Measurements of inclusive W and Z cross sections in pp̄ collisions at √s = 1.96 TeV
Journal of Physics G: Nuclear and Particle Physics 34:12 (2007) 2457-2544
Abstract:
We report the first measurements of inclusive W and Z boson cross-sections times the corresponding leptonic branching ratios for collisions at TeV based on the decays of the W and Z bosons into electrons and muons. The data were recorded with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 72.0 ± 4.3 pb-1. We test e-μ lepton universality in W decays by measuring the ratio of the W → μν to W → eν cross sections and determine a value of 0.991 ± 0.004(stat.) ± 0.011(syst.) for the ratio of W - ℓ - ν couplings (gμ/ge). Since there is no sign of non-universality, we combine our cross-section measurements in the different lepton decay modes and obtain σw × Br (pp̄ → W → ℓv) = 2.749 ± 0.010(stat.) ± 0.053(syst.) ± 0.165 (lum.) nb and σγ* × Br (pp̄ → γ*/Z → ℓℓ) = 254.9 ± 3.3(stat.) ± 4.6(syst.) ± 15.2(lum.) pb for dilepton pairs in the mass range between 66 GeV/c2 and 116 GeV/c2. We compute the ratio R of the W → ℓν to Z → ℓℓ cross sections taking all correlations among channels into account and obtain R = 10.84 ± 0.15(stat.) ± 0.14(syst.) including a correction for the virtual photon exchange component in our measured γ*/Z → ℓℓ cross section. Based on the measured value of R, we extract values for the W leptonic branching ratio, Br(W → ℓν)= 0.1082 ± 0.0022; the total width of the W boson, Γ(W)= 2092 ± 42 MeV; and the ratio of W and Z boson total widths, Γ(W)/Γ(Z)= 0.838 ± 0.017. In addition, we use our extracted value of Γ(W) whose value depends on various electroweak parameters and certain CKM matrix elements to constrain the Vcs CKM matrix element, |Vcs| = 0.976 ± 0.030. © 2007 IOP Publishing Ltd.Observation of the Heavy Baryons Sigma b and Sigma b*.
Phys Rev Lett 99:20 (2007) 202001
Abstract:
We report an observation of new bottom baryons produced in pp collisions at the Tevatron. Using 1.1 fb(-1) of data collected by the CDF II detector, we observe four Lambda b 0 pi+/- resonances in the fully reconstructed decay mode Lambda b 0-->Lambda c + pi-, where Lambda c+-->pK* pi+. We interpret these states as the Sigma b(*)+/- baryons and measure the following masses: m Sigma b+=5807.8 -2.2 +2.0(stat.)+/-1.7(syst.) MeV/c2, m Sigma b- =5815.2+/-1.0(stat.)+/-1.7(syst.) MeV/c2, and m(Sigma b*)-m(Sigma b)=21.2-1.9 +2.0(stat.)-0.3+0.4(syst.) MeV/c2.Observation of the heavy baryons Σb and Σb*
Physical Review Letters 99:20 (2007)
Abstract:
We report an observation of new bottom baryons produced in pp̄ collisions at the Tevatron. Using 1.1fb-1 of data collected by the CDF II detector, we observe four Λb0π± resonances in the fully reconstructed decay mode Λb0→Λc+π-, where Λc+→pK-π+. We interpret these states as the Σb(*) ± baryons and measure the following masses: mΣb+=5807.8-2.2+2. 0(stat.)±1.7(syst.)MeV/c2, mΣb-=5815.2±1.0(stat.)±1. 7(syst.)MeV/c2, and m(Σb*)-m(Σb)=21.2-1.9+2.0(stat.)-0.3+0. 4(syst.)MeV/c2. © 2007 The American Physical Society.Search for chargino-neutralino production in pp collisions at sq rt[s] = 1.96 TeV.
Phys Rev Lett 99:19 (2007) 191806
Abstract:
We present a search for associated production of the chargino and neutralino supersymmetric particles using up to 1.1 fb{-1} of integrated luminosity collected by the CDF II experiment at the Tevatron pp collider at sq rt[s]=1.96 TeV. We analyze events with a large transverse momentum imbalance and either three charged leptons or two charged leptons of the same electric charge. The numbers of observed events are consistent with standard model expectations. Upper limits on the production cross section are derived in different theoretical models.Precise measurement of the top-quark mass in the lepton+jets topology at CDF II.
Phys Rev Lett 99:18 (2007) 182002