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Sensitivity of $W$ -boson measurements to low-mass right-handed neutrinos

Rodrigo Alonso and Michael Spannowsky

Sam Bates and Chris Hays ^*

Chris Pollard

Institute of Particle Physics Phenomenology, University of Durham, Durham, United Kingdom

Department of Physics, University of Oxford, Oxford, United Kingdom

Department of Physics, University of Warwick, Coventry, United Kingdom

^*Contact author: chris.hays@physics.ox.ac.uk

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Phys. Rev. D 112, 112007 – Published 11 December, 2025

DOI: https://doi.org/10.1103/xzh4-lx5v

Abstract

A low-mass right-handed neutrino could interact with electroweak bosons via mixing, a mediator particle, or loop corrections. Using an effective field theory, we determine constraints on these interactions from $W$ -boson measurements at hadron colliders. Due to the difference in the initial states at the Tevatron and the LHC, $W$ -boson decays to a right-handed neutrino would artificially increase the mass measured at the Tevatron while only affecting the difference between $W^{+}$ and $W^{-}$ mass measurements at the LHC. Measurements from CDF and the LHC are used to infer the corresponding parameter values, which are found to be inconsistent between the two. The LHC experiments can improve sensitivity to these interactions by measuring the cosine of the helicity angle using $W$ bosons produced with transverse momentum above $\approx 50 GeV$ .

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References (60)

ATLAS Collaboration, Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC, Phys. Lett. B 716, 1 (2012).
CMS Collaboration, A new boson with a mass of 125 GeV observed with the CMS experiment at the Large Hadron Collider, Science 338, 1569 (2012).
CMS Collaboration, A portrait of the Higgs boson by the CMS experiment ten years after the discovery, Nature (London) 607, 60 (2022).
ATLAS Collaboration, Characterising the Higgs boson with ATLAS data from Run 2 of the LHC, Phys. Rep. 11, 001 (2024).
F. Englert and R. Brout, Broken symmetry and the mass of gauge vector mesons, Phys. Rev. Lett. 13, 321 (1964).
P. W. Higgs, Broken symmetries and the masses of gauge bosons, Phys. Rev. Lett. 13, 508 (1964).
G. S. Guralnik, C. R. Hagen, and T. W. B. Kibble, Global conservation laws and massless particles, Phys. Rev. Lett. 13, 585 (1964).
R. N. Mohapatra and G. Senjanović, Neutrino mass and spontaneous parity nonconservation, Phys. Rev. Lett. 44, 912 (1980).
See [10, 11] for reviews of the SMEFT.
I. Brivio and M. Trott, The standard model as an effective field theory, Phys. Rep. 793, 1–98 (2019).
G. Isidori, F. Wilsch, and D. Wyler, The standard model effective field theory at work, Rev. Mod. Phys. 96, 015006 (2024).
P. Minkowski, $μ \to e γ$ at a rate of one out of 109 muon decays?, Phys. Lett. 67B, 421 (1977).
T. Yanagida, Horizontal gauge symmetry and masses of neutrinos, Conf. Proc. C 7902131, 95 (1979).
M. Gell-Mann, P. Ramond, and R. Slansky, Complex spinors and unified theories, Conf. Proc. C 790927, 315 (1979).
A. Boyarsky, M. Drewes, T. Lasserre, S. Mertens, and O. Ruchayskiy, Sterile neutrino dark matter, Prog. Part. Nucl. Phys. 104, 1 (2019).
J. Alcaide, S. Banerjee, M. Chala, and A. Titov, Probes of the standard model effective field theory extended with a right-handed neutrino, J. High Energy Phys. 08 (2019) 031.
J. M. Butterworth, M. Chala, C. Englert, M. Spannowsky, and A. Titov, Higgs phenomenology as a probe of sterile neutrinos, Phys. Rev. D 100, 115019 (2019).
R. Beltrán, G. Cottin, J. Günther, M. Hirsch, A. Titov, and Z. S. Wang, Heavy neutral leptons and top quarks in effective field theory, J. High Energy Phys. 05 (2025) 238.
M. Mitra, S. Mandal, R. Padhan, A. Sarkar, and M. Spannowsky, Reexamining right-handed neutrino EFTs up to dimension six, Phys. Rev. D 106, 113008 (2022).
M. Mitra, S. Saha, M. Spannowsky, and M. Takeuchi, Probing right-handed neutrinos via trilepton signals at the HL-LHC, Phys. Rev. D 111, 015005 (2025).
F. del Águila, S. Bar-Shalom, A. Soni, and J. Wudka, Heavy majorana neutrinos in the effective lagrangian description: Application to hadron colliders, Phys. Lett. B 670, 399 (2009).
A renormalizable Yukawa term $Y^{i} {\bar{L}}_{i} ν_{R} \tilde{H}$ (as well as the operator with coefficient $c_{L N H}^{i}$ ) generates neutrino mixing and produces the opposite-chirality interactions that we do not consider in our phenomenological study. This mixing is constrained to be small ( $Y v / m_{N} ≪ 1$ ), see, e.g., [23, 24]. The $c_{N W}^{i}$ term is loop-generated in weakly coupled renormalizable UV completions, and is thus small in general.
D. A. Bryman and R. Shrock, Constraints on sterile neutrinos in the MeV to GeV mass range, Phys. Rev. D 100, 073011 (2019).
E. Fernández-Martínez, M. González-López, J. Hernández-García, M. Hostert, and J. López-Pavón, Effective portals to heavy neutral leptons, J. High Energy Phys. 09 (2023) 001.
L. Duarte, J. Peressutti, and O. A. Sampayo, Majorana neutrino decay in an effective approach, Phys. Rev. D 92, 093002 (2015).
A. Falkowski, M. González-Alonso, and O. Naviliat-Cuncic, Comprehensive analysis of beta decays within and beyond the standard model, J. High Energy Phys. 04 (2020) 126.
W. Fetscher, Muon decay, SciPost Phys. Proc. 5, 006 (2021).
G. Aad et al. (ATLAS Collaboration), Search for heavy neutral leptons in decays of $W$ bosons using leptonic and semileptonic displaced vertices in $\sqrt{s} = 13 TeV pp$ collisions with the ATLAS detector, J. High Energy Phys. 07 (2025) 196.
A. Tumasyan et al. (CMS Collaboration), Search for long-lived heavy neutral leptons with displaced vertices in proton-proton collisions at $\sqrt{s} = 13 TeV$ , J. High Energy Phys. 07 (2022) 081.
H. Kanda, M. Sato, Y.-k. Suzuki, T. Takayanagi, and Z. Wei, Search for long-lived heavy neutral leptons with lepton flavour conserving or violating decays to a jet and a charged lepton, J. High Energy Phys. 03 (2023) 105.
H. Minakata, Search for long-lived heavy neutral leptons in proton-proton collision events with a lepton-jet pair associated with a secondary vertex at $\sqrt{s} = 13 TeV$ , J. High Energy Phys. 02 (2024) 036.
A. Hayrapetyan et al. (CMS Collaboration), Review of searches for vector-like quarks, vector-like leptons, and heavy neutral leptons in proton–proton collisions at $\sqrt{s} = 13$ TeV at the CMS experiment, Phys. Rep. 1115, 570 (2025).
S. Amoroso et al. (LHC-TeV MW Working Group), Compatibility and combination of world $W$ -boson mass measurements, Eur. Phys. J. C 84, 451 (2024).
V. Chekhovsky et al. (CMS Collaboration), High-precision measurement of the W boson mass with the CMS experiment at the LHC, arXiv:2412.13872.
G. Aad et al. (ATLAS Collaboration), Measurement of the $W$ -boson mass and width with the ATLAS detector using proton–proton collisions at $\sqrt{s} = 7 TeV$ , Eur. Phys. J. C 84, 1309 (2024).
M. Aaboud et al. (ATLAS Collaboration), Measurement of the $W$ -boson mass in pp collisions at $\sqrt{s} = 7 TeV$ with the ATLAS detector, Eur. Phys. J. C 78, 110 (2018); 78, 898(E) (2018).
M. Levi, S. Mougiakakos, and M. Vieira, Measurement of the $W$ boson mass, J. High Energy Phys. 01 (2021) 036.
T. Aaltonen et al. (CDF Collaboration), High-precision measurement of the $W$ boson mass with the CDF II detector, Science 376, 170 (2022).
V. M. Abazov et al. (D0 Collaboration), Measurement of the $W$ boson mass with the D0 detector, Phys. Rev. D 89, 012005 (2014).
V. M. Abazov et al. (D0 Collaboration), Measurement of the $W$ boson mass, Phys. Rev. Lett. 103, 141801 (2009).
The $W$ boson width is also affected by $c_{H N e}^{i}$ , however its current value of $2014 \pm 50 MeV$ [42] corresponds to a 95% confidence-level constraint of $c_{H N e}^{i} < 1.6$ for $Λ = v$ [17]. This is significantly weaker than the constraints we consider. Interpreting the recent ATLAS width measurement [35] in terms of $c_{H N e}^{i}$ would give $c_{H N e}^{i} = 1.4 \pm 0.6$ , in agreement with the value we obtain from the CDF $m_{W}$ measurement but in tension with that obtained from LHC measurements of $m_{W^{+}} - m_{W^{-}}$ .
S. Navas et al. (Particle Data Group), Review of particle physics, Phys. Rev. D 110, 030001 (2024).
S. Biswas, V. P. K., and A. Thapa, Connecting pseudo-Nambu-Goldstone dark matter with pseudo-Dirac neutrinos in a left-right symmetry model, Phys. Rev. D 111, 075007 (2025).
K. Agashe, S. Airen, R. Franceschini, D. Kim, A. V. Kotwal, L. Ricci, and D. Sathyan, “Unification” of BSM searches and SM measurements: The case of $lepton + E_{T}$ and $m_{W}$ , J. High Energy Phys. 02 (2024) 139.
R. Alonso, D. Dimakou, and M. West, Fractional-charge hadrons and leptons to tell the standard model group apart, Phys. Lett. B 863, 139354 (2025).
A. de Giorgi, F. Koutroulis, L. Merlo, and S. Pokorski, Flavour and Higgs physics in Z2-symmetric 2HD models near the decoupling limit, Nucl. Phys. B994, 116323 (2023).
A. Giarnetti, J. Herrero-Garcia, S. Marciano, D. Meloni, and D. Vatsyayan, Neutrino masses from new Weinberg-like operators: Phenomenology of TeV scalar multiplets, J. High Energy Phys. 05 (2023) 055.
T. A. Chowdhury, K. Ezzat, S. Khalil, E. Ma, and D. Nanda, Higgs quadruplet impact on $W$ mass shift, dark matter, and LHC signatures, Phys. Rev. D 109, 075039 (2024).
A. Ahriche, M. L. Bellilet, M. O. Khojali, M. Kumar, and A.-T. Mulaudzi, Scale invariant scotogenic model: CDF-II W-boson mass and the 95 GeV excesses, Phys. Rev. D 110, 015025 (2024).
K. Agashe, S. Airen, R. Franceschini, D. Kim, A. V. Kotwal, L. Ricci, and D. Sathyan, A new purpose for the $W$ -boson mass measurement: Searching for new physics in $lepton + MET$ , Phys. Lett. B 855, 138774 (2024).
J. Alwall, R. Frederix, S. Frixione, V. Hirschi, F. Maltoni, O. Mattelaer, H. S. Shao, T. Stelzer, P. Torrielli, and M. Zaro, The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations, J. High Energy Phys. 07 (2014) 079.
V. M. Abazov et al. (D0 Collaboration), Measurement of the electron charge asymmetry in $p \bar{p} \to W + X \to e ν + X$ decays in $p \bar{p}$ collisions at $\sqrt{s} = 1.96 TeV$ , Phys. Rev. D 91, 032007 (2015); 91, 079901(E) (2015).
V. M. Abazov et al. (D0 Collaboration), Measurement of the muon charge asymmetry in $p \bar{p} \to W + X \to μ ν + X$ events at $\sqrt{s} = 1.96 TeV$ , Phys. Rev. D 88, 091102 (2013).
T. Aaltonen et al. (CDF Collaboration), Direct measurement of the $W$ production charge asymmetry in $p \bar{p}$ collisions at $\sqrt{s} = 1.96 TeV$ , Phys. Rev. Lett. 102, 181801 (2009).
S. Chatrchyan et al. (CMS Collaboration), Measurement of the polarization of $W$ bosons with large transverse momenta in $W + jets$ events at the LHC, Phys. Rev. Lett. 107, 021802 (2011).
G. Aad et al. (ATLAS Collaboration), Measurement of the polarisation of $W$ bosons produced with large transverse momentum in $p p$ collisions at $\sqrt{s} = 7 TeV$ with the ATLAS experiment, Eur. Phys. J. C 72, 2001 (2012).
We only discuss the most constraining measurements in the mass range 0.1–100 MeV. We have also investigated the constraint arising from $e^{+} e^{-} \to W^{+} W^{-}$ production at LEP [58], and find it to be weaker than the others ( $| c_{H N ℓ} | < 0.51$ ).
S. Schael et al. (ALEPH, DELPHI, L3, OPAL, LEP Electroweak Collaborations), Electroweak measurements in electron-positron collisions at $W$ -boson-pair energies at LEP, Phys. Rep. 532, 119 (2013).
A. Aguilar-Arevalo et al. (PIENU Collaboration), Improved measurement of the $π \to e ν$ branching ratio, Phys. Rev. Lett. 115, 071801 (2015).
M. Daum, P.-R. Kettle, B. Jost, R. M. Marshall, R. C. Minehart, W. A. Stephens, and K. O. H. Ziock, Search for admixtures of massive neutrinos in the decay $π^{+} \to μ^{+} + ν$ , Phys. Rev. D 36, 2624 (1987).

Phys. Rev. D 112, 112007– Published 11 December, 2025

Vol. 112, Iss. 11 — 1 December 2025

Received 14 August 2025
Accepted 7 November 2025

DOI: https://doi.org/10.1103/xzh4-lx5v

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Sensitivity of $W$ -boson measurements to low-mass right-handed neutrinos

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Sensitivity of W-boson measurements to low-mass right-handed neutrinos

Abstract

Physics Subject Headings (PhySH)

Article Text

References (60)

Sensitivity of $W$ -boson measurements to low-mass right-handed neutrinos