Measurement of the doubly Cabibbo suppressed decay $D^0 \to K^+\pi^-$ and a search for charm mixing

TL;DR

This paper reports the measurement of the rare doubly Cabibbo suppressed decay of D0 mesons and searches for charm mixing, providing branching ratios, CP asymmetry, and limits on mixing parameters based on FOCUS data.

Contribution

It presents the first measurement of the decay rate of D0 to K+pi- and explores charm mixing and CP violation using experimental data.

Findings

Branching ratio of D0 to K+pi- is approximately 0.429%.

No significant CP violation observed in the decay.

Limits on charm mixing parameters are established.

Abstract

We present an analysis of the decay $D^0 \to K^+\pi^-$ based on FOCUS data. From a sample of 234 signal events, we find a branching ratio of $\frac{\Gamma(D^0 \to K^+\pi^-)}{\Gamma(D^0 \to K^-\pi^+)} = (0.429^{+0.063}_{-0.061}\pm 0.027)%$ under the assumptions of no mixing and no CP violation. Allowing for CP violation, we find a branching ratio of $(0.429 \pm 0.063 \pm 0.028)%$ and a \textit{CP} asymmetry of $0.18 \pm 0.14 \pm 0.04$. The branching ratio for the case of mixing with no CP violation is $(0.381^{+0.167}_{-0.163} \pm 0.092)%$. We also present limits on charm mixing.