Common origin of nonzero θ13 and baryon asymmetry of the Universe in a TeV scale seesaw model with A4 flavor symmetry

Borah, Debasish (Department of Physics, Indian Institute of Technology Guwahati, Assam 781039, India) ; Das, Mrinal Kumar (Department of Physics, Tezpur University, Tezpur 784028, India) ; Mukherjee, Ananya (Department of Physics, Tezpur University, Tezpur 784028, India)

08 June 2018

Abstract: We study the possibility of generating nonzero reactor mixing angle θ13 and baryon asymmetry of the Universe within the framework of an A4 flavor symmetric model. Using the conventional type I seesaw mechanism we construct the Dirac and Majorana mass matrices that give rise to the correct light neutrino mass matrix. Keeping the right-handed neutrino mass matrix structure trivial so that it gives rise to a (quasi) degenerate spectrum of heavy neutrinos suitable for resonant leptogenesis at TeV scale, we generate the nontrivial structure of Dirac neutrino mass matrix that can lead to the light neutrino mixing through the type I seesaw formula. Interestingly, such a setup naturally leads to nonzero θ13 due to the existence of antisymmetric contraction of the product of two triplet representations of A4. Such an antisymmetric part of the triplet products usually vanishes for right-handed neutrino Majorana mass terms, leading to μτ symmetric scenarios in the most economical setups. We constrain the model parameters from the requirement of producing the correct neutrino data as well as baryon asymmetry of the Universe for right-handed neutrino mass scale around TeV. The A4 symmetry is augmented by additional Z3×Z2 symmetry to make sure that the splitting between right-handed neutrinos required for resonant leptogenesis is generated only by next to leading order terms, making it naturally small. We find that the inverted hierarchical light neutrino masses give more allowed parameter space consistent with neutrino and baryon asymmetry data.

Published in: Physical Review D 97 (2018)
Published by: APS
DOI: 10.1103/PhysRevD.97.115009
arXiv: 1711.02445
License: CC-BY-4.0

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