Search for associated production of Higgs boson with top anti-top pair with Higgs decaying to tau pair.

A precise measurement of the ttH production rate provides a direct sensitivity to the Yukawa coupling of the top quark to the Higgs boson. The large mass of the top quark might be a hint of a special role in the mechanism for electroweak symmetry breaking. It is therefore of great interest to improve upon the precision of the present measurements.
 
The ttH with H →ττ analysis has been divided into several exclusive categories depending on the number of reconstructed leptons and τ lepton decay products. In this seminar, result will be presented on the search for ttH production in events   containing one lepton and one hadronically decaying tau in the final state with 2017 data samples with integrated luminosity 41.53 fb^-1. Selection of ttH events, main background contributions, machine learning technique based on boosted decision trees to differentiate signal and background processes and expected upper limit on the ttH production cross section will be discussed in the presentation.