Search For Scalar Top Quark Pair Production In Scenario With Violated R Parity In Ppu00af Collisions At U221as

A search for the pair production of supersymmetric partner of the top quark in scenario with R-parity violation is presented. The quantum number called R-parity distinguishes particles in standard model from supersymmetric particles. A scalar top quark (stop) is assumed to decay only via Rp-violating supersymmetric coupling into tau lepton and b-quark. To collect events with multiple taus, a new special tau trigger (the lepton plus track trigger) is installed in Run II experiment of the Collider Detector at Fermilab (CDF). The goal of the lepton plus track trigger is to collect generic dilepton (ll, l?, ??) events with lower pT threshold (8 GeV/c) and without prescale even at high luminosity. The Z → ?? event, where one ?-lepton decays leptonically and the other hadronically, is a good benchmark to calibrate the lepton plus track trigger and ? identification. The data sample of 72 pb-1, collected using the electron plus track trigger, contains clear a ? signal from Z → ?? events. The data used in stop search correspond to 200 pb-1. The lower stop mass bound of 134 GeV/c2 at a 95% confidence level is obtained. This limit is also directly applicable to the case of the third generation scalar leptoquark (LQ3) assuming a 100% branching for the LQ3 → ?b decay mode.