Measurements of polarization and spin correlation and observation of entanglement in top quark pairs using lepton+jets events from proton-proton collisions at $\sqrt{s}$ = 13 TeV

Abstract

Measurements of the polarization and spin correlation in top quark pairs ($\mathrm{t}\bar{\mathrm{t}}$) are presented using events with a single electron or muon and jets in the final state. The measurements are based on proton-proton collision data from the LHC at $\sqrt{s}$ = 13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138 fb${}^{-1}$. All coefficients of the polarization vectors and the spin correlation matrix are extracted simultaneously by performing a binned likelihood fit to the data. The measurement is performed inclusively and in bins of additional observables, such as the mass of the $\mathrm{t}\bar{\mathrm{t}}$ system and the top quark scattering angle in the $\mathrm{t}\bar{\mathrm{t}}$ rest frame. The measured polarization and spin correlation are in agreement with the standard model. From the measured spin correlation, conclusions on the $\mathrm{t}\bar{\mathrm{t}}$ spin entanglement are drawn by applying the Peres-Horodecki criterion. The standard model predicts entangled spins for $\mathrm{t}\bar{\mathrm{t}}$ states at the production threshold and at high masses of the $\mathrm{t}\bar{\mathrm{t}}$ system. Entanglement is observed for the first time in events at high $\mathrm{t}\bar{\mathrm{t}}$ mass, where a large fraction of the $\mathrm{t}\bar{\mathrm{t}}$ decays are space-like separated, with an expected and observed significance of above 5 standard deviations.

arXiv commentReplaced with the published version. Added the journal reference and the DOI. All the figures and tables, including additional supplementary figures, can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-23-007 (CMS Public Pages)

References in corpus (64)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• The anti-k_t jet clustering algorithm
• An Introduction to PYTHIA 8.2
• Separability Criterion for Density Matrices
• FastJet user manual
• A New Method for Combining NLO QCD with Shower Monte Carlo Algorithms
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• Herwig++ Physics and Manual
• Parton distributions from high-precision collider data
• The total top quark pair production cross-section at hadron colliders through O(alpha_S^4)
• Separability criterion and inseparable mixed states with positive partial transposition
• Top++: a program for the calculation of the top-pair cross-section at hadron colliders
• A Positive-Weight Next-to-Leading-Order Monte Carlo for Heavy Flavour Hadroproduction
• Comparative study of various algorithms for the merging of parton showers and matrix elements in hadronic collisions
• Particle-flow reconstruction and global event description with the CMS detector
• The CMS trigger system
• Merging meets matching in MC@NLO
• -- HATHOR -- HAdronic Top and Heavy quarks crOss section calculatoR
• Matching matrix elements and shower evolution for top-quark production in hadronic collisions
• Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV
• Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV
• Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Extraction and validation of a new set of CMS PYTHIA8 tunes from underlying-event measurements
• Combining QCD and electroweak corrections to dilepton production in FEWZ
• Trial factors for the look elsewhere effect in high energy physics
• HATHOR for single top-quark production: Updated predictions and uncertainty estimates for single top-quark production in hadronic collisions
• String Formation Beyond Leading Colour
• Performance of the CMS Level-1 trigger in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Precision luminosity measurement in proton-proton collisions at $\sqrt{s}=$ 13 TeV in 2015 and 2016 at CMS
• Measurements of Inclusive W and Z Cross Sections in pp Collisions at sqrt(s)=7 TeV
• Electron and photon reconstruction and identification with the CMS experiment at the CERN LHC
• Performance of missing transverse momentum reconstruction in proton-proton collisions at $\sqrt{s}=$ 13 TeV using the CMS detector
• Measurement of the inelastic proton-proton cross section at $\sqrt{s}=$ 13 TeV
• Jet Flavour Classification Using DeepJet
• Measurement of the top quark mass using proton-proton data at sqrt(s) = 7 and 8 TeV
• Entanglement and quantum tomography with top quarks at the LHC
• QCD-corrected spin analysing power of jets in decays of polarized top quarks
• Effects of color reconnection on $t\bar{t}$ final states at the LHC
• Quantum information with top quarks in QCD
• Quantum tops at the LHC: from entanglement to Bell inequalities
• Spin Correlation Effects in Top Quark Pair Production at the LHC
• Observation of quantum entanglement in top-quark pairs using the ATLAS detector
• Improved tests of entanglement and Bell inequalities with LHC tops
• Observation of spin correlation in ttbar events from pp collisions at sqrt(s) = 7 TeV using the ATLAS detector
• Measurement of the top quark polarization and $\mathrm{t}\bar{\mathrm{t}}$ spin correlations using dilepton final states in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in pp Collisions at $\sqrt{s}=8$ TeV Using the ATLAS Detector
• Neural Networks for Full Phase-space Reweighting and Parameter Tuning
• Constraining new physics in entangled two-qubit systems: top-quark, tau-lepton and photon pairs
• Observation of quantum entanglement in top quark pair production in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Measurements of t t-bar spin correlations and top-quark polarization using dilepton final states in pp collisions at sqrt(s) = 7 TeV
• Evidence for spin correlation in ttbar production
• Next-to-next-to-leading order event generation for top-quark pair production
• A set of top quark spin correlation and polarization observables for the LHC: Standard Model predictions and new physics contributions
• Measurements of top-quark pair spin correlations in the $e\mu$ channel at $\sqrt{s}=13$ TeV using $pp$ collisions in the ATLAS detector
• A New Twist on Top Quark Spin Correlations
• When the Machine Chimes the Bell: Entanglement and Bell Inequalities with Boosted $t\bar{t}$
• Measurements of spin correlation in top-antitop quark events from proton-proton collisions at $\sqrt{s}=7$ TeV using the ATLAS detector
• Signatures of toponium formation in LHC run 2 data
• Measurements of t t-bar spin correlations and top quark polarization using dilepton final states in pp collisions at sqrt(s) = 8 TeV
• Measurement of spin correlations in t t-bar production using the matrix element method in the muon + jets final state in pp collisions at sqrt(s) = 8 TeV
• Top quark pair production near threshold: single/double distributions and mass determination
• Development and validation of HERWIG 7 tunes from CMS underlying-event measurements
• Measurement of spin correlation between top and antitop quarks produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV
• Polarization of top and chargino from stop decay in natural SUSY

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• Quantum Information meets High-Energy Physics: Input to the update of the European Strategy for Particle Physics
• Entanglement and Bell nonlocality with bottom-quark pairs at hadron colliders
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• TOP2024: an overview of experimental results
• Global $\Lambda$ hyperon polarization in low-energy heavy ion collisions -- a scenario without vorticity
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