Neutrino masses and heavy triplet leptons at the LHC: Testability of the type III seesaw mechanism

Journal Article · Sun Nov 01 04:00:00 EST 2009 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.80.093003· OSTI ID:21325455

Tong, Li ^[1]; Xiaogang, He ^[1]

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1. Center for High Energy Physics, Peking University, Beijing, 100871 (China)

We study LHC signatures of the type III seesaw mechanism in which SU(2){sub L} triplet leptons are introduced to supply the heavy seesaw masses. To detect the signals of these heavy triplet leptons, one needs to understand their decays to standard model particles which depend on how light and heavy leptons mix with each other. We concentrate on the usual solutions with small light and heavy lepton mixing of the order of the square root of the ratio of light and heavy masses, (m{sub {nu}}/M{sub {nu}}{sub {sub R}}){sup 1/2}. This class of solutions can lead to a visible displaced vertex detectable at the LHC which can be used to distinguish small mixing and large mixing between light and heavy leptons. We show that, in this case, the couplings of light and heavy triplet leptons to gauge and Higgs bosons, which determine the decay widths and branching ratios, can be expressed in terms of light neutrino masses and their mixing. Using these relations, we study heavy triplet lepton decay patterns and production cross section at the LHC. If these heavy triplet leptons are below a TeV or so, they can be easily produced at the LHC due to their gauge interactions from being nontrivial representations of SU(2){sub L}. We consider two ideal production channels, (1) E{sup +}E{sup -}{yields}l{sup +}l{sup +}l{sup -}l{sup -}jj (l=e, {mu}, {tau}) and (2) E{sup {+-}}N{yields}l{sup {+-}}l{sup {+-}}jjjj in detail. For case 1, we find that with one or two of the light leptons being {tau} it can also be effectively studied. With judicious cuts at the LHC, the discovery of the heavy triplet leptons as high as a TeV can be achieved with 100 fb{sup -1} integrated luminosity.

• OSTI ID: 21325455
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 9 Vol. 80; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BRANCHING RATIO
CERN LHC
CROSS SECTIONS
ELECTRONS
HEAVY LEPTONS
HIGGS BOSONS
INTERACTIONS
LUMINOSITY
MASS
MATHEMATICAL SOLUTIONS
MIXING
NEUTRINOS
PARTICLE DECAY
POSITRONS
STANDARD MODEL
SU-2 GROUPS
TEV RANGE
TRIPLETS