Search for same-sign top-quark pair production at √s=7 TeV and limits on flavour changing neutral currents in the top sector.

Abstract

An inclusive search for same-sign top-quark pair production in pp collisions at √s = 7TeV is performed using a data sample recorded with the CMS detector in 2010, corresponding to an integrated luminosity of 35 pb-1. This analysis is motivated by recent studies of pp ̅ →tt ̅ reporting mass-dependent forward-backward asymmetries larger than expected from the standard model. These asymmetries could be due to Flavor Changing Neutral Currents (FCNC) in the top sector induced by t-channel exchange of a massive neutral vector boson (Z’). Models with such a Z' also predict enhancement of same-sign top-pair production in pp or pp ̅ collisions. Limits are set as a function of the Z’ mass and its couplings to u and t quarks. These limits disfavour the FCNC interpretation of the Tevatron results.