Spin Correlation in tt-bar Production from pp-bar Collisions at sqrt(s)=1.8 TeV

TL;DR

This study investigates the spin correlation in top-antitop quark pairs produced in proton-antiproton collisions at 1.8 TeV, comparing experimental results with Standard Model predictions.

Contribution

First measurement of spin correlation in tt-bar production at Tevatron energies, testing Standard Model predictions with limited event data.

Findings

Measured correlation coefficient k > -0.25 at 68% CL

Results are consistent with SM prediction of k=0.88

Supports the transmission of spin information from production to decay

Abstract

The D0 collaboration has performed a study of spin correlation in tt-bar production for the process tt-bar to bb-bar W^+W^-, where the W bosons decay to e-nu or mu-nu. A sample of six events was collected during an exposure of the D0 detector to an integrated luminosity of approximately 125 pb^-1 of sqrt{s}=1.8 TeV pp-bar collisions. The standard model (SM) predicts that the short lifetime of the top quark ensures the transmission of any spin information at production to the tt-bar decay products. The degree of spin correlation is characterized by a correlation coefficient k. We find that k>-0.25 at the 68% confidence level, in agreement with the SM prediction of k=0.88.