We report a measurement of the {lambda}{sub b}{sup 0} lifetime in the exclusive decay {lambda}{sub b}{sup 0}{yields}J/{psi}{lambda}{sup 0} in pp collisions at {radical}(s)=1.96 TeV using an ...integrated luminosity of 1.0 fb{sup -1} of data collected by the CDF II detector at the Fermilab Tevatron. Using fully reconstructed decays, we measure {tau}({lambda}{sub b}{sup 0})=1.593{sub -0.078}{sup +0.083}(stat){+-}0.033(syst) ps. This is the single most precise measurement of {tau}({lambda}{sub b}{sup 0}) and is 3.2{sigma} higher than the current world average.
We present the first observation of the baryon decay {lambda}{sub b}{sup 0}{yields}{lambda}{sub c}{sup +}{pi}{sup -} followed by {lambda}{sub c}{sup +}{yields}pK{sup -}{pi}{sup +} in 106 pb{sup -1} ...pp collisions at {radical}(s)=1.96 TeV in the CDF experiment. In order to reduce systematic error, the measured rate for {lambda}{sub b}{sup 0} decay is normalized to the kinematically similar meson decay B{sup 0}{yields}D{sup +}{pi}{sup -} followed by D{sup +}{yields}{pi}{sup +}K{sup -}{pi}{sup +}. We report the ratio of production cross sections ({sigma}) times the ratio of branching fractions (B) for the momentum region integrated above p{sub T}>6 GeV/c and pseudorapidity range |{eta}|<1.3: {sigma}(pp{yields}{lambda}{sub b}{sup 0}X)/{sigma}(pp{yields}B{sup 0}X)xB({lambda}{sub b}{sup 0}{yields}{lambda}{sub c}{sup =} +{pi}{sup -})/B(B{sup 0}{yields}D{sup +}{pi}{sup -})=0.82{+-} 0.08(stat){+-}0.11(syst){+-}0.22B({lambda}{sub c}{sup +}{yields}pK{sup -}{pi}{sup +}).
We report on a measurement of the inclusive jet production cross section as a function of the jet transverse momentum in pp collisions at {radical}(s)=1.96 TeV using data collected with the upgraded ...Collider Detector at Fermilab in run II, corresponding to an integrated luminosity of 385 pb{sup -1}. The measurement is carried out for jets with rapidity 0.1< vertical bar y{sup jet} vertical bar<0.7 and transverse momentum in the range 54<p{sub T}{sup jet}<700 GeV/c. Next-to-leading order perturbative QCD predictions are in good agreement with the measured cross section after the necessary nonperturbative parton-to-hadron corrections are included.
We measure the dipion mass spectrum in X(3872){yields}J/{psi}{pi}{sup +}{pi}{sup -} decays using 360 pb{sup -1} of pp collisions at {radical}(s)=1.96 TeV collected with the CDF II detector. The ...spectrum is fit with predictions for odd C-parity ({sup 3}S{sub 1}, {sup 1}P{sub 1}, and {sup 3}D{sub J}) charmonia decaying to J/{psi}{pi}{sup +}{pi}{sup -}, as well as even C-parity states in which the pions are from {rho}{sup 0} decay. The latter case also encompasses exotic interpretations, such as a D{sup 0}D*{sup 0} molecule. Only the {sup 3}S{sub 1} and J/{psi}{rho} hypotheses are compatible with our data. Since {sup 3}S{sub 1} is untenable on other grounds, decay via J/{psi}{rho} is favored, which implies C=+1 for the X(3872). Models for different J/{psi}-{rho} 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.
We report an upper limit on the fraction of V+A current, f{sub V+A}, in top-quark decays, using approximately 700 pb{sup -1} of pp collisions at {radical}(s)=1.96 TeV acquired by the upgraded ...Collider Detector at Fermilab. For the decay t{yields}Wb{yields}l{nu}b (where l=e or {mu}), the invariant mass of the charged lepton and the bottom quark jet is sensitive to the polarization of the W boson. We determine f{sub V+A}=-0.06{+-}0.25 given a top-quark mass of 175 GeV/c{sup 2}. We set an upper limit on f{sub V+A} of 0.29 at the 95% confidence level, an improvement by a factor of 2 on the previous best direct limit.
We present a search for Higgs bosons decaying into bb and produced in association with W bosons in pp collisions at {radical}(s)=1.96 TeV. This search uses 320 pb{sup -1} of the data set accumulated ...by the upgraded Collider Detector at Fermilab. Events are selected that have a high-transverse momentum electron or muon, missing transverse energy, and two jets, at least one of which is consistent with the hadronization of a b quark. Both the number of events and the dijet mass distribution are consistent with standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching ratio for the Higgs boson or any new particle with similar decay kinematics. These upper limits range from 10 pb for m{sub H}=110 GeV/c{sup 2} to 3 pb for m{sub H}=150 GeV/c{sup 2}.
We report the first evidence for a fully reconstructed decay mode of the B{sub c}{sup {+-}} meson in the channel B{sub c}{sup {+-}}{yields}J/{psi}{pi}{sup {+-}}, with J/{psi}{yields}{mu}{sup ...+}{mu}{sup -}. The analysis is based on an integrated luminosity of 360 pb{sup -1} in pp 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/{psi}{pi}{sup {+-}} mass spectrum yields a B{sub c}{sup {+-}} mass of 6285.7{+-}5.3(stat){+-}1.2(syst) MeV/c{sup 2}. The probability of a peak of this magnitude occurring by random fluctuation in the search region is estimated as 0.012%.
We report the results of a search for a charged Higgs boson in the decays of top quarks produced in pp collisions at a center-of-mass energy of 1.96 TeV. We use a data sample corresponding to an ...integrated luminosity of 193 pb{sup -1} collected by the upgraded Collider Detector at Fermilab. No evidence for charged Higgs production is found, allowing 95% C.L. upper limits to be placed on BR(t{yields}H{sup +}b) for different charged Higgs decay scenarios. In addition, we present in the minimal supersymmetric standard model (m{sub H{sup {+-}}},tan{beta}) plane the first exclusion regions with radiative and Yukawa coupling corrections.
We report two measurements of the top-quark mass M{sub top} using the CDF II detector at the Fermilab Tevatron in a 318 pb{sup -1} data sample of tt events in the lepton+jets final state. One method ...uses an event-based likelihood technique resulting in M{sub top}=173.2{sub -2.4}{sup +2.6}(stat){+-}3.2(syst) GeV/c{sup 2} or 173.2{sub -4.0}{sup +4.1} GeV/c{sup 2}. The second method reconstructs a top-quark mass in each event using the measured invariant mass of the hadronically decaying W boson to constrain the jet energy scale to obtain a value for M{sub top} of 173.5{sub -3.6}{sup +3.7}(stat){+-}1.3(syst) GeV/c{sup 2} or 173.5{sub -3.8}{sup +3.9} GeV/c{sup 2}. We take the latter, which is more precise, as our result.
We present a search for neutral supersymmetric Higgs bosons decaying to {tau} pairs produced in pp collisions at {radical}(s)=1.96 TeV. The data, corresponding to 310 pb{sup -1} integrated ...luminosity, were collected with the Collider Detector at Fermilab in run II of the Tevatron. No significant excess above the standard model backgrounds is observed. We set exclusion limits on the production cross section times branching fraction to {tau} pairs for Higgs boson masses in the range from 90 to 250 GeV/c{sup 2}.
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