We present a measurement of the strong-phase difference between $D^0$ and ${\overline{D}}^0\to K_{\mathrm{S},\mathrm{L}}^0{K}^{+}{K}^{-}$ decays, performed through a study of quantum-entangled pairs of charm mesons. The measurement exploits a data sample equivalent to an integrated luminosity of $2.93{\mathrm{fb}}^{-1}$, collected by the BESIII detector in $e^{+}{e}^{-}$ collisions corresponding to the mass of the $\psi (3770)$ resonance. The strong-phase difference is an essential input to the determination of the Cabibbo-Kobayashi-Maskawa (CKM) angle $\gamma /{\varphi }_3$ through the decay $B^{-}\to D{K}^{-}$, where $D$ can be either a $D^0$ or a ${\overline{D}}^0$ decaying to $K_{\mathrm{S},\mathrm{L}}^0{K}^{+}{K}^{-}$. This is the most precise measurement to date of the strong-phase difference in these decays.

• Received 17 July 2020
• Accepted 26 August 2020

DOI:https://doi.org/10.1103/PhysRevD.102.052008

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Published by the American Physical Society