Collider limits on leptophilic interactions

  • Francisco del Aguila
  • Mikael Chala
  • Jose Santiago
  • Yasuhiro Yamamoto
Open Access
Regular Article - Theoretical Physics


Leptophilic interactions can only be observed at the LHC in four-lepton final states. If these interactions are mediated by a resonance in the di-leptonic channel with renormalizable couplings, the mediator must have spin 1. We study the LHC reach for such a vector boson allowing for arbitrary couplings. We find that only couplings to muons can be probed at the LHC because lepton flavor violating couplings are constrained by rare processes, couplings to electrons by LEP and the LHC is not sensitive to final states involving taus in this case. The ILC becomes then complementary to the LHC as it will provide the best limits on Z couplings to tau leptons. A prominent example is the case of the anomaly-free Z coupling to the muon minus tau lepton number LμLτ. If no departure from the Standard Model is observed at the LHC, the most stringent bounds on this vector boson are provided from events with only three charged leptons plus missing energy. Masses of the order of 1 TeV can be probed at the high-luminosity phase of the LHC for Z couplings of order one. Generic four-lepton operators parametrizing leptophilic interactions can be also constrained using three and four (or two at the ILC) charged-lepton samples, but the corresponding limits are marginal, if meaningful, because the resonant behavior appears to be essential for the signal to be significant.


Beyond Standard Model Technicolor and Composite Models 


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]
    F. Englert and R. Brout, Broken symmetry and the mass of gauge vector mesons, Phys. Rev. Lett. 13 (1964) 321 [INSPIRE].CrossRefADSMathSciNetGoogle Scholar
  2. [2]
    P.W. Higgs, Broken symmetries and the masses of gauge bosons, Phys. Rev. Lett. 13 (1964) 508 [INSPIRE].CrossRefADSMathSciNetGoogle Scholar
  3. [3]
    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 (2012) 1 [arXiv:1207.7214] [INSPIRE].ADSGoogle Scholar
  4. [4]
    CMS collaboration, Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC, Phys. Lett. B 716 (2012) 30 [arXiv:1207.7235] [INSPIRE].ADSGoogle Scholar
  5. [5]
    CMS collaboration, Search for narrow resonances using the dijet mass spectrum in pp collisions at \( \sqrt{s} \) = 8 TeV, Phys. Rev. D 87 (2013) 114015 [arXiv:1302.4794] [INSPIRE].ADSGoogle Scholar
  6. [6]
    ATLAS collaboration, Search for new phenomena in the dijet mass distribution using pp collision data at \( \sqrt{s} \) = 8 TeV with the ATLAS detector, arXiv:1407.1376 [INSPIRE].
  7. [7]
    CMS collaboration, Search for massive resonances in dijet systems containing jets tagged as W or Z boson decays in pp collisions at \( \sqrt{s} \) = 8 TeV, JHEP 08 (2014) 173 [arXiv:1405.1994] [INSPIRE].Google Scholar
  8. [8]
    ATLAS collaboration, Search for pair and single production of new heavy quarks that decay to a Z boson and a third-generation quark in pp collisions at \( \sqrt{s} \) = 8 TeV with the ATLAS detector, JHEP 11 (2014) 104 [arXiv:1409.5500] [INSPIRE].ADSGoogle Scholar
  9. [9]
    CMS collaboration, Search for top-quark partners with charge 5/3 in the same-sign dilepton final state, Phys. Rev. Lett. 112 (2014) 171801 [arXiv:1312.2391] [INSPIRE].CrossRefADSGoogle Scholar
  10. [10]
    CMS collaboration, Inclusive search for a vector-like T quark with charge 2/3 in pp collisions at \( \sqrt{s} \) = 8 TeV, Phys. Lett. B 729 (2014) 149 [arXiv:1311.7667] [INSPIRE].ADSGoogle Scholar
  11. [11]
    CMS collaboration, Search for gluino mediated bottom- and top-squark production in multijet final states in pp collisions at 8 TeV, Phys. Lett. B 725 (2013) 243 [arXiv:1305.2390] [INSPIRE].ADSGoogle Scholar
  12. [12]
    ATLAS collaboration, Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using \( \sqrt{s} \) = 8 TeV proton-proton collision data, JHEP 09 (2014) 176 [arXiv:1405.7875] [INSPIRE].ADSGoogle Scholar
  13. [13]
    CMS collaboration, Search for new physics in the multijet and missing transverse momentum final state in proton-proton collisions at \( \sqrt{s} \) = 8 TeV, JHEP 06 (2014) 055 [arXiv:1402.4770] [INSPIRE].ADSGoogle Scholar
  14. [14]
    CMS collaboration, Search for heavy narrow dilepton resonances in pp collisions at \( \sqrt{s} \) = 7 TeV and \( \sqrt{s} \) = 8 TeV, Phys. Lett. B 720 (2013) 63 [arXiv:1212.6175] [INSPIRE].ADSGoogle Scholar
  15. [15]
    ATLAS collaboration, Search for high-mass dilepton resonances in pp collisions at \( \sqrt{s} \) = 8 TeV with the ATLAS detector, Phys. Rev. D 90 (2014) 052005 [arXiv:1405.4123] [INSPIRE].ADSGoogle Scholar
  16. [16]
    F. del Aguila, J. de Blas and M. Pérez-Victoria, Electroweak limits on general new vector bosons, JHEP 09 (2010) 033 [arXiv:1005.3998] [INSPIRE].CrossRefGoogle Scholar
  17. [17]
    F. del Aguila and J. de Blas, Electroweak constraints on new physics, Fortsch. Phys. 59 (2011) 1036 [arXiv:1105.6103] [INSPIRE].CrossRefADSGoogle Scholar
  18. [18]
    J. de Blas, Electroweak limits on physics beyond the standard model, EPJ Web Conf. 60 (2013) 19008 [arXiv:1307.6173] [INSPIRE].CrossRefGoogle Scholar
  19. [19]
    J. de Blas, M. Chala and J. Santiago, Global constraints on lepton-quark contact interactions, Phys. Rev. D 88 (2013) 095011 [arXiv:1307.5068] [INSPIRE].ADSGoogle Scholar
  20. [20]
    H. Baer et al., The International Linear Collider technical design reportvolume 2: physics, arXiv:1306.6352 [INSPIRE].
  21. [21]
    F. Del Aguila and M. Cvetič, Diagnostic power of future colliders for Z couplings to quarks and leptons: e + e versus pp colliders, Phys. Rev. D 50 (1994) 3158 [hep-ph/9312329] [INSPIRE].ADSGoogle Scholar
  22. [22]
    F. Del Aguila, M. Cvetič and P. Langacker, Reconstruction of the extended gauge structure from Z observables at future colliders, Phys. Rev. D 52 (1995) 37 [hep-ph/9501390] [INSPIRE].ADSGoogle Scholar
  23. [23]
    A. Freitas et al., Exploring quantum physics at the ILC, arXiv:1307.3962 [INSPIRE].
  24. [24]
    F. del Aguila, M. Chala, A. Santamaria and J. Wudka, Discriminating between lepton number violating scalars using events with four and three charged leptons at the LHC, Phys. Lett. B 725 (2013) 310 [arXiv:1305.3904] [INSPIRE].CrossRefADSGoogle Scholar
  25. [25]
    F. del Aguila, M. Chala, A. Santamaria and J. Wudka, Distinguishing between lepton number violating scalars at the LHC, EPJ Web Conf. 60 (2013) 17002 [arXiv:1307.0510] [INSPIRE].CrossRefGoogle Scholar
  26. [26]
    F. del Águila and M. Chala, LHC bounds on lepton number violation mediated by doubly and singly-charged scalars, JHEP 03 (2014) 027 [arXiv:1311.1510] [INSPIRE].CrossRefGoogle Scholar
  27. [27]
    F. del Aguila, M. Chala, A. Santamaria and J. Wudka, Lepton number violation and scalar searches at the LHC, Acta Phys. Polon. B 44 (2013) 2139 [arXiv:1311.2950] [INSPIRE].CrossRefADSGoogle Scholar
  28. [28]
    B. Holdom, Two U(1)’s and ϵ charge shifts, Phys. Lett. B 166 (1986) 196 [INSPIRE].CrossRefADSGoogle Scholar
  29. [29]
    F. del Aguila, G.A. Blair, M. Daniel and G.G. Ross, Superstring inspired models, Nucl. Phys. B 272 (1986) 413 [INSPIRE].CrossRefADSGoogle Scholar
  30. [30]
    F. del Aguila, G.D. Coughlan and M. Quirós, Gauge coupling renormalization with several U(1) factors, Nucl. Phys. B 307 (1988) 633 [Erratum ibid. B 312 (1989) 751] [INSPIRE].
  31. [31]
    C.D. Carone and H. Murayama, Realistic models with a light U(1) gauge boson coupled to baryon number, Phys. Rev. D 52 (1995) 484 [hep-ph/9501220] [INSPIRE].ADSGoogle Scholar
  32. [32]
    F. del Aguila, M. Masip and M. Pérez-Victoria, Physical parameters and renormalization of U(1)a × U(1)b models, Nucl. Phys. B 456 (1995) 531 [hep-ph/9507455] [INSPIRE].CrossRefADSGoogle Scholar
  33. [33]
    V.V. Andreev, P. Osland and A.A. Pankov, Precise determination of Z-Z mixing at the CERN LHC, Phys. Rev. D 90 (2014) 055025 [arXiv:1406.6776] [INSPIRE].ADSGoogle Scholar
  34. [34]
    F. Aguila, M. Chala, J. Santiago and Y. Yamamoto, Four-lepton signals of leptophilic gauge interactions at large colliders, in preparation.Google Scholar
  35. [35]
    R. Foot, X.G. He, H. Lew and R.R. Volkas, Model for a light Z boson, Phys. Rev. D 50 (1994) 4571 [hep-ph/9401250] [INSPIRE].ADSGoogle Scholar
  36. [36]
    F. del Aguila, A. Carmona and J. Santiago, Neutrino masses from an A 4 symmetry in holographic composite Higgs models, JHEP 08 (2010) 127 [arXiv:1001.5151] [INSPIRE].CrossRefADSGoogle Scholar
  37. [37]
    F. del Aguila, A. Carmona and J. Santiago, Tau custodian searches at the LHC, Phys. Lett. B 695 (2011) 449 [arXiv:1007.4206] [INSPIRE].CrossRefADSGoogle Scholar
  38. [38]
    T. Han and B. Zhang, Signatures for Majorana neutrinos at hadron colliders, Phys. Rev. Lett. 97 (2006) 171804 [hep-ph/0604064] [INSPIRE].CrossRefADSGoogle Scholar
  39. [39]
    F. del Aguila, J.A. Aguilar-Saavedra and R. Pittau, Heavy neutrino signals at Large Hadron Colliders, JHEP 10 (2007) 047 [hep-ph/0703261] [INSPIRE].CrossRefGoogle Scholar
  40. [40]
    A. Atre, T. Han, S. Pascoli and B. Zhang, The search for heavy Majorana neutrinos, JHEP 05 (2009) 030 [arXiv:0901.3589] [INSPIRE].CrossRefADSGoogle Scholar
  41. [41]
    P.S.B. Dev, A. Pilaftsis and U.-K. Yang, New production mechanism for heavy neutrinos at the LHC, Phys. Rev. Lett. 112 (2014) 081801 [arXiv:1308.2209] [INSPIRE].CrossRefADSGoogle Scholar
  42. [42]
    ALEPH, DELPHI, L3, OPAL and LEP Electroweak collaborations, S. Schael et al., Electroweak measurements in electron-positron collisions at W-boson-pair energies at LEP, Phys. Rept. 532 (2013) 119 [arXiv:1302.3415] [INSPIRE].CrossRefADSGoogle Scholar
  43. [43]
    SINDRUM collaboration, U. Bellgardt et al., Search for the decay μ +e + e + e , Nucl. Phys. B 299 (1988) 1 [INSPIRE].ADSGoogle Scholar
  44. [44]
    K. Hayasaka et al., Search for lepton flavor violating τ decays into three leptons with 719 million produced τ + τ pairs, Phys. Lett. B 687 (2010) 139 [arXiv:1001.3221] [INSPIRE].CrossRefADSGoogle Scholar
  45. [45]
    M. Cvetič and P. Langacker, V Z and V W production as tests of heavy gauge boson couplings at future hadron colliders, Phys. Rev. D 46 (1992) 4943 [Erratum ibid. D 48 (1993) 4484] [hep-ph/9207216] [INSPIRE].
  46. [46]
    M. Cvetič, P. Langacker and B. Kayser, Determination of g R /g L in left-right symmetric models at hadron colliders, Phys. Rev. Lett. 68 (1992) 2871 [INSPIRE].CrossRefADSGoogle Scholar
  47. [47]
    F. del Aguila, B. Alles, L. Ametller and A. Grau, Z decays in four fermions, Phys. Rev. D 48 (1993) 425 [hep-ph/9206219] [INSPIRE].ADSGoogle Scholar
  48. [48]
    E. Fuchs, S. Thewes and G. Weiglein, Interference effects in BSM processes with a generalised narrow-width approximation, arXiv:1411.4652 [INSPIRE].
  49. [49]
    C. Degrande et al., UFOthe Universal FeynRules Output, Comput. Phys. Commun. 183 (2012) 1201 [arXiv:1108.2040] [INSPIRE].CrossRefADSGoogle Scholar
  50. [50]
    N.D. Christensen and C. Duhr, FeynRulesFeynman rules made easy, Comput. Phys. Commun. 180 (2009) 1614 [arXiv:0806.4194] [INSPIRE].CrossRefADSGoogle Scholar
  51. [51]
    A. Alloul, N.D. Christensen, C. Degrande, C. Duhr and B. Fuks, FeynRules 2.0 — a complete toolbox for tree-level phenomenology, Comput. Phys. Commun. 185 (2014) 2250 [arXiv:1310.1921] [INSPIRE].CrossRefADSGoogle Scholar
  52. [52]
    J. Alwall, M. Herquet, F. Maltoni, O. Mattelaer and T. Stelzer, MadGraph 5: going beyond, JHEP 06 (2011) 128 [arXiv:1106.0522] [INSPIRE].CrossRefADSGoogle Scholar
  53. [53]
    J. Heeck and W. Rodejohann, Gauged L μ -L τ symmetry at the electroweak scale, Phys. Rev. D 84 (2011) 075007 [arXiv:1107.5238] [INSPIRE].ADSGoogle Scholar
  54. [54]
    K. Harigaya, T. Igari, M.M. Nojiri, M. Takeuchi and K. Tobe, Muon g-2 and LHC phenomenology in the L μ -L τ gauge symmetric model, JHEP 03 (2014) 105 [arXiv:1311.0870] [INSPIRE].CrossRefADSGoogle Scholar
  55. [55]
    N.F. Bell, Y. Cai, R.K. Leane and A.D. Medina, Leptophilic dark matter with Z interactions, Phys. Rev. D 90 (2014) 035027 [arXiv:1407.3001] [INSPIRE].ADSGoogle Scholar
  56. [56]
    E. Ma, D.P. Roy and S. Roy, Gauged L μ -L τ with large muon anomalous magnetic moment and the bimaximal mixing of neutrinos, Phys. Lett. B 525 (2002) 101 [hep-ph/0110146] [INSPIRE].CrossRefADSGoogle Scholar
  57. [57]
    W. Altmannshofer, S. Gori, M. Pospelov and I. Yavin, Quark flavor transitions in L μ -L τ models, Phys. Rev. D 89 (2014) 095033 [arXiv:1403.1269] [INSPIRE].ADSGoogle Scholar
  58. [58]
    W. Altmannshofer, S. Gori, M. Pospelov and I. Yavin, Neutrino trident production: a powerful probe of new physics with neutrino beams, Phys. Rev. Lett. 113 (2014) 091801 [arXiv:1406.2332] [INSPIRE].CrossRefADSGoogle Scholar
  59. [59]
    T. Sjöstrand, S. Mrenna and P.Z. Skands, PYTHIA 6.4 physics and manual, JHEP 05 (2006) 026 [hep-ph/0603175] [INSPIRE].
  60. [60]
    DELPHES 3 collaboration, J. de Favereau et al., DELPHES 3, a modular framework for fast simulation of a generic collider experiment, JHEP 02 (2014) 057 [arXiv:1307.6346] [INSPIRE].ADSGoogle Scholar
  61. [61]
    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].CrossRefADSMathSciNetGoogle Scholar
  62. [62]
    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].CrossRefGoogle Scholar
  63. [63]
    M. Cacciari, G.P. Salam and G. Soyez, FastJet user manual, Eur. Phys. J. C 72 (2012) 1896 [arXiv:1111.6097] [INSPIRE].CrossRefADSGoogle Scholar
  64. [64]
    ATLAS collaboration, Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in 21 fb of pp collisions at \( \sqrt{s} \) = 8 TeV with the ATLAS detector, ATLAS-CONF-2013-035, CERN, Geneva Switzerland (2013).
  65. [65]
    Particle Data Group collaboration, K.A. Olive et al., Review of particle physics, Chin. Phys. C 38 (2014) 090001 [INSPIRE].Google Scholar
  66. [66]
    G. Cowan, K. Cranmer, E. Gross and O. Vitells, Asymptotic formulae for likelihood-based tests of new physics, Eur. Phys. J. C 71 (2011) 1554 [Erratum ibid. C 73 (2013) 2501] [arXiv:1007.1727] [INSPIRE].

Copyright information

© The Author(s) 2015

Authors and Affiliations

  • Francisco del Aguila
    • 1
  • Mikael Chala
    • 1
    • 2
  • Jose Santiago
    • 1
    • 3
  • Yasuhiro Yamamoto
    • 1
  1. 1.CAFPE and Departamento de Física Teórica y del CosmosUniversidad de GranadaGranadaSpain
  2. 2.DESYHamburgGermany
  3. 3.CERN, Theory DivisionGeneva 23Switzerland

Personalised recommendations