Direct search for dirac magnetic monopoles in pp̄ collisions at s=1.96TeV
Physical Review Letters 96:20 (2006)
Abstract:
We search for pair-produced Dirac magnetic monopoles in 35.7pb-1 of proton-antiproton collisions at s=1.96TeV with the Collider Detector at Fermilab (CDF). We find no monopole candidates corresponding to a 95% confidence-level cross-section limit σ<0.2pb for a monopole with mass between 200 and 700GeV/c2. Assuming a Drell-Yan pair-production mechanism, we set a mass limit m>360GeV/c2. © 2006 The American Physical Society.Evidence for the exclusive decay Bc±→J/ψπ± and measurement of the mass of the Bc± meson
Physical Review Letters 96:8 (2006)
Abstract:
We report the first evidence for a fully reconstructed decay mode of the Bc± meson in the channel Bc±→J/ψπ±, with J/ψ→μ+μ-. The analysis is based on an integrated luminosity of 360pb-1 in pp̄ collisions at 1.96 TeV center of mass energy collected by the Collider Detector at Fermilab. We observe 14.6±4.6 signal events with a background of 7.1±0.9 events, and a fit to the J/ψπ± mass spectrum yields a Bc± mass of 6285.7±5.3(stat)±1. 2(syst)MeV/c2. The probability of a peak of this magnitude occurring by random fluctuation in the search region is estimated as 0.012%. © 2006 The American Physical Society.Measurement of the dipion mass spectrum in X(3872)→J/ψπ+π- decays
Physical Review Letters 96:10 (2006)
Abstract:
We measure the dipion mass spectrum in X(3872)→J/ψπ+π- decays using 360pb-1 of p̄p collisions at s=1.96TeV collected with the CDFÂ II detector. The spectrum is fit with predictions for odd C-parity (S13, P11, and DJ3) charmonia decaying to J/ψπ+π-, as well as even C-parity states in which the pions are from ρ0 decay. The latter case also encompasses exotic interpretations, such as a D0D̄*0 molecule. Only the S13 and J/ψρ hypotheses are compatible with our data. Since S13 is untenable on other grounds, decay via J/ψρ is favored, which implies C=+1 for the X(3872). Models for different J/ψ-ρ angular momenta L are considered. Flexibility in the models, especially the introduction of ρ-ω interference, enables good descriptions of our data for both L=0 and 1. © 2006 The American Physical Society.Measurement of the inclusive jet cross section using the kT algorithm in pp̄ collisions at s=1.96TeV
Physical Review Letters 96:12 (2006)
Abstract:
We report on a measurement of the inclusive jet production cross section as a function of the jet transverse momentum in pp̄ collisions at s=1.96TeV using data collected with the upgraded Collider Detector at Fermilab in run II, corresponding to an integrated luminosity of 385pb-1. The measurement is carried out for jets with rapidity 0.1<|yjet|<0.7 and transverse momentum in the range 54Measurement of the ratios of branching fractions B(Bs0→Ds-π+)/ B(B0→D-π+) and B(B+→D̄0π+)/B(B0→D-π+)
Physical Review Letters 96:19 (2006)