Final results of μp capture rate ΛS and pseudoscalar coupling gP

Abstract

We present the final results of muon capture on proton μ- + p → νμ + n, which were obtained by the MuCap Collaboration at the Paul Scherrer Institute. The singlet μp capture rate ΛS is determined as the difference between the lifetimes of μp and μ+. Our result is ΛSMuCap = 714.9 ± 5.4stat ± 5.1syst s-1 in excellent agreement with the prediction of chiral perturbation theory ΛSCHPT = 712.7 ± 4.3 s-1. The induced pseudoscalar coupling constant results as gPMuCap = 8.06 ± 0.48exp ± 0.28th whereas gPCHPT = 8.26 ± 0.23.