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

TL;DR

This paper reports a highly precise measurement of the absolute branching fraction of the decay D+ → K̄0 μ+ νμ using BESIII data, refining previous results and enabling better understanding of charm semileptonic decays.

Contribution

The study provides the most precise measurement to date of the D+ → K̄0 μ+ νμ branching fraction, improving the accuracy of charm decay data and ratios of partial widths.

Findings

Measured branching fraction: (8.72 ± 0.07(stat) ± 0.18(sys))%.

Determined partial width ratios: 0.963 ± 0.044 and 0.988 ± 0.033.

Results are consistent with previous measurements but with improved precision.

Abstract

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 ${\mathcal B}(D^{+}\rightarrow\bar K^0\mu^{+}\nu_{\mu})=(8.72 \pm 0.07_{\rm stat.} \pm 0.18_{\rm sys.})\%$, which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of ${\mathcal B}(D^0\to K^-\mu^+\nu_\mu)$, ${\mathcal B}(D^{+}\rightarrow\bar K^0 e^{+}\nu_{e})$, 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: $\Gamma(D^0\to K^-\mu^+\nu_\mu)/\Gamma(D^{+}\rightarrow\bar K^0\mu^{+}\nu_{\mu})=0.963\pm0.044$ and $\Gamma(D^{+}\rightarrow\bar K^0 \mu^{+}\nu_{\mu})/\Gamma(D^{+}\rightarrow\bar K^0 e^{+}\nu_{e})=0.988\pm0.033$.