Search for CP 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.