Lepton asymmetry and primordial nucleosynthesis in the era of precision cosmology
- Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, 80805 Munich (Germany)
We calculate and display the primordial light-element abundances as a function of a neutrino degeneracy parameter {xi} common to all flavors. It is the only unknown parameter characterizing the thermal medium at the primordial nucleosynthesis epoch. The observed primordial helium abundance Y{sub p} is the most sensitive cosmic 'leptometer'. Adopting the conservative Y{sub p} error analysis of Olive and Skillman implies -0.04 < or approx. {xi} < or approx. 0.07 whereas the errors stated by Izotov and Thuan imply {xi}=0.0245{+-}0.0092 (1{sigma}). Improved determinations of the baryon abundance have no significant impact on this situation. A determination of Y{sub p} that reliably distinguishes between a vanishing or nonvanishing {xi} is a crucial test of the cosmological standard assumption that sphaleron effects equilibrate the cosmic lepton and baryon asymmetries.
- OSTI ID:
- 20709617
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 71, Issue 12; Other Information: DOI: 10.1103/PhysRevD.71.127301; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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