CERN Accelerating science

Thesis
Report number	2017SACLS205 ; CERN-THESIS-2017-371
Title	Etude de la production de boson de Higgs en association avec une paire de quarks top-antitop dans l’expérience ATLAS
Translation of title	Study of the Higgs boson produced in association with a top-antitop quark pair in the ATLAS experiment
Author(s)	Le Quilleuc, Eloi (IRFU, Saclay, DPP)
Publication	152.
Thesis note	PhD : U. Paris-Saclay : 2017
Note	presented 28 Sep 2017
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Keywords	Particles ; ATLAS ; Higgs boson ; top quark ; LHC ; Standard Model
Abstract	Since its discovery, the Higgs boson has been a source of many studies at the LHC. It is particularly important to understand how the boson interacts with the elementary particles of the Standard Model. This thesis, within the ATLAS experiment, takes part in the study of the Higgs boson, with a contribution to the measurement of the coupling strength between the Higgs boson and the top quark. It also includes a study on the identification of jets coming from the hadronization of a bottom quark, called b-jets, produced in proton collisions. The coupling strength is measured by analyzing proton collisions that produce a top-antitop quark pair in association with a Higgs boson, called $t\bar{t}H$ events, as these events involve an interaction between the top quark and the Higgs boson. The study of this thesis relates more particularly to an analysis of boosted ttH¯ events, which produce top quarks and Higgs bosons at high momentum, and with a Higgs boson decaying into a pair of bottom-antibottom quark ($H \to b\bar{b}$) and a top-antitop quark pair decaying by emitting a single electron or muon. With four bottom quarks produced in these targeted events, the identification of b-jets plays a vital role in this analysis. The second study that was conducted deals with the development of techniques and algorithms used by the ATLAS collaboration to identify the b-jets. The analyzed data come from proton collisions provided by the LHC at 13 TeV energy in the center of mass, recorded from 2015 to 2016 by the ATLAS detector.

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