Probing the Higgs coupling to top quark in events with associated Higgs production with top-anti top pair and Higgs decay in two photons

We present here the results of the first search for the associated production of the Higgs boson with a $t \bar t$ pair, using the events where the Higgs boson decays to two photons in CMS. In order to maximize acceptance and sensitivity to such a small signal, we device two different sets of event selection criteria, optimized for leptonic and all-hadronic $t \bar t$ decays. In the absence of a significant excess over the background-only predictions, we proceed to set an observed (expected) 95\% confidence level upper limit on $t\bar t H$ production cross section times $BR(H \to \gamma \gamma)$ of 5.4 (5.3) times the Standard model value using $19.6 fb^{-1}$ of 8 TeV $pp$ collisions.