Nuclear weak interaction rates in primordial nucleosynthesis

TL;DR

This paper calculates weak interaction rates for light nuclei during Big Bang Nucleosynthesis and evaluates their effects on element abundances and nuclear flow histories, highlighting potential impacts in non-standard scenarios.

Contribution

It provides detailed calculations of weak interaction rates for specific light nuclei during BBN, including their potential influence on nuclear processes and element yields.

Findings

Standard BBN yields are minimally affected by these weak processes.

Weak processes can slightly alter nuclear flow histories.

Non-standard scenarios may be significantly impacted by these rates.

Abstract

We calculate the weak interaction rates of selected light nuclei during the epoch of Big Bang Nucleosynthesis (BBN), and we assess the impact of these rates on nuclear abundance flow histories and on final light element abundance yields. We consider electron and electron antineutrino captures on 3He and 7Be, and the reverse processes of positron capture and electron neutrino capture on 3H and 7Li. We also compute the rates of positron and electron neutrino capture on 6He. We calculate beta and positron decay transitions where appropriate. As expected, the final standard BBN abundance yields are little affected by addition of these weak processes, though there can be slight alterations of nuclear flow histories. However, non-standard BBN scenarios, e.g., those involving out of equilibrium particle decay with energetic final state neutrinos, may be affected by these processes.