Measurements Of Top Quark Properties Research Articles

Top quark physics with the ATLAS detector: recent highlights

The top quark is the heaviest known fundamental particle. As it is the only quark that decays without hadronisation, it provides the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider (LHC). This article will present highlights of a few recent precision measurements of the top quark using 13 TeV collision data with the ATLAS experiment. Top-quark pair and single top production cross sections, including differential distributions and production in association with bosons, will be presented alongside top quark properties measurements. Measurements of the top-quark mass and searches for rare top decays are also presented.

Highlights of top-quark properties measurements at the ATLAS experiment

The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, this gives a unique opportunity to probe the properties of pseudo-bare quarks. This proceeding focuses on a few recent precision measurements of top-quark properties in top-quark pair events by the ATLAS Collaboration using LHC proton-proton collision data. Among these is the measurement of color flow and measurement of spin correlations in tt‾ pair production. Measurements of the top-quark mass and searches for rare top-quark decays are also presented.

Top quark properties and mass measurements with the ATLAS detector

Highlights on recent measurements of top quark properties in ATLAS, using pp collision data at s = 8 TeV and 13 TeV, are presented. The measurements of the top quark polarization and spin correlation coefficients, the W boson helicity fractions, the structure of the Wtb vertex, the associated production of a tt‾ pair with a vector boson or a photon, and the top quark mass are all in agreement with the Standard Model expectations.

Top quark measurements in the CMS experiment

Experimental results on top-quark physics obtained at the CMS experiment are reported based on the data recorded at centre-of-mass energy up to 13 TeV. Inclusive and differential cross sections for both top-quark pair and single top-quark production are presented, as well as measurements of top-quark properties in production and decay, and searches for anomalous couplings. The presented measurements test theoretical predictions, including recent perturbative QCD calculations, provide constraints of fundamental standard model parameters, and set limits on physics beyond the standard model.

Top quark measurements at ATLAS

The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, it allows us to probe the properties of bare quarks at the Large Hadron Collider. Highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data will be presented: top-quark pair and single top production cross sections including differential distributions will be presented alongside measurements of top-quark properties, including results using boosted top quarks, probe our understanding of top-quark production in the TeV regime. Measurements of the top-quark mass and searches for rare top quark decays are also presented.

Results on top-quark physics and top-quark-like signatures by CMS

This report reviews the results obtained by the CMS Collaboration on top quark physics, focusing on the latest ones based on p–p collisions provided by the LHC at during Run II. It covers measurements of single-top, top quark pairs and associated productions as well as measurements of top quark properties. Finally several beyond the standard model searches involving top quark in the final states are presented, such as searches for supersymmetry in the third generation, heavy resonances decaying into a top quark pair, or dark matter produced in association to a single-top or a top quark pair.

Top Quark Properties Measurements with the ATLAS Experiment

Results on recent measurements of top quark properties with the ATLAS experiment at the European Laboratory, CERN, are shown. The measurements are performed using the full data set recorded during the LHC Run-I. The full data set consists of a collected integrated luminosities ∫Tdt of 4.6 fb-1 recorded at a proton-proton collision energy of √s = 7 TeV and 20.3 fb-1 collected at 8 TeV. The mentioned top quark properties include: spin correlation, charge asymmetry, W-boson polarization, color flow, top mass and top width in events with a top and anti-top quark pair (tt). An introduction to the LHC and the ATLAS detector is included and latest main results from this experiment. The contents include the current world benchmark results for the different properties and plans for future measurements during the ongoing LHC Run-II.

Measurements of top quark properties in top pair production and decay at the LHC using the CMS detector

Measurements are presented of the properties of top quarks in pair production and decay from proton-proton collisions at the LHC. The data were collected at centre-of-mass energies of 7 and 8 TeV by the CMS experiment during the years 2011 and 2012. The top quark-antiquark charge asymmetry is measured using the difference of the absolute rapidities of the reconstructed top and anti-top kinematics, as well as from distributions of the top quark decay products. The measurements are performed in the decay channels of the tt‾ pair into both one and two leptons in the final state. The polarization of top quarks and top pair spin correlations are measured from the angular distributions of top quark decay products. The W-boson helicity fractions and angular asymmetries are extracted and limits on anomalous contributions to the Wtb vertex are determined. The flavor content in top-quark pair events is measured using the fraction of top quarks decaying into a W-boson and a b-quark relative to all top quark decays, R=B(t→Wb)/B(t→Wq), and the result is used to determine the CKM matrix element Vtb as well as the width of the top quark resonance. All of the results are found to be in good agreement with standard model predictions.

Results on top physics by CMS

In this talk, several measurements in the top-quark sector are presented, ob- tained from the CMS data collected in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV. The production cross section of tpairs is measured in several decay channels: lep- ton+jets, dilepton and fully hadronic channels, including channels with the τ lepton. Dif- ferential cross sections are measured and are provided as a function of various kinematic observables; the results are compared with precise theory calculations. Measurements of several top-quark properties are reported, including the top pair charge asymmetry, the W helicity in top decays, the measurement of the production of t¯ t pairs with W, Z, gamma, the spin correlation and the search for anomalous couplings and flavor-changing neutral currents. The results are compared with predictions from the standard model as well as new physics models. The cross sections for the electroweak production of single top quarks are measured in the t-channel and in association with W-bosons. Measurements of top-quark properties in single top quark production are also presented. The results include the W-helicity in top quark decays and the searches for the s-channel production and anomalous couplings.

Measurements of top quark properties with the ATLAS detector

Measurements of top quark properties with the ATLAS detector

Measurements of top quark properties with the ATLAS detector

A selection of recent top quark measurements performed with the ATLAS detector is presented here, with data taken in 2011 and 2012 at centre-of-mass energies of 7 TeV and 8 TeV, respectively. The analyses cover the determination of the top pole mass by a cross-section measurement, the top/anti-top quark mass difference, the spin correlation and the charge asymmetry. No hints for physics beyond the Standard Model have been found but a great reduction of uncertainties compared to former results was achieved.

Top-quark mass at hadron colliders

Top-quarks can be produced abundantly at hadron colliders like the Tevatron at Fermilab and the Large Hadron Collider at CERN, and a variety of measurements of top-quark properties have been gathered in the recent years from four experiments: CDF and D0 at the Tevatron and ATLAS and CMS at the Large Hadron Collider. In this review the most recent results on the measurement of the top-quark mass by the four different collaborations, with various techniques and considering different topologies, are reported.

Measurement of top quark properties at the Tevatron and LHC

Almost two decades after its discovery at Fermilab's Tevatron collider experiments, the top quark is still under the spotlight due to its connections to some of the most interesting puzzles in the Standard Model. The Tevatron has been shut down two years ago, yet some interesting results are coming out of the CDF and D0 collaborations. The LHC collider at CERN produced two orders of magnitude more top quarks than Tevatron's, thus giving birth to a new era for top quark physics. While the LHC is also down at the time of this writing, many top quark physics results are being extracted out of the 7 TeV and 8 TeV proton proton collisions by the ATLAS and CMS collaborations, and many more are expected to appear before the LHC will be turned on again sometime in 2015. These proceedings cover a selection of recent results produced by the Tevatron and LHC experiments.

Measurements of top-quark properties at the Tevatron

Recent measurements of top-quark properties at the Tevatron are presented. CDF uses data corresponding up to 9.0 fb−1 to measure the ratio R of the branching fractions , the branching fraction for top-quarks decaying into τ leptons and the cross section for the production of an additional γ in tt̄ production. The results from all these measurements agree well with their respective Standard Model expectation. DØ uses 5.3 fb−1 of data to measure the tt̄ cross section as a function of the time. A time dependency would imply Lorentz invariance violation as implemented by the Standard Model extension. No time dependency is observed and DØ sets first limits in the top-quark sector for Lorentz invariance violation. DØ also determines indirectly the top quark width using the results of earlier measurements at DØ. The measured top quark width is in agreement with the SM expectation and does not show any hints for new physics contributions.

Measurement of the Top Quark Properties with the ATLAS Detector

The top quark, discovered at the Tevatron in 1995 by the CDF and DO collaborations, is the heaviest known particle. The measurement of its properties are of interest to the under- standing of the strong and weak forces, as well as searches for physics beyond the Standard Model. Several measurements of top quark properties are presented using data collected at the ATLAS experiment located at the Large Hadron Collider (LHC) at √ s = 7 TeV centre-of-mass energy. The measurements include top quark polarisation, spin correlation, production of tand t¯γ ,a s well as top mass and Wtbvertex measurements in both the lepton + jets and dilepton channel.

Single top quark production with CMS

Measurements of single top quark production performed using the CMS experiment [1] data collected in 2011 at centre-of-mass energies of 7 TeV and in 2012 at 8 TeV, are presented. The cross sections for the electroweak production of single top quarks in the t-channel and in association with W-bosons is measured and the results are used to place constraints on the CKM matrix element Vtb . Measurements of top quark properties in single top quark production are also presented. The results include the measurement of the charge ratio in the single top t-channel.

RECENT STUDIES OF TOP QUARK PROPERTIES AND DECAYS AT HADRON COLLIDERS

The top quark is the heaviest known elementary particle. Observed for the first time in 1995 at the Tevatron by the CDF and D0 experiments, it has become object of several studies aimed to fully characterize its properties and decays. Precise determinations of top quark characteristics verify the internal consistency of the Standard Model (SM) and are sensitive to new physics phenomena. With the advent of the large top quark production rates generated at the LHC, top quark studies have reached unprecedented statistical precision. This review summarizes the recent measurements of top quark properties and studies of its decays performed at the LHC and Tevatron.

Top quark properties

Since the top quark was discovered at Tevatron in 1995, many top quark properties have been measured. However, the top quark is still interesting due to unique features which originate from the extremely heavy mass, and providing various test grounds on the Standard Model as well as searches for a new physics. Though the measurements of the top quark had been performed only at Tevatron so far, LHC is now ready for measurements with more top quarks than Tevatron. In this article, recent measurements of top quark properties from Tevatron (CDF and DO) as well as LHC (ATLAS and CMS) are presented.

QCD and Top physics studies in proton-proton collisions at 7 TeV centre-of-mass energy with the ATLAS detector

Beginning from 2010, ATLAS collected proton-proton collision data at a centre-of-mass energy of 7 TeV, accumulating by the Spring of 2011 an integrated luminosity of ∼200 pb−1. The high energy gives the possibility to produce a sizeable amount of top quarks, allowing for measurements of top quark properties and searches for heavy exotic resonances decaying to top-antitop pairs. Measurements of jet cross-sections confirm the predictions of perturbative QCD at the high energy of the Large Hadron Collider.

Top Physics at CDF

Top quark physics is one of the most important successes of the concluding Tevatron program. In this paper, a summary of the most recent measurements of top quark properties, including the mass and its 2011 average, will be presented. Some common techniques and discussion of major systematic uncertainties for top measurements will also be presented.