arbitrary mass Majorana neutrinos in neutrinoless double beta decay, Phys. Rev. D90 (2014) 096010, [arXiv:1408.6077]

2014 arXiv
[140]

A. D. Dolgov and F. L. Villante,BBN bounds on active sterile neutrino mixing, Nucl. Phys. B679 (2004) 261–298, [hep-ph/0308083]

2004 arXiv
[141]

Bondarenko, A

K. Bondarenko, A. Boyarsky, D. Gorbunov, and O. Ruchayskiy,Phenomenology of GeV-scale Heavy Neutral Leptons, JHEP 11 (2018) 032, [arXiv:1805.08567]

2018 arXiv
[142]

Gorbunov and M

D. Gorbunov and M. Shaposhnikov,How to ﬁnd neutral leptons of theνMSM?, JHEP 10 (2007) 015, [arXiv:0705.1729]. [Erratum: JHEP11,101(2013)]

2007 arXiv
[143]

Canetti, M

L. Canetti, M. Drewes, T. Frossard, and M. Shaposhnikov,Dark Matter, Baryogenesis and Neutrino Oscillations from Right Handed Neutrinos, Phys. Rev. D87 (2013) 093006, [arXiv:1208.4607]. 54

2013 arXiv
[144]

Ballett, T

P. Ballett, T. Boschi, and S. Pascoli,Heavy Neutral Leptons from low-scale seesaws at the DUNE Near Detector, arXiv:1905.00284

1905 arXiv
[145]

Ruchayskiy and A

O. Ruchayskiy and A. Ivashko,Restrictions on the lifetime of sterile neutrinos from primordial nucleosynthesis, JCAP 1210 (2012) 014, [arXiv:1202.2841]

2012 arXiv
[146]

Hernandez, M

P. Hernandez, M. Kekic, and J. Lopez-Pavon,Neﬀ in low-scale seesaw models versus the lightest neutrino mass, Phys. Rev. D90 (2014) 065033, [arXiv:1406.2961]

2014 arXiv
[147]

G. J. Feldman and R. D. Cousins,A Uniﬁed approach to the classical statistical analysis of small signals, Phys. Rev. D57 (1998) 3873–3889, [physics/9711021]

1998 arXiv
[148]

PIENU: M. Aokiet. al., Search for Massive Neutrinos in the Decayπ→eν, Phys. Rev.D84 (2011) 052002, [arXiv:1106.4055]

2011 arXiv
[149]

Aguilar-Arevaloet

PIENU: A. Aguilar-Arevaloet. al., Improved search for heavy neutrinos in the decayπ→eν, Phys. Rev.D97 (2018) 072012, [arXiv:1712.03275]

2018 arXiv
[150]

Bernardiet

G. Bernardiet. al., FURTHER LIMITS ON HEAVY NEUTRINO COUPLINGS, Phys. Lett. B203 (1988) 332–334

1988
[151]

Bergsmaet

CHARM: F. Bergsmaet. al., A Search for Decays of Heavy Neutrinos in the Mass Range 0.5-GeV to 2.8-GeV, Phys. Lett. B166 (1986) 473–478

1986
[152]

Orloﬀ, A

J. Orloﬀ, A. N. Rozanov, and C. Santoni,Limits on the mixing of tau neutrino to heavy neutrinos, Phys. Lett.B550 (2002) 8–15, [hep-ph/0208075]

2002 arXiv
[153]

A. T. Shaykhiev, Yu. G. Kudenko, and A. N. Khotyantsev, Searches for heavy neutrinos in the decays of positively charged kaons, Phys. Atom. Nucl. 74 (2011) 788–793. [Yad. Fiz.74,814(2011)]

2011
[154]

E949: A. V. Artamonovet. al., Search for heavy neutrinos inK+→µ+νH decays, Phys. Rev. D 91 (2015) 052001, [arXiv:1411.3963]. [Erratum: Phys. Rev. D 91,no.5,059903(2015)]

2015 arXiv
[155]

Vaitaitiset

NuTeV, E815: A. Vaitaitiset. al., Search for neutral heavy leptons in a high-energy neutrino beam, Phys. Rev. Lett.83 (1999) 4943–4946, [hep-ex/9908011]

1999 arXiv
[156]

DELPHI: P. Abreuet. al., A Study of the reaction e+e−→µ+µ−γ(ISR) at LEP and search for new physics at annihilation energies near 80-GeV, Z. Phys. C75 (1997) 581–592

1997
[157]

Lurkinet

NA62: N. Lurkinet. al., Heavy neutrino searches and NA62 status, inProceedings, 52nd Rencontres de Moriond on Electroweak Interactions and Uniﬁed Theories: La Thuile, Italy, March 18-25, 2017 (2017) 171–178, [arXiv:1808.00827]

2017 arXiv
[158]

ATLAS Collaboration: G. Aadet. al., Search for heavy Majorana neutrinos with the ATLAS detector in pp collisions at√s = 8 TeV, JHEP 07 (2015) 162, [arXiv:1506.06020]

2015 arXiv
[159]

CMS Collaboration: A. M. Sirunyanet. al., Search for heavy neutral leptons in events with three charged leptons in proton-proton collisions at√s = 13 TeV, Phys. Rev. Lett.120 (2018) 221801, [arXiv:1802.02965]

2018 arXiv
[160]

ATLAS: G. Aadet. al., Search for heavy neutral leptons in decays ofW bosons produced in 13 TeV pp collisions using prompt and displaced signatures with the ATLAS detector, arXiv:1905.09787

1905 arXiv
[161]

Collaboration,Search for heavy Majorana neutrinos in the same-sign dilepton channel in proton-proton collisions at√s = 13 TeV,

CMS: C. Collaboration,Search for heavy Majorana neutrinos in the same-sign dilepton channel in proton-proton collisions at√s = 13 TeV,
[162]

CMS: A. M. Sirunyanet. al., Search for heavy Majorana neutrinos in same-sign dilepton channels in proton-proton collisions at√s = 13 TeV, JHEP 01 (2019) 122, [arXiv:1806.10905]

2019 arXiv
[163]

LHCb: R. Aaijet. al., Search for Majorana neutrinos inB−→π+µ−µ−decays, Phys. Rev. Lett.112 (2014) 131802, [arXiv:1401.5361]

2014 arXiv
[164]

Shuve and M

B. Shuve and M. E. Peskin,Revision of the LHCb Limit on Majorana Neutrinos, Phys. Rev.D94 (2016) 113007, [arXiv:1607.04258]

2016 arXiv
[165]

Antusch, E

S. Antusch, E. Cazzato, and O. Fischer,Sterile neutrino searches via displaced vertices at LHCb, Phys. Lett.B774 (2017) 114–118, [arXiv:1706.05990]

2017 arXiv
[166]

LHCb: R. Aaijet. al., Search for massive long-lived particles decaying semileptonically in the LHCb detector, Eur. Phys. J.C77 (2017) 224, [arXiv:1612.00945]

2017 arXiv
[167]

H. O. Backet. al., New experimental limits on heavy neutrino mixing in B-8 decay obtained with the Borexino Counting Test Facility, JETP Lett. 78 (2003) 261–266. [Pisma Zh. Eksp. Teor. Fiz.78,707(2003)]

2003
[168]

Hagner, M

C. Hagner, M. Altmann,et. al., Experimental search for the neutrino decay neutrino (3) —> j-neutrino + e+ + e- and limits on neutrino mixing, Phys. Rev.D52 (1995) 1343–1352

1995
[169]

Abela, M

R. Abela, M. Daum,et. al., Search for an Admixture of Heavy Neutrino in Pion Decay, Phys. Lett.105B (1981) 263–266. [Erratum: Phys. Lett.106B,513(1981)]

1981
[170]

WA66: A. M. Cooper-Sarkaret. al., Search for Heavy Neutrino Decays in the BEBC Beam Dump Experiment, Phys. Lett.160B (1985) 207–211. 55

1985
[171]

S. A. Baranovet. al., Search for heavy neutrinos at the IHEP-JINR neutrino detector, Phys. Lett. B302 (1993) 336–340

1993
[172]

D. I. Brittonet. al., Improved search for massive neutrinos in pi+ —> e+ neutrino decay, Phys. Rev.D46 (1992) R885–R887

1992
[173]

OKA: A. S. Sadovskyet. al., Search for heavy neutrino inK+→µ+νH decay, Eur. Phys. J. C78 (2018) 92, [arXiv:1709.01473]

2018 arXiv
[174]

Aguilar-Arevaloet

PIENU: A. Aguilar-Arevaloet. al., Search for Heavy Neutrinos inπ→µνDecay, arXiv:1904.03269

1904 arXiv
[175]

ISTRA+: V. A. Duket. al., Search for Heavy Neutrino inK−−>µ−νh(νh−>νγ) Decay at ISTRA+ Setup, Phys. Lett.B710 (2012) 307–317, [arXiv:1110.1610]

2012 arXiv
[176]

Astieret

NOMAD: P. Astieret. al., Search for heavy neutrinos mixing with tau neutrinos, Phys. Lett. B506 (2001) 27–38, [hep-ex/0101041]

2001 arXiv
[177]

Cortina Gilet

NA62: E. Cortina Gilet. al., Search for heavy neutral lepton production inK+ decays, Phys. Lett.B778 (2018) 137–145, [arXiv:1712.00297]

2018 arXiv
[178]

Liventsevet

Belle: D. Liventsevet. al., Search for heavy neutrinos at Belle, Phys. Rev.D87 (2013) 071102, [arXiv:1301.1105]. [Erratum: Phys. Rev.D95,no.9,099903(2017)]

2013 arXiv
[179]

R. S. Hayanoet. al., HEAVY NEUTRINO SEARCH USING K(mu2) DECAY, Phys. Rev. Lett.49 (1982) 1305

1982
[180]

Yamazakiet

T. Yamazakiet. al., Search for Heavy Neutrinos in Kaon Decay, . [Conf. Proc.C840719,262(1984)]

1984
[181]

T2K: K. Abeet. al., Search for heavy neutrinos with the T2K near detector ND280, arXiv:1902.07598

1902 arXiv
[182]

S. S. Wilks,The Large-Sample Distribution of the Likelihood Ratio for Testing Composite Hypotheses, Annals Math. Statist.9 (1938) 60–62

1938
[183]

T. Abe, M. Fujiwara, and J. Hisano,Loop corrections to dark matter direct detection in a pseudoscalar mediator dark matter model, arXiv:1810.01039

arXiv
[184]

GAMBIT Collaboration, Supplementary Data: A Frequentist Analysis of Three Right-Handed Neutrinos with GAMBIT, (2019), https://doi.org/10.5281/zenodo.3334971

2019 doi
[185]

Balázs, A

GAMBIT Collider Workgroup: C. Balázs, A. Buckley,et. al., ColliderBit: a GAMBIT module for the calculation of high-energy collider observables and likelihoods, Eur. Phys. J. C77 (2017) 795, [arXiv:1705.07919]

2017 arXiv
[186]

Athron, C

GAMBIT Collaboration: P. Athron, C. Balázs, et. al., Combined collider constraints on neutralinos and charginos, Eur. Phys. J.C79 (2019) 395, [arXiv:1809.02097]

2019 arXiv
[187]

Scott,Pippi – painless parsing, post-processing and plotting of posterior and likelihood samples, Eur

P. Scott,Pippi – painless parsing, post-processing and plotting of posterior and likelihood samples, Eur. Phys. J. Plus127 (2012) 138, [arXiv:1206.2245]

2012 arXiv
[188]

Drewes, J

M. Drewes, J. Hajer, J. Klaric, and G. Lanfranchi, NA62 sensitivity to heavy neutral leptons in the low scale seesaw model, JHEP 07 (2018) 105, [arXiv:1801.04207]

2018 arXiv
[189]

Hernandez, M

P. Hernandez, M. Kekic, J. Lopez-Pavon, J. Racker, and J. Salvado,Testable Baryogenesis in Seesaw Models, JHEP 08 (2016) 157, [arXiv:1606.06719]

2016 arXiv
[190]

P. D. Bolton, F. F. Deppisch, and P. S. B. Dev, Neutrinoless double beta decay versus other probes of heavy sterile neutrinos, arXiv:1912.03058

1912 arXiv
[191]

Aghanimet

Planck: N. Aghanimet. al., Planck 2018 results. VI. Cosmological parameters, arXiv:1807.06209

2018 arXiv
[192]

Drewes and J

M. Drewes and J. Hajer,Heavy Neutrinos in displaced vertex searches at the LHC and HL-LHC, arXiv:1903.06100

1903 arXiv
[193]

Akhmedov, A

E. Akhmedov, A. Kartavtsev, M. Lindner, L. Michaels, and J. Smirnov,Improving Electro-Weak Fits with TeV-scale Sterile Neutrinos, JHEP 05 (2013) 081, [arXiv:1302.1872]

2013 arXiv
[194]

J. Fan, M. Reece, and L.-T. Wang,Possible Futures of Electroweak Precision: ILC, FCC-ee, and CEPC, JHEP 09 (2015) 196, [arXiv:1411.1054]

2015 arXiv
[195]

Abbiendiet

OPAL: G. Abbiendiet. al., Precise determination of the Z resonance parameters at LEP: ’Zedometry’, Eur. Phys. J.C19 (2001) 587–651, [hep-ex/0012018]

2001 arXiv
[196]

Goudzovski,Lepton ﬂavour universality test at the CERN NA62 experiment, Nucl

NA62: E. Goudzovski,Lepton ﬂavour universality test at the CERN NA62 experiment, Nucl. Phys. Proc. Suppl.210-211 (2011) 163–168, [arXiv:1008.1219]

2011 arXiv
[197]

J. L. Feng, I. Galon, F. Kling, and S. Trojanowski, ForwArd Search ExpeRiment at the LHC, Phys. Rev.D97 (2018) 035001, [arXiv:1708.09389]

2018 arXiv
[198]

J. P. Chou, D. Curtin, and H. J. Lubatti,New Detectors to Explore the Lifetime Frontier, Phys. Lett.B767 (2017) 29–36, [arXiv:1606.06298]

2017 arXiv
[199]

Kling and S

F. Kling and S. Trojanowski,Heavy Neutral Leptons at FASER, Phys. Rev.D97 (2018) 095016, [arXiv:1801.08947]

2018 arXiv
[200]

V. V. Gligorov, S. Knapen, M. Papucci, and D. J. Robinson, Searching for Long-lived Particles: A Compact Detector for Exotics at LHCb, Phys. Rev. D97 (2018) 015023, [arXiv:1708.09395]

2018 arXiv
[201]

Curtinet

D. Curtinet. al., Long-Lived Particles at the Energy Frontier: The MATHUSLA Physics Case, 56 arXiv:1806.07396

arXiv
[202]

Dercks, H

D. Dercks, H. K. Dreiner, M. Hirsch, and Z. S. Wang,Long-Lived Fermions at AL3X, Phys. Rev. D99 (2019) 055020, [arXiv:1811.01995]

2019 arXiv
[203]

Alpigianiet

MATHUSLA: C. Alpigianiet. al., A Letter of Intent for MATHUSLA: A Dedicated Displaced Vertex Detector above ATLAS or CMS., arXiv:1811.00927

arXiv
[204]

J. C. Helo, M. Hirsch, and Z. S. Wang,Heavy neutral fermions at the high-luminosity LHC, JHEP 07 (2018) 056, [arXiv:1803.02212]

2018 arXiv
[205]

Alekhinet

S. Alekhinet. al., A facility to Search for Hidden Particles at the CERN SPS: the SHiP physics case, Rept. Prog. Phys.79 (2016) 124201, [arXiv:1504.04855]

2016 arXiv
[206]

Anelliet

SHiP: M. Anelliet. al., A facility to Search for Hidden Particles (SHiP) at the CERN SPS, arXiv:1504.04956

arXiv
[207]

Ahdidaet

SHiP: C. Ahdidaet. al., Sensitivity of the SHiP experiment to Heavy Neutral Leptons, JHEP 04 (2019) 077, [arXiv:1811.00930]

2019 arXiv
[208]

FCC: A. Abadaet. al., FCC-ee: The Lepton Collider, Eur. Phys. J. ST228 (2019) 261–623

2019
[209]

CEPC Study Group: M. Donget. al., CEPC Conceptual Design Report: Volume 2 - Physics & Detector, arXiv:1811.10545

arXiv
[210]

E. J. Chunet. al., Probing Leptogenesis, Int. J. Mod. Phys.A33 (2018) 1842005, [arXiv:1711.02865]

2018 arXiv
[211]

Bringmann, J

GAMBIT Dark Matter Workgroup: T. Bringmann, J. Conrad,et. al., DarkBit: A GAMBIT module for computing dark matter observables and likelihoods, Eur. Phys. J. C77 (2017) 831, [arXiv:1705.07920]

2017 arXiv
[212]

B. C. Allanachet. al., SUSY Les Houches Accord 2, Comp. Phys. Comm.180 (2009) 8–25, [arXiv:0801.0045]

2009 arXiv
[213]

GAMBIT Flavour Workgroup: F. U. Bernlochner, M. Chrząszcz,et. al., FlavBit: A GAMBIT module for computing ﬂavour observables and likelihoods, Eur. Phys. J. C77 (2017) 786, [arXiv:1705.07933]

2017 arXiv
[214]

Athron, C

GAMBIT Models Workgroup: P. Athron, C. Balázs,et. al., SpecBit, DecayBit and PrecisionBit: GAMBIT modules for computing mass spectra, particle decay rates and precision observables, Eur. Phys. J. C78 (2018) 22, [arXiv:1705.07936]

2018 arXiv
[215]

Kuno and Y

Y. Kuno and Y. Okada,Muon decay and physics beyond the standard model, Rev. Mod. Phys.73 (2001) 151–202, [hep-ph/9909265]

2001 arXiv
[216]

Abada, M

A. Abada, M. E. Krauss,et. al., Lepton ﬂavor violation in low-scale seesaw models: SUSY and non-SUSY contributions, JHEP 11 (2014) 048, [arXiv:1408.0138]

2014 arXiv
[217]

T. S. Kosmas, S. Kovalenko, and I. Schmidt, Nuclear muon- e- conversion in strange quark sea, Phys. Lett. B511 (2001) 203, [hep-ph/0102101]

2001 arXiv
[218]

Alonso, M

R. Alonso, M. Dhen, M. B. Gavela, and T. Hambye,Muon conversion to electron in nuclei in type-I seesaw models, JHEP 01 (2013) 118, [arXiv:1209.2679]

2013 arXiv
[219]

J. L. Rosner, S. Stone, and R. S. Van de Water, Leptonic Decays of Charged Pseudoscalar Mesons - 2015, Submitted to: Particle Data Book(2015) [arXiv:1509.02220]

2015 arXiv
[220]

Colquhoun, C

HPQCD: B. Colquhoun, C. T. H. Davies,et. al., B-meson decay constants: a more complete picture from full lattice QCD, Phys. Rev.D91 (2015) 114509, [arXiv:1503.05762]

2015 arXiv
[221]

Ebert, R

D. Ebert, R. N. Faustov, and V. O. Galkin, Relativistic treatment of the decay constants of light and heavy mesons, Phys. Lett.B635 (2006) 93–99, [hep-ph/0602110]

2006 arXiv
[222]

Dhiman and H

N. Dhiman and H. Dahiya,Decay constants of pseudoscalar and vectorB and D mesons in the light-cone quark model, Eur. Phys. J. Plus133 (2018) 134, [arXiv:1708.07274]

2018 arXiv
[223]

Bečirević, G

D. Bečirević, G. Duplančić, B. Klajn, B. Melić, and F. Sanﬁlippo,Lattice QCD and QCD sum rule determination of the decay constants ofηc, J/ψand hc states, Nucl. Phys.B883 (2014) 306–327, [arXiv:1312.2858]

2014 arXiv

Pith tools

Reviewed August 14, 2026 · model on record in the stance chip above.

[1] [1]

Minkowski,µ→eγat a Rate of One Out of 109 Muon Decays?, Phys

P. Minkowski,µ→eγat a Rate of One Out of 109 Muon Decays?, Phys. Lett. B67 (1977) 421–428

1977

[2] [2]

R. N. Mohapatra and G. Senjanovic,Neutrino Mass and Spontaneous Parity Violation, Phys. Rev. Lett.44 (1980) 912. [,231(1979)]

1980

[3] [3]

R. N. Mohapatra and G. Senjanovic,Neutrino Masses and Mixings in Gauge Models with Spontaneous Parity Violation, Phys. Rev. D23 (1981) 165

1981

[4] [4]

Gell-Mann, P

M. Gell-Mann, P. Ramond, and R. Slansky, Complex Spinors and Uniﬁed Theories, Conf. Proc. C790927 (1979) 315–321, [arXiv:1306.4669]

arXiv 1979

[5] [5]

Yanagida,Horizontal Symmetry and Masses of Neutrinos, Prog

T. Yanagida,Horizontal Symmetry and Masses of Neutrinos, Prog. Theor. Phys.64 (1980) 1103

1980

[6] [6]

de Gouvea,See-saw energy scale and the LSND anomaly, Phys

A. de Gouvea,See-saw energy scale and the LSND anomaly, Phys. Rev.D72 (2005) 033005, [hep-ph/0501039]

arXiv 2005

[7] [7]

Asaka and T

T. Asaka and T. Tsuyuki,Perturbativity in the seesaw mechanism, Phys. Lett. B753 (2016) 147–149, [arXiv:1509.02678]

arXiv 2016

[8] [8]

Fukugita and T

M. Fukugita and T. Yanagida,Baryogenesis Without Grand Uniﬁcation, Phys. Lett. B174 (1986) 45–47

1986