Search for Z ' resonances decaying to t-tbar in dilepton plus jets final states in pp collisions at root 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 root 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 M-Z' < 1.3 TeV for Gamma(Z') = 0.012M(Z'), and M < 1.9 TeV for Gamma(Z') = 0.10M(Z').