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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
Summary
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.
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.
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