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Big bang nucleosynthesis (BBN) has been used as a probe of beyond-standardphysics in the early Universe, which includes a time-dependent quark mass m_q.We investigate effects of a quark mass variation delta m_q on the crosssections of the 7Be(n, p)7Li reaction and primordial light element abundancestaking into account roles of 8Be resonances in the reaction during BBN. Thisresonant reaction has not been investigated although behaviors of low-lyingresonances are not trivial. It is found that a resonance at the resonanceenergy E_r=0.33 MeV enhances the reaction rate and lowers the 7Li abundancesignificantly when the quark mass variation is negative. Based upon up-to-dateobservational limits on primordial abundances of D, 4He and Li, the quark massvariation in the BBN epoch are derived. In a model in which the resonanceenergies of the reactions 3He(d, p)4He and 3H(d, n)4He are insensitive to thequark mass, we find that the Li abundance can be consistent with observationsfor delta m_q/m_q = (4--8) times 10^{-3}.

Roles of $^7$Be$(n,p)^7$Li resonances in big bang nucleosynthesis with time-dependent quark mass and Li reduction by a heavy quark mass