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Title: Reconciling BICEP2 and Planck results with right-handed Dirac neutrinos in the fundamental representation of grand unified E{sub 6}

The tensor-to-scalar ratio (r = 0.20{sup +0.07}{sub −0.05}) inferred from the excess B-mode power observed by the Background Imaging of Cosmic Extragalactic Polarization (BICEP2) experiment is almost twice as large as the 95% CL upper limits derived from temperature measurements of the WMAP (r < 0.13) and Planck (r < 0.11) space missions. Very recently, it was suggested that additional relativistic degrees of freedom beyond the three active neutrinos and photons can help to relieve this tension: the data favor an effective number of light neutrino species N{sub eff} = 3.86±0.25. Since the BICEP2 ratio implies the energy scale of inflation (V{sub *}{sup 1/4} ∼ 2 × 10{sup 16} GeV) is comparable to the grand unification scale, in this paper we investigate whether we can accommodate the required N{sub eff} with three right-handed (partners of the left-handed standard model) neutrinos living in the fundamental representation of a grand unified exceptional E{sub 6} group. We show that the superweak interactions of these Dirac states (through their coupling to a TeV-scale Z' gauge boson) lead to decoupling of right-handed neutrino just above the QCD cross over transition: 175 MeV∼
Authors:
;  [1] ;  [2] ;  [3]
  1. Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, 53201 (United States)
  2. Department of Physics, Northeastern University, Boston, MA, 02115 (United States)
  3. Department of Physics, National Taiwan Normal University, Taipei, 116 Taiwan (China)
Publication Date:
OSTI Identifier:
22373510
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 06; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMOLOGICAL INFLATION; COUPLING; DEGREES OF FREEDOM; NEUTRINOS; PHOTONS; POLARIZATION; QUANTUM CHROMODYNAMICS; RELATIVISTIC RANGE; SPACE; STANDARD MODEL; TEMPERATURE MEASUREMENT; TENSORS; TEV RANGE