6,756 research outputs found

    Forward-backward asymmetry in t¯t production

    Get PDF
    We present new measurements of the forward-backward asymmetry in t¯t production, performed with 5 fb−1 of Tevatron p¯p collisions at center of mass energy 1.96 TeV, recorded and analyzed at CDF. Significant inclusive asymmetries are observed in both the lepton+jets and the dilepton decay modes of the t¯t pair. In the dilepton mode, the asymmetry is observed in the reconstructed top rapidity, and in the lepton rapidity difference which is independent of any top reconstruction. In the lepton plus jets sample, the full reconstruction of the top kinematics is used to measure the dependence of the asymmetry on the rapidity difference Δy and the invariant mass Mt¯t of the t¯t system, and the asymmetry is found to be most significant at large rapidity and mass

    Asymmetries in top quark pair production at hadron colliders

    Full text link
    We review the asymmetries in top quark pair production at the Tevatron and the LHC. We summarize the experimental measurements and the interpretations of a possible excess in terms of new physics. We also review other top quark properties-emphasizing effects related to the ttˉt \bar t asymmetries-as well as other collider signals.Comment: RevTeX 40 pages. Final version to be published in Reviews of Modern Physics, with several addition

    First ADS analysis of B- -> D0K- decays in hadron collisions

    Full text link
    Proceedings of DISCRETE 2010, Symposium on Prospects in the Physics of Discrete Symmetries, Rome (IT), 6-11 December 2010Comment: 7 pages, 5 figure

    Characterization of the background spectrum in DAMIC at SNOLAB

    Full text link
    We construct the first comprehensive radioactive background model for a dark matter search with charge-coupled devices (CCDs). We leverage the well-characterized depth and energy resolution of the DAMIC at SNOLAB detector and a detailed geant4-based particle-transport simulation to model both bulk and surface backgrounds from natural radioactivity down to 50  eVee. We fit to the energy and depth distributions of the observed ionization events to differentiate and constrain possible background sources, for example, bulk 3H from silicon cosmogenic activation and surface 210Pb from radon plate-out. We observe the bulk background rate of the DAMIC at SNOLAB CCDs to be as low as 3.1±0.6  counts kg−1 day−1 keV−1ee, making it the most sensitive silicon dark matter detector. Finally, we discuss the properties of a statistically significant excess of events over the background model with energies below 200  eVee

    Measurement of the charge asymmetry of electrons from the decays of W bosons produced in p p ¯ collisions at s =1.96 TeV

    Get PDF
    Publisher Copyright: © 2021 authors. Published by the American Physical Society.At the Fermilab Tevatron proton-antiproton (pp¯) collider, high-mass electron-neutrino (eν) pairs are produced predominantly in the process pp¯→W(→eν)+X. The asymmetry of the electron and positron yield as a function of their pseudorapidity constrain the slope of the ratio of the u- to d-quark parton distributions versus the fraction of the proton momentum carried by the quarks. This paper reports on the measurement of the electron-charge asymmetry using the full data set recorded by the Collider Detector at Fermilab in 2001-2011 and corresponding to 9.1 fb-1 of integrated luminosity. The measurement significantly improves the precision of the Tevatron constraints on the parton-distribution functions of the proton. Numerical tables of the measurement are provided.Peer reviewe