Rare Higgs decays and couplings to quarks
PT-CERN Call 2021/1
Sandro Fonseca de Souza
Instituto Superior Técnico (Universidade de Lisboa)
Laboratório de Instrumentação e Física Experimental de Partículas
Since the discovery of the Higgs boson at the LHC in 2012, by the CMS and ATLAS experiments, the focus has been placed in measuring its properties. In particular, on the determination of how it couples to the other standard model (SM) particles. In 2018, both CMS and ATLAS have detected the couplings of the Higgs to the heaviest quarks: the top (ttH) and the bottom (H->bb). Evidence for the muonic decay was also reported in 2020 by CMS. The next big, and natural, step in this endeavour is to access the H couplings to the lighter quarks. The thesis project consists in the search for Higgs boson decays to a quarkonium state and a photon, using the large dataset collected by CMS at the LHC. The motivation for the study is to experimentally constrain the Higgs-quark couplings, and help decide whether our new boson is indeed the particle at the core of the SM, or detect evidence for contributions of New Physics beyond the SM via the Higgs sector.