Muon capture rate on hydrogen and the values of g_A and g _πNN

Motivated by the recent developments in the determination of the experimental values of the nucleon axial-vector coupling constant g_A and the pion-nucleon coupling constant g_πNN, we carry out a heavy-baryon chiral perturbation calculation of the hyperfine-singlet μp capture rate Γ₀ to next-to-next-to-leading order (N2LO), with the use of the latest values of g_A and g_πNN. The calculated N2LO value is Γ0theor(μ ^-p→ν_μn)=718±7sec^-1, where the estimated next-to-next-to-next-to-leading order contribution dominates the error. This value is in excellent agreement with the experimental value reported by the MuCap Collaboration.