Quark Pair Production Cross Section Research Articles

First measurement of the top quark pair production cross section in proton-proton collisions at sqrt{s} = 13.6 TeV

The first measurement of the top quark pair ( textrm{t}overline{textrm{t}} ) production cross section in proton-proton collisions at sqrt{s} = 13.6 TeV is presented. Data recorded with the CMS detector at the CERN LHC in Summer 2022, corresponding to an integrated luminosity of 1.21 fb−1, are analyzed. Events are selected with one or two charged leptons (electrons or muons) and additional jets. A maximum likelihood fit is performed in event categories defined by the number and flavors of the leptons, the number of jets, and the number of jets identified as originating from b quarks. An inclusive textrm{t}overline{textrm{t}} production cross section of 881 ± 23 (stat + syst) ± 20 (lumi) pb is measured, in agreement with the standard model prediction of {924}_{-40}^{+32} pb.

Measurement of the inclusive mathrm{t}overline{mathrm{t}} production cross section in proton-proton collisions at sqrt{s} = 5.02 TeV

The top quark pair production cross section is measured in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data were collected in a special LHC low-energy and low-intensity run in 2017, and correspond to an integrated luminosity of 302 pb−1. The measurement is performed using events with one electron and one muon of opposite charge, and at least two jets. The measured cross section is 60.7 ± 5.0 (stat) ± 2.8 (syst) ± 1.1 (lumi) pb. A combination with the result in the single lepton + jets channel, based on data collected in 2015 at the same center-of-mass energy and corresponding to an integrated luminosity of 27.4 pb−1, is then performed. The resulting measured value is 63.0 ± 4.1 (stat) ± 3.0 (syst+lumi) pb, in agreement with the standard model prediction of {66.8}_{-3.1}^{+2.9} pb.

Recent top quark measurements with the CMS experiment

Latest results on top quark pair and single top quark production cross sections (inclusive and differential) are presented using proton-proton collision data collected by CMS. The results are used to constrain the standard model parameters. For the first time, the third row of the CKM matrix is measured from single top quark events and multidifferential cross sections are used to constrain simultaneously the top quark pole mass, α S , and PDFs. Moreover, recent results on top quark properties, such as mass measurements or constraints on top Yukawa from differential cross sections are also presented.

Measurement of differential tt¯ production cross sections using top quarks at large transverse momenta in pp collisions at s=13 TeV

A measurement is reported of differential top quark pair ($\mathrm{t\bar{t}}$) production cross sections, where top quarks are produced at large transverse momenta. The data collected with the CMS detector at the LHC are from pp collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The measurement uses events where at least one top quark decays as t $\to$ Wb $\to$ qq'b and is reconstructed as a large-radius jet with transverse momentum in excess of 400 GeV. The second top quark is required to decay either in a similar way, or leptonically, as inferred from a reconstructed electron or muon, a bottom quark jet, and a missing transverse momentum due to the undetected neutrino. The cross section is extracted as a function of kinematic variables of individual top quarks or of the $\mathrm{t\bar{t}}$ system. The results are presented at the particle level, within a region of phase space close to that of the experimental acceptance, and at the parton level, and are compared to various theoretical models. In both decay channels the observed absolute cross sections are significantly lower than the predictions from theory, while the normalized differential measurements are well described.

Measurement of the tbar{t} production cross-section and lepton differential distributions in emu dilepton events from pp collisions at sqrt{s}=13,text {TeV} with the ATLAS detector

The inclusive top quark pair (tbar{t}) production cross-section sigma _{tbar{t}} has been measured in proton–proton collisions at sqrt{s}=13,text {TeV}, using 36.1 fb^{-1} of data collected in 2015–2016 by the ATLAS experiment at the LHC. Using events with an opposite-charge emu pair and b-tagged jets, the cross-section is measured to be: σtt¯=826.4±3.6(stat)±11.5(syst)±15.7(lumi)±1.9(beam)pb,\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$\\begin{aligned} \\sigma _{t\\bar{t}} = 826.4 \\pm 3.6\\,\\mathrm {(stat)}\\ \\pm 11.5\\,\\mathrm {(syst)}\\ \\pm 15.7\\,\\mathrm {(lumi)}\\ \\pm 1.9\\,\\mathrm {(beam)}\\,\\mathrm {pb}, \\end{aligned}$$\\end{document}where the uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, the integrated luminosity, and the LHC beam energy, giving a total uncertainty of 2.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. It is used to determine the top quark pole mass via the dependence of the predicted cross-section on m_t^{mathrm{pole}}, giving m_t^{mathrm{pole}}=173.1^{+2.0}_{-2.1},text {GeV}. It is also combined with measurements at sqrt{s}=7,text {TeV} and sqrt{s}=8,text {TeV} to derive ratios and double ratios of tbar{t} and Z cross-sections at different energies. The same event sample is used to measure absolute and normalised differential cross-sections as functions of single-lepton and dilepton kinematic variables, and the results are compared with predictions from various Monte Carlo event generators.

Measurement of the top quark pair production cross section in dilepton final states containing one \u03c4 lepton in pp collisions at sqrt{s} = 13 TeV

The cross section of top quark pair production is measured in the mathrm{t}overline{mathrm{t}}to left(ell {nu}_{ell}right)left({uptau}_{mathrm{h}}{nu}_{uptau}right)mathrm{b}overline{mathrm{b}} final state, where τh refers to the hadronic decays of the τ lepton, and ℓ is either an electron or a muon. The data sample corresponds to an integrated luminosity of 35.9 fb−1 collected in proton-proton collisions at sqrt{s} = 13 TeV with the CMS detector. The measured cross section is {sigma}_{mathrm{t}overline{mathrm{t}}} = 781 ± 7 (stat) ± 62 (syst) ± 20 (lumi) pb, and the ratio of the partial width Γ(t → τντb) to the total decay width of the top quark is measured to be 0.1050 ± 0.0009 (stat) ± 0.0071 (syst). This is the first measurement of the mathrm{t}overline{mathrm{t}} production cross section in proton-proton collisions at sqrt{s} = 13 TeV that explicitly includes τ leptons. The ratio of the cross sections in the ℓτh and ℓℓ final states yields a value {R}_{ell {uptau}_{mathrm{h}}/mathcal{ll}} = 0.973 ± 0.009 (stat) ± 0.066 (syst), consistent with lepton universality.

Differential top quark pair production at the LHC: Challenges for PDF fits

We present the results of a PDF fit to differential top quark production within the MMHT framework. We in particular consider ATLAS data in the lepton + jet and dilepton channels and CMS data in the lepton + jet channel, at 8 TeV. While the fit quality to the ATLAS dilepton data is good, for the CMS case we see some issues in achieving a good fit quality for certain distributions. However, we focus on the ATLAS lepton + jet data, for which correlations of the statistical and systematic errors are provided across the four relevant distributions for PDF determination, namely p_T^t, M_{tt}, y_t and y_{tt}. We find severe difficulties in fitting these distributions simultaneously, with particular sensitivity to the precise degree of correlation taken between the dominant two-point MC uncertainties in the data. We investigate the effect of some reasonable decorrelation of these uncertainties, finding the impact on the fit quality to be significant and the resultant gluon not negligible. This is in particular found to be larger than the effect of including NNLO QCD and NLO EW corrections in the top quark pair production cross section on the fit, motivating a closer understanding of the physics underlying these errors sources and in particular the uncertainty on the degree of correlation in them.

Measurement of the inclusive mathrm{t}overline{mathrm{t}} cross section in pp collisions at sqrt{s}=5.02 TeV using final states with at least one charged lepton

The top quark pair production cross section left({sigma}_{mathrm{t}overline{mathrm{t}}}right) is measured for the first time in pp collisions at a center-of-mass energy of 5.02 TeV. The data were collected by the CMS experiment at the LHC and correspond to an integrated luminosity of 27.4 pb−1. The measurement is performed by analyzing events with at least one charged lepton. The measured cross section is {sigma}_{mathrm{t}overline{mathrm{t}}} = 69.5 ± 6.1 (stat) ± 5.6 (syst) ± 1.6 (lumi) pb, with a total relative uncertainty of 12%. The result is in agreement with the expectation from the standard model. The impact of the presented measurement on the determination of the gluon distribution function is investigated.

Search for pair production of vector-like T and B quarks in single-lepton final states using boosted jet substructure in proton-proton collisions at sqrt{s}=13 TeV

A search for pair production of massive vector-like T and B quarks in proton-proton collisions at sqrt{s}=13 TeV is presented. The data set was collected in 2015 by the CMS experiment at the LHC and corresponds to an integrated luminosity of up to 2.6 fb−1. The T and B quarks are assumed to decay through three possible channels into a heavy boson (either a W, Z or Higgs boson) and a third generation quark. This search is performed in final states with one charged lepton and several jets, exploiting techniques to identify W or Higgs bosons decaying hadronically with large transverse momenta. No excess over the predicted standard model background is observed. Upper limits at 95% confidence level on the T quark pair production cross section are set that exclude T quark masses below 860 GeV in the singlet, and below 830 GeV in the doublet branching fraction scenario. For other branching fraction combinations with ℬ(T → tH) + ℬ(T → bW) ≥ 0.4, lower limits on the T quark range from 790 to 940 GeV. Limits are also set on pair production of singlet vector-like B quarks, which can be excluded up to a mass of 730 GeV. The techniques showcased here for understanding highly-boosted final states are important as the sensitivity to new particles is extended to higher masses.

ISR effects on loop corrections of a top pair-production at the ILC

Precise predictions for an e+e− → tt̄ cross section are presented at an energy region from 400 GeV to 800 GeV. Cross sections are estimated including the beam-polarization effects with full , and also with effects of the initial-state photon emission. A resummation technique is used for the initial-state photon emission up to two-loop order. A pure-weak correction is defined as the full electroweak corrections without the initial-state photonic corrections. As a result, it is obtained that the total cross section of a top quark pair-production receives the pure-weak corrections of +4% over the trivial initial state corrections at a center of mass energy of 500 GeV. Among the initial state contributions, a contribution from two-loop diagrams gives −5% correction over the one-loop ones at the center of mass energy of 500 GeV.

αs from the top quark pair production cross section

Five measurements of the top quark pair production cross section from hadron colliders are compared with the theoretical prediction (up the next-to-next-to-leading order in QCD) in order to determine the strong coupling constant αs. The determination is performed for several PDF sets. The individual determinations of αs are combined to form a single best estimate using the Best Linear Unbiased Estimate (BLUE) procedure. Preliminary combined results indicate a higher value of αs than that determined in a previous extraction of αs from the top quark pair production cross section.

Measurements of the mathrm{t}overline{mathrm{t}} production cross section in lepton+jets final states in pp collisions at 8 ,text {TeV} and ratio of 8 to 7\xa0,text {TeV} cross sections

A measurement of the top quark pair production (mathrm{t}overline{mathrm{t}} ) cross section in proton–proton collisions at the centre-of-mass energy of 8,text {TeV} is presented using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.6,text {fb}^{-text {1}}. This analysis is performed in the mathrm{t}overline{mathrm{t}} decay channels with one isolated, high transverse momentum electron or muon and at least four jets, at least one of which is required to be identified as originating from hadronization of a b quark. The calibration of the jet energy scale and the efficiency of b jet identification are determined from data. The measured mathrm{t}overline{mathrm{t}} cross section is 228.5 pm 3.8,text {(stat)} pm 13.7,text {(syst)} pm 6.0,text {(lumi)} text { pb} . This measurement is compared with an analysis of 7,text {TeV} data, corresponding to an integrated luminosity of 5.0,text {fb}^{-text {1}}, to determine the ratio of 8,text {TeV} to 7,text {TeV} cross sections, which is found to be 1.43 pm 0.04,text {(stat)} pm 0.07,text {(syst)} pm 0.05,text {(lumi)} . The measurements are in agreement with QCD predictions up to next-to-next-to-leading order.

Top quark pair production cross section using the ATLAS detector at the LHC

Measurements of the inclusive top quark pair production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented. The measurements are performed requiring one or two electrons or muons in the final state. Various experimental techniques are compared. The most accurate result in obtained requiring opposite sign electrons and muons, achieves a precision of a few percent, and is in good agreement with a recent NNLO+NNLL QCD calculation. In addition, a differential measurement of the top transverse momentum and kinematic properties of the top pair system are presented. This measurement requires one electron or muon in the final state and probes our understanding of top pair production in the TeV regime and is compared to recent Monte Carlo generators and theory calculations.

Measurement of the Top Quark Pair Production Cross Section in Proton-Proton Collisions at √[s]=13 TeV.

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 pb^{-1}. 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.

Running a typical ROOT HEP analysis on Hadoop MapReduce

We evaluate how a typical ROOT High Energy Physics (HEP) analysis can be executed on Hadoop MapReduce. We take into account several aspects and we propose a method to perform the analysis in a completely transparent way to ROOT, the data and the user: the goal is to let ROOT run without any modifications and to store the data in its original format. The solutions which has been found to solve the encountered problems can be easily ported to any HEP code, and in general to any code working on binary data relying on independent sub-problems like HEP particle collision events. We tested the method by running an analysis code for the top quark pair production cross section measurement with the ATLAS experiment at the Large Hadron Collider in the CERN laboratory.

Top quark pair production cross section with the ATLAS experiment

This document reviews the existing results of inclusive top quark pair production cross section measurements in proton-proton collisions at a center of mass energies of 7 and 8 TeV performed with the ATLAS detector at the Large Hadron Collider. These measurements cover the different analysis channels, single lepton, dilepton and all hadronic channel, as well as dedicated analysis for channels including tau leptons decaying hadronically. All measurements shown in this document are in good agreement with the Standard Model expectation.

Top quark physics with the CMS experiment

An overview of recent top quark measurements in proton-proton collisions at √ s = 7 and 8 Te V in data collected with the CMS experiment at the LHC, using a data sample collected during the years 2011 and 2012 is presented. Measurements of top quark pair production cross sections in several top quark final states are reported, as well as electroweak production of single top quarks in both t- and tW-channels. The mass of the top quark is estimated by different methods.

Measurement of the top quark pair production cross section with ATLAS in pp collisions at = 7 TeV in the single-lepton channel using semileptonic b decays

The cross section for top quark pair production in pp collisions at = 7 TeV is measured using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected requiring a single high transverse momentum isolated electron or muon, missing transverse momentum and jets. Semileptonic b decays are identified by a lower momentum muon close to a jet, leading to substantially different sources of systematic uncertainty compared with other measurements. With a data sample corresponding to 4.66 fb−1 of integrated luminosity, the top quark pair production cross section is measured to bein agreement with theoretical predictions based on perturbative QCD and with other measurements which used different techniques or decay channels.

Precision measurements in the top quark sector with the CMS experiment at the LHC

A review of the measurements of the tt̄ production cross section (inclusive and differential) performed by the CMS experiment at the LHC is given. The results are used to constrain the magnitude of most of the relevant systematics affecting precision measurements in the top quark sector. In addition from the determination of the top quark pair production cross section it is possible to determine the strong coupling constant as αS(mZ) = 0.1178+0.0046−0.0040 in agreement with the current world average. After the combination of several channels and techniques explored to measure the top quark mass in data, a precise determination of this quantity is made at CMS: mt = 173.4±0.4stat ± 0.9syst GeV. The measurement of the difference Δmt = mt − mt̄ is also presented.

Measurement of the [Formula: see text] production cross section in the tau + jets channel using the ATLAS detector.

A measurement of the top quark pair production cross section in the final state with a hadronically decaying tau lepton and jets is presented. The analysis is based on proton–proton collision data recorded by the ATLAS experiment at the LHC, with a centre-of-mass energy of 7 TeV. The data sample corresponds to an integrated luminosity of 1.67 fb−1. The cross section is measured to be sigma_{tbar{t}} = 194 pm18 (mbox{stat}.) pm46 (mbox{syst}.)~mbox{pb} and is in agreement with other measurements and with the Standard Model prediction.