Measurement of the W boson polarization in top quark decays with the ATLAS detector

Abstract

This paper presents measurements of the polarization of W bosons in top quark decays, derived from ttbar events with missing transverse momentum, one charged lepton and at least four jets, or two charged leptons and at least two jets. Data from pp collisions at a centre-of-mass energy of 7 TeV were collected with the ATLAS experiment at the LHC and correspond to an integrated luminosity of 1.04 fb^-1. The measured fractions of longitudinally, left- and right-handed polarization are F_0=0.67+/-0.07, F_L=0.32+/-0.04 and F_R=0.01+/-0.05, in agreement with the Standard Model predictions. As the polarization of the W bosons in top quark decays is sensitive to the Wtb vertex Lorentz structure and couplings, the measurements were used to set limits on anomalous contributions to the Wtb couplings.

arXiv comment24 pages plus author list (47 pages total), 7 figures, 4 tables, submitted to JHEP

References in corpus (52)

• PYTHIA 6.4 Physics and Manual
• PYTHIA 6.2 Physics and Manual
• The anti-k_t jet clustering algorithm
• New Generation of Parton Distributions with Uncertainties from Global QCD Analysis
• A New Method for Combining NLO QCD with Shower Monte Carlo Algorithms
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• Event generation with SHERPA 1.1
• HERWIG 6.5: an event generator for Hadron Emission Reactions With Interfering Gluons (including supersymmetric processes)
• ALPGEN, a generator for hard multiparton processes in hadronic collisions
• Matching NLO QCD computations and parton shower simulations
• The ATLAS Simulation Infrastructure
• Observation of Top Quark Production in Pbar-P Collisions
• Observation of the Top Quark
• Implications of CTEQ global analysis for collider observables
• Tuning Monte Carlo Generators: The Perugia Tunes
• -- HATHOR -- HAdronic Top and Heavy quarks crOss section calculatoR
• Single-top hadroproduction in association with a W boson
• Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics
• Matching NLO QCD and parton showers in heavy flavour production
• Multiparton Interactions in Photoproduction at HERA
• Improved luminosity determination in pp collisions at sqrt(s) = 7 TeV using the ATLAS detector at the LHC
• Jet energy measurement with the ATLAS detector in proton-proton collisions at sqrt(s) = 7 TeV
• Electron performance measurements with the ATLAS detector using the 2010 LHC proton-proton collision data
• A minimal set of top anomalous couplings
• Theoretical status and prospects for top-quark pair production at hadron colliders
• Luminosity Determination in pp Collisions at sqrt(s)=7 TeV Using the ATLAS Detector at the LHC
• BAT - The Bayesian Analysis Toolkit
• Systematic event generator tuning for the LHC
• Measurement of the top quark-pair production cross section with ATLAS in pp collisions at $\sqrt{s}=7\TeV$
• Single-top production in MC@NLO
• Effective-Field-Theory Approach to Top-Quark Production and Decay
• A minimal set of top-Higgs anomalous couplings
• Single top quark production at LHC with anomalous Wtb couplings
• Helicity fractions of W bosons from top quark decays at NNLO in QCD
• Combination of CDF and DO results on the mass of the top quark using up to 5.8~fb-1 of data
• Probing anomalous Wtb couplings in top pair decays
• W polarisation beyond helicity fractions in top quark decays
• The Monte Carlo Event Generator AcerMC 1.0 with Interfaces to PYTHIA 6.2 and HERWIG 6.3
• Anomalous Wtb coupling effects in the weak radiative B-meson decay
• Measurement of the cross section for top-quark pair production in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector using final states with two high-pt leptons
• Collider aspects of flavour physics at high Q
• Electroweak and finite width corrections to top quark decays into transverse and longitudinal $W$-bosons
• Probing anomalous tWb interactions with rare B decays
• Constraints on Non-standard Top Quark Couplings
• Measurement of the W boson helicity in top quark decays using 5.4 fb^-1 of ppbar collision data
• Precise determination of the Wtb couplings at LHC
• Combination of searches for anomalous top quark couplings with 5.4 fb^-1 of ppbar collisions
• Measurement of W-Boson Polarization in Top-quark Decay in ppbar Collisions at sqrt(s) = 1.96 TeV
• Interplay of t --> b W Decay and B_q Meson Mixing in Minimal Flavor Violating Models
• Search for anomalous Wtb couplings in single top quark production in ppbar collisions at sqrt(s) = 1.96 TeV
• Tevatron-for-LHC Report of the QCD Working Group
• Effective operators in top physics

Cited by in corpus (72)

• A handbook of vector-like quarks: mixing and single production
• Galactic Searches for Dark Matter
• Top-Quark Decay at Next-to-Next-to-Leading Order in QCD
• O new physics, where art thou? A global search in the top sector
• Constraining the top-Higgs sector of the Standard Model Effective Field Theory
• Right-handed charged currents in the era of the Large Hadron Collider
• Constraining top quark effective theory in the LHC Run II era
• Measurement of $W^{\pm }Z$ production cross sections and gauge boson polarisation in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Is there room for CP violation in the top-Higgs sector?
• Light Higgs and Vector-like Quarks without Prejudice
• Electroweak gauge boson polarisation at the LHC
• Search for anomalous Wtb couplings and flavour-changing neutral currents in t-channel single top quark production in pp collisions at sqrt(s) = 7 and 8 TeV
• A New Twist on Top Quark Spin Correlations
• Global and optimal probes for the top-quark effective field theory at future lepton colliders
• Search for supersymmetry in pp collisions at sqrt(s) = 7 TeV in events with a single lepton, jets, and missing transverse momentum
• Alternatives to an Elementary Higgs
• Breaking down the entire W boson spin observables from its decay
• Measurement of the W boson helicity fractions in the decays of top quark pairs to lepton + jets final states produced in pp collisions at sqrt(s) = 8 TeV
• Electromagnetic dipole moments of the top quark
• Measurement of the $W$ boson polarisation in $t\bar{t}$ events from $pp$ collisions at $\sqrt{s}$ = 8 TeV in the lepton+jets channel with ATLAS
• Measurement of the W-boson helicity in top-quark decays from ttbar production in lepton+jets events in pp collisions at sqrt(s) = 7 TeV
• Measurement of the W boson helicity in events with a single reconstructed top quark in pp collisions at sqrt(s) = 8 TeV
• Top effective operators at the ILC
• New directions for top quark polarization in the $t$-channel process
• Search for anomalous couplings in the $Wtb$ vertex from the measurement of double differential angular decay rates of single top quarks produced in the $t$-channel with the ATLAS detector
• Top-Quark Physics: Status and Prospects
• Studying the $Wtb$ vertex structure using recent LHC results
• Combination of the W boson polarization measurements in top quark decays using ATLAS and CMS data at $\sqrt{s}=$ 8 TeV
• Search for supersymmetry in events with b-quark jets and missing transverse energy in pp collisions at 7 TeV
• New limits on anomalous contributions to the $Wtb$ vertex
• Anomalous Top Couplings at Hadron Colliders Revisited
• Model-independent measurement of the top quark polarisation
• Measurement of W-Boson Polarization in Top-quark Decay using the Full CDF Run II Data Set
• Probing anomalous $Wtb$ couplings at the LHC in single top quark production through $t$-channel
• The Top Quark
• Top-quark physics at the Large Hadron Collider
• Analysis of the $Wtb$ vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the $t$-channel at $\sqrt{s}$ = 8 TeV with the ATLAS detector
• Correlating uncertainties in global analyses within SMEFT matters
• Observation of gauge boson joint-polarisation states in $W^{\pm }Z$ production from $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Top quark anomalous tensor couplings in the two-Higgs-doublet models
• Higgs Bosons from Top Quark Decays
• $tbW$ Anomalous Couplings in the Two Higgs Doublet Model
• Light Top Squark in Precision Top Quark Sample
• Pseudoscalar couplings in $t\bar{t}H$ production at NLO+NLL accuracy
• On the Trail of the Higgs Boson
• Precise probing and discrimination of third-generation scalar leptoquarks
• Measuring the polarization of boosted, hadronic $W$ bosons with jet substructure observables
• Search for supersymmetry in events with one lepton and multiple jets exploiting the angular correlation between the lepton and the missing transverse momentum in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Top quark precision physics at the International Linear Collider
• Electroweak Top Couplings, Partial Compositeness and Top Partner Searches
• Lepton Polarization Asymmetries of $H\to \gamma {\tau }^{+}{\tau }^{-}$ Decays in Standard Model
• Boosted Top Quarks and Jet Structure
• Anomalous top charged-current contact interactions in single top production at the LHC
• Properties of the Top Quark
• Top Couplings: pre-Snowmass Energy Frontier 2013 Overview
• The right top coupling in the aligned two-Higgs-doublet model
• W boson polarization measurement in the ttbar dilepton channel using the CDF II Detector
• Single Top Quark Production with and without a Higgs Boson
• Reconstruction of top quark pair dilepton decays in electron-positron collisions
• A $W^{\pm }$ polarization analyzer from Deep Neural Networks
• Staying on Top of SMEFT-Likelihood Analyses
• Top quark effective couplings from top-pair tagged photoproduction in $p{e}^{-}$ collisions
• $W^{+}{W}^{-}H$ production through bottom quarks fusion at hadron colliders
• Top quark physics in the Large Hadron Collider era
• New physics in top decay
• Di-vector boson production in association with a Higgs boson at hadron colliders
• Recent results on Top quark Physics with the ATLAS and CMS experiments
• A Global Analysis of the Standard Model Effective Field Theory in the Production and Decay Channels of a Single Top Quark
• Study of Top Effective Operators at the ILC
• Top Decays in the Standard Model and Beyond
• Jet Substructure and Multivariate Analysis Aid in Polarization Study of Boosted, Hadronic $W$ Fatjet at the LHC
• Searches for new physics in top decays at the LHC