Neutrino statistics and big bang nucleosynthesis

Abstract

Neutrinos may possibly violate the spin-statistics theorem, and hence obey Bose statistics or mixed statistics despite having spin half. We find the generalized equilibrium distribution function of neutrinos which depends on a single fermi-bose parameter, κ, and interpolates continuously between the bosonic and fermionic distributions when κchanges from -1 to +1. We consider modification of the Big Bang Nucleosynthesis (BBN) in the presence of bosonic or partly bosonic neutrinos. For pure bosonic neutrinos the abundances change (in comparison with the usual Fermi-Dirac case) by -3.2% for 4He (which is equivalent to a decrease of the effective number of neutrinos by ΔN_ν= - 0.6), +2.6% for 2H and -7% for 7Li. These changes provide a better fit to the BBN data. Future BBN studies will be able to constrain the fermi-bose parameter to κ> 0.5, if no deviation from fermionic nature of neutrinos is found. We also evaluate the sensitivity of future CMB and LSS observations to the fermi-bose parameter.

11 pages, 3 figures, matches version in JCAP, discussion and references extended slightly

References in corpus (4)

• Big Bang Nucleosynthesis (in "The Review of Particle Properties" 2004)
• Nuclear Reaction Network for Primordial Nucleosynthesis: a detailed analysis of rates, uncertainties and light nuclei yields
• New cosmological mass limit on thermal relic axions
• Do observations prove that cosmological neutrinos are thermally distributed?

Cited by in corpus (23)

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• What can CMB observations tell us about the neutrino distribution function?
• An Improved Limit on Pauli-Exclusion-Principle Forbidden Atomic Transitions
• WMAP 5-year constraints on lepton asymmetry and radiation energy density: Implications for Planck
• X rays test the Pauli exclusion principle
• Neutrinos in Cosmology and Astrophysics
• Probing Beyond the Standard Model Physics with Double-beta Decays
• Non-thermal Hot Dark Matter from Inflaton/Moduli Decay: The Momentum Distribution and Relaxing the Cosmological Mass Bound
• Possible violation of the spin-statistics relation for neutrinos: checking through future galactic supernova
• Cosmology and New Physics
• Experimental test of the Pauli Exclusion Principle
• Cosmological bounds on neutrino statistics
• Fermi-Boltzmann statistics of neutrinos and relativistic effective degrees of freedom
• Neutrino statistics and non-standard commutation relations
• Violation of the Spin Statistics Theorem and the Bose-Einstein Condensation of Particles with Half Integer Spin
• First-order vortices in a gauged $CP(2)$ model with a Chern-Simons term
• Exotic quantum statistics and thermodynamics from a number-conserving theory of Majorana fermions
• Constraint on Neutrino Statistics from Cosmological Data
• Relativistic effective degrees of freedom and quantum statistics of neutrinos