Thesis

Measurement of the Yukawa couplings of top quarks to Higgs boson at the LHC

• Call:

  IDPASC Portugal - PHD Programme 2016

• Academic Year:

  2016 / 2017

• Domains:

  Theoretical Particle Physics | Experimental Particle Physics

• Supervisor:

  Antonio Onofre

• Co-Supervisor:

  Ricardo Gonçalo

• Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  The discovery, July 2012, of the Higgs boson by the ATLAS and CMS collaborations at the Large Hadron Collider (LHC), at CERN, was a remarkable milestone for the understanding of the Universe and the Standard Model of Particle Physics. Following discovery, the need of understanding, with high precision the properties of the newly discovered boson and, in particular, the nature of its couplings to fundamental particles is of utmost importance. The large set of data expected to be collected by the ATLAS experiment during the Run 2 of the LHC at a centre-of-mass energy of 13 TeV, opens up the possibility of studying the structure of the Higgs boson and top quarks vertex and the Yukawa coupling associated to it, with unprecedent precision. In this thesis proposal, the measurement of the structure of the top-Higgs vertex nature and Yukawa coupling are the main goals. In particular effects related to spin correlations between the top quarks and how they are affected by the presence of the Higgs boson is explored in ttH events decaying into final states with several isolated leptons (at least one or 2, according to the decay channels of the top quarks). The main Standard Model decay modes of the Higgs boson are explored, including the possibility of decays to tau leptons. An analysis program dedicated to extract the signal from the large set of data collected by the ATLAS experiment during the Run 2 at the LHC is expected to be developed, with the possibility of fully reconstruct the final state particles (including the undetected neutrinos). Upon analysis of the events, total rates are expected to be measured and the associated Yukawa couplings of the Higgs boson. The measurements performed will be used to set limits on possible extensions of the Standard Model that could be sensitive to New Physics in the Higgs and top quark sectors. The work is to be developped under the supervision of the following supervisors: Antonio Onofre and Ricardo Goncalo.