Hamburg 2016 – scientific programme

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T: Fachverband Teilchenphysik

T 15: Top Quark I (Ladungsasymmetrie, Spin)

T 15.5: Talk

Monday, February 29, 2016, 12:00–12:15, VMP9 HS

Measurement of Spin Correlations in tt Systems in the muon+jets Channel using a Matrix Element Method with the CMS Detector at the LHC — •Kelly Beernaert — Deutsches Elektronen-Synchrotron

The spin correlation strength in top-quark pair production is measured and the consistency of the result with the standard model (SM) prediction is tested. In the data, produced in pp–collisions at a centre-of-mass energy of 8 TeV and collected by the CMS detector corresponding to an integrated luminosity of 19.7  fb⁻¹, top-quark pair events with one muon and jets in the final state are selected. The data are compared with the expectation for the spin correlation predicted by the SM and with the expectation of no correlation. Using a template fit method, the fraction of events that show SM spin correlations is measured to be 0.72 ± 0.08 (stat)  _− 0.13^+ 0.15 (syst), representing the most precise measurement of this quantity in the lepton+jets final state to date.