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

Journal Article · Tue Jun 17 04:00:00 EDT 2014 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2014/06/042· OSTI ID:22454498

Anchordoqui, Luis A. ^[1]; Goldberg, Haim ^[2]; Huang, Xing ^[3]; Vlcek, Brian J. ^[1]

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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)

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 heating of the left-handed neutrinos (and photons). Consistency (within 1σ) with the favored N{sub eff} is achieved for 4.5 TeV

• Sponsoring Organization: SCOAP3, CERN, Geneva (Switzerland)
• OSTI ID: 22454498
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 06 Vol. 2014; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

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DEGREES OF FREEDOM
GEV RANGE
MEV RANGE
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NEUTRINOS
PHOTONS
POLARIZATION
QUANTUM CHROMODYNAMICS
RELATIVISTIC RANGE
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