Effect of quark mass variation on big bang nucleosynthesis

摘要

We calculate the effect of variation in the light-current quark mass,mq, on standard big bang nucleosynthesis. A change inmqduring the era of nucleosynthesis affects nuclear reaction rates, and hence primordial abundances, via changes in the binding energies of light nuclei. It is found that a relative variation ofδmq/mq=0.016±0.005provides better agreement between observed primordial abundances and those predicted by theory. This is largely due to resolution of the existing discrepancies for7Li. However this method ignores possible changes in the position of resonances in nuclear reactions. The predicted7Li abundance has a strong dependence on the cross-section of the resonant reactionsHe3(d,p)He4andt(d,n)He4. We show that changes inmqat the time of BBN could shift the position of these resonances away from the Gamow window and lead to an increased production of7Li, exacerbating the lithium problem.