research

Constraints on Lepton Asymmetry from Nucleosynthesis in a Linearly Coasting Cosmology

Abstract

We study the effect of neutrino degeneracy on primordial nucleosynthesis in a universe in which the cosmological scale factor evolves linearly with time. The degeneracy parameter of electron type neutrinos (ξe\xi_e) determines the n/pn/p (neutron to proton) ratio, which in turn determines the abundance of 4^4He in a manner quite distinct from the Standard Scenario. The observed abundances of 4^4He, YP\mathrm{Y}_P=0.254±\pm0.003, and the minimum metallicity that is essential for fragmentation and cooling processes in star forming prestellar gas clouds (Z = Zcr_{cr} = 10−6^{-6}Z⊙_\odot), constrain the baryon to photon ratio, ηB\eta_B=(3.927±\pm0.292)10−9^{-9}, corresponding to a baryonic matter density, ΩB\Omega_B=0.263±\pm 0.026 and ξe\xi_e=-2.165±\pm0.171. This closes the dynamic mass estimates of matter in the universe by baryons alone. Useful byproducts are the threshold X(CNO) abundances required to trigger the CNO cycle in the observed low metallicity stars in the universe.Comment: 18 Pages, 9 Figures. Matches published versio

    Similar works

    Full text

    thumbnail-image

    Available Versions