First measurement of the W-boson mass in run II of the Tevatron.

We present a measurement of the W-boson mass using 200 pb{-1} of data collected in pp[over ] collisions at sqrt[s]=1.96 TeV by the CDF II detector at run II of the Fermilab Tevatron. With a sample of 63 964 W-->enu candidates and 51 128 W-->munu candidates, we measure M_{W}=80 413+/-34{stat}+/-34{syst}=80,413+/-48 MeV/c;{2}. This is the most precise single measurement of the W-boson mass to date.

Search for new physics in high-mass electron-positron events in pp[over] collisions at square root s = 1.96 TeV.

We report the results of a search for a narrow resonance in electron-positron events in the invariant mass range of 150-950 GeV/c(2) using 1.3 fb(-1) of pp[over] collision data at square root s = 1.96 TeV collected by the CDF II detector at Fermilab. No significant evidence of such a resonance is observed and we interpret the results to exclude the standard-model-like Z' with a mass below 923 GeV/c(2) and the Randall-Sundrum graviton with a mass below 807 GeV/c(2) for k/M[over](pl) = 0.1, both at the 95% confidence level. Combining with diphoton data excludes the Randall-Sundrum graviton for masses below 889 GeV/c(2) for k/M[over](pl) = 0.1.

Search for high-mass diphoton states and limits on Randall-Sundrum gravitons at CDF.

We have performed a search for new particles which decay to two photons using 1.2 fb(-1) of integrated luminosity from pp[over] collisions at square root s = 1.96 TeV collected using the CDF II detector at the Fermilab Tevatron. We find the diphoton mass spectrum to be in agreement with the standard model expectation, and set limits on the cross section times branching ratio for the Randall-Sundrum graviton, as a function of diphoton mass. We subsequently derive lower limits for the graviton mass of 230 GeV/c(2) and 850 GeV/c(2), at the 95% confidence level, for coupling parameters (k/M[over](Pl)) of 0.01 and 0.1, respectively.

Precise measurement of the top-quark mass in the lepton+jets topology at CDF II.

We present a measurement of the mass of the top quark from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. We analyze events from the single lepton plus jets final state (tt-->W(+)bW(-)b-->lnubqq'b). The top-quark mass is extracted using a direct calculation of the probability density that each event corresponds to the tt final state. The probability is a function of both the mass of the top quark and the energy scale of the calorimeter jets, which is constrained in situ by the hadronic W boson mass. Using 167 events observed in 955 pb(-1) of integrated luminosity, we achieve the single most precise measurement of the top-quark mass, 170.8+/-2.2(stat.)+/-1.4(syst.) GeV/c(2).

Search for heavy long-lived particles that decay to photons at CDF II.

We present the first search for heavy, long-lived particles that decay to photons at a hadron collider. We use a sample of gamma + jet + missing transverse energy events in pp[over] collisions at square root[s] = 1.96 TeV taken with the CDF II detector. Candidate events are selected based on the arrival time of the photon at the detector. Using an integrated luminosity of 570 pb(-1) of collision data, we observe 2 events, consistent with the background estimate of 1.3+/-0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross section limits in a supersymmetric model with [Formula: see text] and place the world-best 95% C.L. lower limit on the [Formula: see text] mass of 101 GeV/c(2) at [Formula: see text].

Polarizations of J/psi and psi(2S) mesons produced in pp collisions at square root s = 1.96 TeV.

We have measured the polarizations of J/psi and psi(2S) mesons as functions of their transverse momentum p(T) when they are produced promptly in the rapidity range |y| < 0.6 with p(T) > or =5 GeV/c. The analysis is performed using a data sample with an integrated luminosity of about 800 pb(-1) collected by the CDF II detector. For both vector mesons, we find that the polarizations become increasingly longitudinal as p(T) increases from 5 to 30 GeV/c. These results are compared to the predictions of nonrelativistic quantum chromodynamics and other contemporary models. The effective polarizations of J/psi and psi(2S) mesons from B-hadron decays are also reported.

Observation and mass measurement of the baryon Xib-.

We report the observation and measurement of the mass of the bottom, strange baryon Xi(b)- through the decay chain Xi(b)- -->J/psiXi-, where J/psi-->mu+mu-, Xi- -->Lambdapi-, and Lambda-->ppi-. A signal is observed whose probability of arising from a background fluctuation is 6.6 x 10(-15), or 7.7 Gaussian standard deviations. The Xi(b)- mass is measured to be 5792.9+/-2.5(stat) +/- 1.7(syst) MeV/c2.

Inclusive search for new physics with like-sign dilepton events in pp collisions at square root of s =1.96 TeV.

We describe a search for anomalous production of events with two leptons (e or mu) of the same electric charge in pp[over ] collisions at a center-of-mass energy of 1.96 TeV. Many extensions to the standard model predict the production of two leptons of the same electric charge. This search has a significant increase in sensitivity compared to earlier searches. Using a data sample corresponding to 1 fb(-1) of integrated luminosity recorded by the CDF II detector, we observe no significant excess in an inclusive selection (expect 33.2+/-4.7 events, observe 44) or in a supersymmetry-optimized selection (expect 7.8+/-1.1 events, observe 13.).

Measurement of sigma chi c2 B(chi c2-->J/psi gamma)/sigma chi c1 B(chi c1 -->J/psi gamma) in pp collisions at square root s=1.96 TeV.

We measure the ratio of cross section times branching fraction, Rp=sigma chi c2 B(chi c2-->J/psi gamma)/sigma chi c1 B(chi c1-->J/psi gamma), in 1.1 fb(-1) of pp collisions at square root s=1.96 TeV. This measurement covers the kinematic range pT(J/psi)>4.0 GeV/c, |eta(J/psi)<1.0, and pT(gamma)>1.0 GeV/c. For events due to prompt processes, we find Rp=0.395+/-0.016(stat)+/-0.015(syst). This result represents a significant improvement in precision over previous measurements of prompt chi c1,2 hadro production.

First measurement of the ratio of central-electron to forward-electron W partial cross sections in pp[over] collisions at (square root)s =1.96 TeV.

We present a measurement of sigma(pp[over] --> W) x B(W --> e nu) at (square root)s = 1.96 TeV, using electrons identified in the forward region (1.2 < |eta| < 2.8) of the CDF II detector, in 223 pb(-1) of data. We measure sigma x B = 2796 +/- 13(stat)(-90)(+95)(syst) +/- 162(lum) pb. Combining this result with a previous CDF measurement obtained using electrons in the central region (|eta| approximately < 1), we present the first measurement of the ratio of central-electron to forward-electron W partial cross sections R(exp) = 0.925 +/- 0.006(stat) +/- 0.032(syst), consistent with theoretical predictions using Coordinated Theoretical-Experimental Project on QCD (CTEQ) and Martin-Roberts-Stirling-Thorne (MRST) parton distribution functions.

Observation of exclusive electron-positron production in hadron-hadron collisions.

We present the first observation of exclusive e(+)e(-) production in hadron-hadron collisions, using pp[over] collision data at (square root) s = 1.96 TeV taken by the run II Collider Detector at Fermilab, and corresponding to an integrated luminosity of 532 pb(-1). We require the absence of any particle signatures in the detector except for an electron and a positron candidate, each with transverse energy E(T) > 5 GeV and pseudorapidity |eta| < 2. With these criteria, 16 events are observed compared to a background expectation of 1.9+/-0.3 events. These events are consistent in cross section and properties with the QED process pp[over] --> p + e(+)e(-) + p[over] through two-photon exchange. The measured cross section is 1.6(-0.3)(+0.5)(stat) +/- 0.3(syst) pb. This agrees with the theoretical prediction of 1.71+/-0.01 pb.

Measurement of the Lambda b0 lifetime in Lambda b0-->J/psi Lambda 0 in pp collisions at square root s=1.96 TeV.

We report a measurement of the Lambda b0 lifetime in the exclusive decay Lambda b0-->J/psi Lambda 0 in pp collisions at square root s=1.96 TeV using an integrated luminosity of 1.0 fb-1 of data collected by the CDF II detector at the Fermilab Tevatron. Using fully reconstructed decays, we measure tau(Lambda b0)=1.593(-0.078)(+0.083)(stat)+/-0.033(syst) ps. This is the single most precise measurement of tau(Lambda b0) and is 3.2sigma higher than the current world average.

Measurement of sigma Lambda b0/sigma B0 x B(Lambda b0-->Lambda c+pi-)/B(B0-->D+pi-) in pp collisions at square root s=1.96 TeV.

We present the first observation of the baryon decay Lambda b0-->Lambda c+pi- followed by Lambda c+-->pK-pi+ in 106 pb-1 pp collisions at square root s=1.96 TeV in the CDF experiment. In order to reduce systematic error, the measured rate for Lambda b0 decay is normalized to the kinematically similar meson decay B0-->D+pi- followed by D+-->pi+K-pi+. We report the ratio of production cross sections (sigma) times the ratio of branching fractions (B) for the momentum region integrated above pT>6 GeV/c and pseudorapidity range |eta|<1.3: sigma(pp-->Lambda b0X)/sigma(pp-->B0X)xB(Lambda b0-->Lambda c+pi-)/B(B0-->D+pi-)=0.82+/-0.08(stat)+/-0.11(syst)+/-0.22[B(Lambda c+-->pK-pi+)].

Analysis of the quantum numbers J(PC) of the X(3872) particle.

We present an analysis of angular distributions and correlations of the X(3872) particle in the exclusive decay mode X(3872)-->J/psipi+ pi- with J/psi-->mu+ mu-. We use 780 pb-1 of data from pp[over ] collisions at sqrt[s]=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We derive constraints on spin, parity, and charge conjugation parity of the X(3872) particle by comparing measured angular distributions of the decay products with predictions for different J(PC) hypotheses. The assignments J(PC)=1++ and 2-+ are the only ones consistent with the data.

Search for anomalous production of multilepton events in pp collisions at sqrt s=1.96 TeV.

We report a search for the anomalous production of events with multiple charged leptons in pp[over] collisions at sqrt[s]=1.96 TeV using a data sample corresponding to an integrated luminosity of 346 pb(-1) collected by the CDF II detector at the Fermilab Tevatron. The search is divided into three-lepton and four-or-more-lepton data samples. We observe six events in the three-lepton sample and zero events in the > or =4-lepton sample. Both numbers of events are consistent with standard model background expectations. Within the framework of an R-parity-violating supergravity model, the results are interpreted as mass limits on the lightest neutralino (chi[over](1)(0)) and chargino (chi[over](1+/-) particles. For one particular choice of model parameters, the limits are M(chi[over](1)(0)>110 GeV/c2 and M(chi[over](1+/-)>203 GeV/c2 at 95% confidence level; the variation of these mass limits with model parameters is presented.

Measurement of the top-quark mass in all-hadronic decays in pp collisions at CDF II.

We present a measurement of the top-quark mass Mtop in the all-hadronic decay channel tt-->W+bW-b-->q1q2bq3q4b. The analysis is performed using 310 pb-1 of sqrt[s]=1.96 TeV pp[over ] collisions collected with the CDF II detector using a multijet trigger. The mass measurement is based on an event-by-event likelihood which depends on both the sample purity and the value of the top-quark mass, using 90 possible jet-to-parton assignments in the six-jet final state. The joint likelihood of 290 selected events yields a value of Mtop=177.1+/-4.9(stat)+/-4.7(syst) GeV/c2.

Observation of WZ production.

We report the first observation of the associated production of a W boson and a Z boson. This result is based on 1.1 fb;-1 of integrated luminosity from pp collisions at sqrt[s]=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We observe 16 WZ candidates passing our event selection with an expected background of 2.7+/-0.4 events. A fit to the missing transverse energy distribution indicates an excess of events compared to the background expectation corresponding to a significance equivalent to 6 standard deviations. The measured cross section is sigma(pp-->WZ)=5.0(-1.6)(+1.8) pb, consistent with the standard model expectation.

Measurement of the ratios of branching fractions B(B0s --> Ds- pi+ pi+ pi-)/B(B0-->D- pi+ pi+ pi-) and B(B0s --> Ds- pi+)/B(B0-->D- pi+).

Using 355 pb;{-1} of data collected by the CDF II detector in pp[over ] collisions at sqrt[s]=1.96 TeV at the Fermilab Tevatron, we study the fully reconstructed hadronic decays B_{(s)};{0}-->D_{(s)};{-}pi;{+} and B_{(s)};{0}-->D_{(s)};{-}pi;{+}pi;{+}pi;{-}. We present the first measurement of the ratio of branching fractions B(B_{s};{0}-->D_{s};{-}pi;{+}pi;{+}pi;{-})/B(B;{0}-->D;{-}pi;{+}pi;{+}pi;{-})=1.05+/-0.10(stat)+/-0.22(syst). We also update our measurement of B(B_{s};{0}-->D_{s};{-}pi;{+})/B(B;{0}-->D;{-}pi;{+}) to 1.13+/-0.08(stat)+/-0.23(syst), improving the statistical uncertainty by more than a factor of 2. We find B(B_{s};{0}-->D_{s};{-}pi;{+})=[3.8+/-0.3(stat)+/-1.3(syst)]x10;{-3} and B(B_{s};{0}-->D_{s};{-}pi;{+}pi;{+}pi;{-})=[8.4+/-0.8(stat)+/-3.2(syst)]x10;{-3}.

Search for V+A current in top-quark decays in pp collisions at sqrts=1.96 TeV.

We report an upper limit on the fraction of V+A current, fV+A, in top-quark decays, using approximately 700 pb-1 of pp[over ] collisions at sqrts=1.96 TeV acquired by the upgraded Collider Detector at Fermilab. For the decay t-->Wb-->lnub (where l=e or micro), the invariant mass of the charged lepton and the bottom quark jet is sensitive to the polarization of the W boson. We determine fV+A=-0.06+/-0.25 given a top-quark mass of 175 GeV/c2. We set an upper limit on fV+A of 0.29 at the 95% confidence level, an improvement by a factor of 2 on the previous best direct limit.

Search for chargino-neutralino production in pp collisions at sq rt[s] = 1.96 TeV.

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.