Big Bang Nucleosynthesis with Gaussian Inhomogeneous Neutrino Degeneracy

Abstract

We consider the effect of inhomogeneous neutrino degeneracy on Big Bang nucleosynthesis for the case where the distribution of neutrino chemical potentials is given by a Gaussian. The chemical potential fluctuations are taken to be isocurvature, so that only inhomogeneities in the electron chemical potential are relevant. Then the final element abundances are a function only of the baryon-photon ratio $\eta$, the effective number of additional neutrinos $\Delta N_{\nu }$, the mean electron neutrino degeneracy parameter $\bar{\xi }$, and the rms fluctuation of the degeneracy parameter, ${\sigma }_{\xi }$. We find that for fixed $\eta$, $\Delta N_{\nu }$, and $\bar{\xi }$, the abundances of helium-4, deuterium, and lithium-7 are, in general, increasing functions of ${\sigma }_{\xi }$. Hence, the effect of adding a Gaussian distribution for the electron neutrino degeneracy parameter is to decrease the allowed range for $\eta$. We show that this result can be generalized to a wide variety of distributions for $\xi$.

9 pages, 3 figures, added discussion of neutrino oscillations, altered presentation of figures

References in corpus (5)

• Cosmological bounds on neutrino degeneracy improved by flavor oscillations
• Stringent Constraints on Cosmological Neutrino-Antineutrino Asymmetries from Synchronized Flavor Transformation
• High-energy neutrino conversion and the lepton asymmetry in the universe
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Cited by in corpus (4)

• Primordial Nucleosynthesis: from precision cosmology to fundamental physics
• Future constraints on neutrino isocurvature perturbations in the curvaton scenario
• Mass Varying Neutrinos, Quintessence, and the Accelerating Expansion of the Universe
• Does inhomogeneous big bang nucleosynthesis produce an inhomogeneous element distribution today?