Measurement of spin correlation between top and antitop quarks produced in ${p}$$\bar{p}$ at √s = 1.96 TeV

We present a measurement of the correlation between the spins of t and ¯t quarks produced in proton– antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the D0 de-tector that correspond to an integrated luminosity of 9.7 fb−1. The measured value of the correlation coefficient in the off-diagonal basis, Ooff = 0.89 ± 0.22 (stat + syst), is in agreement with the standard model prediction, and represents evidence for a top–antitop quark spin correlation difference from zero at a level of 4.2 standard deviations.