Heavy neutral fermions at the high-luminosity LHC

  • Juan Carlos Helo
  • Martin Hirsch
  • Zeren Simon Wang
Open Access
Regular Article - Theoretical Physics


Long-lived light particles (LLLPs) appear in many extensions of the standard model. LLLPs are usually motivated by the observed small neutrino masses, by dark matter or both. Typical examples for fermionic LLLPs (a.k.a. heavy neutral fermions, HNFs) are sterile neutrinos or the lightest neutralino in R-parity violating supersymmetry. The high luminosity LHC is expected to deliver up to 3/ab of data. Searches for LLLPs in dedicated experiments at the LHC could then probe the parameter space of LLLP models with unprecedented sensitivity. Here, we compare the prospects of several recent experimental proposals, FASER, CODEX-b and MATHUSLA, to search for HNFs and discuss their relative merits.s


Beyond Standard Model Neutrino Physics Supersymmetric Standard Model 


Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.


  1. [1]
    R. Essig et al., Working Group Report: New Light Weakly Coupled Particles, in Proceedings of 2013 Community Summer Study on the Future of U.S. Particle Physics: Snowmass on the Mississippi (CSS2013), Minneapolis U.S.A. (2013) [arXiv:1311.0029] [INSPIRE].
  2. [2]
    S. Alekhin et 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] [INSPIRE].ADSCrossRefGoogle Scholar
  3. [3]
    LBNE collaboration, C. Adams et al., The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe, arXiv:1307.7335 [INSPIRE].
  4. [4]
    NA62 collaboration, E. Cortina Gil et al., The Beam and detector of the NA62 experiment at CERN, 2017 JINST 12 P05025 [arXiv:1703.08501] [INSPIRE].
  5. [5]
    CERN, The High-Luminosity LHC, 2015-11-11 (2015).
  6. [6]
    J.P. Chou, D. Curtin and H.J. Lubatti, New Detectors to Explore the Lifetime Frontier, Phys. Lett. B 767 (2017) 29 [arXiv:1606.06298] [INSPIRE].ADSCrossRefGoogle Scholar
  7. [7]
    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. D 97 (2018) 015023 [arXiv:1708.09395] [INSPIRE].
  8. [8]
    J.L. Feng, I. Galon, F. Kling and S. Trojanowski, ForwArd Search ExpeRiment at the LHC, Phys. Rev. D 97 (2018) 035001 [arXiv:1708.09389] [INSPIRE].
  9. [9]
    J.L. Feng, I. Galon, F. Kling and S. Trojanowski, Dark Higgs bosons at the ForwArd Search ExpeRiment, Phys. Rev. D 97 (2018) 055034 [arXiv:1710.09387] [INSPIRE].
  10. [10]
    F. Kling and S. Trojanowski, Heavy Neutral Leptons at FASER, Phys. Rev. D 97 (2018) 095016 [arXiv:1801.08947] [INSPIRE].
  11. [11]
    A. Atre, T. Han, S. Pascoli and B. Zhang, The Search for Heavy Majorana Neutrinos, JHEP 05 (2009) 030 [arXiv:0901.3589] [INSPIRE].ADSCrossRefGoogle Scholar
  12. [12]
    ATLAS collaboration, Search for heavy Majorana neutrinos with the ATLAS detector in pp collisions at \( \sqrt{s}=8 \) TeV, JHEP 07 (2015) 162 [arXiv:1506.06020] [INSPIRE].
  13. [13]
    CMS collaboration, Search for heavy neutral leptons in events with three charged leptons in proton-proton collisions at \( \sqrt{s}=13 \) TeV, Phys. Rev. Lett. 120 (2018) 221801 [arXiv:1802.02965] [INSPIRE].
  14. [14]
    DELPHI collaboration, P. Abreu et al., Search for neutral heavy leptons produced in Z decays, Z. Phys. C 74 (1997) 57 [Erratum ibid. C 75 (1997) 580] [INSPIRE].
  15. [15]
    J.C. Helo, M. Hirsch and S. Kovalenko, Heavy neutrino searches at the LHC with displaced vertices, Phys. Rev. D 89 (2014) 073005 [Erratum ibid. D 93 (2016) 099902] [arXiv:1312.2900] [INSPIRE].
  16. [16]
    CMS collaboration, Search for new long-lived particles at \( \sqrt{s}=13 \) TeV, Phys. Lett. B 780 (2018)432 [arXiv:1711.09120] [INSPIRE].
  17. [17]
    G. Cottin, J.C. Helo and M. Hirsch, Searches for light sterile neutrinos with multitrack displaced vertices, Phys. Rev. D 97 (2018) 055025 [arXiv:1801.02734] [INSPIRE].
  18. [18]
    D. Gorbunov and I. Timiryasov, Decaying light particles in the SHiP experiment. II. Signal rate estimates for light neutralinos, Phys. Rev. D 92 (2015) 075015 [arXiv:1508.01780] [INSPIRE].
  19. [19]
    J. de Vries, H.K. Dreiner and D. Schmeier, R-Parity Violation and Light Neutralinos at SHiP and the LHC, Phys. Rev. D 94 (2016) 035006 [arXiv:1511.07436] [INSPIRE].
  20. [20]
    P.F. de Salas, D.V. Forero, C.A. Ternes, M. Tortola and J.W.F. Valle, Status of neutrino oscillations 2018: 3σ hint for normal mass ordering and improved CP sensitivity, Phys. Lett. B 782 (2018) 633 [arXiv:1708.01186] [INSPIRE].
  21. [21]
    R.N. Mohapatra and J.W.F. Valle, Neutrino Mass and Baryon Number Nonconservation in Superstring Models, Phys. Rev. D 34 (1986) 1642 [INSPIRE].ADSGoogle Scholar
  22. [22]
    J.A. Casas and A. Ibarra, Oscillating neutrinos and μe, γ, Nucl. Phys. B 618 (2001) 171 [hep-ph/0103065] [INSPIRE].
  23. [23]
    G. Anamiati, M. Hirsch and E. Nardi, Quasi-Dirac neutrinos at the LHC, JHEP 10 (2016) 010 [arXiv:1607.05641] [INSPIRE].ADSCrossRefGoogle Scholar
  24. [24]
    R. Barbier et al., R-parity violating supersymmetry, Phys. Rept. 420 (2005) 1 [hep-ph/0406039] [INSPIRE].
  25. [25]
    H.K. Dreiner, An Introduction to explicit R-parity violation, hep-ph/9707435 [INSPIRE].
  26. [26]
    M. Hirsch, M.A. Diaz, W. Porod, J.C. Romao and J.W.F. Valle, Neutrino masses and mixings from supersymmetry with bilinear R parity violation: A Theory for solar and atmospheric neutrino oscillations, Phys. Rev. D 62 (2000) 113008 [Erratum ibid. D 65 (2002)119901] [hep-ph/0004115] [INSPIRE].
  27. [27]
    Particle Data Group collaboration, C. Patrignani et al., Review of Particle Physics, Chin. Phys. C 40 (2016) 100001 [INSPIRE].
  28. [28]
    H.K. Dreiner, S. Heinemeyer, O. Kittel, U. Langenfeld, A.M. Weber and G. Weiglein, Mass Bounds on a Very Light Neutralino, Eur. Phys. J. C 62 (2009) 547 [arXiv:0901.3485] [INSPIRE].
  29. [29]
    W. Porod, M. Hirsch, J. Romao and J.W.F. Valle, Testing neutrino mixing at future collider experiments, Phys. Rev. D 63 (2001) 115004 [hep-ph/0011248] [INSPIRE].
  30. [30]
    A. Bartl, W. Majerotto and N. Oshimo, On the Production of Neutralinos at the Z and W and Their Decay Into Higgs Bosons, Phys. Lett. B 216 (1989) 233 [INSPIRE].ADSCrossRefGoogle Scholar
  31. [31]
    ATLAS collaboration, Search for electroweak production of supersymmetric states in scenarios with compressed mass spectra at \( \sqrt{s}=13 \) TeV with the ATLAS detector, Phys. Rev. D 97 (2018) 052010 [arXiv:1712.08119] [INSPIRE].
  32. [32]
    F. Staub, SARAH 4: A tool for (not only SUSY) model builders, Comput. Phys. Commun. 185 (2014)1773 [arXiv:1309.7223] [INSPIRE].
  33. [33]
    W. Porod and F. Staub, SPheno 3.1: Extensions including flavour, CP-phases and models beyond the MSSM, Comput. Phys. Commun. 183 (2012) 2458 [arXiv:1104.1573] [INSPIRE].
  34. [34]
    W. Porod, SPheno, a program for calculating supersymmetric spectra, SUSY particle decays and SUSY particle production at e + e colliders, Comput. Phys. Commun. 153 (2003) 275 [hep-ph/0301101] [INSPIRE].
  35. [35]
    ATLAS collaboration, Search for invisible decays of a Higgs boson using vector-boson fusion in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector, JHEP 01 (2016) 172 [arXiv:1508.07869] [INSPIRE].
  36. [36]
    ATLAS collaboration, Search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a Z boson in pp collisions at \( \sqrt{s}=13 \) TeV with the ATLAS detector, Phys. Lett. B 776 (2018) 318 [arXiv:1708.09624] [INSPIRE].
  37. [37]
    J. Albrecht, F. Bernlochner, M. Kenzie, S. Reichert, D. Straub and A. Tully, Future prospects for exploring present day anomalies in flavour physics measurements with Belle II and LHCb, arXiv:1709.10308 [INSPIRE].
  38. [38]
    LHCb collaboration, Expression of Interest for a Phase-II LHCb Upgrade: Opportunities in flavour physics and beyond, in the HL-LHC era, CERN-LHCC-2017-003 (2017).
  39. [39]
    C. Degrande, C. Duhr, B. Fuks, D. Grellscheid, O. Mattelaer and T. Reiter, UFO — The Universal FeynRules Output, Comput. Phys. Commun. 183 (2012) 1201 [arXiv:1108.2040] [INSPIRE].ADSCrossRefGoogle Scholar
  40. [40]
    J. Alwall et al., The automated computation of tree-level and next-to-leading order differential cross sections and their matching to parton shower simulations, JHEP 07 (2014) 079 [arXiv:1405.0301] [INSPIRE].ADSCrossRefGoogle Scholar
  41. [41]
    J. Alwall et al., A Standard format for Les Houches event files, Comput. Phys. Commun. 176 (2007) 300 [hep-ph/0609017] [INSPIRE].
  42. [42]
    E. Conte, B. Fuks and G. Serret, MadAnalysis 5, A User-Friendly Framework for Collider Phenomenology, Comput. Phys. Commun. 184 (2013) 222 [arXiv:1206.1599] [INSPIRE].ADSMathSciNetCrossRefGoogle Scholar
  43. [43]
    E. Conte, B. Dumont, B. Fuks and C. Wymant, Designing and recasting LHC analyses with MadAnalysis 5, Eur. Phys. J. C 74 (2014) 3103 [arXiv:1405.3982] [INSPIRE].
  44. [44]
    A. Jakovác, A. Patkós and P. Pósfay, Non-Gaussian fixed points in fermionic field theories without auxiliary Bose-fields, Eur. Phys. J. C 75 (2015) 2 [arXiv:1406.3195] [INSPIRE].
  45. [45]
    T. Sjöstrand, S. Mrenna and P.Z. Skands, PYTHIA 6.4 Physics and Manual, JHEP 05 (2006) 026 [hep-ph/0603175] [INSPIRE].
  46. [46]
    T. Sjöstrand et al., An Introduction to PYTHIA 8.2, Comput. Phys. Commun. 191 (2015) 159 [arXiv:1410.3012] [INSPIRE].
  47. [47]
    LHCb collaboration, Prompt charm production in pp collisions at \( \sqrt{s}=7 \) TeV, LHCb-CONF-2010-013 (2010).
  48. [48]
    LHCb collaboration, Prompt charm production in pp collisions at \( \sqrt{s}=7 \) TeV, Nucl. Phys. B 871 (2013) 1 [arXiv:1302.2864] [INSPIRE].
  49. [49]
    LHCb collaboration, Measurements of prompt charm production cross-sections in pp collisions at \( \sqrt{s}=13 \) TeV, JHEP 03 (2016) 159 [Erratum ibid. 1609 (2016) 013] [arXiv:1510.01707] [INSPIRE].
  50. [50]
    LHCb collaboration, Measurement of the b-quark production cross-section in 7 and 13 TeV pp collisions, Phys. Rev. Lett. 118 (2017) 052002 [arXiv:1612.05140] [INSPIRE].
  51. [51]
    M. Cacciari, M. Greco and P. Nason, The p T spectrum in heavy flavor hadroproduction, JHEP 05 (1998) 007 [hep-ph/9803400] [INSPIRE].
  52. [52]
    M. Cacciari, S. Frixione and P. Nason, The p T spectrum in heavy flavor photoproduction, JHEP 03 (2001) 006 [hep-ph/0102134] [INSPIRE].
  53. [53]
    M. Cacciari, S. Frixione, N. Houdeau, M.L. Mangano, P. Nason and G. Ridolfi, Theoretical predictions for charm and bottom production at the LHC, JHEP 10 (2012) 137 [arXiv:1205.6344] [INSPIRE].ADSCrossRefGoogle Scholar
  54. [54]
    M. Cacciari, M.L. Mangano and P. Nason, Gluon PDF constraints from the ratio of forward heavy-quark production at the LHC at \( \sqrt{S}=7 \) and 13TeV,Eur. Phys. J. C 75(2015)610 [arXiv:1507.06197] [INSPIRE].
  55. [55]
    ATLAS collaboration, Measurement of W ± and Z-boson production cross sections in pp collisions at \( \sqrt{s}=13 \) TeV with the ATLAS detector, Phys. Lett. B 759 (2016) 601 [arXiv:1603.09222] [INSPIRE].
  56. [56]
    LHC Higgs Cross Section Working Group collaboration, D. de Florian et al., Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector, arXiv:1610.07922 [INSPIRE].
  57. [57]
    G. Bernardi et al., Further limits on heavy neutrino couplings, Phys. Lett. B 203 (1988) 332 [INSPIRE].
  58. [58]
    J.A. Evans, Detecting Hidden Particles with MATHUSLA, Phys. Rev. D 97 (2018) 055046 [arXiv:1708.08503] [INSPIRE].
  59. [59]
    K. Bondarenko, A. Boyarsky, D. Gorbunov and O. Ruchayskiy, Phenomenology of GeV-scale Heavy Neutral Leptons, arXiv:1805.08567 [INSPIRE].
  60. [60]
    M. Drewes, J. Hajer, J. Klaric and G. Lanfranchi, NA62 sensitivity to heavy neutral leptons in the low scale seesaw model, arXiv:1801.04207 [INSPIRE].
  61. [61]
    NA62 collaboration, S. Kholodenko, New limits on heavy neutrino from NA62, J. Phys. Conf. Ser. 934 (2017) 012002 [INSPIRE].
  62. [62]
    F.F. Deppisch, P.S. Bhupal Dev and A. Pilaftsis, Neutrinos and Collider Physics, New J. Phys. 17 (2015) 075019 [arXiv:1502.06541] [INSPIRE].
  63. [63]
    S.A. Baranov et al., Search for heavy neutrinos at the IHEP-JINR neutrino detector, Phys. Lett. B 302 (1993) 336 [INSPIRE].
  64. [64]
    CHARM collaboration, F. Bergsma et al., A Search for Decays of Heavy Neutrinos in the Mass Range 0.5-GeV to 2.8-GeV, Phys. Lett. B 166 (1986) 473 [INSPIRE].
  65. [65]
    C. Arbeláez, M. González, S. Kovalenko and M. Hirsch, QCD-improved limits from neutrinoless double beta decay, Phys. Rev. D 96 (2017) 015010 [arXiv:1611.06095] [INSPIRE].

Copyright information

© The Author(s) 2018

Authors and Affiliations

  1. 1.Departamento de Física, Facultad de CienciasUniversidad de La SerenaLa SerenaChile
  2. 2.Centro-Científico-Tecnológico de ValparaísoValparaísoChile
  3. 3.AHEP Group, Instituto de Física Corpuscular - C.S.I.C./Universitat de ValènciaValènciaSpain
  4. 4.Bethe Center for Theoretical Physics & Physikalisches Institut der Universität BonnBonnGermany

Personalised recommendations