A novel measurement of the strong-phase difference between $D^0\to K^-\pi^+$ and $\bar{D}^0\to K^-\pi^+$ decays using $C$-even and $C$-odd quantum-correlated $D\bar{D}$ pairs

TL;DR

This paper introduces a new quantum-correlated technique to measure the strong-phase difference between $D^0$ and $ar{D}^0$ decays, providing the first such measurement using $C$-eigenstate pairs from $e^+e^-$ collisions.

Contribution

It presents a novel method leveraging quantum correlations in $Dar{D}$ pairs to determine the strong-phase difference, a key parameter in charm physics.

Findings

Measured the strong-phase difference $oldsymbol{ ext{δ}^D_{K ext{π}}}$ as approximately 193°.

First determination of this phase using quantum-correlated $Dar{D}$ pairs.

Demonstrated the effectiveness of the new measurement technique.

Abstract

A novel measurement technique of strong-phase differences between the decay amplitudes of $D^0$ and $\bar{D}^0$ mesons is introduced which exploits quantum-correlated $D\bar{D}$ pairs produced by $e^+e^-$ collisions at energies above the $\psi(3770)$ production threshold, where $D\bar{D}$ pairs are produced in both even and odd eigenstates of the charge-conjugation symmetry. Employing this technique, the first determination of a $D^0$-$\bar{D^0}$ relative strong phase is reported with such data samples. The strong-phase difference between $D^0\to K^-\pi^+$ and $\bar{D}^0\to K^-\pi^+$ decays, $\delta^{D}_{K\pi}$, is measured to be $\delta^{D}_{K\pi}=\left(192.8^{+11.0 + 1.9}_{-12.4 -2.4}\right)^\circ$, using a dataset corresponding to an integrated luminosity of 7.13 $\text{fb}^{-1}$ collected at center-of-mass energies between $4.13-4.23 \text{ GeV}$ by the BESIII experiment.