Study of CP Violation in Flavor Tagged and Untagged $D^0 \rightarrow K^-\pi^+$ Decays

TL;DR

This paper reviews $CP$ violation in $D^0 ightarrow K^-\pi^+$ decays, highlighting the importance of the asymmetry difference between tagged and untagged decays and proposing a new method to determine the strong phase difference.

Contribution

It introduces a novel expression to extract the strong phase difference independently of existing experimental methods and emphasizes the significance of the $CP$ asymmetry difference in future experiments.

Findings

The $CP$ asymmetry difference between tagged and untagged decays can be significant.

The paper provides a new way to measure the strong phase difference.

The asymmetry difference is not zero in principle and relevant for future experiments.

Abstract

We review $CP$-violating observables in flavor tagged and untagged $D^0 \rightarrow K^{-}\pi^{+}$ decays and evaluate the $CP$ asymmetry difference between the two decays. We note that this commonly neglected difference is not zero in principle and can be significant in future $B$ factory experiments. We also construct an expression to extract the strong phase difference between $\bar{D}^0 \rightarrow K^-\pi^+$ and $D^0 \rightarrow K^-\pi^+$ decays, independently of existing experimental methods.