Congeniality Bounds on Quark Masses from Nucleosynthesis

TL;DR

This paper reevaluates the range of quark masses compatible with nucleosynthesis, finding that the viable 'congenial' region is much narrower than previously thought, and may be reduced to the physical quark mass point.

Contribution

It refines the bounds on quark masses compatible with nucleosynthesis by imposing additional astrophysical and nuclear constraints, narrowing the congeniality region.

Findings

The congenial region shrinks from about 29 MeV to 2.2 MeV in quark mass difference.

Additional nucleosynthesis constraints further restrict the viable quark mass range.

The physical quark mass point may be the only viable option under these bounds.

Abstract

The work of Jaffe, Jenkins and Kimchi [Phys. Rev. D79, 065014 (2009)] is revisited to see if indeed the region of congeniality found in their analysis survives further restrictions from nucleosynthesis. It is observed that much of their congenial region disappears when imposing conditions required to produce the correct and required abundances of the primordial elements as well as ensure that stars can continue to burn hydrogen nuclei to form helium as the first step in forming heavier elements in stellar nucleosynthesis. The remaining region is a very narrow slit reduced in width from around 29 MeV found by Jaffe et al. to only about 2.2 MeV in the difference of the nucleon/quark masses. Further bounds on $\delta m_q /m_q$ seem to reduce even this narrow slit to the physical point itself.