• Open Access

Dark sector equilibration during nucleosynthesis

Asher Berlin, Nikita Blinov, and Shirley Weishi Li
Phys. Rev. D 100, 015038 – Published 24 July 2019

Abstract

Light, weakly coupled dark sectors may be naturally decoupled in the early Universe and enter equilibrium with the Standard Model bath during the epoch of primordial nucleosynthesis. The equilibration and eventual decoupling of dark sector states modifies the expansion rate of the Universe, which alters the predicted abundances of the light elements. This effect can be encompassed in a time-varying contribution to Neff, the effective number of neutrino species, such that Neff during nucleosynthesis differs from its measured value at the time of recombination. We investigate the impact of such variations on the light element abundances with model-independent templates for the time dependence of Neff as well as in specific models where a dark sector equilibrates with neutrinos or photons. We find that significant modifications of the expansion rate are consistent with the measured abundances of light nuclei, provided that they occur during specific periods of nucleosynthesis. In constraining concrete models, the relative importance of the cosmic microwave background and primordial nucleosynthesis is highly model dependent.

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  • Received 16 April 2019

DOI:https://doi.org/10.1103/PhysRevD.100.015038

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & AstrophysicsParticles & Fields

Authors & Affiliations

Asher Berlin1, Nikita Blinov1,2, and Shirley Weishi Li1

  • 1SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
  • 2Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA

Article Text

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Issue

Vol. 100, Iss. 1 — 1 July 2019

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