Big Bang Nucleosynthesis with Time-dependent Quark Mass

Kanji Mori (University of Tokyo, NAOJ)


The standard Big Bang nucleosynthesis (BBN) model predicts primordial abundances of hydrogen, helium and lithium which are in reasonable agreement with astronomical observations except for 7Li. Recent precise reanalysis of an absorption system along the line-of-sight toward high red-shift quasar Q1243+307 has placed tighter observational constraint on the primordial abundance of deuterium. Comparing this observational result with the theoretical prediction allows us to explore possible beyond-standard physics. In particular, the BBN is sensitive to quark mass variations because they change nuclear binding energies. The effect of the quark mass variations on the BBN has been studied, but it was the case ignoring the roles of the 7Be(n, p)7Li resonant reaction which is known to affect the primordial abundance of 7Be. In this talk, I report for the first time that this reaction significantly decreases the abundance of the A=7 nuclear systems when the quark mass variation is negative. This is because the resonance at E=0.33 MeV is found to contribute strongly to the reaction rates at the BBN temperature. I also report that the 7Li abundance significantly decreases if the quark mass is larger than the present value, although this is the conclusion assuming that the resonance energies are independent of the quark mass variation. In order to prove this solution, more careful theoretical studies of the binding energies of the excited states are desirable.

host contact: Masato Shirasaki