Journal of High Energy Physics

, 2013:131 | Cite as

Probing exotic fermions from a seesaw/radiative model at the LHC

  • Kristian L. McDonald


There exist tree-level generalizations of the Type-I and Type-III seesaw mechanisms that realize neutrino mass via low-energy effective operators with d > 5. However, these generalizations also give radiative masses that can dominate the seesaw masses in regions of parameter space — i.e. they are not purely seesaw models, nor are they purely radiative models, but instead they are something in between. A recent work detailed the remaining minimal models of this type. Here we study the remaining model with d = 9 and investigate the collider phenomenology of the exotic quadruplet fermions it predicts. These exotics can be pair produced at the LHC via electroweak interactions and their subsequent decays produce a host of multi-lepton signals. Furthermore, the branching fractions for events with distinct charged-leptons encode information about both the neutrino mass hierarchy and the leptonic mixing phases. In large regions of parameter-space discovery at the LHC with a 5σ significance is viable for masses approaching the TeV scale.


Neutrino Physics Beyond Standard Model Solar and Atmospheric Neutrinos 


  1. [1]
    P. Minkowski, μeγ at a Rate of One Out of 1-Billion Muon Decays?, Phys. Lett. B 67 (1977) 421 [INSPIRE].ADSCrossRefGoogle Scholar
  2. [2]
    T. Yanagida, Horizontal symmetry and masses of neutrinos, in Workshop on Unified Theories, KEK report 79-18 pg. 95 (1979).Google Scholar
  3. [3]
    M. Gell-Mann, P. Ramond and R. Slansky, Complex spinors and unified theories, in Supergravity, P. van Nieuwenhuizen and D. Freedman eds., North Holland, Amsterdam The Netherlands (1979), pg. 315.Google Scholar
  4. [4]
    S.L. Glashow, The future of elementary particle physics, in 1979 Cargese Summer Institute on Quarks and Leptons, M. Levy, J.-L. Basdevant, D. Speiser, J. Weyers, R. Gastmans and M. Jacobs eds., Plenum Press, New York U.S.A. (1980), pg. 687.Google Scholar
  5. [5]
    R. Barbieri, D.V. Nanopoulos, G. Morchio and F. Strocchi, Neutrino Masses in Grand Unified Theories, Phys. Lett. B 90 (1980) 91 [INSPIRE].ADSCrossRefGoogle Scholar
  6. [6]
    R.N. Mohapatra and G. Senjanović, Neutrino Mass and Spontaneous Parity Violation, Phys. Rev. Lett. 44 (1980) 912 [INSPIRE].ADSCrossRefGoogle Scholar
  7. [7]
    R. Foot, H. Lew, X. He and G.C. Joshi, Seesaw Neutrino Masses Induced by a Triplet of Leptons, Z. Phys. C 44 (1989) 441 [INSPIRE].Google Scholar
  8. [8]
    S. Weinberg, Baryon and Lepton Nonconserving Processes, Phys. Rev. Lett. 43 (1979) 1566 [INSPIRE].ADSCrossRefGoogle Scholar
  9. [9]
    K.L. McDonald, Minimal Tree-Level Seesaws with a Heavy Intermediate Fermion, JHEP 07 (2013) 020 [arXiv:1303.4573] [INSPIRE].ADSCrossRefGoogle Scholar
  10. [10]
    K. Babu, S. Nandi and Z. Tavartkiladze, New Mechanism for Neutrino Mass Generation and Triply Charged Higgs Bosons at the LHC, Phys. Rev. D 80 (2009) 071702 [arXiv:0905.2710] [INSPIRE].ADSGoogle Scholar
  11. [11]
    K. Kumericki, I. Picek and B. Radovcic, TeV-scale Seesaw with Quintuplet Fermions, Phys. Rev. D 86 (2012) 013006 [arXiv:1204.6599] [INSPIRE].ADSGoogle Scholar
  12. [12]
    I. Picek and B. Radovcic, Enhancement of hγγ by seesaw-motivated exotic scalars, Phys. Lett. B 719 (2013) 404 [arXiv:1210.6449] [INSPIRE].MathSciNetADSCrossRefGoogle Scholar
  13. [13]
    Y. Liao, Unique Neutrino Mass Operator at any Mass Dimension, Phys. Lett. B 694 (2011) 346 [arXiv:1009.1692] [INSPIRE].ADSCrossRefGoogle Scholar
  14. [14]
    I. Picek and B. Radovcic, Novel TeV-scale seesaw mechanism with Dirac mediators, Phys. Lett. B 687 (2010) 338 [arXiv:0911.1374] [INSPIRE].ADSCrossRefGoogle Scholar
  15. [15]
    K. Kumericki, I. Picek and B. Radovcic, Exotic Seesaw-Motivated Heavy Leptons at the LHC, Phys. Rev. D 84 (2011) 093002 [arXiv:1106.1069] [INSPIRE].ADSGoogle Scholar
  16. [16]
    F. del Aguila and J. Aguilar-Saavedra, Distinguishing seesaw models at LHC with multi-lepton signals, Nucl. Phys. B 813 (2009) 22 [arXiv:0808.2468] [INSPIRE].ADSCrossRefGoogle Scholar
  17. [17]
    Y. Liao, G.-Z. Ning and L. Ren, Flavor Violating Transitions of Charged Leptons from a Seesaw Mechanism of Dimension Seven, Phys. Rev. D 82 (2010) 113003 [arXiv:1008.0117] [INSPIRE].ADSGoogle Scholar
  18. [18]
    E. Del Nobile, R. Franceschini, D. Pappadopulo and A. Strumia, Minimal Matter at the Large Hadron Collider, Nucl. Phys. B 826 (2010) 217 [arXiv:0908.1567] [INSPIRE].ADSCrossRefGoogle Scholar
  19. [19]
    C.-K. Chua and S.S. Law, Phenomenological constraints on minimally coupled exotic lepton triplets, Phys. Rev. D 83 (2011) 055010 [arXiv:1011.4730] [INSPIRE].ADSGoogle Scholar
  20. [20]
    A. Delgado, C. Garcia Cely, T. Han and Z. Wang, Phenomenology of a lepton triplet, Phys. Rev. D 84 (2011) 073007 [arXiv:1105.5417] [INSPIRE].ADSGoogle Scholar
  21. [21]
    S.S. Law and K.L. McDonald, Inverse seesaw and dark matter in models with exotic lepton triplets, Phys. Lett. B 713 (2012) 490 [arXiv:1204.2529] [INSPIRE].ADSCrossRefGoogle Scholar
  22. [22]
    I. Baldes, N.F. Bell, K. Petraki and R.R. Volkas, Two radiative inverse seesaw models, dark matter and baryogenesis, JCAP 07 (2013) 029 [arXiv:1304.6162] [INSPIRE].ADSCrossRefGoogle Scholar
  23. [23]
    A. Alloul, M. Frank, B. Fuks and M.R. de Traubenberg, Doubly-charged particles at the Large Hadron Collider, Phys. Rev. D 88 (2013) 075004 [arXiv:1307.1711] [INSPIRE].ADSGoogle Scholar
  24. [24]
    W.-Y. Keung and G. Senjanović, Majorana Neutrinos and the Production of the Right-handed Charged Gauge Boson, Phys. Rev. Lett. 50 (1983) 1427 [INSPIRE].ADSCrossRefGoogle Scholar
  25. [25]
    A. Pilaftsis, Radiatively induced neutrino masses and large Higgs neutrino couplings in the standard model with Majorana fields, Z. Phys. C 55 (1992) 275 [hep-ph/9901206] [INSPIRE].ADSGoogle Scholar
  26. [26]
    A. Datta, M. Guchait and A. Pilaftsis, Probing lepton number violation via Majorana neutrinos at hadron supercolliders, Phys. Rev. D 50 (1994) 3195 [hep-ph/9311257] [INSPIRE].ADSGoogle Scholar
  27. [27]
    J. Almeida, F.M.L., Y.D.A. Coutinho, J.A. Martins Simoes and M. do Vale, On a signature for heavy Majorana neutrinos in hadronic collisions, Phys. Rev. D 62 (2000) 075004 [hep-ph/0002024] [INSPIRE].
  28. [28]
    O. Panella, M. Cannoni, C. Carimalo and Y. Srivastava, Signals of heavy Majorana neutrinos at hadron colliders, Phys. Rev. D 65 (2002) 035005 [hep-ph/0107308] [INSPIRE].ADSGoogle Scholar
  29. [29]
    T. Han and B. Zhang, Signatures for Majorana neutrinos at hadron colliders, Phys. Rev. Lett. 97 (2006) 171804 [hep-ph/0604064] [INSPIRE].ADSCrossRefGoogle Scholar
  30. [30]
    F. del Aguila, J. Aguilar-Saavedra and R. Pittau, Heavy neutrino signals at large hadron colliders, JHEP 10 (2007) 047 [hep-ph/0703261] [INSPIRE].CrossRefGoogle Scholar
  31. [31]
    S. Bray, J.S. Lee and A. Pilaftsis, Resonant CP-violation due to heavy neutrinos at the LHC, Nucl. Phys. B 786 (2007) 95 [hep-ph/0702294] [INSPIRE].ADSCrossRefGoogle Scholar
  32. [32]
    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
  33. [33]
    C.-Y. Chen and P.B. Dev, Multi-Lepton Collider Signatures of Heavy Dirac and Majorana Neutrinos, Phys. Rev. D 85 (2012) 093018 [arXiv:1112.6419] [INSPIRE].ADSGoogle Scholar
  34. [34]
    P.S.B. Dev, A. Pilaftsis and U.-k. Yang, New Production Mechanism for Heavy Neutrinos at the LHC, arXiv:1308.2209 [INSPIRE].
  35. [35]
    CMS collaboration, Search for heavy Majorana neutrinos in μ + μ +[μ μ ] and e + e +[e e ] events in pp collisions at \( \sqrt{s} \) = 7 TeV, Phys. Lett. B 717 (2012) 109 [arXiv:1207.6079] [INSPIRE].ADSGoogle Scholar
  36. [36]
    ATLAS collaboration, Search for Majorana neutrino production in pp collisions at \( \sqrt{s} \) = 7 TeV in dimuon final states with the ATLAS detector, ATLAS-CONF-2012-139 (2012).
  37. [37]
    R. Franceschini, T. Hambye and A. Strumia, Type-III see-saw at LHC, Phys. Rev. D 78 (2008) 033002 [arXiv:0805.1613] [INSPIRE].ADSGoogle Scholar
  38. [38]
    A. Arhrib, B. Bajc, D.K. Ghosh, T. Han, G.-Y. Huang et al., Collider Signatures for Heavy Lepton Triplet in Type I + III Seesaw, Phys. Rev. D 82 (2010) 053004 [arXiv:0904.2390] [INSPIRE].ADSGoogle Scholar
  39. [39]
    T. Li and X.-G. He, Neutrino Masses and Heavy Triplet Leptons at the LHC: Testability of Type III Seesaw, Phys. Rev. D 80 (2009) 093003 [arXiv:0907.4193] [INSPIRE].ADSGoogle Scholar
  40. [40]
    C. Biggio and F. Bonnet, Implementation of the Type III Seesaw Model in FeynRules/MadGraph and Prospects for Discovery with Early LHC Data, Eur. Phys. J. C 72 (2012) 1899 [arXiv:1107.3463] [INSPIRE].ADSCrossRefGoogle Scholar
  41. [41]
    O. Eboli, J. Gonzalez-Fraile and M. Gonzalez-Garcia, Neutrino Masses at LHC: Minimal Lepton Flavour Violation in Type-III See-saw, JHEP 12 (2011) 009 [arXiv:1108.0661] [INSPIRE].ADSCrossRefGoogle Scholar
  42. [42]
    ATLAS collaboration, Search for Type III Seesaw Model Heavy Fermions in Events with Four Charged Leptons using 5.8 fb −1 of \( \sqrt{s} \) = 8 TeV data with the ATLAS Detector, ATLAS-CONF-2013-019 (2013).
  43. [43]
    CMS collaboration, Search for heavy lepton partners of neutrinos in proton-proton collisions in the context of the type-III seesaw mechanism, Phys. Lett. B 718 (2012) 348 [arXiv:1210.1797] [INSPIRE].ADSGoogle Scholar
  44. [44]
    M.-C. Chen and J. Huang, TeV Scale Models of Neutrino Masses and Their Phenomenology, Mod. Phys. Lett. A 26 (2011) 1147 [arXiv:1105.3188] [INSPIRE].ADSCrossRefGoogle Scholar
  45. [45]
    A. Ibarra, E. Molinaro and S. Petcov, TeV Scale See-Saw Mechanisms of Neutrino Mass Generation, the Majorana Nature of the Heavy Singlet Neutrinos and (ββ)0ν -Decay, JHEP 09 (2010) 108 [arXiv:1007.2378] [INSPIRE].ADSCrossRefGoogle Scholar
  46. [46]
    M. Drewes, The Phenomenology of Right Handed Neutrinos, Int. J. Mod. Phys. E 22 (2013) 1330019 [arXiv:1303.6912] [INSPIRE].ADSCrossRefGoogle Scholar
  47. [47]
    G. Bambhaniya, J. Chakrabortty, S. Goswami and P. Konar, Generation of Neutrino mass from new physics at TeV scale and Multi-lepton Signatures at the LHC, arXiv:1305.2795 [INSPIRE].
  48. [48]
    B. Ren, K. Tsumura and X.-G. He, A Higgs Quadruplet for Type III Seesaw and Implications for μeγ and μe Conversion, Phys. Rev. D 84 (2011) 073004 [arXiv:1107.5879] [INSPIRE].ADSGoogle Scholar
  49. [49]
    K. Hally, H.E. Logan and T. Pilkington, Constraints on large scalar multiplets from perturbative unitarity, Phys. Rev. D 85 (2012) 095017 [arXiv:1202.5073] [INSPIRE].ADSGoogle Scholar
  50. [50]
    K. Earl, K. Hartling, H.E. Logan and T. Pilkington, Constraining models with a large scalar multiplet, Phys. Rev. D 88 (2013) 015002 [arXiv:1303.1244] [INSPIRE].ADSGoogle Scholar
  51. [51]
    M. Cirelli, N. Fornengo and A. Strumia, Minimal dark matter, Nucl. Phys. B 753 (2006) 178 [hep-ph/0512090] [INSPIRE].ADSCrossRefGoogle Scholar
  52. [52]
    S.S. Law and K.L. McDonald, A Class of Inert N-tuplet Models with Radiative Neutrino Mass and Dark Matter, JHEP 09 (2013) 092 [arXiv:1305.6467] [INSPIRE].ADSCrossRefGoogle Scholar
  53. [53]
    F. Bonnet, D. Hernandez, T. Ota and W. Winter, Neutrino masses from higher than D = 5 effective operators, JHEP 10 (2009) 076 [arXiv:0907.3143] [INSPIRE].ADSCrossRefGoogle Scholar
  54. [54]
    K. Babu and J. Julio, Two-Loop Neutrino Mass Generation through Leptoquarks, Nucl. Phys. B 841 (2010) 130 [arXiv:1006.1092] [INSPIRE].ADSCrossRefGoogle Scholar
  55. [55]
    S. Kanemura and T. Ota, Neutrino Masses from Loop-induced d ≥ 7 Operators, Phys. Lett. B 694 (2010) 233 [arXiv:1009.3845] [INSPIRE].ADSCrossRefGoogle Scholar
  56. [56]
    Y. Liao, Neutrino Mass Operators of Dimension up to Nine in Two-Higgs-doublet Model, Phys. Lett. B 698 (2011) 288 [arXiv:1010.5326] [INSPIRE].ADSCrossRefGoogle Scholar
  57. [57]
    M.B. Krauss, T. Ota, W. Porod and W. Winter, Neutrino mass from higher than D = 5 effective operators in SUSY and its test at the LHC, Phys. Rev. D 84 (2011) 115023 [arXiv:1109.4636] [INSPIRE].ADSGoogle Scholar
  58. [58]
    K. Babu and J. Julio, Radiative Neutrino Mass Generation through Vector-like Quarks, Phys. Rev. D 85 (2012) 073005 [arXiv:1112.5452] [INSPIRE].ADSGoogle Scholar
  59. [59]
    M.B. Krauss, D. Meloni, W. Porod and W. Winter, Neutrino Mass from a D = 7 Effective Operator in an SU(5) SUSY-GUT Framework, JHEP 05 (2013) 121 [arXiv:1301.4221] [INSPIRE].ADSCrossRefGoogle Scholar
  60. [60]
    P.W. Angel, N.L. Rodd and R.R. Volkas, Origin of neutrino masses at the LHC: Delta L = 2 effective operators and their ultraviolet completions, Phys. Rev. D 87 (2013) 073007 [arXiv:1212.6111] [INSPIRE].ADSGoogle Scholar
  61. [61]
    P.W. Angel, Y. Cai, N.L. Rodd, M.A. Schmidt and R.R. Volkas, Testable two-loop radiative neutrino mass model based on an LLQd c Qd c effective operator, JHEP 10 (2013) 118 [arXiv:1308.0463] [INSPIRE].ADSCrossRefGoogle Scholar
  62. [62]
    J. Kubo and D. Suematsu, Neutrino masses and CDM in a non-supersymmetric model, Phys. Lett. B 643 (2006) 336 [hep-ph/0610006] [INSPIRE].ADSCrossRefGoogle Scholar
  63. [63]
    Y. Kajiyama, H. Okada and K. Yagyu, Hybrid Seesaw Model in S 3 Flavor Symmetry, arXiv:1309.6234 [INSPIRE].
  64. [64]
    P.B. Dev and A. Pilaftsis, Minimal Radiative Neutrino Mass Mechanism for Inverse Seesaw Models, Phys. Rev. D 86 (2012) 113001 [arXiv:1209.4051] [INSPIRE].ADSGoogle Scholar
  65. [65]
    S.S.C. Law and K.L. McDonald, Generalized Inverse Seesaws, Phys. Rev. D 87 (2013) 113003 [arXiv:1303.4887] [INSPIRE].ADSGoogle Scholar
  66. [66]
    D. Ross and M. Veltman, Neutral Currents in Neutrino Experiments, Nucl. Phys. B 95 (1975) 135 [INSPIRE].ADSCrossRefGoogle Scholar
  67. [67]
    Particle Data Group collaboration, J. Beringer et al., Review of Particle Physics (RPP), Phys. Rev. D 86 (2012) 010001 [INSPIRE].ADSGoogle Scholar
  68. [68]
    P. Fileviez Perez, H.H. Patel, M. Ramsey-Musolf and K. Wang, Triplet Scalars and Dark Matter at the LHC, Phys. Rev. D 79 (2009) 055024 [arXiv:0811.3957] [INSPIRE].ADSGoogle Scholar
  69. [69]
    M. Einhorn, D. Jones and M. Veltman, Heavy Particles and the rho Parameter in the Standard Model, Nucl. Phys. B 191 (1981) 146 [INSPIRE].ADSCrossRefGoogle Scholar
  70. [70]
    T. Schwetz, Neutrino mass and mixing: Status, Pramana 79 (2012) 979.ADSCrossRefGoogle Scholar
  71. [71]
    M. Gavela, T. Hambye, D. Hernandez and P. Hernández, Minimal Flavour Seesaw Models, JHEP 09 (2009) 038 [arXiv:0906.1461] [INSPIRE].ADSCrossRefGoogle Scholar
  72. [72]
    S. Biondini, O. Panella, G. Pancheri, Y. Srivastava and L. Fano, Phenomenology of excited doubly charged heavy leptons at LHC, Phys. Rev. D 85 (2012) 095018 [arXiv:1201.3764] [INSPIRE].ADSGoogle Scholar
  73. [73]
    A. Martin, W. Stirling, R. Thorne and G. Watt, Parton distributions for the LHC, Eur. Phys. J. C 63 (2009) 189 [arXiv:0901.0002] [INSPIRE].ADSCrossRefGoogle Scholar
  74. [74]
    R. Hamberg, W. van Neerven and T. Matsuura, A complete calculation of the order \( \alpha_s^2 \) correction to the Drell-Yan K factor, Nucl. Phys. B 359 (1991) 343 [Erratum ibid. B 644 (2002) 403-404] [INSPIRE].
  75. [75]
    CMS collaboration, Search for a heavy gauge boson Win the final state with an electron and large missing transverse energy in pp collisions at \( \sqrt{s} \) = 7 TeV, Phys. Lett. B 698 (2011) 21 [arXiv:1012.5945] [INSPIRE].ADSGoogle Scholar
  76. [76]
    J. Aguilar-Saavedra, P. Boavida and F. Joaquim, Flavoured searches for type-III seesaw at the LHC, arXiv:1308.3226 [INSPIRE].
  77. [77]
    A. Akeroyd, M. Aoki and H. Sugiyama, Probing Majorana Phases and Neutrino Mass Spectrum in the Higgs Triplet Model at the CERN LHC, Phys. Rev. D 77 (2008) 075010 [arXiv:0712.4019] [INSPIRE].ADSGoogle Scholar
  78. [78]
    S. Kanemura, K. Yagyu and H. Yokoya, First constraint on the mass of doubly-charged Higgs bosons in the same-sign diboson decay scenario at the LHC, Phys. Lett. B 726 (2013) 316 [arXiv:1305.2383] [INSPIRE].ADSCrossRefGoogle Scholar
  79. [79]
    T. Ma, B. Zhang and G. Cacciapaglia, Lepton Triplet at the LHC, arXiv:1309.7396 [INSPIRE].

Copyright information

© SISSA, Trieste, Italy 2013

Authors and Affiliations

  1. 1.ARC Centre of Excellence for Particle Physics at the Terascale, School of PhysicsThe University of SydneySydneyAustralia

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