Study of ttH production with H->bb in ATLAS at the HL-LHC

António Manuel Mendes Jacques da Costa

Key information

Authors:

António Manuel Mendes Jacques da Costa (António Manuel Mendes Jacques da Costa)

Supervisors:

José Ricardo Morais Silva Gonçalo; Pedro Morais Salgueiro Teixeira de Abreu (Pedro Morais Salgueiro Teixeira de Abreu)

Published in

11/12/2018

Abstract

A feasibility study for an experimental analysis searching for ttH(H->bb) production at the LHC and its high luminosity phase is presented in this thesis. Unlike search strategies currently being used in experimental collaborations, the present analysis exploits jet substructure techniques and focuses on the reconstruction of boosted Higgs bosons, to obtain sensitivity to the signal in a simple cut-based analysis. The tt+jets background may be constrained in the proposed analysis through a control region with very small signal contamination. Using this analysis strategy, the ttH(H->bb) process could be observed at the LHC, in the semi-leptonic channel alone, with a significance of 5.41+/-0.12 for an integrated luminosity of 300/fb. For the same integrated luminosity, in the High Luminosity LHC scenario with an upgraded detector, a significance of 6.13+/-0.11 may be obtained. The top Yukawa coupling could be measured with a 35% uncertainty using an integrated luminosity of 300/fb of LHC data and of 17% at the HL-LHC scenario with an integrated luminosity of 3000/fb. In the same luminosity scenarios, the signal strength is equally expected to have a 18% and 5% uncertainty, respectively. It was also found that re-clustered jets may be used without loss of efficiency.