Search for violation in decays in proton-proton collisions at .

A search is reported for charge-parity violation in decays, using data collected in proton-proton collisions at recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6 , which consists of about 10 billion events containing a pair of b hadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays and . The asymmetry in is measured to be , where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the asymmetry in the decay. This is the first asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state.