Jens Konrath
We present recent measurements of the top quark pair production cross-section in the dilepton, lepton+jets and lepton+tau final states with the D0 detector in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV.
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This article describes the analyses presented at the XXVIII Physics in Collision conference about top quark cross sections performed at Tevatron.
The observation of the top quark will be an important milestone in ATLAS. This talk reviews methods that ATLAS plans to use to observe the top quark pair production process and measure its cross section.
Latest results on inclusive top-quark pair production cross-sections are presented using collision data collected by ATLAS and CMS experiments at the LHC. Inclusive and differential measurements of top-quark pair production cross-sections from ATLAS and CMS are presented in the resolved and boosted kinematic regions. The cross-sections are measured as a function of various kinematic observables of the top quarks, the jets and leptons of the event final state.
The measurement of heavy quark cross-sections provides important tests of the QCD theory. This paper reviews recent measurements of single b-quark and correlated b-quark cross-sections at CDF. Two new measurements of the single b-quark production at CDF agree with the first result from CDF Run II. This clarifies the experimental situation and confirms the recent agreement of theoretical prediction with data. A new measurement of the correlated $b\bar{b}$ cross-section with dimuon events at CDF is presented. It agrees with theory and it does not confirm the anomalously large $b\bar{b}$ cross-se…
An accurate determination of the top quark pair production cross section at the LHC provides a valuable check of the Standard Model. Given the high statistics which will be available (about one top quark pair per second, at a luminosity of 10^33 cm^-2 s^-1), this check can be performed relatively fast after the turn on of the LHC. The prospects for measuring the total top quark pair cross section with the ATLAS detector during the initial period of LHC running will be presented here. The cross section is determined in the single lepton channel and in the dilepton channel.
The top quark, discovered in 1995 by the CDF and D0 collaborations at the Tevatron proton antiproton collider at Fermilab, has undergone intense studies in the last 20 years. Currently, CDF and D0 converge on their measurements of top-antitop quark production cross sections using the full Tevatron data sample. In these proceedings, the latest results on inclusive and differential measurements of top-antitop quark production cross sections at the Tevatron are reported.
Top quark mass and cross section at ATLAS and CMS
该文介绍了ATLAS与CMS合作组在大型强子对撞机上开展的顶夸克产生截面及质量的最新测量研究，顶夸克作为已知最重基本粒子是标准模型研究的重要对象。
ATLAS and CMS measured the top quark pair production inclusive cross section using proton-proton collision data collected at 7 TeV c.m. energy at the LHC during the year 2011 in several channels. This article presents the measurements of the cross section using selections of top quark pair production events with one hadronically decaying τ lepton or no leptons at all.
Absolute and normalised differential cross-sections of single top quarks produced in the $t$-channel are presented. 20.2 fb$^{-1}$ of proton-proton collision data at a centre-of-mass energy of 8 TeV collected by the ATLAS experiment at the LHC are used. Differential cross-sections as a function of the transverse momentum and the absolute value of the rapidity of the top quarks and the top antiquarks are measured at both parton level and particle level. The transverse momentum and rapidity differential cross-sections of the scattered light-quark jets are extracted at particle level. The measure…
We use higher-order quantum chromodynamics calculations to extract the mass of the top quark from the ttbar cross section measured in the lepton+jets channel in ppbar collisions at sqrt(s)=1.96 TeV using 5.3 fb-1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. The extracted top quark pole mass and MSbar mass are compared to the current Tevatron average top quark mass obtained from direct measurements.
An overview of the recent measurements of the top antitop quark pair production cross section in proton antiproton collisions at \sqrt{s}=1.96 TeV in lepton + jets and dilepton final states is presented. These measurements are based on 1 -- 2.8 fb^{-1} of data collected with the D0 and CDF experiments at the Fermilab Tevatron collider. The cross section is measured with a precision close to 8% and found to be compatible with the standard model prediction. Interpretations of the cross-section measurements for charge higgs search and for top quark mass measurement are also discussed.
Preliminary results obtained by the CDF and D0 Collaborations on the top quark pair production cross-section in p pbar collisions at a center-of-mass energy of 1.96 TeV are presented. The measurements are obtained using various final states from top quark pair production and decays, and are based on data collected during years 2002-2004 of the Tevatron Run II.
Using data collected during the 1992-93 collider run at Fermilab, CDF has made measurements of correlated $b$ quark cross section where one $b$ is detected via a muon from semileptonic decay and the second $b$ is detected with secondary vertex techniques. We report on measurements of the cross section as a function of the momentum of the second $b$ and as a function of the azimuthal separation of the two $b$ quarks, for transverse momentum of the initial $b$ quark greater than 15 GeV. Results are compared to QCD predictions.
We report a measurement of the ratio of the bottom quark production cross section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom quarks with transverse momenta greater than 10.75 GeV identified through their semileptonic decays and long lifetimes. The measured ratio sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with next-to-leading order (NLO) quantum chromodynamics (QCD).
In this document, differential cross-section measurements of $t$-channel single top-quark production are presented. 20.2fb$^{-1}$ of data collected by the ATLAS experiment in proton-proton collisions in the LHC at a centre-of-mass energy of 8TeV are used. Differential cross-sections as a function of the transverse momentum and rapidity of both the top quark and the top antiquark have been measured at both parton and particle level. The transverse momentum and rapidity differential cross-sections of the scattered light-quark jet have been measured at particle level. All measurements are compare…
At the Tevatron, the collider experiments CDF and DO have data sets at their disposal that compromise several hundreds of reconstructed top-antitop-quark pairs and allow for precision measurements of the cross section and production and decay properties. Besides comparing the measurements to standard model predictions, these data sets open a window to physics beyond the standard model. Dedicated analyses look for new heavy gauge bosons, fourth generation quarks, and flavor-changing neutral currents.
Measurements of the inclusive and differential cross section for the production of top quark pairs in proton-(anti)proton collision at center-of-mass energies of 1.96, 7.0 and 8.0 TeV are presented and compared with the latest theory predictions and Monte-Carlo models. In addition, first measurements of the production of top quark pairs in association with additional jets or with a boson are highlighted. All measurements are in good agreement with the Standard Model.
Preliminary results on the top pair production cross section measurements by the D0 and CDF experiments in Run II at the Tevatron are presented. The measurements are obtained using various final state signatures.
We report the first top quark mass measurement that uses a cross section constraint to improve the mass determination. This measurement is made with a dilepton $t\bar{t}$ event sample collected with the CDF II detector. From a data sample corresponding to an integrated luminosity of 1.2 fb$^{-1}$, we measure a top quark mass of $\rm{170.7^{+4.2}_{-3.9}(stat)\pm2.6(syst)}$ $\rm{\pm2.4(theory) GeV/{\it{c}}^{2}}$. The measurement without the cross section constraint results in a top quark mass of $\rm{169.7^{+5.2}_{-4.9}(stat)\pm3.1(syst) GeV/{\it{c}}^{2}}$.
Using data collected during the 1992-1993 collider run at Fermilab, CDF has made measurements of correlated $b$ quark cross sections where one $b$ is detected from the lepton from semileptonic decay and the second $b$ is detected with secondary vertex techniques. We report on measurements of the cross section as a function of the momentum of the second $b$ and as a function of the azimuthal separation of the two $b$ quarks, for transverse momentum of the initial $b$ quark greater than 15 GeV. The vertex reconstruction techniques are valid over a large range in transverse momentum, starting at …
Run II of the Tevatron collider at Fermilab is well under way and data samples larger than those of Run I are at hand. In this contribution I summarize the current status of cross-section measurements for top-quark pair production at the CDF and D0 experiments.
The inclusive cross section of top quark-antiquark pairs produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV is measured in the lepton$+$jets and dilepton decay channels. The data sample corresponds to 9.7 fb${}^{-1}$ of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Employing multivariate analysis techniques we measure the cross section in the two decay channels and we perform a combined cross section measurement. For a top quark mass of 172.5 GeV, we measure a combined inclusive top quark-antiquark pair production cross section of $σ…
Inclusive beauty-quark production in two-photon collisions has been measured at LEP using an integrated luminosity of 698 pb-1 collected by the ALEPH detector with sqrt(s) between 130 and 209 GeV. The b quarks were identified using lifetime information. The cross section is found to be sigma(e+ e- --> e+ e- b \bar{b} X) = (5.4 +/- 0.8 (stat) +/- 0.8 (syst)) pb which is consistent with Next-to-Leading Order QCD.
An overview of recent measurements of inclusive and differential single top quark cross sections at 13 TeV with the CMS experiment is given in this note. This includes measurements targeting the $t$-channel and tW production modes resulting in inclusive cross sections of $σ_{t\mathrm{\mbox{-}ch.}}=238\pm32~\mathrm{pb}$ and $σ_\mathrm{tW}=63.1\pm6.6~\mathrm{pb}$ respectively. In addition, the $t$-channel cross section has been measured differentially as a function of the top quark transverse momentum and rapidity. The results are found in agreement with the standard model expectations. Furtherm…
An overview of the preliminary results of the top quark pair production cross section measurements at a center-of-mass energy of 1.96 TeV carried out by the CDF and D0 collaborations is presented. The data samples used for the analyses are collected in the current Tevatron run and correspond to an integrated luminosity from 360 pb-1 up to 760 pb-1.
We have studied tbar-t production using multijet final states in pbar-p collisions at a center-of-mass energy of 1.8 TeV, with an integrated luminosity of 110.3 pb(-1). Each of the top quarks with these final states decays exclusively to a bottom quark and a W boson, with the W bosons decaying into quark-antiquark pairs. The analysis has been optimized using neural networks to achieve the smallest expected fractional uncertainty on the tbar-t production cross section, and yields a cross section of 7.1 +/- 2.8(stat.) +/- 1.5(syst.) pb, assuming a top quark mass of 172.1 GeV/c^(2). Combining thi…
We present a measurement of the top-quark pair production cross-section in proton-antiproton collisions at $\sqrt{s}$=1.96 TeV. The data were collected at the Fermilab Tevatron by the CDF II detector and correspond to an integrated luminosity of 8.8 fb$^{-1}$, representing the complete CDF Run II data set. We select events consistent with the production of top-quark pairs by requiring the presence of two reconstructed leptons, an imbalance in the total event transverse momentum, and jets. At least one jet is required to be identified as consistent with the fragmentation of a bottom quark using…
Measurements of differential cross sections of top quark pair production in association with jets by the ATLAS experiment at the LHC are presented. The measurements are performed as functions of the top quark transverse momentum, the transverse momentum of the top quark-antitop quark system and the out-of-plane transverse momentum using data from $pp$ collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the LHC in 2015 and corresponding to an integrated luminosity of 3.2 fb$^{-1}$. The top quark pair events are selected in the lepton (electron or muon) + jets channel. The measure…
Higher-order QCD predictions are used to extract the top quark mass, both in the pole and in the $\bar{\mathrm{MS}}$ scheme, from the top quark pair production cross section measured in the dilepton final state. The analysed dataset corresponds to an integrated luminosity of 1.14 fb$^{-1}$ collected by the CMS experiment in 2011 in proton-proton collisions at $\sqrt{s} = 7$ TeV.
This article reviews recent cross-section measurements of top-quark pair production in association with a photon, W or Z boson at the Large Hadron Collider (LHC). All measurements reviewed use proton-proton (pp) datasets collected by the ATLAS and CMS experiments between 2016 and 2018 from collisions at a centre-of-mass energy of 13 TeV during the LHC Run 2. Differential and inclusive cross-section measurements are discussed along with the constraints on the effective field theory operators accessible through each process. Finally, we discuss the potential for measurements of these processes a…
The latest results on the measurements of electroweak top-quark production at the Tevatron are presented with the full RunII dataset. The CDF and D0 Collaborations have performed measurements of the s, t, and s+t channels in both l+jets and MET+jets final states. Evidence for the production of the s channel is presented for the first time.
Preliminary results of ttbar cross section measurements and single top exclusion limits of the Tevatron experiments CDF and D0 are presented. The different measurements are based on a dataset between 140 and 200 inverse pb corresponding to a data taking period from spring 2002 to September 2003. The ttbar cross section measurements are consistent with each other and the Standard Model prediction. Data and Monte-Carlo prediction are in good agreement in the search for single top quark. Its observation is anticipated with roughly 2 inverse fb integrated luminosity.
Top quark pair production cross section has been measured at the Tevatron by CDF and $DØ$ collaborations using different channels and methods, in order to test standard model predictions, and to search for new physics hints affecting the $t\bar t$ production mechanism or decay. Measurements are carried out with an integrated luminosity of 1.0 to 2.0 fb$^{-1}$, and are found to be consistent with standard model expectations.
Cross-section measurements of top-quark pair production where the hadronically decaying top quark has transverse momentum greater than $355$ GeV and the other top quark decays into $\ell νb$ are presented using 139 fb$^{-1}$ of data collected by the ATLAS experiment during proton-proton collisions at the LHC. The fiducial cross-section at $\sqrt{s}=13$ TeV is measured to be $σ= 1.267 \pm 0.005 \pm 0.053$ pb, where the uncertainties reflect the limited number of data events and the systematic uncertainties, giving a total uncertainty of $4.2\%$. The cross-section is measured differentially as a…
Single top quarks in the $t$ channel are produced though the electroweak force and are therefore an excellent way to probe the electroweak sector of the standard model with top quark physics. The recent cross section measurement of single top $t$-channel production from the CMS collaboration is presented in this poster. The analyzed data was taken during the LHC Run II in 2015 at a center-of-mass energy of $13\,\textrm{TeV}$. A multivariate classifier is used to distinguish signal and background processes and the cross section is then extracted using a binned maximum-likelihood fit.
Measuring the total cross sections of top-quark pair production and single top processes at high precision tests the predictions of the Standard Model and can bring better understanding of properties such as the top-quark mass, electroweak couplings, lepton universality and proton parton distribution functions. Some of the recent measurements by the ATLAS and CMS experiments at the Large Hadron Collider are outlined in this document. Experimental methods are given particular attention, particularly the determination of lepton isolation efficiencies in the ATLAS dilepton measurement of top-quar…
We combine measurements of the top quark pair production cross section in ppbar collisions in the l+jets, ll and tau-l final states (where l is an electron or muon) at a center of mass energy of sqrt(s)=1.96 TeV in 1fb^{-1} of data collected with the D0 detector. For a top quark mass of 170 GeV, we obtain sigma_ttbar=8.18^{+0.98}_{-0.87} pb. In addition, the ratios of ttbar cross sections in different final states are used to set upper limits on the branching fractions B(t -> H^{+}b -> tau nu b) and B(t -> H^{+}b -> c sbar b) as a function of charged Higgs boson mass. Based on predictions from…
With the large data set delivered during the second run of the CERN LHC, inclusive and differential measurements of the top quark-antiquark production cross section at the ATLAS and CMS experiments often reach a precision that is comparable or superior to that of the corresponding theoretical calculations. The results of these measurements can be used to test the validity of perturbative quantum chromodynamics (QCD), and to precisely extract the values of parameters of the QCD Lagrangian such as the top quark mass ($m_\mathrm{t}$). The value of $m_\mathrm{t}$ can also be measured, with higher …
Measurements are presented of differential cross-sections for top quark pair production in pp collisions at sqrt(s) = 7 TeV relative to the total inclusive top quark pair production cross-section. A data sample of 2.05/fb recorded by the ATLAS detector at the Large Hadron Collider is used. Relative differential cross-sections are derived as a function of the invariant mass, the transverse momentum and the rapidity of the top quark pair system. Events are selected in the lepton (electron or muon) + jets channel. The background-subtracted differential distributions are corrected for detector eff…
The cross section for pair production of top quarks (t-tbar) with high transverse momenta is measured in pp collisions, collected with the CMS detector at the LHC with sqrt(s) = 8 TeV in data corresponding to an integrated luminosity of 19.7 inverse femtobarns. The measurement is performed using lepton+jets events, where one top quark decays semileptonically, while the second top quark decays to a hadronic final state. The hadronic decay is reconstructed as a single, large-radius jet, and identified as a top quark candidate using jet substructure techniques. The integrated cross section and th…
Top-quark pairs in association with final state particles are produced in large quantities at the LHC due to the high centre-of-mass energy available in proton-proton collisions. One such topology is that of a prompt photon radiated from the top quark in addition to the final state particles from the top quark decay. Using 36.1 fb$^{-1}$ of data collected at $\sqrt{s}$ = 13 TeV with the ATLAS detector, fiducial cross-section results are shown in the single-lepton and dilepton channels. Object-level and event-level neural networks are used to increase sensitivity.
This article presents measurements of all three single top-quark production channels. Detailed measurements of $t$-channel single top-quark production using data collected by the ATLAS experiment in proton--proton collisions at a centre-of-mass energy of 8 TeV are shown as well es first results using 13 TeV at the LHC. The associated production of a top quark and a $W$ boson is presented for data collected at 13 TeV, while the first evidence of single top-quark production in the $s$-channel is shown for data collected at 8 TeV.
A measurement of the top-quark pair-production cross section in ppbar collisions at sqrt{s}=1.96 TeV using data corresponding to an integrated luminosity of 1.12/fb collected with the Collider Detector at Fermilab is presented. Decays of top-quark pairs into the final states e nu + jets and mu nu + jets are selected, and the cross section and the b-jet identification efficiency are determined using a new measurement technique which requires that the measured cross sections with exactly one and multiple identified b-quarks from the top-quark decays agree. Assuming a top-quark mass of 175 GeV/c^…
Measurements of the top quark production cross section in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented. The measurements require no, one or two electrons or muons in the final state (single lepton, dilepton, hadronic channel). In addition, the decay modes with tau leptons are tested (channels with tau leptons). The main focus is on measurements of differential spectra of $t\bar{t}$ final states, in particular, measurements that are able to constrain the modelling of additional parton radiation like the jet multiplicity distribution.
The production of single top quarks is a cornerstone in understanding the nature of the heaviest known elementary particle and its involvement in electroweak interactions. An early differential cross section measurement of t-channel single-top-quark production is presented. Proton-Proton collision data at a center-of-mass energy of $13~\mathrm{TeV}$ collected in 2015 were analyzed, corresponding to $2.3~\mathrm{fb}^{-1}$. The amount of signal events as a function of the top quark transverse momentum and rapidity is estimated using a multivariate discriminant. The results are unfolded to parton…
The differential cross-section for pair production of top quarks with high transverse momentum is measured in 20.3 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 8 TeV. The measurement is performed for $t\bar{t}$ events in the lepton+jets channel. The cross-section is reported as a function of the hadronically decaying top quark transverse momentum for values above 300 GeV. The hadronically decaying top quark is reconstructed as an anti-$k_t$ jet with radius parameter $R=1.0$ and identified with jet substructure techniques. The observed yield is corrected for detector effe…
The top quark pair production cross section is measured for the first time in proton-proton collisions at sqrt(s) = 13 TeV by the CMS experiment at the CERN LHC, using data corresponding to an integrated luminosity of 43 inverse picobarns. The measurement is performed by analyzing events with at least one electron and one muon of opposite charge, and at least two jets. The measured cross section is 746 +/- 58 (stat) +/- 53 (syst) +/- 36 (lumi) pb, in agreement with the expectation from the standard model.
The t t-bar production cross section and top quark mass are measured in proton-proton collisions at sqrt(s) = 7 TeV in a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected by the CMS experiment. The measurements are performed in events with two leptons (electrons or muons) in the final state. Results of the cross section measurement in events with and without b-quark identification are obtained and combined. The measured value is sigma(t t-bar)=168 +/- 18 (stat.) +/- 14 (syst.) +/- 7 (lumi.) pb, consistent with predictions from the standard model. The top q…
A measurement is reported of the production cross section of top-quark pairs in proton-proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC. Candidate events have a signature consistent with containing two isolated leptons, large missing transverse momentum, and at least two jets. Using a data sample corresponding to an integrated luminosity of 0.70 fb^-1, a t-tbar production cross section sigmattbar=176 +/-5 (stat) +14 -11 (syst) +/- 8 (lum.) pb is measured for an assumed top-quark mass of m_t = 172.5 GeV.
A search is performed for top quark pairs with early data of ATLAS pp collision taken at {\surd}s = 7 TeV. Several candidate events are observed, in both lepton plus jets and dilepton channels. The properties of these events are described, and compared to the expectations from Monte Carlo simulation. A first study of the backgrounds in the lepton plus jets channel is presented including a data-driven determination of the contribution of QCD multi-jet events.
This note details recent measurements of the top mass and cross section that have been performed at the Tevatron. Most of these measurements have been performed with between 1.0 and 2.0 fb-1 of data. Basic top physics concepts are discussed, cross section and mass analysis methods and results are presented, and future analysis prospects are discussed with a special attention given to Electroweak determination of the limits on the Standard Model Higgs mass.
We review the current status of the cross sections measurement of the top-quark at the LHC and at the Tevatron. Total production cross sections, studies using single top quark events and differential $\rm{t}\bar{\rm t}$ cross sections are discussed. The associated production of top quark pairs with photons, Z and W bosons, including $\rm{t}\bar{\rm t}$Z and $\rm{t}\bar{\rm t}$W measurements shown for the first time at LHCP2014, are presented.
The normalized differential cross section for top quark pair (tt-bar) production is measured in pp collisions at a centre-of-mass energy of 8 TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7 inverse femtobarns. The measurements are performed in the lepton + jets (e/mu + jets) and in the dilepton (e+e-, mu+mu-, and e+-mu-+) decay channels. The tt-bar cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt-bar system. The data are compared with sever…
The measurement of the inclusive $Wt$ cross-section at 13 TeV is performed using 3.2$\,\text{fb}{^{-1}}$ of proton--proton collision data collected by the ATLAS detector at the LHC in 2015. Events are required to have at least one jet and two opposite sign leptons. The cross section is measured to be $σ_{Wt} = 94\pm 10\text{(stat.)}^{+28}_{-22}\text{(syst.)}\pm 2\text{(lumi})$pb, corresponding to an observed significance of 4.5\,$σ$ (3.9\,$σ$ expected). The result is consistent with the Standard Model prediction.
We present a measurement of tbar-t production using multijet final states in pbar-p collisions at a center-of-mass energy of 1.8 TeV, with an integrated luminosity of 110.3 pb(-1). The analysis has been optimized using neural networks to achieve the smallest expected fractional uncertainty on the tbar-t production cross section, and yields a cross section of 7.1 +/- 2.8(stat.) +/- 1.5(syst.) pb, assuming a top quark mass of 172.1 GeV/c^(2). Combining this result with previous D0 measurements, where one or both of the W bosons decay leptonically, gives a tbar-t production cross section of 5.9 +…
We present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb$^{-1}$ per experiment. The $t$-channel cross section is measured to be $σ_t = 2.25^{+0.29}_{-0.31}$ pb. We also present the combinations of the two-dimensional measurements of the $s$- vs. $t$-channel cross sections and of the $s+t$ channel cross section measurement resulting in $σ_{s+t} = 3.30^{+0.52}_{-0.40}$ pb, without assuming the standard-mo…
The electroweak production of single-top quarks in the $t$ channel can be changed by any deviation from the standard model, it is therefore an excellent opportunity to search for new physics. In this poster the recent cross-section measurement performed by the CMS collaboration is presented with the full 2015 dataset of the LHC Run II at a center-of-mass energy of 13 TeV. The cross section and the top/antitop ratio is extracted using a binned maximum likelihood fit to the distribution of a multivariate classifier in events containing one isolated muon in the final state.
We present a measurement of the ttbar production cross section in ppbar collisions at root(s) = 1.8TeV by the D0 experiment at the Fermilab Tevatron. The measurement is based on data from an integrated luminosity of approximately 125 pb^-1 accumulated during the 1992-1996 collider run. We observe 39 ttbar candidate events in the dilepton and lepton+jets decay channels with an expected background of 13.7+-2.2 events. For a top quark mass of 173.3GeV/c^2, we measure the ttbar production cross section to be 5.5+-1.8 pb.
Normalised differential top-quark pair production cross sections are measured in pp collisions at a centre-of-mass energy of 7 TeV at the LHC with the CMS detector using data recorded in 2011 corresponding to an integrated luminosity of 5.0 inverse femtobarns. The measurements are performed in the lepton+jets decay channels (e+jets and mu+jets) and the dilepton decay channels (oppositely charged ee, mu mu, and e mu). The t t-bar differential cross section is measured as a function of kinematic properties of the final-state charged leptons and jets associated to b quarks, as well as those of th…
A measurement of the production cross section of top quark pairs (ttbar) in proton-proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the Large Hadron Collider is reported. Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. Using a data sample corresponding to an integrated luminosity of 35 pb^-1, a ttbar production cross section of 171 +/- 20(stat.) +/- 14(syst.) +8-6(lum.) pb is measured for an assumed top quark mass of 172.5 GeV. A second measurement requiring at least one jet identified a…
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