Direct measurement of the total decay width of the top quark

We present a measurement of the total decay width of the top quark using events with top-antitop quark pair candidates reconstructed in the final state with one charged lepton and four or more hadronic jets. We use the full Tevatron run II data set of ?s=1.96 TeV proton-antiproton collisions recorded by the CDF II detector. The top quark mass and the mass of the hadronically decaying W boson are reconstructed for each event and compared with distributions derived from simulated signal and background samples to extract the top quark width (?top) and the energy scale of the calorimeter jets with in situ calibration. For a top quark mass M top=172.5 GeV/c2, we find 1.10<?top<4.05 GeV at 68% confidence level, which is in agreement with the standard model expectation of 1.3 GeV and is the most precise direct measurement of the top quark width to date.We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A.P. Sloan Foundation; the Bundesministerium für Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, UK; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; the Australian Research Council (ARC); and the EU community Marie Curie Fellowship Contract No. 302103

Exclusion of exotic top-like quarks with -4/3 electric charge using jet-charge tagging in single-lepton tt¯ events at CDF

We report on a measurement of the top-quark electric charge in tt events in which one W boson originating from the top-quark pair decays into leptons and the other into hadrons. The event sample was collected by the CDF II detector in ffiffi s p ¼ 1:96 TeV proton-antiproton collisions and corresponds to 5:6 fb 1. We find the data to be consistent with the standard model and exclude the existence of an exotic quark with 4=3 electric charge and mass of the conventional top quark at the 99% confidence level.We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium fu¨r Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, UK; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; and the Australian Research Council (ARC)

Indirect measurement of sin2θW (MW) using e+e− pairs in the Z-boson region with p¯p collisions at a center-of-momentum energy of 1.96 TeV

Drell-Yan lepton pairs are produced in the process p¯p→e+e−+X through an intermediate γ∗/Z boson. The lepton angular distributions are used to provide information on the electroweak-mixing parameter sin2θW via its observable effective-leptonic sin2θW, or sin2θlepteff. A new method to infer sin2θW or, equivalently, the W-boson mass MW in the on-shell scheme, is developed and tested using a previous CDF Run II measurement of angular distributions from electron pairs in a sample corresponding to 2.1  fb−1 of integrated luminosity from p¯p collisions at a center-of-momentum energy of 1.96 TeV. The value of sin2θlepteff is found to be 0.2328±0.0011. Within a specified context of the standard model, this results in sin2θW=0.2246±0.0011, which corresponds to a W-boson mass of 80.297±0.055  GeV/c2, in agreement with previous determinations in electron-position collisions and at the Tevatron collider.We thank T. Riemann for useful discussions and help on zfitter. We thank D. Wackeroth for useful discussions and help on the zgrad2 calculation. We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A.P. Sloan Foundation; the Bundesministerium für Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, UK; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; the Australian Research Council (ARC); and the EU community Marie Curie Fellowship contract 302103

Search for pair production of strongly interacting particles decaying to pairs of jets in pp¯ collisions at √s=1.96 TeV

We present a search for the pair production of a narrow nonstandard-model strongly interacting particle that decays to a pair of quarks or gluons, leading to a final state with four hadronic jets. We consider both nonresonant production via an intermediate gluon as well as resonant production via a distinct nonstandard-model intermediate strongly interacting particle. We use data collected by the CDF experiment in proton-antiproton collisions at √s=1.96  TeV corresponding to an integrated luminosity of 6.6  fb−1. We find the data to be consistent with nonresonant production. We report limits on σ(p¯p→jjjj) as a function of the masses of the hypothetical intermediate particles. Upper limits on the production cross sections for nonstandard-model particles in several resonant and nonresonant processes are also derived.We thank Martin Schmaltz, Gustavo Tavares, Can Kilic, Bogdan Dobrescu, Dirk Zerwas, and Felix Yu for useful suggestions and technical advice. We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium für Bildung und Forschung, Germany; the Korean World Class University Program and the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, U.K.; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; and the Australian Research Council (ARC)ARC

Measurement of W-boson polarization in top-quark decay using the full CDF Run II data set

We measure the polarization of W bosons from top-quark (t) decays into final states with a charged lepton and jets, t¯t→W+bW−¯b→ℓνbq¯q′¯b, using the full Run II data set collected by the CDF II detector, corresponding to an integrated luminosity of 8.7  fb−1. A model-independent method simultaneously determines the fraction of longitudinal (f0) and right-handed (f+) W bosons to yield f0=0.726±0.066(stat)±0.067(syst) and f+=−0.045±0.044(stat)±0.058(syst) with a correlation coefficient of −0.69. Additional results are presented under various standard model assumptions. No significant discrepancies with the standard model are observed.We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science, and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium für Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, U.K.; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; and the Australian Research Council (ARC)ARC

Search for B0s→μ+μ− and B0→μ+μ− decays with the full CDF Run II data set

We report on a search for B0s→μ+μ− and B0→μ+μ− decays using proton-antiproton collision data at √s=1.96  TeV corresponding to 10  fb−1 of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. The observed number of B0 candidates is consistent with background-only expectations and yields an upper limit on the branching fraction of B(B0→μ+μ−)<4.6×10−9 at 95% confidence level. We observe an excess of B0s candidates. The probability that the background processes alone could produce such an excess or larger is 0.94%. The probability that the combination of background and the expected standard model rate of B0s→μ+μ− could produce such an excess or larger is 6.8%. These data are used to determine a branching fraction B(B0s→μ+μ−)=(1.3+0.9−0.7)×10−8 and provide an upper limit of B(B0s→μ+μ−)<3.1×10−8 at 95% confidence levelWe thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium für Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, UK; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; the Australian Research Council (ARC); and the EU community Marie Curie Fellowship Contract No. 302103

Search for the production of ZW and ZZ boson pairs decaying into charged leptons and jets in pp¯ collisions at √s=1.96 TeV

We present a measurement of the production cross section for ZW and ZZ boson pairs in final states with a pair of charged leptons, from the decay of a Z boson, and at least two jets, from the decay of a W or Z boson, using the full sample of proton-antiproton collisions recorded with the CDF II detector at the Tevatron, corresponding to 8.9  fb−1 of integrated luminosity. We increase the sensitivity to vector-boson decays into pairs of quarks using a neural-network discriminant that exploits the differences between the spatial spread of energy depositions and charged-particle momenta contained within the jet of particles originating from quarks and gluons. Additionally, we employ new jet energy corrections to Monte Carlo simulations that account for differences in the observed energy scales for quark and gluon jets. The number of signal events is extracted through a simultaneous fit to the dijet mass spectrum in three classes of events: events likely to contain jets with a heavy-quark decay, events likely to contain jets originating from light quarks, and events that fail these identification criteria. We determine the production cross section to be σZW+ZZ=2.5+2.0−1.0  pb (<6.1  pb at the 95% confidence level), consistent with the standard model prediction of 5.1 pb.We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium für Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, United Kingdom; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; the Australian Research Council (ARCARC); and the EU community Marie Curie Fellowship Contract No. 302103

Measurement of the top quark forward-backward production asymmetry and its dependence on event kinematic properties

We present new measurements of the inclusive forward-backward t¯t production asymmetry, AFB, and its dependence on several properties of the t¯t system. The measurements are performed with the full Tevatron data set recorded with the CDF II detector during p¯p collisions at √s=1.96  TeV, corresponding to an integrated luminosity of 9.4  fb−1. We measure the asymmetry using the rapidity difference Δy=yt−y¯t. Parton-level results are derived, yielding an inclusive asymmetry of 0.164±0.047(stat+syst). We establish an approximately linear dependence of AFB on the top-quark pair mass Mt¯t and the rapidity difference |Δy| at detector and parton levels. Assuming the standard model, the probabilities to observe the measured values or larger for the detector-level dependencies are 7.4×10−3 and 2.2×10−3 for Mt¯t and |Δy| respectively. Lastly, we study the dependence of the asymmetry on the transverse momentum of the t¯t system at the detector level. These results are consistent with previous lower-precision measurements and provide additional quantification of the functional dependencies of the asymmetry.We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium für Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, UK; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; and the Australian Research Council (ARC)

Measurement of the cross section for direct-photon production in association with a heavy quark in pp¯ collisions at vs=1.96 TeV

We report on a measurement of the cross section for direct-photon production in association with a heavy quark using the full data set of √s=1.96  TeV proton-antiproton collisions corresponding to 9.1  fb−1 of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron. The measurements are performed as a function of the photon transverse momentum, covering a photon transverse momentum between 30 and 300 GeV, photon rapidities |yγ|20  GeV, and jet rapidities |yjet|<1.5. The results are compared with several theoretical predictions.We are grateful to A. V. Lipatov, M. A. Malyshev, N. P. Zotov, F. Siegert, T. P. Stavreva, and J. F. Owens for providing theoretical predictions and for many useful discussions. We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium für Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, UK; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; the Australian Research Council (ARC); and the EU community Marie Curie Fellowship Contract No. 302103

Observation of the production of a W boson in association with a single charm quark

The first observation of the production of a W boson with a single charm quark (c) jet in p¯p collisions at √s=1.96  TeV is reported. The analysis uses data corresponding to 4.3  fb−1, recorded with the CDF II detector at the Fermilab Tevatron. Charm quark candidates are selected through the identification of an electron or muon from charm-hadron semileptonic decay within a hadronic jet, and a Wc signal is observed with a significance of 5.7 standard deviations. The production cross section σWc(pTc>20  GeV/c,|ηc|0.71 at the 95% confidence level, assuming that the Wc production through c to s quark coupling is dominant.We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; the Swiss National Science Foundation; the A. P. Sloan Foundation; the Bundesministerium für Bildung und Forschung, Germany; the Korean World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council, the Royal Society and the Leverhulme Trust, U.K.; the Russian Foundation for Basic Research; the Ministerio de Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; the Academy of Finland; and the Australian Research Council (ARC)