Measurement of mass and width of the excited charmed meson states D10 and D2*0 at CDF
Physical Review D - Particles, Fields, Gravitation and Cosmology 73:5 (2006)
Abstract:
We report on precision measurements of the masses and widths of the narrow, orbitally excited states D10 and D2*0 using the CDF II detector at the Fermilab Tevatron. Both states (collectively called D**) are reconstructed in the decay channel D**→D*+π-. The D2*0 is also reconstructed in the D**→D+π- channel. Using a data set with an integrated luminosity of 210pb-1, the measured masses and widths for the D10 are 2421.7±0.7±0.6 MeV/c2 and 20.0±1.7±1.3 MeV/c2 respectively, while for the D2*0 they are 2463.3±0.6±0.8 MeV/c2 and 49.2±2.3±1.2 MeV/c2. These values are currently the single best measurements available. © 2006 The American Physical Society.A photometric redshift of z = 6.39 ± 0.12 for GRB 050904
Nature 440:7081 (2006) 181-183
Abstract:
Gamma-ray bursts (GRBs) and their afterglows are the most brilliant transient events in the Universe. Both the bursts themselves and their afterglows have been predicted to be visible out to redshifts of z ≈ 20, and therefore to be powerful probes of the early Universe1,2. The burst GRB 000131, at z = 4.50, was hitherto the most distant such event identified3. Here we report the discovery of the bright near-infrared afterglow of GRB 050904 (ref. 4). From our measurements of the near-infrared afterglow, and our failure to detect the optical afterglow, we determine the photometric redshift of the burst to be z = 6.39-0.12+0.11 (refs 5-7). Subsequently, it was measured8 spectroscopically to be z = 6.29 ± 0.01, in agreement with our photometric estimate. These results demonstrate that GRBs can be used to trace the star formation, metallicity, and reionization histories of the early Universe. © 2006 Nature Publishing Group.Search for anomalous semileptonic decay of heavy flavor hadrons produced in association with a W boson at CDF II
Physical Review D - Particles, Fields, Gravitation and Cosmology 73:5 (2006)
Abstract:
We present a search for anomalous semileptonic decays of heavy flavor hadrons produced in association with a W boson in proton-antiproton collisions at s=1.96TeV. We use 162pb-1 of data collected with the CDF II detector at the Fermilab Tevatron Collider. We select events with one W boson and at least one jet with an identified secondary vertex. In the jets with a secondary vertex we look for a semileptonic decay to a muon. We compare the number of jets with both a secondary vertex and a semileptonic decay and the kinematic properties of these jets, with the standard model expectation of W plus heavy flavor production and decay. No discrepancy is seen between the observation and the expectation, and we set limits on the production cross section of a B-like hadron with an anomalously high semileptonic branching ratio. © 2006 The American Physical Society.Search for second-generation scalar leptoquarks in pp̄ collisions at s=1.96TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 73:5 (2006)
Abstract:
Results on a search for pair production of second-generation scalar leptoquark in pp̄ collisions at s=1.96TeV are reported. The data analyzed were collected by the CDF detector during the 2002-2003 Tevatron Run II and correspond to an integrated luminosity of 198pb-1. Leptoquarks (LQ) are sought through their decay into (charged) leptons and quarks, with final state signatures represented by two muons and jets and one muon, large transverse missing energy and jets. We observe no evidence for LQ production and derive 95% C.L. upper limits on the LQ production cross sections as well as lower limits on their mass as a function of β, where β is the branching fraction for LQ→μq. © 2006 The American Physical Society.Evidence for the exclusive decay B(c)+- --> J/psi pi+- and measurement of the mass of the B(c)+- meson.
Phys Rev Lett 96:8 (2006) 082002