Non-Thermal Cosmic Rays During Big Bang Nucleosynthesis to Solve the Lithium Problem

Abstract: The discrepancy between the theoretical prediction of primordial lithium abundances and astronomical observations is called the Lithium Problem. We find that extra contributions from non-thermal hydrogen and helium during Big Bang nucleosynthesis can explain the discrepancy, for both Li-7 and Li-6, and will change the deuterium abundance only little. The allowed parameter space of such an amount of non-thermal particles and the energy range is shown. The hypothesis is stable regardless of the cross-section uncertainty of relevant reactions and the explicit shape of the energy spectrum.