Search for pair production of the scalar top quark in muon + tau final states

We present a search for the pair production of scalar top quarks (t˜1), the lightest supersymmetric partners of the top quarks, in pp¯ collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of 7.3fb−1 collected with the D0 experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a b quark, a charged lepton, and a scalar neutrino (ν˜). We investigate final states arising from t˜1t˜¯1→bb¯μτν˜ν˜ and t˜1t˜¯1→bb¯ττν˜ν˜. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the (mt˜1,mν˜) plane.