Thesis

Higgs couplings to light quarks

• Call:

  IDPASC Portugal - PHD Programme 2019

• Academic Year:

  2019 / 2020

• Domain:

  Experimental Particle Physics

• Supervisor:

  Nuno Leonardo

• Co-Supervisor:

• Institution:

  Instituto Superior Técnico

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  The couplings of the Higgs boson to the third fermion family have been recently detected. During 2018, ATLAS and CMS have reported the observation of the couplings to the heaviest fermions, the top and bottom quarks. The important step that follows is then to investigate the couplings to the lighter quarks. This goal is nonetheless challenging, for two reasons: as the Higgs couples in proportion to the particle’s mass, the relevant processes are rarer; also, there are backgrounds (QCD) that result in quark-pair production considerably more abundantly than Higgs decays to quark pairs. There is an alternative approach, however. The quark-antiquark pairs originating from the Higgs decay may bind together (thus forming a meson state). Experimentally, this gives rise to a striking, clean signature: an energetic photon back-to-back to a dilepton resonance. In this thesis project the student will investigate such exclusive decays of the Higgs boson using data just collected by CMS during LHC Run2. The motivation for the work is two-fold: experimentally constrain the Higgs-quark couplings and detect the effects of potential new physics that may be revealed in these sensitive processes.