Search for <i>CP</i> violation in D<SUP>0</SUP> → K_S<SUP>0</SUP>K_S<SUP>0</SUP> decays in proton-proton collisions at √<i>s</i>=13TeV

A search is reported for charge-parity CP violation in D-0 -> (KSKS0)-K-0 decays, using data collected in proton-proton collisions at root s =13 TeV recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6fb(-1), 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 D*(+) -> D-0 pi(+) and D*(-) -> (D) over bar (0)pi(-). The CP asymmetry in D-0 -> (KSKS0)-K-0 is measured to be A(CP)((KSKS0)-K-0) = (6.2 +/- 3.0 +/- 0.2 +/- 0.8)%, where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the CP asymmetry in the D-0 -> K-S(0)pi(+)pi(-) decay. This is the first CP asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state.