Neutron injection during primordial nucleosynthesis alleviates the primordial 7Li problem

TL;DR

This paper investigates how injecting free neutrons during primordial nucleosynthesis can reduce the 7Li abundance, potentially solving the lithium problem without disrupting other elemental abundances.

Contribution

It introduces a parametrized model of neutron injection during nucleosynthesis, showing that dark matter decay or annihilation could explain the lithium problem.

Findings

Neutron injection can lower 7Li levels effectively.

Dark matter particles of 1-30 GeV could cause the necessary neutron injection.

Other elemental abundances remain consistent with observations.

Abstract

We present a parametrized study of the effects of free thermal neutron injection on primordial nucleosynthesis, where both the rate and the time scale of injection are varied. This generic approach is found to yield a successful solution for reducing the 7Li abundance without causing significant problems to other elemental abundances. Our analysis demonstrates that hadronic injection, possibly due to decays or annihilations of dark matter particles with a mass of about 1 to 30 GeV, provides a possible solution to an outstanding problem in the standard Big Bang model.