Quantum correlation of neutral charmed mesons at BESIII

Abstract

BESIII has recently accumulated a large data sample near the $ψ(3770)$ production threshold corresponding to an integrated luminosity of $20\text{ fb}^{-1}$. Neutral $D^0\bar{D}^0$ pairs produced at the $ψ(3770)$ 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 $D\to K^+K^-π^+π^-$ decays. Additionally reported is the first observation of correlated $DD$ pairs produced at $e^+e^-$ center-of-mass energies above the $ψ(3770)$ 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.

Figures (3)

• Figure 1: Cross-sectional view of the BESIII detector.
• Figure 2: (Left, Center) Examples of fits to determine the yields of ${D}\xspace{\overline{ {D}}\xspace}\xspace\to K^+K^-\pi^+\pi^- \text{vs.}$ tag decay modes from Ref. BESIII:2025wqu. (Right) Determinations of the $c_i$ and $s_i$ parameters in Ref. BESIII:2025wqu as black points compared to predictions from an amplitude modelLHCb:2023yjo as blue crosses.
• Figure 3: Corrected yields of ${D}\xspace{\overline{ {D}}\xspace}\xspace$ final states expected to be significantly affected by the presence of quantum correlations normalized to the expectation in the absence of correlations from Refs. BESIII:2025podBESIII:2025xed. The predicted ratios of yields in the presence of correlations are shown for comparison.