© 2016 American Physical Society. We measure the forward-backward asymmetry of the production of top-quark and antiquark pairs in proton-antiproton collisions at center-of-mass energy s=1.96 TeV using the full data set collected by the Collider Detector at Fermilab (CDF) in Tevatron Run II corresponding to an integrated luminosity of 9.1 fb-1. The asymmetry is characterized by the rapidity difference between top quarks and antiquarks (Δy) and measured in the final state with two charged leptons (electrons and muons). The inclusive asymmetry, corrected to the entire phase space at parton level, is measured to be AFBtt=0.12±0.13, consistent with the expectations from the standard model (SM) and previous CDF results in the final state with a single charged lepton. The combination of the CDF measurements of the inclusive AFBtt in both final states yields AFBtt=0.160±0.045, which is consistent with the SM predictions. We also measure the differential asymmetry as a function of Δy. A linear fit to AFBtt(|Δy|), assuming zero asymmetry at Δy=0, yields a slope of α=0.14±0.15, consistent with the SM prediction and the previous CDF determination in the final state with a single charged lepton. The combined slope of AFBtt(|Δy|) in the two final states is α=0.227±0.057, which is 2.0σ larger than the SM prediction.

© 2015 American Physical Society. We study charged particle production (pT>0.5 GeV/c, |η|<0.8) in proton-antiproton collisions at total center-of-mass energies s=300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of η-φ space: "toward", "away", and "transverse." The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the "underlying event." The transverse region is divided into a MAX and MIN transverse region, which helps separate the "hard component" (initial and final-state radiation) from the "beam-beam remnant" and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event is studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

© 2016 American Physical Society. At the Fermilab Tevatron proton-antiproton (pp) collider, Drell-Yan lepton pairs are produced in the process pp→e+e-+X through an intermediate γ∗/Z boson. The forward-backward asymmetry in the polar-angle distribution of the e- as a function of the e+e - pair mass is used to obtain sin2θefflept, the effective leptonic determination of the electroweak-mixing parameter sin2θW. The measurement sample, recorded by the Collider Detector at Fermilab (CDF), corresponds to 9.4 fb-1 of integrated luminosity from pp collisions at a center-of-momentum energy of 1.96 TeV, and is the full CDF Run II data set. The value of sin2θefflept is found to be 0.23248±0.00053. The combination with the previous CDF measurement based on μ+μ- pairs yields sin2θefflept=0.23221±0.00046. This result, when interpreted within the specified context of the standard model assuming sin2θW=1-MW2/MZ2 and that the W- and Z-boson masses are on-shell, yields sin2θW=0.22400±0.00045, or equivalently a W-boson mass of 80.328±0.024 GeV/c2.

© 2017 American Physical Society. We report on a measurement of the D+-meson production cross section as a function of transverse momentum (pT) in proton-antiproton (pp) collisions at 1.96 TeV center-of-mass energy, using the full data set collected by the Collider Detector at Fermilab in Tevatron Run II and corresponding to 10 fb-1 of integrated luminosity. We use D+→K-π+π+ decays fully reconstructed in the central rapidity region |y|<1 with transverse momentum down to 1.5 GeV/c, a range previously unexplored in pp collisions. Inelastic pp-scattering events are selected online using minimally biasing requirements followed by an optimized offline selection. The K-π+π+ mass distribution is used to identify the D+ signal, and the D+ transverse impact-parameter distribution is used to separate prompt production, occurring directly in the hard-scattering process, from secondary production from b-hadron decays. We obtain a prompt D+ signal of 2950 candidates corresponding to a total cross section σ(D+,1.5

We use a new method to estimate with 5% accuracy the contribution of pion and kaon in-flight-decays to the dimuon data set acquired with the CDF detector. Based on this improved estimate, we show that the total number and the properties of the collected dimuon events are not yet accounted for by ordinary sources of dimuons which also include the contributions, as measured in the data, of heavy flavor, Υ{hooked}, and Drell-Yan production in addition to muons mimicked by hadronic punchthrough. The number of unaccounted events corresponds to (12.8±3.2)% of the bb̄ production. We find that (23±6)% of the unaccounted events contain additional muon candidates. For comparison, this fraction is (6.9±0.4)% for events due to bb̄ production. © 2011 The Author(s).

© 2016 authors. Published by the American Physical Society. An updated measurement of the single top quark production cross section is presented using the full data set collected by the Collider Detector at Fermilab (CDF), corresponding to 9.5 fb-1 of integrated luminosity from proton-antiproton collisions at 1.96 TeV center-of-mass energy. The events selected contain an imbalance in the total transverse momentum, jets identified as containing b quarks, and no identified leptons. The sum of the s- and t-channel single top quark cross sections is measured to be 3.53-1.16+1.25 pb and a lower limit on the magnitude of the top-to-bottom quark coupling, |Vtb| of 0.63, is obtained at the 95% credibility level. These measurements are combined with previously reported CDF results obtained from events with an imbalance in total transverse momentum, jets identified as originating from b quarks, and one identified lepton. The combined cross section is measured to be 3.02-0.48+0.49 pb and a lower limit on |Vtb| of 0.84 is obtained at the 95% credibility level.

© 2016 American Physical Society. A search for a Higgs boson with suppressed couplings to fermions, hf, assumed to be the neutral, lower-mass partner of the Higgs boson discovered at the Large Hadron Collider, is reported. Such a Higgs boson could exist in extensions of the standard model with two Higgs doublets, and could be produced via pp→H±hf→W∗hfhf→4γ+X, where H± is a charged Higgs boson. This analysis uses all events with at least three photons in the final state from proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the Collider Detector at Fermilab, corresponding to an integrated luminosity of 9.2 fb-1. No evidence of a signal is observed in the data. Values of Higgs-boson masses between 10 and 100 GeV/c2 are excluded at 95% Bayesian credibility.

© 2019 authors. Published by the American Physical Society. We report on a search for a spin-zero non-standard model particle in proton-antiproton collisions collected by the Collider Detector at Fermilab at a center-of-mass-energy of 1.96 TeV. This particle, the φ boson, is expected to decay into a bottom-antibottom quark pair and to be produced in association with at least one bottom quark. The data sample consists of events with three jets identified as initiated by bottom quarks and corresponds to 5.4 fb-1 of integrated luminosity. In each event, the invariant mass of the two most energetic jets is studied by looking for deviations from the multijet background, which is modeled using data. No evidence is found for such a particle. Exclusion upper limits ranging from 20 to 2 pb are set for the product of production cross sections times branching fraction for the hypothetical φ boson with mass between 100 and 300 GeV/c2. These are the most stringent constraints to date.

© 2016 American Physical Society. We report a measurement of the forward-backward asymmetry, AFB, in bb pairs produced in proton-antiproton collisions and identified by muons from semileptonic b-hadron decays. The event sample is collected at a center-of-mass energy of s=1.96 TeV with the CDF II detector and corresponds to 6.9 fb-1 of integrated luminosity. We obtain an integrated asymmetry of AFB(bb)=(1.2±0.7)% at the particle level for b-quark pairs with invariant mass, mbb, down to 40 GeV/c2 and measure the dependence of AFB(bb) on mbb. The results are compatible with expectations from the standard model.

© 2016 American Physical Society. We present a measurement of the total WW and WZ production cross sections in pp collision at s=1.96 TeV, in a final state consistent with leptonic W boson decay and jets originating from heavy-flavor quarks from either a W or a Z boson decay. This analysis uses the full data set collected with the CDF II detector during Run II of the Tevatron collider, corresponding to an integrated luminosity of 9.4 fb-1. An analysis of the dijet mass spectrum provides 3.7σ evidence of the summed production processes of either WW or WZ bosons with a measured total cross section of σWW+WZ=13.7±3.9 pb. Independent measurements of the WW and WZ production cross sections are allowed by the different heavy-flavor decay patterns of the W and Z bosons and by the analysis of secondary-decay vertices reconstructed within heavy-flavor jets. The productions of WW and of WZ dibosons are independently seen with significances of 2.9σ and 2.1σ, respectively, with total cross sections of σWW=9.4±4.2 pb and σWZ=3.7-2.2+2.5 pb. The measurements are consistent with standard-model predictions.