Quantum correlation of neutral charmed mesons at BESIII

Abstract

BESIII has recently accumulated a large data sample near the $\psi(3770)$ production threshold corresponding to an integrated luminosity of $20\text{ fb}^{-1}$. Neutral $D^0\bar{D}^0$ pairs produced at the $\psi(3770)$ are in a $C$-odd correlated state, providing a unique laboratory to measure the strong-phase differences between $D^0$ and $\bar{D}^0$ decays. These parameters are essential inputs to the study of CP violation in heavy-flavor physics, primarily in the determinations of the CKM angle gamma and charm-mixing parameters. These proceedings report new measurements of strong-phase differences in different neutral $D$ decays at BESIII, including new measurements of the strong phases in $D\to K^+K^-\pi^+\pi^-$ decays. Additionally reported is the first observation of correlated $DD$ pairs produced at $e^+e^-$ center-of-mass energies above the $\psi(3770)$ threshold, where $e^+e^-\to D^{*}\bar{D}$ and $e^+e^-\to D^{*}\bar{D}^{*}$ processes also occur. These processes produce both $C$-odd and $C$-even correlated $D^0\bar{D}^0$ pairs, which allow for new measurement techniques to determine strong-phases from previously unused datasets.