• Energy Research

A simultaneous measurement of the top-quark, W-boson, and neutrino masses is reported for tt¯ events selected in the dilepton final state from a data sample corresponding to an integrated luminosity of 5.0 fb−1 collected by the CMS experiment in pp collisions at s√=7 TeV. The analysis is based on endpoint determinations in kinematic distributions. When the neutrino and W-boson masses are constrained to their world-average values, a top-quark mass value of Mt=173.9±0.9 (stat.)+1.7−2.1 (syst.) GeV is obtained. When such constraints are not used, the three particle masses are obtained in a simultaneous fit. In this unconstrained mode the study serves as a test of mass determination methods that may be used in beyond standard model physics scenarios where several masses in a decay chain may be unknown and undetected particles lead to underconstrained kinematics. The European Physical Journal C, 73 (7) ISSN:1434-6044 ISSN:1434-6052

We report first evidence for a fully reconstructed decay mode of the B_c^{\pm} meson in the channel B_c^{\pm} \to J/psi ��^{\pm}, with J/psi \to mu^+mu^-. The analysis is based on an integrated luminosity of 360 pb$^{-1} in p\bar{p} collisions at 1.96 TeV center of mass energy collected by the Collider Detector at Fermilab. We observe 14.6 \pm 4.6 signal events with a background of 7.1 \pm 0.9 events, and a fit to the J/psi pi^{\pm} mass spectrum yields a B_c^{\pm} mass of 6285.7 \pm 5.3(stat) \pm 1.2(syst) MeV/c^2. The probability of a peak of this magnitude occurring by random fluctuation in the search region is estimated as 0.012%. 7 pages, 3 figures. Version 3, accepted by PRL

We describe a search for anomalous production of events with two leptons ($e$ or $��$) of the same electric charge in \ppbar collisions at a center-of-mass energy of 1.96 TeV. Many extensions to the standard model predict the production of two leptons of the same electric charge. This search has a significant increase in sensitivity compared to earlier searches. Using a data sample corresponding to 1 \invfb of integrated luminosity recorded by the CDF II detector, we observe no significant excess in an inclusive selection (expect $33.2\pm4.7$ events, observe 44) or in a SUSY-optimized selection (expect $7.8\pm1.1$ events, observe 13.) replaced with published version