30 Aralık 2024 Dergi makalesi Açık Erişim

CERN İşbirliği

Citation Style Language JSON

{
  "DOI": "10.1103/PhysRevD.110.112016", 
  "abstract": "<p>Measurements of the polarization and spin correlation in top quark pairs ($t\\overline{t}$) 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 $\\sqrt{s}=13\\text{}\\text{}\\mathrm{TeV}$ collected by the CMS experiment, corresponding to an integrated luminosity of $138\\text{}\\text{}{\\mathrm{fb}}^{-1}$. 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 $t\\overline{t}$ system and the top quark scattering angle in the $t\\overline{t}$ rest frame. The measured polarization and spin correlation are in agreement with the standard model. From the measured spin correlation, conclusions on the $t\\overline{t}$ spin entanglement are drawn by applying the Peres-Horodecki criterion. The standard model predicts entangled spins for $t\\overline{t}$ states at the production threshold and at high masses of the $t\\overline{t}$ system. Entanglement is observed for the first time in events at high $t\\overline{t}$ mass, where a large fraction of the $t\\overline{t}$ decays are spacelike separated, with an expected and observed significance of above 5 standard deviations.</p>", 
  "author": [
    {
      "family": "CERN \u0130\u015fbirli\u011fi"
    }
  ], 
  "container_title": "Physical Review D", 
  "id": "274467", 
  "issue": "11", 
  "issued": {
    "date-parts": [
      [
        2024, 
        12, 
        30
      ]
    ]
  }, 
  "title": "Measurements of polarization and spin correlation and observation of entanglement in top quark pairs using $\\mathrm{lepton}+\\text{jets}$ events from proton-proton collisions at $\\sqrt{s}=13\\text{}\\text{}\\mathrm{TeV}$", 
  "type": "article-journal", 
  "volume": "110"
}