44 research outputs found
Inclusive Search for Standard Model Higgs Boson Production in the WW Decay Channel Using the CDF II Detector
No full textWe present a search for standard model (SM) Higgs boson production using pp̅ collision data at √s=1.96 TeV, collected with the CDF II detector and corresponding to an integrated luminosity of 4.8 fb[superscript -1]. We search for Higgs bosons produced in all processes with a significant production rate and decaying to two W bosons. We find no evidence for SM Higgs boson production and place upper limits at the 95% confidence level on the SM production cross section (σ[subscript H]) for values of the Higgs boson mass (m[subscript H]) in the range from 110 to 200 GeV. These limits are the most stringent for m[subscript H]>130 GeV and are 1.29 above the predicted value of σ[subscript H] for m[subscript H]=165 GeV.Academy of FinlandSlovak R&D AgencyPrograma Consolider-Ingenio 2010, SpainMinisterio de Ciencia e Innovación, SpainRussian Foundation for Basic ResearchInstitut National de Physique Nucleaire et Physique des Particules/CNRSScience and Technology Facilities Council and the Royal Society, UKNational Research Foundation of KoreaWorld Class University ProgramBundesministerium für Bildung und Forschung, GermanyAlfred P. Sloan FoundationSwiss National Science FoundationNational Science Council of the Republic of ChinaNatural Sciences and Engineering Research Council of CanadaMinistry of Education, Culture, Sports, Science and Technology of JapanItalian Istituto Nazionale di Fisica NucleareNational Science FoundationUnited States. Dept. of Energ
Measurement of the Lambda(0)(b) Lifetime in Lambda(0)(b) -> Lambda(+)(c)pi(-) Decays in p(p)over-bar Collisions at root s=1.96 TeV
No full textWe report a measurement of the lifetime of the Lambda(0)(b) baryon in decays to the Lambda(+)(c)pi(-) final state in a sample corresponding to 1.1 fb(-1) collected in p (p) over bar collisions at root s = 1.96 TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed Lambda(0)(b) events we measure tau(Lambda(0)(b) ) = 1.401 +/- 0.046(stat) +/- 0.035(syst) ps (corresponding to c tau(Lambda(0)(b)) = 420.1 +/- 13.7(stat) +/- 10.6(syst) mu m, where c is the speed of light). The ratio of this result and the world average B-0 lifetime yields tau(Lambda(0)(b))/tau(B-0) = 0.918 +/- 0.038 (stat) and (syst), in good agreement with recent theoretical predictions
Search for R-Parity Violating Decays of Sneutrinos to e mu, mu tau, and e tau Pairs in p(p)over-bar Collisions at root s=1.96 TeV
No full textWe present a search for supersymmetric neutrino (nu) over tilde production using the Tevatron p (p) over bar collision data collected with the CDF II detector and corresponding to an integrated luminosity of 1 fb(-1). We focus on the scenarios predicted by the R-parity violating (RPV) supersymmetric models in which sneutrinos decay to two charged leptons of different flavor. With the data consistent with the standard model expectations, we set upper limits on sigma(p (p) over bar -> (nu) over tilde) BR((nu) over tilde -> e mu, mu tau, e tau) and use these results to constrain the RPV couplings as a function of the sneutrino mass
Exclusion of an Exotic Top Quark with-4/3 Electric Charge Using Soft Lepton Tagging
No full textWe present a measurement of the electric charge of the top quark using p (p) over bar collisions corresponding to an integrated luminosity of 2: 7 fb(-1) at the CDF II detector. We reconstruct t (t) over bar events in the lepton + jets final state. We use soft lepton taggers to determine the flavor of the b jets, which we use to reconstruct the top quark's electric charge and exclude an exotic top quark with -4/3 charge at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose
Measurement of the top quark mass and pp̅ →tt̅ cross section in the all-hadronic mode with the CDF II detector
No full textWe present a measurement of the top quark mass and of the top-antitop (tt̅ ) pair production cross section using pp̅ data collected with the CDF II detector at the Tevatron Collider at the Fermi National Accelerator Laboratory and corresponding to an integrated luminosity of 2.9 fb-1. We select events with six or more jets satisfying a number of kinematical requirements imposed by means of a neural-network algorithm. At least one of these jets must originate from a b quark, as identified by the reconstruction of a secondary vertex inside the jet. The mass measurement is based on a likelihood fit incorporating reconstructed mass distributions representative of signal and background, where the absolute jet energy scale (JES) is measured simultaneously with the top quark mass. The measurement yields a value of 174.8±2.4(stat+JES)-1.0+1.2(syst) GeV/c2, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure also measures the amount of signal from which we derive a cross section, σtt̅ =7.2±0.5(stat)±1.0(syst)±0.4(lum) pb, for the measured values of top quark mass and JES.United States Department of EnergyNational Science FoundationIstituto Nazionale di Fisica Nucleare of ItalyMinistry of Education, Culture, Sports, Science and Technology of JapanNatural Sciences and Engineering Research Council of CanadaNational Science Council of the Republic of ChinaSwiss National Science FoundationAlfred P. Sloan FoundationBundesministerium für Bildung und Forschung, GermanyWorld Class University Program (Korea)National Research Foundation of KoreaScience and Technology Facilities Council, United KingdomRoyal Society, United KingdomInstitut National de Physique Nucleaire et Physique des Particules/CNRSRussian Foundation for Basic ResearchMinisterio de Ciencia e Innovación, SpainPrograma Consolider-Ingenio 2010, SpainSlovak R&D AgencyAcademy of Finlan
Measurement of W-Boson Polarization in Top-Quark Decay in p(p)over-bar Collisions at root s=1.96 TeV
No full textWe report measurements of the polarization of W bosons from top-quark decays using 2.7 fb(-1) of p (p) over bar collisions collected by the CDF II detector. Assuming a top-quark mass of 175 GeV/c(2), three measurements are performed. A simultaneous measurement of the fraction of longitudinal (f(0)) and right-handed (f(0)) W bosons yields the model- independent results f(0) =0. 88 +/- 0.11(stat) +/- 0.06(syst) and f(+) = 0.15 +/- 0.07(stat) +/- 0.06(syst) with a correlation coefficient of -0.59. A measurement of f(0) [f(+)] constraining f(+) [f(0)] to its standard model value of 0.0 [0.7] yields f(0) 0.70 + 0.07(stat) +/- 0.04(syst) [f(+) - 0.01 +/- 0.02(stat) +/- 0.05(syst)]. All these results are consistent with standard model expectations. We achieve the single most precise measurements of f(0) for both the model- independent and modeldependent determinations
Measurements of branching fraction ratios and CP asymmetries in B±→DCPK± decays in hadron collisions
No full textWe reconstruct B[superscript ±]→DK[superscript ±] decays in a data sample collected by the CDF II detector at the Tevatron collider corresponding to 1 fb[superscript -1] of integrated luminosity. We select decay modes where the D meson decays to either K-π+ (flavor eigenstate) or K[superscript -]K[superscript +], π[superscript -]π[superscript +] (CP-even eigenstates), and measure the direct CP asymmetry A[subscript CP+]=0.39±0.17(stat)±0.04(syst), and the double ratio of CP-even to flavor eigenstate branching fractions R[subscript CP+]=1.30±0.24(stat)±0.12(syst). These measurements will improve the determination of the Cabibbo-Kobayashi-Maskawa angle γ. They are performed here for the first time using data from hadron collisions.United States. Dept. of EnergyNational Science FoundationIstituto Nazionale di Fisica Nucleare of ItalyMinistry of Education, Culture, Sports, Science and Technology of JapanNatural Sciences and Engineering Research Council of CanadaNational Science Council of the Republic of ChinaSwiss National Science FoundationAlfred P. Sloan FoundationBundesministerium für Bildung und Forschung, GermanyKorean Science and Engineering FoundationKorean Research FoundationScience and Technology Facilities Council, United KingdomRoyal Society, United KingdomInstitut National de Physique Nucleaire et Physique des Particules/CNRSRussian Foundation for Basic ResearchMEC (Spain)Slovak R&D AgencyAcademy of Finlan
Measurement of the W+W- Production Cross Section and Search for Anomalous WW gamma and WWZ Couplings in p(p)over-bar Collisions at root s 1.96 TeV
No full textThis Letter describes the current most precise measurement of the W boson pair production cross section and most sensitive test of anomalous WW gamma and WWZ couplings in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV. The WW candidates are reconstructed from decays containing two charged leptons and two neutrinos. Using data collected by the CDF II detector from 3: 6 fb(-1) of integrated luminosity, a total of 654 candidate events are observed with an expected background of 320 +/- 47 events. The measured cross section is sigma(p (p) over bar -> W+W- +X) = 12.1 +/- 0.9(stat)(-1.4)(+1.6)(syst) pb, which is in good agreement with the standard model prediction. The same data sample is used to place constraints on anomalous WW gamma and WWZ couplings
Search for WW and WZ Resonances Decaying to Electron, Missing E-T, and Two Jets in p(p)over-bar Collisions at root s=1.96 TeV.
No full textUsing data from 2: 9 fb(-1) of integrated luminosity collected with the CDF II detector at the Tevatron, we search for resonances decaying into a pair of on-shell gauge bosons, WW or WZ, where one W decays into an electron and a neutrino, and the other boson decays into two jets. We observed no statistically significant excess above the expected standard model background, and we set cross section limits at 95% confidence level on G* (Randall-Sundrum graviton), Z', and W' bosons. By comparing these limits to theoretical cross sections, mass exclusion regions for the three particles are derived. The mass exclusion regions for Z' and W' are further evaluated as a function of their gauge coupling strength
Search for Supersymmetry with Gauge-Mediated Breaking in Diphoton Events with Missing Transverse Energy at CDF II
No full textWe present the results of a search for supersymmetry with gauge-mediated breaking and (chi) over tilde (1)(0) -> gamma(G) over tilde in the gamma gamma + missing transverse energy final state. In 2.6 +/- 0.2 fb(-1) of p (p) over bar collisions at root s 1.96 TeV recorded by the CDF II detector we observe no candidate events, consistent with a standard model background expectation of 1.4 +/- 0.4 events. We set limits on the cross section at the 95% C.L. and place the world's best limit of 149 GeV/c(2) on the (chi) over tilde (1)(0) mass at tau((chi) over tilde 01) << 1 ns. We also exclude regions in the (chi) over tilde (1)(0) mass-lifetime plane for tau((chi) over tilde 01) less than or similar to 2 ns
