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Article
Report number arXiv:2409.11067 ; CMS-TOP-23-007 ; CERN-EP-2024-231 ; CMS-TOP-23-007-003
Title Measurements of polarization and spin correlation and observation of entanglement in top quark pairs using lepton+jets events from proton-proton collisions at s= 13 TeV
Author(s) CMS Collaboration  Show all 2403 authors
Corporate Author(s) CMS Collaboration
Publication 2024-12-01
Imprint 17 Sep 2024
Number of pages 69
Note Submitted to Physical Review D. All figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-23-007 (CMS Public Pages)
In: Phys. Rev. D 110 (2024) 112016
DOI 10.1103/PhysRevD.110.112016
Subject category Particle Physics - Experiment
Accelerator/Facility, Experiment CERN LHC ; CMS
Free keywords top physics
Abstract Measurements of the polarization and spin correlation in top quark pairs (t¯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 s= 13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138 fb1. 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 t¯t system and the top quark scattering angle in the t¯t rest frame. The measured polarization and spin correlation are in agreement with the standard model. From the measured spin correlation, conclusions on the t¯t spin entanglement are drawn by applying the Peres-Horodecki criterion. The standard model predicts entangled spins for t¯t states at the production threshold and at high masses of the t¯t system. Entanglement is observed for the first time in events at high t¯t mass, where a large fraction of the t¯t decays are space-like separated, with an expected and observed significance of above 5 standard deviations.
Related document supersedes: CMS-PAS-TOP-23-007
Copyright/License Preprint: © 2024-2025 CERN (License: CC-BY-4.0)



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Email contact: cms-publication-committee-chair@cern.ch


 Record created 2024-09-17, last modified 2025-01-07


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