Time Dependent Quark Masses and Big Bang Nucleosynthesis Revisited
  We reinvestigate the constraints from primordial nucleosynthesis on a possible time-dependent quark mass. The limits on such quark-mass variations are particularly sensitive to the adopted observational abundance constraints. Hence, in the present study we have considered updated light-element abundances and uncertainties deduced from observations. We also consider new nuclear reaction rates and an independent analysis of the influence of such quark-mass variations on the resonance properties of the important 3He(d,p)4He reaction. We find that the updated abundance and resonance constraints imply a narrower range on the possible quark-mass variations in the early universe. We also find that, contrary to previous investigations, the optimum concordance region reduces to a (95% C.L.) value of -0.005 < delta m_q/m_q < 0.007 consistent with no variation in the averaged quark mass. 
Myung-Ki Cheoun, Toshitaka Kajino, Motohiko Kusakabe, Grant J. Mathews
astro-ph.CO hep-ph