Inhomogeneous neutrino degeneracy and big bang nucleosynthesis
- Department of Physics, State University of New York, Buffalo, New York 14260 (United States)
- Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)
We examine big bang nucleosynthesis (BBN) in the case of inhomogeneous neutrino degeneracy, in the limit where the fluctuations are sufficiently small on large length scales that the present-day element abundances are homogeneous. We consider two representative cases: degeneracy of the electron neutrino alone and equal chemical potentials for all three neutrinos. We use a linear programming method to constrain an arbitrary distribution of the chemical potentials. For the current set of (highly restrictive) limits on the primordial element abundances, homogeneous neutrino degeneracy barely changes the allowed range of the baryon-to-photon ratio {eta}. Inhomogeneous degeneracy allows for little change in the lower bound on {eta}, but the upper bound in this case can be as large as {eta}=1.1x10{sup -8} (only {nu}{sub e} degeneracy) or {eta}=1.0x10{sup -9} (equal degeneracies for all three neutrinos). For the case of inhomogeneous neutrino degeneracy, we show that there is no BBN upper bound on the neutrino energy density, which is bounded in this case only by limits from structure formation and the cosmic microwave background. (c) 2000 The American Physical Society.
- OSTI ID:
- 20216145
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 61, Issue 8; Other Information: PBD: 15 Apr 2000; ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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