Measurement of $CP$ asymmetry in $D^0\to K_S^0{K}_S^0$ decays

Abstract

A measurement of the $CP$ asymmetry in $D^0\to K_S^0{K}_S^0$ decays is reported, based on a data sample of proton-proton collisions collected by the LHCb experiment from 2015 to 2018, corresponding to an integrated luminosity of 6 fb${}^{-1}$. The flavor of the $D^0$ candidate is determined using the charge of the $D^{\ast \pm }$ meson, from which the decay is required to originate. The $D^0\to K^{+}{K}^{-}$ decay is used as a calibration channel. The time-integrated $CP$ asymmetry for the $D^0\to K_S^0{K}_S^0$ mode is measured to be: $$A^{CP}(D^0\to K_S^0{K}_S^0)=(-3.1\pm 1.2\pm 0.4\pm 0.2)\%,$$ where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the $CP$ asymmetry of the calibration channel. This is the most precise determination of this quantity to date.

All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2020-047.html (LHCb public pages)