Improved measurement of the absolute branching fraction of D^{+}\rightarrow \bar{K}^0 \mu ^{+}\nu _{\mu }

By analyzing 2.93 fb(^{-1}) of data collected at (sqrt{s}=3.773) GeV with the BESIII detector, we measure the absolute branching fraction ({mathcal B}(D^{+}rightarrow bar{K}^0mu ^{+}nu _{mu })=(8.72 pm 0.07_mathrm{stat.} pm 0.18_mathrm{sys.})%), which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of ({mathcal B}(D^0rightarrow K^-mu ^+nu _mu )), ({mathcal B}(D^{+}rightarrow bar{K}^0 e^{+}nu _{e})), and the lifetimes of the (D^0) and (D^+) mesons with the value of ({mathcal B}(D^{+}rightarrow bar{K}^0 mu ^{+}nu _{mu })) measured in this work, we determine the following ratios of partial widths: (Gamma (D^0rightarrow K^-mu ^+nu _mu )/Gamma (D^{+}rightarrow bar{K}^0mu ^{+}nu _{mu })=0.963pm 0.044) and (Gamma (D^{+}rightarrow bar{K}^0 mu ^{+}nu _{mu })/Gamma (D^{+}rightarrow bar{K}^0 e^{+}nu _{e})=0.988pm 0.033).