Neutrino Masses and a Fourth Generation of Fermions

Abstract

We study neutrino mass generation in models with four chiral families of leptons and quarks and four right handed neutrinos. Generically, in these models there are three different contributions to the light neutrino masses: the usual see-saw contribution, the tree-level contribution due to mixing of light neutrinos with neutrino of the fourth generation, and the two loop contribution due to the Majorana mass term of the fourth neutrino. We study properties of these contributions and their experimental bounds. The regions of the parameters (mixings of the fourth neutrino, masses of RH neutrino components, etc.) have been identified where various contributions dominate. New possibilities of a realization of the flavour symmetries in the four family context are explored. In particular, we consider applications of the smallest groups, e.g. SG(20,3), with irreducible representation 4.

33 pages, 4 figures; Eq. (18) corrected and thus corrections to Eqs. (21,26-28,41,42,44-46) and figures, the loop contribution reduced by 2 orders of magnitude; general conclusions unchanged; accepted by Nucl. Phys. B

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• Precision Constraints on Extra Fermion Generations
• Revising Limits on Neutrino-Majoron Couplings
• The discovery of the fourth family at the LHC: what if?
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• Tribimaximal Mixing From Small Groups
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• The smallest neutrino mass
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• An extended scalar sector to address the tension between a fourth generation and Higgs searches at the LHC
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• A fourth generation, anomalous like-sign dimuon charge asymmetry and the LHC
• Four Generations, Higgs Physics, and the MSSM
• Fourth Generation Bound States
• Approaching a strong fourth family
• An A_5 Model of Four Lepton Generations
• Impact of the relatively light fourth family neutrino on the Higgs boson search
• Searches for the $t^{\prime }$ of a fourth family
• Revisiting Constraints on Fourth Generation Neutrino Masses
• Anomalous Single Production of the Fourth Generation Quarks at the LHC
• Constraints on fourth generation Majorana neutrinos
• Neutrino masses from new generations
• An Updated Numerical Analysis of eV Seesaw with Four Generations

Cited by in corpus (5)

• Finite flavour groups of fermions
• Large mass splittings for fourth generation fermions allowed by LHC Higgs exclusion
• On the nature of the fourth generation neutrino and its implications
• Binary Icosahedral Flavor Symmetry for Four Generations of Quarks and Leptons
• Constraints on electroweak gauged unparticle model from the oblique parameters S and T