Search for Z' bosons decaying to top-antitop pairs in dilepton+jets final state in pp collisions at $\sqrt{s} = 7 TeV$

We present a search for narrow-width resonances decaying to top-antitop pairs using 5.0~$\rm{fb^{-1}}$ of data recorded by the CMS detector in $pp$ collisions at $\sqrt{s} = 7$~TeV. No significant deviations from the expected Standard Model background are observed. Upper limits, at 95\% confidence level, are presented for the production cross section times branching fraction for narrow-width resonances decaying to top-antitop pairs for resonance masses from 500 to 2000 GeV. The existence of a leptophobic topcolor particle $Z'$ of width $\Gamma_{Z'} = 0.012M_{Z'}$ with mass $M_{Z'} < 1.1$~TeV is excluded at $95\%$ C.L.