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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{sub −0.05}{sup +0.07}) 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{sup ′} gauge boson) lead to decoupling of right-handed neutrino just above the QCD cross over transition: 175 MeV≲T{sub ν{sub R}{sup dec}}≲250 MeV. For decoupling in this transition region, the contribution of the three right-handed neutrinos to N{sub eff} is suppressed by heatingmore » of the left-handed neutrinos (and photons). Consistency (within 1σ) with the favored N{sub eff} is achieved for 4.5 TeV« less
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  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:
22454498
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 06; Other Information: PUBLISHER-ID: JCAP06(2014)042; OAI: oai:repo.scoap3.org:2840; Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)
Sponsoring Org:
SCOAP3, CERN, Geneva (Switzerland)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COSMOLOGICAL INFLATION; DECOUPLING; DEGREES OF FREEDOM; GEV RANGE; MEV RANGE; MICROWAVE RADIATION; NEUTRINOS; PHOTONS; POLARIZATION; QUANTUM CHROMODYNAMICS; RELATIVISTIC RANGE; SCALARS; STANDARD MODEL; TEMPERATURE MEASUREMENT; TENSORS; TEV RANGE