51ÁÔÆæÈë¿Ú

Abstract:

We report on a search for pair production of first-generation scalar leptoquarks (LQ) in pp̄ collisions at s=1.96 TeV using an integrated luminosity of 203 pb-1 collected at the Fermilab Tevatron collider by the CDF experiment. We observe no evidence for LQ production in the topologies arising from LQLQ̄→eqeq and LQLQ̄→eqνq, and derive 95% C.L. upper limits on the LQ production cross section. The results are combined with those obtained from a separately reported CDF search in the topology arising from LQLQ̄→νqνq and 95% C.L. lower limits on the LQ mass as a function of β=BR(LQ→eq) are derived. The limits are 236, 205 and 145GeV/c2 for β=1, β=0.5 and β=0.1, respectively. © 2005 The American Physical Society.

Abstract:

We report on a search for Λb0→pπ- and Λb0→pK- (and charge conjugate) decays in pp̄ collisions at s=1.96TeV using 193pb-1 of data collected by the CDF II experiment at the Fermilab Tevatron Collider. Data were collected using a track trigger that has been optimized to select tracks belonging to a secondary vertex that is typical of two-body charmless decays of b-flavored hadrons, including Λb0 baryons. As no Λb0 signal was observed, we set the upper limits on the branching fraction B(Λb0→ph-), where h is K or π, of 2.3×10-5 at 90% C.L. and 2.9×10-5 at 95% C.L. © 2005 The American Physical Society.