Big Bang Nucleosynthesis: The Strong Nuclear Force meets the Weak Anthropic Principle

TL;DR

This paper challenges the idea that increasing the strong nuclear force would eliminate hydrogen in the big bang, showing that moderate increases still allow hydrogen survival due to earlier nucleosynthesis and delayed formation of certain particles.

Contribution

It demonstrates that a moderate increase in the strong force strength does not destroy hydrogen, revising previous assumptions about nuclear stability and the conditions of the early universe.

Findings

Hydrogen remains abundant if the strong force increases by less than 50%.

Nucleosynthesis occurs earlier at higher temperatures with increased strong force.

Delayed production of diprotons and dineutrons affects element abundances.

Abstract

Contrary to a common argument that a small increase in the strength of the strong force would lead to destruction of all hydrogen in the big bang due to binding of the diproton and the dineutron with a catastrophic impact on life as we know it, we show that provided the increase in strong force coupling constant is less than about 50% substantial amounts of hydrogen remain. The reason is that an increase in strong force strength leads to tighter binding of the deuteron, permitting nucleosynthesis to occur earlier in the big bang at higher temperature than in the standard big bang. Photodestruction of the less tightly bound diproton and dineutron delays their production to after the bulk of nucleosynthesis is complete. The decay of the diproton can, however, lead to relatively large abundances of deuterium.