Influence of the variation of fundamental constants on the primordial nucleosynthesis

TL;DR

This study examines how variations in fundamental constants could influence primordial nucleosynthesis, finding minimal effects on key nuclear reaction rates but highlighting the importance of weak interaction rates.

Contribution

It provides a detailed analysis of how changing fundamental constants affects nuclear reaction rates during Big Bang nucleosynthesis, especially for unstable nuclei like 5Li, 5He, and 8Be.

Findings

Variation in constants has limited impact on key reaction rates.

Weak interaction rates are the dominant influence on nucleosynthesis.

The triple-alpha process remains ineffective unless 8Be is stable.

Abstract

We investigate the effect of a variation of fundamental constants on primordial element production in Big Bang nucleosynthesis (BBN). We focus on the effect of a possible change in the nucleon-nucleon interaction on nuclear reaction rates involving the A=5 (5Li and 5He) and A=8 (8Be) unstable nuclei. The reaction rates for 3He(d,p)4He and 3H(d,n)4He are dominated by the properties of broad analog resonances in 5Li and 5He compound nuclei respectively. While the triple-alpha process 4He(aa,g)12C is normally not effective in BBN, its rate is very sensitive to the position of the "Hoyle state" and could in principle be drastically affected if 8Be were stable during BBN. We found that the effect of the variation of constants on the 3He(d,p)4He, 3H(d,n)4He nd 4He(aa,g)12C reaction rates is not sufficient to induce a significant effect on BBN, even with a stable 8Be. The main influences come from the weak rates and the A=2, n(p,g)d, bottleneck reaction.