Reconciling BICEP2 and Planck results with right-handed Dirac neutrinos in the fundamental representation of grand unified E_6

Abstract

The tensor-to-scalar ratio (r = 0.20^{+0.07}_{-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_{eff} = 3.86 \pm 0.25. Since the BICEP2 ratio implies the energy scale of inflation (V_*^{1/4} \sim 2 \times 10^{16} GeV) is comparable to the grand unification scale, in this paper we investigate whether we can accommodate the required N_{eff} with three right-handed (partners of the left-handed standard model) neutrinos living in the fundamental representation of a grand unified exceptional E_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 < T_{ν_R}^{dec} < 250 MeV. For decoupling in this transition region, the contribution of the three right-handed neutrinos to N_{eff} is suppressed by heating of the left-handed neutrinos (and photons). Consistency (within 1σ) with the favored N_{eff} is achieved for 4.5 TeV < M_{Z'} < 7.5 TeV. The model is fully predictive and can be confronted with future data from LHC14.

arXiv comment14 pages revtex, 4 figures

References in corpus (37)

• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
• The 6dF Galaxy Survey: Baryon Acoustic Oscillations and the Local Hubble Constant
• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Final Maps and Results
• SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems
• The Baryon Oscillation Spectroscopic Survey of SDSS-III
• Baryon Acoustic Oscillations in the Sloan Digital Sky Survey Data Release 7 Galaxy Sample
• A 3% Solution: Determination of the Hubble Constant with the Hubble Space Telescope and Wide Field Camera 3
• The Physics of Heavy Z' Gauge Bosons
• Precision Electroweak Measurements on the Z Resonance
• The WiggleZ Dark Energy Survey: mapping the distance-redshift relation with baryon acoustic oscillations
• The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations in the Data Release 9 Spectroscopic Galaxy Sample
• Precise Relic WIMP Abundance and its Impact on Searches for Dark Matter Annihilation
• Relic neutrino decoupling including flavour oscillations
• A 2% Distance to z=0.35 by Reconstructing Baryon Acoustic Oscillations - I : Methods and Application to the Sloan Digital Sky Survey
• Equation of state and QCD transition at finite temperature
• A Measurement of the Damping Tail of the Cosmic Microwave Background Power Spectrum with the South Pole Telescope
• The Atacama Cosmology Telescope: Cosmological Parameters from the 2008 Power Spectra
• Quark mass thresholds in QCD thermodynamics
• A Measurement of the Cosmic Microwave Background Damping Tail from the 2500-square-degree SPT-SZ survey
• The Atacama Cosmology Telescope: Temperature and Gravitational Lensing Power Spectrum Measurements from Three Seasons of Data
• Galaxy clusters discovered via the Sunyaev-Zel'dovich effect in the first 720 square degrees of the South Pole Telescope survey
• Cosmological parameter estimation and the inflationary cosmology
• The Atacama Cosmology Telescope: likelihood for small-scale CMB data
• Neutrinos And Big Bang Nucleosynthesis
• New Light Species and the CMB
• ATLAS search for new phenomena in dijet mass and angular distributions using pp collisions at sqrt(s)=7 TeV
• The Z-Z' Mass Hierarchy in a Supersymmetric Model with a Secluded U(1)'-Breaking Sector
• Search for heavy narrow dilepton resonances in pp collisions at sqrt(s) = 7 TeV and sqrt(s) = 8 TeV
• Neutrino Masses in an Extended Gauge Model with E_6 Particle Content
• Search for narrow resonances in dilepton mass spectra in pp collisions at sqrt(s) = 7 TeV
• Search for high-mass resonances decaying to dilepton final states in pp collisions at a center-of-mass energy of 7 TeV with the ATLAS detector
• A theory of extra radiation in the Universe
• Right-Handed Neutrinos as the Dark Radiation: Status and Forecasts for the LHC
• Primordial Nucleosynthesis Constraints on Z' Properties
• Neutrino Cosmology after WMAP and LHC7
• Dark Radiation Confronting LHC in Z' Models
• S-dual Inflation: BICEP2 data without unlikeliness

Cited by in corpus (6)

• The trouble with $H_0$
• Blue Tensor Spectrum from Particle Production during Inflation
• Robustness of cosmic neutrino background detection in the cosmic microwave background
• Dynamical Fractional Chaotic Inflation -- Dynamical Generation of a Fractional Power-Law Potential for Chaotic Inflation
• First Test of High Frequency Gravity Waves from Inflation using ADVANCED LIGO
• More Is Different: Reconciling eV Sterile Neutrinos with Cosmological Mass Bounds