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arxiv: 2606.16166 · v1 · pith:WVI36S2Hnew · submitted 2026-06-15 · ✦ hep-ph · hep-ex

Massive right-handed neutrinos in bar{B} to D^* τ bar X decay

Nilakshi Das , Alakabha Datta , Tejhas Kapoor , Danny Marfatia , Lopamudra Mukherjee This is my paper

Pith reviewed 2026-06-27 03:43 UTC · model grok-4.3

classification ✦ hep-ph hep-ex
keywords right-handed neutrinosB meson decaystau decaysnew physics operatorseffective field theoryangular distributionsdifferential distributionsinvisible particles
0
0 comments X

The pith

Full differential distributions in B to D* tau X decays reveal signatures of massive right-handed neutrinos through their sensitivity to new physics operators.

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

The paper computes the complete set of differential distributions for the decay chain from a B meson to a D star meson, a tau lepton, and an invisible particle, with the tau decaying to a pion and neutrino, all expressed in terms of observable particles. It works within the standard model effective field theory extended by a right-handed neutrino whose mass lies between a few MeV and a few GeV. These distributions are calculated for the first time including the tau decay, allowing direct comparison with data. The analysis then shows how the shapes of various angular and kinematic distributions respond to the additional operators introduced by the right-handed neutrino. A reader would care because the results supply concrete, measurable handles that experiments can use to search for or constrain such neutrinos without needing a specific ultraviolet completion.

Core claim

We explore signatures of a massive right-handed neutrino (RHN) in angular distributions of B-bar to D-star (to D pi) tau (to pi nu_tau) X-bar decays, where X is an invisible state. We assume the new physics is described by the standard model effective field theory extended with an RHN in the MeV-GeV mass range. We calculate for the first time the full differential distributions in terms of the visible final states, including the decay of the tau lepton. We evaluate the sensitivity of various distributions to the new physics operators.

What carries the argument

The full differential distributions in visible final-state variables of the B to D* tau X decay chain, computed in SMEFT extended by a massive right-handed neutrino.

If this is right

  • Certain angular distributions become sensitive probes of the new operators generated by the right-handed neutrino.
  • The visible final-state kinematics allow experiments to set limits on the strength of these operators for right-handed neutrino masses in the MeV-GeV window.
  • The calculation supplies templates that can be directly folded with detector efficiencies and used in fits to existing or future data sets.
  • Different operators produce distinct patterns across the set of distributions, offering a way to discriminate among them.

Where Pith is reading between the lines

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

  • The same method of computing full visible-state distributions could be applied to other modes such as B to D tau X or semileptonic decays of other heavy mesons to test the same right-handed neutrino hypothesis.
  • Absence of signals in these distributions would translate into upper bounds on the mixing parameters between the right-handed neutrino and active neutrinos within the effective theory.
  • Combining the angular information with rate measurements or with searches in other channels could tighten the overall constraints on the right-handed neutrino parameter space.

Load-bearing premise

All new physics effects are captured by the standard model effective field theory extended with a right-handed neutrino whose mass is in the MeV to GeV range.

What would settle it

A precision measurement of the angular and kinematic distributions in B to D* tau X that shows no deviation from standard model predictions in the directions predicted by the right-handed neutrino operators would falsify the existence of detectable signatures at the level claimed.

read the original abstract

We explore signatures of a massive right-handed neutrino (RHN) in angular distributions of $\bar{B} \to D^* (\to D \pi) \tau (\to \pi \nu_\tau ) \bar X$ decays, where $X$ is an invisible state. We assume the new physics is described by the standard model effective field theory extended with an RHN in the MeV-GeV mass range. We calculate for the first time the full differential distributions in terms of the visible final states, including the decay of the $\tau$ lepton. We evaluate the sensitivity of various distributions to the new physics operators.

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

0 major / 1 minor

Summary. The manuscript explores signatures of a massive right-handed neutrino (RHN) in angular distributions of the decay ar{B} o D^* ( o D \pi) au ( o \pi u_ au) ar X, where X is invisible. It assumes new physics is described by SMEFT extended with an RHN in the MeV-GeV mass range, claims to calculate for the first time the full differential distributions in visible final states including the au decay, and evaluates sensitivity of various distributions to the new physics operators.

Significance. If the differential calculations are correct and the operator sensitivity analysis holds, the work supplies new predictions for visible-state distributions that can be directly compared to data, strengthening probes of RHN in the MeV-GeV window at Belle II and LHCb. The emphasis on full visible kinematics is a concrete advance over prior partial calculations.

minor comments (1)
  1. Abstract states the calculation is performed 'for the first time'; the introduction should explicitly contrast the new visible-state distributions against prior literature on B o D^* au u with RHN or SMEFT operators to substantiate the novelty claim.

Simulated Author's Rebuttal

0 responses · 1 unresolved

We thank the referee for their review of our manuscript. The report acknowledges the potential value of our full visible-state differential distributions if the calculations are correct, but provides no specific major comments or points of technical concern. We address this below.

standing simulated objections not resolved
  • The referee's recommendation is listed as 'uncertain' and the significance is conditional on the correctness of the differential calculations, yet no concrete issues, errors, or requests for clarification are identified in the report. Without specific points we cannot provide a targeted response or revision.

Circularity Check

0 steps flagged

No significant circularity; forward calculation of distributions

full rationale

The paper computes full differential distributions for visible final states in B to D* tau decay including massive RHNs in SMEFT. The central claim is a first-time calculation of these distributions and their sensitivities to operators. No equations, parameters, or results are shown to reduce to fitted inputs, self-definitions, or self-citation chains. The derivation is presented as an independent forward computation from the effective Lagrangian to observable distributions, with no load-bearing steps that collapse by construction to the inputs.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 1 invented entities

Abstract-only review; ledger populated from stated assumptions in the abstract. No free parameters, axioms, or invented entities are quantified beyond the model assumption.

axioms (1)
  • domain assumption New physics is described by SMEFT extended with an RHN in the MeV-GeV mass range
    Directly stated in the abstract as the framework for the calculation.
invented entities (1)
  • Massive right-handed neutrino no independent evidence
    purpose: To provide new physics signatures in B to D* tau X decays
    Postulated as the source of new operators; no independent evidence or falsifiable prediction outside the model is given in the abstract.

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Forward citations

Cited by 1 Pith paper

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

  1. Probing Light Dark Fermions in $B \to D^{(*)}\ell X_{\rm inv}$ via Rate Distributions

    hep-ph 2026-06 unverdicted novelty 5.0

    Massive dark fermions modify rate distributions in B to D(*) lepton invisible decays within weak effective theory, affecting |V_cb| extraction.

Reference graph

Works this paper leans on

31 extracted references · 19 linked inside Pith · cited by 1 Pith paper

  1. [1]

    Abazajian et al.,Light Sterile Neutrinos: A White Paper,1204.5379

    K.N. Abazajian et al.,Light Sterile Neutrinos: A White Paper,1204.5379

    Pith/arXiv arXiv

  2. [2]

    Buchmuller and D

    W. Buchmuller and D. Wyler,Effective Lagrangian Analysis of New Interactions and Flavor Conservation,Nucl. Phys. B268(1986) 621

    1986

  3. [3]

    Grzadkowski, M

    B. Grzadkowski, M. Iskrzynski, M. Misiak and J. Rosiek,Dimension-Six Terms in the Standard Model Lagrangian,JHEP10(2010) 085 [1008.4884]

    Pith/arXiv arXiv 2010

  4. [4]

    del Aguila, S

    F. del Aguila, S. Bar-Shalom, A. Soni and J. Wudka,Heavy Majorana Neutrinos in the Effective Lagrangian Description: Application to Hadron Colliders,Phys. Lett. B670(2009) 399 [0806.0876]

    Pith/arXiv arXiv 2009

  5. [5]

    Aparici, K

    A. Aparici, K. Kim, A. Santamaria and J. Wudka,Right-handed neutrino magnetic moments,Phys. Rev. D80(2009) 013010 [0904.3244]

    Pith/arXiv arXiv 2009

  6. [6]

    Bhattacharya and J

    S. Bhattacharya and J. Wudka,Dimension-seven operators in the standard model with right handed neutrinos,Phys. Rev. D94(2016) 055022 [1505.05264]

    Pith/arXiv arXiv 2016

  7. [7]

    Liao and X.-D

    Y. Liao and X.-D. Ma,Operators up to Dimension Seven in Standard Model Effective Field Theory Extended with Sterile Neutrinos,Phys. Rev.D96(2017) 015012 [1612.04527]

    Pith/arXiv arXiv 2017

  8. [8]

    Bischer and W

    I. Bischer and W. Rodejohann,General neutrino interactions from an effective field theory perspective,Nucl. Phys. B947(2019) 114746 [1905.08699]. [9]BaBarcollaboration,Evidence for an excess of ¯B→D (∗)τ −¯ντ decays,Phys. Rev. Lett.109 (2012) 101802 [1205.5442]. [10]BaBarcollaboration,Measurement of an Excess of ¯B→D (∗)τ −¯ντ Decays and Implications for ...

    arXiv 2019

  9. [9]

    He and G

    X.-G. He and G. Valencia,Bdecays withτleptons in nonuniversal left-right models,Phys. Rev. D87(2013) 014014 [1211.0348]

    Pith/arXiv arXiv 2013

  10. [10]

    Cvetiˇ c, F

    G. Cvetiˇ c, F. Halzen, C.S. Kim and S. Oh,Anomalies in (semi)-leptonicBdecays B± →τ ±ν,B ± →Dτ ±νandB ± →D ∗τ ±ν, and possible resolution with sterile neutrino, Chin. Phys. C41(2017) 113102 [1702.04335]

    Pith/arXiv arXiv 2017

  11. [11]

    Asadi, M.R

    P. Asadi, M.R. Buckley and D. Shih,It’s all right(-handed neutrinos): a new W ? model for theR D(∗) anomaly,JHEP09(2018) 010 [1804.04135]

    Pith/arXiv arXiv 2018

  12. [12]

    Greljo, D.J

    A. Greljo, D.J. Robinson, B. Shakya and J. Zupan,R(D (?)) from W ? and right-handed neutrinos,JHEP09(2018) 169 [1804.04642]

    Pith/arXiv arXiv 2018

  13. [13]

    K.S. Babu, B. Dutta and R.N. Mohapatra,A theory of R(D ∗, D) anomaly with right-handed currents,JHEP01(2019) 168 [1811.04496]

    Pith/arXiv arXiv 2019

  14. [14]

    Mandal, C

    R. Mandal, C. Murgui, A. Pe˜ nuelas and A. Pich,The role of right-handed neutrinos in b→cτ¯νanomalies,JHEP08(2020) 022 [2004.06726]

    arXiv 2020

  15. [15]

    Fedele, M

    M. Fedele, M. Blanke, A. Crivellin, S. Iguro, U. Nierste, S. Simula et al.,Discriminating B→D*ℓνform factors via polarization observables and asymmetries,Phys. Rev. D108 (2023) 055037 [2305.15457]

    arXiv 2023

  16. [16]

    Blanke, A

    M. Blanke, A. Crivellin, S. de Boer, T. Kitahara, M. Moscati, U. Nierste et al.,Impact of polarization observables andB c →τ νon new physics explanations of theb→cτ νanomaly, Phys. Rev. D99(2019) 075006 [1811.09603]

    Pith/arXiv arXiv 2019

  17. [17]

    Impact of polarization observables andB c →τ νon new physics explanations of theb→cτ ν anomaly

    M. Blanke, A. Crivellin, T. Kitahara, M. Moscati, U. Nierste and I. Niˇ sandˇ zi´ c,Addendum to “Impact of polarization observables andB c →τ νon new physics explanations of theb→cτ ν anomaly”,1905.08253

    arXiv 1905

  18. [18]

    Bhattacharya, T.E

    B. Bhattacharya, T.E. Browder, Q. Campagna, A. Datta, S. Dubey, L. Mukherjee et al., Implications for the∆AFB anomaly in B¯0→D*+ℓ-ν¯using a new Monte Carlo event generator,Phys. Rev. D107(2023) 015011 [2206.11283]

    arXiv 2023

  19. [19]

    Nierste, S

    U. Nierste, S. Trine and S. Westhoff,Charged-Higgs effects in a new B —>D tau nu differential decay distribution,Phys. Rev. D78(2008) 015006 [0801.4938]

    Pith/arXiv arXiv 2008

  20. [21]

    Alonso, A

    R. Alonso, A. Kobach and J. Martin Camalich,New physics in the kinematic distributions of ¯B→D (∗)τ −(→ℓ −¯νℓντ)¯ντ,Phys. Rev. D94(2016) 094021 [1602.07671]

    Pith/arXiv arXiv 2016

  21. [22]

    Bhattacharya, T.E

    B. Bhattacharya, T.E. Browder, A. Datta, T. Kapoor, E. Kou and L. Mukherjee,New physics searches via angular distributions of B→D ∗ (→Dπ)τ(→ℓν τ νℓ) ντ decays,JHEP 04(2025) 135 [2411.09414]

    Pith/arXiv arXiv 2025

  22. [23]

    Bhattacharya, A

    B. Bhattacharya, A. Datta, S. Kamali and D. London,A measurable angular distribution for B→D ∗τ −vτ decays,JHEP07(2020) 194 [2005.03032]

    arXiv 2020

  23. [24]

    Navas et al.,Particle data group,Phys

    S. Navas et al.,Particle data group,Phys. Rev. D110(2024) 030001

    2024

  24. [25]

    K¨ all´ en,Elementary particle physics, Addison-Wesley, Reading, MA (1964)

    G. K¨ all´ en,Elementary particle physics, Addison-Wesley, Reading, MA (1964)

    1964

  25. [26]

    Sakaki, M

    Y. Sakaki, M. Tanaka, A. Tayduganov and R. Watanabe,Testing leptoquark models in ¯B→D (∗)τ¯ν,Phys. Rev. D88(2013) 094012 [1309.0301]. [37]HPQCDcollaboration,B-meson decay constants: a more complete picture from full lattice QCD,Phys. Rev. D91(2015) 114509 [1503.05762]. – 30 – [38]BaBar, Bellecollaboration,The Physics of the B Factories,Eur. Phys. J. C74(2...

    Pith/arXiv arXiv 2013

  26. [27]

    T. Han, J. Liao, H. Liu and D. Marfatia,Right-handed Dirac and Majorana neutrinos at Belle II,JHEP04(2023) 013 [2207.07029]

    arXiv 2023

  27. [28]

    Bhattacharya, A

    B. Bhattacharya, A. Datta, S. Kamali and D. London,CP Violation in ¯B0 →D ∗+µ−¯νµ, JHEP05(2019) 191 [1903.02567]

    arXiv 2019

  28. [29]

    Beˇ cirevi´ c, M

    D. Beˇ cirevi´ c, M. Fedele, I. Niˇ sandˇ zi´ c and A. Tayduganov,Lepton Flavor Universality tests through angular observables of B→D (∗)ℓνdecay modes,1907.02257

    Pith/arXiv arXiv 1907

  29. [30]

    C.G. Boyd, B. Grinstein and R.F. Lebed,Precision corrections to dispersive bounds on form-factors,Phys. Rev. D56(1997) 6895 [hep-ph/9705252]

    Pith/arXiv arXiv 1997

  30. [31]

    Kapoor, Z.-R

    T. Kapoor, Z.-R. Huang and E. Kou,New physics search via angular distribution of B→D ∗ℓνℓ decay in the light of the new lattice data,JHEP02(2025) 053 [2401.11636]. [46]Fermilab Lattice, MILC, Fermilab Lattice, MILCcollaboration,Semileptonic form factors forB→D ∗ℓνat nonzero recoil from2 + 1-flavor lattice QCD: Fermilab Lattice and MILC Collaborations,Eur....

    arXiv 2025

  31. [32]

    D. Bigi, P. Gambino and S. Schacht,R(D ∗),|V cb|, and the Heavy Quark Symmetry relations between form factors,JHEP11(2017) 061 [1707.09509]. [48]Bellecollaboration,Measurement of the CKM matrix element|V cb|fromB 0 →D ∗−ℓ+νℓ at Belle,Phys. Rev. D100(2019) 052007 [1809.03290]. – 31 –

    Pith/arXiv arXiv 2017