BBN with light dark matter

TL;DR

This paper investigates how light millicharged dark matter particles influence primordial nucleosynthesis, revealing potential overproduction of Helium-4 and suggesting that lepton asymmetry can reconcile models with observations.

Contribution

It introduces the effects of light millicharged dark matter on Big Bang nucleosynthesis and explores conditions for consistency with observational data.

Findings

Light dark matter causes Helium-4 overproduction

Lepton asymmetry can align models with observations

Neutrino-to-photon ratio differs from standard cosmology

Abstract

Effects of light millicharged dark matter particles on primordial nucleosynthesis are considered. It is shown that if the mass of such particles is much smaller than the electron mass, they lead to strong overproduction of Helium-4. An agreement with observations can be achieved by non-vanishing lepton asymmetry. Baryon-to-photon ratio at BBN and neutrino- to-photon ratio both at BBN and at recombination are noticeably different as compared to the standard cosmological model. The latter ratio and possible lepton asymmetry could be checked by Planck. For higher mass of new particles the effect is much less pronounced and may even have opposite sign.