Search for the standard model Higgs boson decaying to a bb pair in events with two oppositely charged leptons using the full CDF data set.

We present a search for the standard model Higgs boson produced in association with a Z boson in data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45 fb(-1). In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electron or muon pairs, we set 95% credibility level upper limits on the ZH production cross section times the H→bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125 GeV/c(2), we observe (expect) a limit of 7.1 (3.9) times the standard model value.

Combined search for the standard model Higgs boson decaying to a bb pair using the full CDF data set.

We combine the results of searches for the standard model (SM) Higgs boson based on the full CDF Run II data set obtained from sqrt[s]=1.96 TeV pp collisions at the Fermilab Tevatron corresponding to an integrated luminosity of 9.45 fb(-1). The searches are conducted for Higgs bosons that are produced in association with a W or Z boson, have masses in the range 90-150 GeV/c(2), and decay into bb pairs. An excess of data is present that is inconsistent with the background prediction at the level of 2.5 standard deviations (the most significant local excess is 2.7 standard deviations).

Search for the standard model Higgs boson decaying to a bb pair in events with one charged lepton and large missing transverse energy using the full CDF data set.

We present a search for the standard model Higgs boson produced in association with a W boson in sqrt[s]=1.96 TeV pp collision data collected with the CDF II detector at the Tevatron corresponding to an integrated luminosity of 9.45 fb(-1). In events consistent with the decay of the Higgs boson to a bottom-quark pair and the W boson to an electron or muon and a neutrino, we set 95% credibility level upper limits on the WH production cross section times the H→bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125 GeV/c(2), we observe (expect) a limit of 4.9 (2.8) times the standard model value.

Search for the standard model Higgs boson decaying to a bb pair in events with no charged leptons and large missing transverse energy using the full CDF data set.

We report on a search for the standard model Higgs boson produced in association with a vector boson in the full data set of proton-antiproton collisions at sqrt[s]=1.96 TeV recorded by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45 fb(-1). We consider events having no identified charged lepton, a transverse energy imbalance, and two or three jets, of which at least one is consistent with originating from the decay of a b quark. We place 95% credibility level upper limits on the production cross section times standard model branching fraction for several mass hypotheses between 90 and 150 GeV/c(2). For a Higgs boson mass of 125 GeV/c(2), the observed (expected) limit is 6.7 (3.6) times the standard model prediction.

Search for a low-mass standard model Higgs boson in the ττ decay channel in pp collisions at sqrt[s]=1.96 TeV.

We report on a search for the standard model Higgs boson decaying into pairs of τ leptons in pp collisions produced by the Tevatron at sqrt[s]=1.96 TeV. The analyzed data sample was recorded by the CDFII detector and corresponds to an integrated luminosity of 6.0 fb(-1). The search is performed in the final state with one τ decaying leptonically and the second one identified through its semihadronic decay. Since no significant excess is observed, a 95% credibility level upper limit on the production cross section times branching ratio to the ττ final state is set for hypothetical Higgs boson masses between 100 and 150 GeV/c2. For a Higgs boson of 120 GeV/c2 the observed (expected) limit is 14.6 (15.3) the predicted value.

Precise measurement of the W-boson mass with the CDF II detector.

We have measured the W-boson mass M(W) using data corresponding to 2.2 fb(-1) of integrated luminosity collected in pp collisions at sqrt[s] = 1.96 TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470,126 W → eν candidates and 624,708 W → µν candidates yield the measurement M(W) = 80,387 ± 12(stat.) ± 15(syst.) = 80,387 ± 19 MeV/c2. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined.

Measurements of the angular distributions in the decays B→K(*)µ(+)µ(-) at CDF.

We report an indirect search for nonstandard model physics using the flavor-changing neutral current decays B→K(*)µ(+)µ(-). We reconstruct the decays and measure their angular distributions, as a function of q(2)=M(µµ)(2)c(2), where M(µµ) is the dimuon mass, in pp¯ collisions at √s=1.96 TeV using a data sample corresponding to an integrated luminosity of 6.8 fb(-1). The transverse polarization asymmetry A(T)(2) and the time-reversal-odd charge-and-parity asymmetry A(im) are measured for the first time, together with the K* longitudinal polarization fraction F(L) and the muon forward-backward asymmetry A(FB) for the decays B(0)→K(*0)µ(+)µ(-) and B(+)→K(*+)µ(+)µ(-). The B→K*µ(+)µ(-) forward-backward asymmetry in the most sensitive kinematic regime, 1≤q(2)<6 GeV(2)/c(2), is measured to be A(FB)=0.29(-0.23)(+0.20)(stat)±0.07(syst), the most precise result to date. No deviations from the standard model predictions are observed.

Search for a Higgs boson in the diphoton final state in pp collisions at sqrt[s]=1.96 TeV.

A search for a narrow Higgs boson resonance in the diphoton mass spectrum is presented based on data corresponding to 7.0 fb{-1} of integrated luminosity from pp collisions at sqrt[s]=1.96 TeV collected by the CDF experiment. No evidence of such a resonance is observed, and upper limits are set on the cross section times branching ratio of the resonant state as a function of Higgs boson mass. The limits are interpreted in the context of the standard model and one fermiophobic benchmark model where the data exclude fermiophobic Higgs bosons with masses below 114 GeV/c{2} at a 95% Bayesian credibility level.

Measurement of the forward-backward asymmetry in the B→K*µ(+)µ(-) decay and first observation of the B(s)0→ϕµ(+)µ(-) decay.

We reconstruct the rare decays B(+)→K(+)µ(+0µ(-0, B90)→K*(892)(0)µ(+)µ(-), and B(s)(0)→ϕ(1020)µ(+)µ(-) in a data sample corresponding to 4.4 fb(-1) collected in pp collisions at √[s]=1.96 TeV by the CDF II detector at the Tevatron Collider. Using 121±16 B(+)→K(+)µ(+)µ(-) and 101±12 B(0)→K(*0)µ(+)µ(-) decays we report the branching ratios. In addition, we report the differential branching ratio and the muon forward-backward asymmetry in the B(+) and B(0) decay modes, and the K(*0) longitudinal polarization fraction in the B(0) decay mode with respect to the squared dimuon mass. These are consistent with the predictions, and most recent determinations from other experiments and of comparable accuracy. We also report the first observation of the B(s)(0)→ϕµ(+)µ(-) decay and measure its branching ratio BR(B(s)(0)→ϕµ(+)µ(-))=[1.44±0.33±0.46]×10(-6) using 27±6 signal events. This is currently the most rare B(s)(0) decay observed.

Observation of the Ξ(b)(0) baryon.

The observation of the bottom, strange baryon Ξ(b)(0) through the decay chain Ξ(b)(0)→Ξ(c)(+)π-, where ΞΞ(c)(+)→Ξ- π+ π+, Ξ-→Λπ-, and Λ→pπ-, is reported by using data corresponding to an integrated luminosity of 4.2 fb(-1) from pp collisions at square root(s)=1.96 TeV recorded with the Collider Detector at Fermilab. A signal of 25.3(-5.4)(+5.6) candidates is observed whose probability of arising from a background fluctuation is 3.6×10(-12), corresponding to 6.8 gaussian standard deviations. The Ξ(b)(0) mass is measured to be 5787.8±5.0(stat)±1.3(syst) MeV/c2. In addition, the Ξ(b)- baryon is observed through the process Ξ(b)-→Ξ(c)(0)π-, where Ξ(c)(0)→Ξ- π+, Ξ-→Λπ-, and Λ→pπ-.

Measurement of the cross section for prompt isolated diphoton production in pp collisions at square root(s) = 1.96 TeV.

This Letter reports a measurement of the cross section of prompt isolated photon pair production in pp collisions at a total energy square root(s)=1.96 TeV using data of 5.36 fb(-1) integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured cross section, differential in basic kinematic variables, is compared with three perturbative QCD predictions, a leading order parton shower calculation and two next-to-leading order calculations. The next-to-leading order calculations reproduce most aspects of the data. By including photon radiation from quarks before and after hard scattering, the parton shower prediction becomes competitive with the next-to-leading order predictions.

First search for multijet resonances in sqrt(s) = 1.96 TeV pp collisions.

We present the first model independent search for three-jet hadronic resonances within multijet events in sqrt(s) = 1.96 TeV pp collisions at the Fermilab Tevatron using the CDF II detector. Pair production of supersymmetric gluinos and squarks with hadronic R-parity violating decays is employed as an example of a new physics benchmark for this signature. Selection criteria based on the kinematic properties of an ensemble of jet combinations within each event help to extract signal from copious QCD background. No significant excess outside the top quark mass window is observed in data with an integrated luminosity of 3.2 fb(-1). We place 95% confidence level limits on the production cross section σ(pp → XX')×BR(gg → 3 jet + 3 jet) where X, X' = g, q, or q, with q, q → g + jet, as a function of gluino mass, in the range of 77 GeV/c2 to 240 GeV/c2.

Limits on anomalous trilinear gauge couplings in Zγ events from pp¯ collisions at √s=1.96 TeV.

Using Zγ candidate events collected by the CDF detector at the Tevatron Collider, we search for potential anomalous (non-standard-model) couplings between the Z boson and the photon. Zγ couplings vanish at tree level and are heavily suppressed at higher orders; hence any evidence of couplings indicates new physics. Measurements are performed using data corresponding to an integrated luminosity of 4.9 fb(-1) in the Z→νν¯ decay channel and 5.1 fb(-1) in the Z→l(+)l(-) (l=µ, e) decay channels. The combination of these measurements provides the most stringent limits to date on Zγ trilinear gauge couplings. Using an energy scale of Λ=1.5 TeV to allow for a direct comparison with previous measurements, we find limits on the CP-conserving parameters that describe Zγ couplings to be |h(3)(γ,Z)|<0.022 and |h(4)(γ,Z)|<0.0009. These results are consistent with standard model predictions.

Search for new dielectron resonances and Randall-Sundrum gravitons at the collider detector at Fermilab.

A search for new dielectron-mass resonances using data recorded by the CDF II detector and corresponding to an integrated luminosity of 5.7 fb(-1) is presented. No significant excess over the expected standard model prediction is observed. In this data set, an event with the highest dielectron mass ever observed (960 GeV/c(2)) was recorded. The results are interpreted in the Randall-Sundrum (RS) model. Combined with the 5.4 fb(-1) diphoton analysis, the RS-graviton lower-mass limit for the coupling k/M¯(Pl)=0.1 is 1058 GeV/c(2), making it the strongest limit to date.

Measurement of polarization and search for CP violation in B(s)0→φφ decays.

We present the first measurement of polarization and CP-violating asymmetries in a B(s)(0) decay into two light vector mesons, B(s)(0)→φφ, and an improved determination of its branching ratio using 295 decays reconstructed in a data sample corresponding to 2.9 fb(-1) of integrated luminosity collected by the CDF experiment at the Fermilab Tevatron collider. The fraction of longitudinal polarization is determined to be f(L)=0.348±0.041(stat)±0.021(syst), and the branching ratio B(B(s)(0)→φφ)=[2.32±0.18(stat)±0.82(syst)]×10(-5). Asymmetries of decay angle distributions sensitive to CP violation are measured to be A(u)=-0.007±0.064(stat)±0.018(syst) and A(v)=-0.120±0.064(stat)±0.016(syst).

Search for a heavy toplike quark in pp collisions at √s=1.96 TeV.

We present the results of a search for pair production of a heavy toplike (t') quark decaying to Wq final states using data corresponding to an integrated luminosity of 5.6 fb(-1) collected by the CDF II detector in pp collisions at √s=1.96 TeV. We perform parallel searches for t'→Wb and t'→Wq (where q is a generic down-type quark) in events containing a lepton and four or more jets. By performing a fit to the two-dimensional distribution of total transverse energy versus reconstructed t' quark mass, we set upper limits on the t't' production cross section and exclude a standard model fourth-generation t' quark decaying to Wb (Wq) with mass below 358 (340) GeV/c(2) at 95% C.L.

Measurement of the B(s)0 lifetime in fully and partially reconstructed B(s)0→D(s)(-)(ϕπ(-))X decays in p¯p collisions at √s=1.96 TeV.

We present a measurement of the B(s)(0) lifetime in fully and partially reconstructed B(s)(0)→D(s)(-)(ϕπ(-))X decays in 1.3 fb(-1) collected in pp ¯ collisions at √s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. We measure τ(B(s)(0))=1.518±0.041(stat)±0.027(syst) ps. The ratio of this result and the world average B(0) lifetime yields τ(B(s)(0))/τ(B(0))=0.99±0.03, which is in agreement with recent theoretical predictions.

Search for B(s)(0) → µ+ µ- and B(0) → µ+ µ- decays with CDF II.

A search has been performed for B(s)(0) → µ+ µ- and B(0) → µ+ µ- decays using 7 fb(-1) of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. The observed number of B(0) candidates is consistent with background-only expectations and yields an upper limit on the branching fraction of B(B(0) → µ+ µ-) < 6.0 × 10(-9) at 95% confidence level. We observe an excess of B(s)(0) candidates. The probability that the background processes alone could produce such an excess or larger is 0.27%. The probability that the combination of background and the expected standard model rate of B(s)(0) → µ+ µ- could produce such an excess or larger is 1.9%. These data are used to determine B(B(s)(0)→ µ+ µ-) = (1.8(-0.9) (+1.1)) × 10(-8) and provide an upper limit of B(B(s)(0) → µ+ µ-) < 4.0 × 10(-8) at 95% confidence level.