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Charge Asymmetry In Top Quark Pair Production At S
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Book Synopsis Measurement of the Charge Asymmetry in Top Quark Pair Production in Pp Collisions at $\sqrt{s}$ by :
Download or read book Measurement of the Charge Asymmetry in Top Quark Pair Production in Pp Collisions at $\sqrt{s}$ written by and published by . This book was released on 2015 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Measurement of the Charge Asymmetry in Top-quark Pair Production in Proton-proton Collisions at Sqrt(s) by :
Download or read book Measurement of the Charge Asymmetry in Top-quark Pair Production in Proton-proton Collisions at Sqrt(s) written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Charge Asymmetry in Top Quark Pair Production at √s by : Robert Vallance
Download or read book Charge Asymmetry in Top Quark Pair Production at √s written by Robert Vallance and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurements of the Charge Asymmetry in Top-quark Pair Production in the Dilepton Final State at S by :
Download or read book Measurements of the Charge Asymmetry in Top-quark Pair Production in the Dilepton Final State at S written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the top-antitop quark pair production charge asymmetry in the dilepton channel, characterized by two high-pT leptons (electrons or muons), are presented using data corresponding to an integrated luminosity of 20.3 fb–1 from pp collisions at a center-of-mass energy √s = 8 TeV collected with the ATLAS detector at the Large Hadron Collider at CERN. Inclusive and differential measurements as a function of the invariant mass, transverse momentum, and longitudinal boost of the tt¯ system are performed both in the full phase space and in a fiducial phase space closely matching the detector acceptance. Two observables are studied: AllC based on the selected leptons and Att¯C based on the reconstructed tt¯ final state. As a result, the inclusive asymmetries are measured in the full phase space to be AllC=0.008±0.006 and Att¯C=0.021±0.016, which are in agreement with the Standard Model predictions of AllC=0.0064±0.0003 and Att¯C=0.0111±0.0004.
Book Synopsis Charge Asymmetry Measurements in Top Quark Pair Production at Sqrt(s) by : Frank Roscher
Download or read book Charge Asymmetry Measurements in Top Quark Pair Production at Sqrt(s) written by Frank Roscher and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurement of the Charge Asymmetry in Top Quark Pair Production in Pp Collision Data at √s by :
Download or read book Measurement of the Charge Asymmetry in Top Quark Pair Production in Pp Collision Data at √s written by and published by . This book was released on 2012 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurements of the charge asymmetry in top quark pair production at the LHC with the ATLAS detector by : Francesco Rubbo
Download or read book Measurements of the charge asymmetry in top quark pair production at the LHC with the ATLAS detector written by Francesco Rubbo and published by . This book was released on 2014 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurement of the Charge Asymmetry in Top Quark Pair Production in Pp Collision Data at √s by : Fabian Kohn
Download or read book Measurement of the Charge Asymmetry in Top Quark Pair Production in Pp Collision Data at √s written by Fabian Kohn and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurement of Charge Asymmetry in Top Quark Pair Production at the Large Hadron Collider by : Burton Andrew Betchart
Download or read book Measurement of Charge Asymmetry in Top Quark Pair Production at the Large Hadron Collider written by Burton Andrew Betchart and published by . This book was released on 2013 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: "We present a measurement of charge asymmetry in the production of top and antitop quark pairs in proton-proton collisions, in a sample of 19:6 fb−1 of data collected by the CMS experiment at 8TeV center of mass energy in 2012. Selected events have a single isolated electron or muon, and at least four jets, at least one of which is likely due to a bottom quark. A template technique is employed to measure top-antitop asymmetry in two kinematic observables simultaneously, which allows attribution of contributions to the observed forward-central asymmetry from distinct Standard Model production mechanisms. An asymmetry Ayc = (0:15 ± 0:42)% is measured in the difference of absolute rapidities of top-antitop pairs, of which (0:00 ± 0:43)% is attributable to quark-antiquark initial states, and (0:18 ± 0:15)% is attributable to quark-gluon initial states. The first measurement of the transverse top quark charge asymmetry is also presented, with the result A[phi]c = (0:44 ± 0:50)%. Measurements of the inclusive asymmetry on selections with high and low top system mass and absolute rapidity are consistent with the main result. The results are compared to Standard Model predictions and measurements from the LHC and the Tevatron"--Page vii.
Book Synopsis Inclusive and Differential Measurements of the $\mathrm{ T \bar{t} }$ Charge Asymmetry in Pp Collisions at $\sqrt{s} by :
Download or read book Inclusive and Differential Measurements of the $\mathrm{ T \bar{t} }$ Charge Asymmetry in Pp Collisions at $\sqrt{s} written by and published by . This book was released on 2015 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The tt charge asymmetry is measured in proton-proton collisions at a centre-of-mass energy of 8 TeV. The data, collected with the CMS experiment at the LHC, correspond to an integrated luminosity of 19.7 fb-1 . Selected events contain an electron or a muon and four or more jets, where at least one jet is identified as originating from b-quark hadronization. The inclusive charge asymmetry is found to be 0.0010 " 0.0068 (stat) " 0.0037 (syst). In addition, differential charge asymmetries as a function of rapidity, transverse momentum, and invariant mass of the tt system are studied. For the first time at the LHC, our measurements are also performed in a reduced fiducial phase space of top quark pair production, with an integrated result of -0.0035 " 0.0072 (stat) " 0.0031 (syst). Additionally, all measurements are consistent within two standard deviations with zero asymmetry as well as with the predictions of the standard model.
Book Synopsis First Measurement of the Charge Asymmetry in Boosted Top Quark Pair Production in the ATLAS Experiment Using the Grid-based Tier-3 Facility at IFIC-Valencia by : Victoria Sánchez Martínez
Download or read book First Measurement of the Charge Asymmetry in Boosted Top Quark Pair Production in the ATLAS Experiment Using the Grid-based Tier-3 Facility at IFIC-Valencia written by Victoria Sánchez Martínez and published by . This book was released on 2016 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Symmetry in Particle Physics by : Michal Hnatič
Download or read book Symmetry in Particle Physics written by Michal Hnatič and published by MDPI. This book was released on 2021-06-24 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particle physics is a science about the symmetries of our world. The Standard Model is the fundamental theory of microworld. Particle dynamics in the Standard Model obeys strict symmetry laws with explicit experimental consequences. Priority problems of particle physics based on the Standard Model are more accurate theoretical predictions, experimental measurements and data analysis, proof of existence or non-existence of supersymmetry, top quark properties, Higgs boson, exotic quark states, and physics of neutrinos. In this collection of articles, many of these problems are discussed. We recommend this book for students, graduate students, and scientists working in the field of high energy physics.
Book Synopsis Top Quark Pair Production Cross Section and Forward-Backward Asymmetry at the Tevatron by :
Download or read book Top Quark Pair Production Cross Section and Forward-Backward Asymmetry at the Tevatron written by and published by . This book was released on 2008 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present recent results on top quark pair production cross section and forward-backward asymmetry at the Tevatron. Three new cross section measurements from CDF and one new measurement from DO are presented that utilize the full dataset available. A new DO top cross section combination gives a ttbar production cross section of sigma ttbar = 7.83 + 0.46-0.45 (stat) + 0.64-0.53 (syst) +-0.48 (lumi). The new CDF cross section combination for ttbar production is found to be 7.0 +- 0.3 (stat) +- 0.4 (syst) +- 0.4 (lumi) pb giving a total uncertainty of 9%, very close to the that of the current best theoretical predictions. It is important to measure the top cross section in as many different channels as possible and investigate their compatibility. This is useful as new physics might show up differently in the different channels. Thus any significant discrepancy could be a sign of new physics. Three new measurements of the forward-backward asymmetry are also presented. The two CDF measurements unfold the observed asymmetry back to parton level in order to directly compare the values obtained with theoretical predictions. The DO measurement is not unfolded and therefore does not depend on the specific method used for unfolding.
Book Synopsis Measurement of the Charge Asymmetry in Top-antitop Quark Production with the CDF II Experiment by : Julia Weinelt
Download or read book Measurement of the Charge Asymmetry in Top-antitop Quark Production with the CDF II Experiment written by Julia Weinelt and published by . This book was released on 2006 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fermi National Laboratory (Fermilab) operates the Tevatron proton-antiproton collider at a center-of-mass energy of {radical}s = 1.96 TeV, the is therefore the only collider which is today able to produce the heaviest known particle, the top quark. The top quark was discovered at the Tevatron by the CDF and D0 collaborations in 1995. At the Tevatron, most top quarks are produced via the strong interaction, whereby quark-antiquark annihilation dominates with 85%, and gluon fusion contributes with 15%. Considering next-to-leading order (NLO) contributions in the cross section of top-antitop quark production, leads to a slight positive asymmetry in the differential distribution of the production angle {alpha} of the top quarks. This asymmetry is due to the interference of certain NLO contributions. The charge asymmetry A in the cosine of {alpha} is predicted [14] to amount to 4-6%. Information about the partonic rest frame, necessary for a measurement of A in the observable cos {alpha}, is not accessible in the experiment. Thus, they use the rapidity difference of the top and the antitop quark as sensitive variable. This quantity offers the advantage of Lorentz invariance and is uniquely correlated with the cosine of {alpha}, justifying the choice of the rapidity difference to describe the behavior of cos {alpha}. In preparation for a measurement of the charge asymmetry, they conduct several Monte Carlo based studies concerning the effect of different event selection criteria on the asymmetry in the selected event samples. They observe a strong dependence of the measured asymmetry on the number of required jets in the particular event sample. This motivates further studies to understand the influence of additional gluon radiation, which leads to more than four observed jets in an event, on the rapidity distribution of the produced top quarks. They find, that events containing hard gluon radiation are correlated with a strong negative shift of the rapidity distribution of the top quarks. This leads to large negative values of the charge asymmetry in event samples that contain only events with exactly five, six or more jets. This finding requires a modification of the original analysis strategy, since an asymmetry measured in an inclusive sample will be a composition of the asymmetry in the four-jets and five-jets sub-samples. Therefore, they perform for the first time a measurement of the asymmetry separately in the exclusive four- and five-jets sub-samples to separate the contribution of hard gluon radiation to the asymmetry. They analyze a data sample, collected by the CDF II detector in the years 2002-2006, that corresponds to an integrated luminosity of about 955 pb{sup -1}.
Author :Anna Christine Henrichs Publisher :Springer Science & Business Media ISBN 13 :3319014870 Total Pages :231 pages Book Rating :4.3/5 (19 download)
Book Synopsis Top Quark Pair Production by : Anna Christine Henrichs
Download or read book Top Quark Pair Production written by Anna Christine Henrichs and published by Springer Science & Business Media. This book was released on 2013-10-04 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: Before any kind of new physics discovery could be made at the LHC, a precise understanding and measurement of the Standard Model of particle physics' processes was necessary. The book provides an introduction to top quark production in the context of the Standard Model and presents two such precise measurements of the production of top quark pairs in proton-proton collisions at a center-of-mass energy of 7 TeV that were observed with the ATLAS Experiment at the LHC. The presented measurements focus on events with one charged lepton, missing transverse energy and jets. Using novel and advanced analysis techniques as well as a good understanding of the detector, they constitute the most precise measurements of the quantity at that time.
Book Synopsis Evidence for a Mass Dependent Forward-Backward Asymmetry in Top Quark Pair Production by :
Download or read book Evidence for a Mass Dependent Forward-Backward Asymmetry in Top Quark Pair Production written by and published by . This book was released on 2011 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a new measurement of the inclusive forward-backward t{bar t} production asymmetry and its rapidity and mass dependence. The measurements are performed with data corresponding to an integrated luminosity of 5.3 fb−1 of p{bar p} collisions at √s = 1.96 TeV, recorded with the CDF II Detector at the Fermilab Tevatron. Significant inclusive asymmetries are observed in both the laboratory frame and the t{bar t} rest frame, and in both cases are found to be consistent with CP conservation under interchange of t and {bar t}. In the t{bar t} rest frame, the asymmetry is observed to increase with the t{bar t} rapidity difference, [Delta]y, and with the invariant mass M{sub t{bar t}} of the t{bar t} system. Fully corrected parton-level asymmetries are derived in two regions of each variable, and the asymmetry is found to be most significant at large [Delta]y and M{sub t{bar t}}. For M{sub t{bar t}} ≥ 450 GeV/c2, the parton-level asymmetry in the t{bar t} rest frame is A{sup t{bar t}} = 0.475 ± 0.114 compared to a next-to-leading order QCD prediction of 0.088 ± 0.013.
Book Synopsis Search for Same-sign Top-quark Pair Production at Sqrt(s) by :
Download or read book Search for Same-sign Top-quark Pair Production at Sqrt(s) written by and published by . This book was released on 2011 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
