Research Papers in Physics and Astronomy


Date of this Version



Published in Physical Review Letters 103, 132001 (2009). Copyright © 2009 The American Physical Society. Used by permission.


We present a measurement of the mass difference between t and t quarks in lepton + jets final states of tt events in 1 fb-1 of data collected with the D0 detector from Fermilab Tevatron Collider pp collisions at √s = 1.96 TeV. The measured mass difference of 3.8 ± 3.7 GeV is consistent with the equality of t and t masses. This is the first direct measurement of a mass difference between a quark and its antiquark partner.

Included in

Physics Commons