Top-quark mass measurement from dilepton events at CDF II.
Phys Rev Lett 96:15 (2006) 152002
Abstract:
We report a measurement of the top-quark mass using events collected by the CDF II detector from pp collisions at square root of s = 1.96 TeV at the Fermilab Tevatron. We calculate a likelihood function for the top-quark mass in events that are consistent with tt --> bl(-)nu(l)bl'+ nu'(l) decays. The likelihood is formed as the convolution of the leading-order matrix element and detector resolution functions. The joint likelihood is the product of likelihoods for each of 33 events collected in 340 pb(-1) of integrated luminosity, yielding a top-quark mass M(t) = 165.2 +/- 6.1(stat) +/- 3.4(syst) GeV/c2. This first application of a matrix-element technique to tt --> bl+ nu(l)bl'- nu(l') decays gives the most precise single measurement of M(t) in dilepton events. Combined with other CDF run II measurements using dilepton events, we measure M(t) = 167.9 +/- 5.2(stat) +/- 3.7(syst) GeV/c2.Measurement of the dipion mass spectrum in decays.
Phys Rev Lett 96:10 (2006) 102002
Abstract:
We measure the dipion mass spectrum in X(3872)--> J/psipi(+) pi(-) decays using 360 pb(-1) of pp collisions at square root s= 1.96 TeV collected with the CDF II detector. The spectrum is fit with predictions for odd C-parity ((3)S(1), (1)P(1), and (3)D(J)) charmonia decaying to J/psipi(+) pi(-), as well as even C-parity states in which the pions are from rho(0) decay. The latter case also encompasses exotic interpretations, such as a D(0)D(*0) molecule. Only the (3)S(1) and J/psirho hypotheses are compatible with our data. Since (3)S(1) is untenable on other grounds, decay via J/psirho is favored, which implies C= +1 for the X(3872). Models for J/psi - rho different angular momenta L are considered. Flexibility in the models, especially the introduction of rho - omega interference, enables good descriptions of our data for both L = 0 and 1.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.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)