Direct measurement of the mass difference between top and antitop quarks

Abstract

We present a measurement of the mass difference between t and tbar quarks observed in lepton_s16jets final states of ttbar events in 1 fb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider in ppbar collisions at sqrt(s)=1.96 TeV. The observed mass difference of 3.8_s16-3.7 GeV is consistent with the equality of t and tbar masses. This is the first direct measurement of a mass difference between a quark and its antiquark partner.