Abstract

The gauge-extended U(1)C×SU(2)L×U(1)IR×U(1)L model elevates the global symmetries of the standard model (baryon number B and lepton number L) to local gauge symmetries. The U(1)L symmetry leads to three superweakly interacting right-handed neutrinos. This also renders a B-L symmetry nonanomalous. The superweak interactions of these Dirac states permit νR decoupling just above the QCD phase transition: 175≲TνRdec/MeV≲250. In this transitional region, the residual temperature ratio between νL and νR generates extra relativistic degrees of freedom at BBN and at the CMB epochs. Consistency with both WMAP 7-year data and recent estimates of the primordial 4He mass fraction is achieved for 3B-L/TeV

Notes

Originally published in Physical Review Letters v.108 (2012): 081805. DOI: http://link.aps.org/doi/10.1103/PhysRevLett.108.081805”> 10.1103/PhysRevLett.108.081805.

Keywords

local gauge symmetries

Subject Categories

Cosmology, Neutrinos

Disciplines

Physics

Publisher

American Physical Society

Publication Date

2-23-2012

Rights Information

Copyright (2012) American Physical Society

Rights Holder

American Physical Society

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