Search for Z′ resonances decaying to tt̅ in dilepton+jets final states in pp collisions at √s=7 TeV

A search for resonances decaying to top quark-antiquark pairs is performed using a dilepton+jets data sample recorded by the CMS experiment at the LHC in pp collisions at √s=7  TeV corresponding to an integrated luminosity of 5.0  fb-1. No significant deviations from the standard model background are observed. Upper limits are presented for the production cross section times branching fraction of top quark-antiquark resonances for masses from 750 to 3000 GeV. In particular, the existence of a leptophobic topcolor particle Z′ is excluded at the 95% confidence level for resonance masses MZ′<1.3  TeV for ΓZ′=0.012MZ′, and M<1.9  TeV for ΓZ′=0.10MZ′.