Primordial nucleosynthesis as a probe of fundamental physics parameters

We analyze the effect of variation of fundamental couplings and mass scales on primordial nucleosynthesis in a systematic way. The first step establishes the response of primordial element abundances to the variation of a large number of nuclear physics parameters, including nuclear binding energies. We find a strong influence of the n-p mass difference (for the ⁴He abundance), of the nucleon mass (for deuterium), and of $A=3$, 4, 7 binding energies (for ³He, ⁶Li, and ⁷Li). A second step relates the nuclear parameters to the parameters of the standard model of particle physics. The deuterium, and, above all, ⁷Li abundances depend strongly on the average light quark mass ^m≡(mᵤ+md)/2. We calculate the behavior of abundances when variations of fundamental parameters obey relations arising from grand unification. We also discuss the possibility of a substantial shift in the lithium abundance while the deuterium and ⁴He abundances are only weakly affected.