Search for baryon number violation in top-quark decays with the CMS experiment

A search for baryon number violation (BNV) in top-quark decays is performed using p-p collisions produced by the Large Hadron Collider at the energy in the center of mass of 7 TeV and 8 TeV. The top-quark decay considered in this search results in one light lepton (muon or electron), two jets, but no neutrino in the final state. Data used for the analysis were collected by the CMS detector and correspond to an integrated luminosity of 5 inverse femtobarns in 2011 and 19.5 inverse femtobarns in 2012. The event selection is optimized for top quarks produced in pairs, with one having the BNV decay and the other the standard model hadronic decay to three jets. No significant excess of events over the expected yields from standard model processes is observed. The upper limits at 95% confidence level on the branching fraction of the BNV top-quark decay are calculated to be 0.0016 and 0.0017 for the muon and the electron channels, respectively. These limits are the first that have been obtained on a BNV process involving the top quark.