Measurements of Spin Correlation in ttbar Events at D0

TL;DR

This paper reports on two measurements of spin correlation in top-antitop quark pairs at the Tevatron, demonstrating the first analysis capable of excluding the no-correlation hypothesis.

Contribution

It introduces two novel methods for measuring spin correlation in ttbar events, with one method providing the first sufficient analysis to exclude no-correlation.

Findings

First measurement to exclude no-correlation hypothesis

Uses 5.4 fb^-1 of Tevatron data

Employs dilepton final state analysis

Abstract

Two recent measurements by the D0 Collaboration of spin correlation in ttbar production using 5.4 fb^-1 of Tevatron ppbar collider data are presented. Both rely on the dilepton final state of ttbar. One measurement relies on full reconstruction of the top quark kinematics, and the other makes use of leading-order matrix elements to characterize the kinematics. The latter measurement is the first ever to have sufficient analyzing power to exclude the no-correlation hypothesis.