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Setting Limits on Supersymmetry Using Simplified Models
07:46

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Published on: November 15, 2013

Evidence for spin correlation in t ̅t production.

V M Abazov1, B Abbott, B S Acharya

  • 1Joint Institute for Nuclear Research, Dubna, Russia.

Physical Review Letters
|March 10, 2012
PubMed
Summary
This summary is machine-generated.

This study measured top quark spin correlation in proton-antiproton collisions. Results agree with the Standard Model and provide evidence for spin correlation in top quark-antiquark events.

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Area of Science:

  • Particle Physics
  • High-Energy Physics
  • Quantum Chromodynamics

Background:

  • Top quarks are the heaviest known elementary particles.
  • Understanding top quark properties is crucial for testing the Standard Model.
  • Top quark spin correlation provides sensitive probes of production mechanisms.

Purpose of the Study:

  • Measure the ratio of correlated top quark-antiquark (ttbar) spin events to total ttbar events.
  • Investigate the presence of spin correlation in ttbar production.
  • Compare experimental results with Standard Model predictions.

Main Methods:

  • Utilized a matrix-element-based approach.
  • Analyzed 729 ttbar candidate events in single-lepton final states (electron or muon) with at least four jets.
  • Data collected from proton-antiproton collisions at the Fermilab Tevatron (center-of-mass energy √s=1.96 TeV) with an integrated luminosity of 5.3 fb⁻¹.

Main Results:

  • The measured ratio 'f' of correlated spin events is consistent with Standard Model predictions.
  • Combined analysis with dileptonic final states yields agreement with the Standard Model.
  • Evidence for ttbar spin correlation observed with a significance exceeding 3 standard deviations.

Conclusions:

  • The study confirms the presence of top quark spin correlation.
  • Measurements align with the Standard Model, reinforcing its validity.
  • Provides valuable data for future precision measurements in particle physics.