A signature-based search for delayed photons in exclusive photon plus missing transverse energy events from $p \bar{p}$ collisions with $\sqrt{s} = 1.96$ TeV
ArXiv 1307.0474 (2013)
Abstract:
We present the first signature-based search for delayed photons using an exclusive photon plus missing transverse energy final state. Events are reconstructed in a data sample from the CDF II detector corresponding to $6.3 \text{fb}^{-1}$ of integrated luminosity from $\sqrt{s}=1.96$ TeV proton-antiproton collisions. Candidate events are selected if they contain a photon with an arrival time in the detector larger than expected from a promptly-produced photon. The mean number of events from standard model sources predicted by the data-driven background model based on the photon timing distribution is $286 \pm 24$. A total of 322 events are observed. A $p$-value of 12% is obtained, showing consistency of the data with standard model predictions.Measurement of the Differential Cross Section d{\sigma}/d(cos {\theta}t) for Top-Quark Pair Production in p-pbar Collisions at sqrt{s} = 1.96 TeV
(2013)
Measurement of the Differential Cross Section dσ/d(cos θt) for Top-Quark Pair Production in p-pbar Collisions at sqrt{s} = 1.96 TeV
ArXiv 1306.2357 (2013)
Abstract:
We report a measurement of the differential cross section, d{\sigma}/d(cos {\theta}t), for top-quark-pair production as a function of the top-quark production angle in proton-antiproton collisions at sqrt{s} = 1.96 TeV. This measurement is performed using data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.4/fb. We employ the Legendre polynomials to characterize the shape of the differential cross section at the parton level. The observed Legendre coefficients are in good agreement with the prediction of the next-to-leading-order standard-model calculation, with the exception of an excess linear-term coefficient, a1 = 0.40 +- 0.12, compared to the standard-model prediction of a1 = 0.15^{+0.07}_{-0.03}.Measurement of R=B(t→Wb)/B(t→Wq) in top-quark-pair decays using lepton+jets events and the full CDF run II dataset
Physical Review D - Particles, Fields, Gravitation and Cosmology 87:11 (2013)
Abstract:
We present a measurement of the ratio of the top-quark branching fractions R=B(t→Wb)/B(t→Wq), where q represents quarks of type b, s, or d, in the final state with a lepton and hadronic jets. The measurement uses √s=1.96 TeV proton-antiproton collision data from 8.7 fb-1 of integrated luminosity collected with the Collider Detector at Fermilab during Run II of the Tevatron. We simultaneously measure R=0.94±0.09 (stat+syst) and the tt̄ production cross section σtt̄=7. 5±1.0 (stat+syst) pb. The magnitude of the Cabibbo-Kobayashi-Maskawa matrix element, |Vtb|=0.97±0.05 (stat+syst) is extracted assuming three generations of quarks, and a lower limit of |V tb|>0.89 at 95% credibility level is set. © 2013 American Physical Society.Searches for the Higgs boson decaying to W^{+} W^{-} -> l^{+}nu l^{-}nubar with the CDF II detector
(2013)