Forward Backward Asymmetry In Top Quark Production In Ppbar Collisions At Sqrt S
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Forward Backward Asymmetry In Top Quark Production In Ppbar Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2008
Forward Backward Asymmetry In Top Quark Production In Ppbar Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
Reconstructable final state kinematics and charge assignment in the reaction p{bar p} --> t{bar t} allows tests of discrete strong interaction symmetries at high energy. We define frame dependent forward-backward asymmetries for the outgoing top quark in both the p{bar p} and t{bar t} rest frames, correct for experimental distortions, and derive values at the parton-level. Using 1.9 fb−1 of p{bar p} collisions at (square root)s = 1.96 TeV recorded with the CDF II detector at the Fermilab Tevatron, we measure forward-backward top quark production asymmetries in the p{bar p} and t{bar t} rest frames of A{sub FB}{sup p{bar p}} = 0.17 ± 0.08 and A{sub FB}{sup t{bar t}} = 0.24 ± 0.14.
Measurement Of The Forward Backward Asymmetry In Top Quark Antiquark Production In Ppbar Collisions Using The Lepton Jets Channel
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language : en
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Release Date : 2014
Measurement Of The Forward Backward Asymmetry In Top Quark Antiquark Production In Ppbar Collisions Using The Lepton Jets Channel written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Search For Same Sign Top Quark Pair Production At Sqrt S
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language : en
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Release Date : 2011
Search For Same Sign Top Quark Pair Production At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
An inclusive search for same-sign top-quark pair production in pp collisions at sqrt(s) = 7 TeV is performed using a data sample recorded with the CMS detector in 2010, corresponding to an integrated luminosity of 35 inverse picobarns. This analysis is motivated by recent studies of p p-bar to t t-bar reporting mass-dependent forward-backward asymmetries larger than expected from the standard model. These asymmetries could be due to Flavor Changing Neutral Currents (FCNC) in the top sector induced by t-channel exchange of a massive neutral vector boson (Z'). Models with such a Z' also predict enhancement of same-sign top-pair production in pp or p p-bar collisions. Limits are set as a function of the Z' mass and its couplings to u and t quarks. These limits disfavour the FCNC interpretation of the Tevatron results.
Measurement Of The Forward Backward Asymmetry In Low Mass Bottom Quark Pairs Produced In Proton Antiproton Collisions
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language : en
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Release Date : 2016
Measurement Of The Forward Backward Asymmetry In Low Mass Bottom Quark Pairs Produced In Proton Antiproton Collisions written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
We report a measurement of the forward-backward asymmetry, $A_{FB}$, in $b\bar{b}$ pairs produced in proton-antiproton collisions and identified by muons from semileptonic $b$-hadron decays. The event sample was collected at a center-of-mass energy of $\sqrt{s}=1.96$ TeV with the CDF II detector and corresponds to 6.9 fb$^{-1}$ of integrated luminosity. We obtain an integrated asymmetry of $A_{FB}(b\bar{b})=(1.2 \pm 0.7)$\% at the particle level for $b$-quark pairs with invariant mass, $m_{b\bar{b}}$, down to $40$ GeV/$c^2$ and measure the dependence of $A_{FB}(b\bar{b})$ on $m_{b\bar{b}}$. The results are compatible with expectations from the standard model.
Forward Backward Asymmetry At High Mass In T Bar T Production In P Bar P Collisions At Sqrt S
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language : en
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Release Date : 2011
Forward Backward Asymmetry At High Mass In T Bar T Production In P Bar P Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Current understanding of particle physics postulates that there are 17 fundamental particles that interact via four fundamental forces - gravity, the strong force, the weak force, and the electromagnetic force. These fundamental particles can be classified by their spins into bosons, which are the force-carrying particles with integer spins, and fermions, which have half-integer spins. Fermions can be further divided into quarks and leptons. The particles and three of the four forces - all but gravity - are described by the Standard Model, a local SU(3) x SU(2) x U(1) gauge theory. Electromagnetic and weak interactions as described by Electroweak Theory or Quantum Electrodynamics, SU(2) x U(1). Strong interactions are described by Quantum Chromodynamics or QCD, SU(3). Fermions are grouped into three generations as shown in Table 1.1. Each generation consists of a leptonic doublet containing a charged and a neutral lepton and a weak isospin doublet containing two quarks. The first generation, containing the electron, the electron neutrino, the up quark, and the down quark, is the lightest generation and is thus the most frequently found in nature. The second generation contains the muon, the muon neutrino, the strange quark, and the charm quark. The third generation contains the tau, the tau neutrino, the bottom quark, and the top quark.
Measurement Of The Charge Asymmetry In Top Quark Pair Production In Pp Collisions At Sqrt S
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language : en
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Release Date : 2015
Measurement Of The Charge Asymmetry In Top Quark Pair Production In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The charge asymmetry in the production of top quark and antiquark pairs is measured in proton-proton collisions at a center-of-mass energy of 8 TeV. The data, corresponding to an integrated luminosity of 19.6 fb -1 were collected by the CMS experiment at the LHC. Events with a single isolated electron or muon, and four or more jets, at least one of which is likely to have originated from hadronization of a bottom quark, are selected. A template technique is used to measure the asymmetry in the distribution of differences in the top quark and antiquark absolute rapidities. The measured asymmetry is Ayc= [0.33_0.26 (stat)_0.33 (syst)]%, which is the most precise result to date. The results are compared to calculations based on the standard model and on several beyond-the-standard-model scenarios.
Measurement Of The Charge Asymmetry In Top Quark Pair Production In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2011
Measurement Of The Charge Asymmetry In Top Quark Pair Production In Proton Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
The difference in angular distributions between top quarks and antiquarks, commonly referred to as the charge asymmetry, is measured in pp collisions at the LHC with the CMS experiment. The data sample corresponds to an integrated luminosity of 1.09 fb−1 at a centre-of-mass energy of 7 TeV. Top-quark pairs are selected in the final state with an electron or muon and four or more jets. At least one jet is identified as originating from b-quark hadronization. The charge asymmetry is measured in two variables, one based on the pseudorapidities ([eta]) of the top quarks and the other on their rapidities (y). The results A{sub C}{sup {eta}} = -0.017 ± 0.032(stat.){sub -0.036}{sup +0.025}(syst.) and A{sub C}{sup y} = -0.013 ± 0.028(stat.){sub -0.031}{sup +0.029}(syst.) are consistent within uncertainties with the standard-model predictions.
Measurement Of The Forward Backward Asymmetry In B0 And Bar U039b B0 Baryon Production In P Bar P Collisions At Sqrt S
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language : en
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Release Date : 2015
Measurement Of The Forward Backward Asymmetry In B0 And Bar U039b B0 Baryon Production In P Bar P Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
We measure the forward-backward asymmetry in the production of ?0b and ?¯0b baryons as a function of rapidity in pp¯ collisions at √s = 1.96 TeV using 10.4 fb-1 of data collected with the D0 detector at the Fermilab Tevatron collider. The asymmetry is determined by the preference of ?0b or ?¯0b particles to be produced in the direction of the beam protons or antiprotons, respectively. As a result, the measured asymmetry integrated over rapidity y in the range 0.1
Measurement Of The Ttbar Production Cross Section In Ppbar Collisions At Sqrt S
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language : en
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Release Date : 2010
Measurement Of The Ttbar Production Cross Section In Ppbar Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
We present a measurement of the top quark pair production cross section in p{bar p} collisions at √s = 1.96 TeV using a data sample corresponding to 1.7 fb−1 of integrated luminosity collected with the Collider Detector at Fermilab. We reconstruct t{bar t} events in the lepton+jets channel, consisting of e[nu]+jets and [mu][nu]+jets final states. The dominant background is the production of W bosons in association with multiple jets. To suppress this background, we identify electrons from the semileptonic decay of heavy-flavor jets ('soft electron tags'). From a sample of 2196 candidate events, we obtain 120 tagged events with a background expectation of 51 ± 3 events, corresponding to a cross section of [sigma]{sub t{bar t}} = 7.8 ± 2.4 (stat) ± 1.6 (syst) ± 0.5 (lumi) pb. We assume a top-quark mass of 175 GeV/c2. This is the first measurement of the t{bar t} cross section with soft electron tags in Run II of the Tevatron.
Recent Results On Top Quark Physics At
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language : en
Publisher:
Release Date : 2015
Recent Results On Top Quark Physics At written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
We present the most recent measurements on top-quark physics obtained with Tevatron $p\bar{p}$ collisions recorded by the D0 experiment at $\sqrt{s}= 1.96$ TeV. The full Run II data set of 9.7 fb$^{-1}$ is analyzed. Both lepton+jets and dilepton channels of top-quark pair production are used to measure the differential and inclusive cross sections, the forward-backward asymmetries, the top-quark mass, the spin correlations, and the top-quark polarization.