Search for $t\bar{t}$ resonances in semileptonic final states in pp collisions at $\sqrt{s}$ = 8 TeV

A search for the production of new heavy resonances produced in proton-proton collisions at the CMS Experiment that decay into top quark pairs is presented. Data was recorded at a center of mass energy of 8 TeV and corresponds to an integrated luminosity of 19.6 fb−1. Results are presented as a combination of two dedicated searches, the first optimized for kinematic threshold production of top quark pairs and the second optimized for a highly boosted regime. No excess is observed above the expected yield from SM processes. In the absence of any excess we set the following limits at 95% CL on the production of non-SM particles. Top color Z’ bosons with relative widths of 1.2% and 10% are excluded for masses below 2.10 TeV and 2.68 TeV. Upper limits of 1.94 pb and 0.029 pb are set on the production cross section times branching fraction for narrow resonances with masses of 0.5 TeV and 2 TeV. Likewise, limits of 1.71 pb and 0.045 pb are set for wide resonances with masses of 0.5 TeV and 2 TeV. In addition, Kaluza-Klein excitations of a gluon with masses below 2.54 TeV in the Randall-Sundrum model are excluded and an upper limit of 0.101 pb is set for a resonance mass of 2 TeV.