Thesis

Development of boosted jet triggers for Higgs searches at the ATLAS experiment at the LHC/CERN

• Call:

  FCT / IDPASC call 2011

• Academic Year:

  2011 / 2012

• Domain:

  Experimental Particle Physics

• Supervisor:

  Patricia Conde Muino

• Co-Supervisor:

  Agostinho Gomes

• Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  The search for the Higgs boson is the main goal of the LHC experiments. Current fits to the experimental measurements of the Standard Model favor a low mass Higgs, close to the LEP exclusion limit (114GeV). In this mass regime, the dominant decay channel is H->bb. Recent studies have shown that in a boosted regime, where the W/Z and the Higgs have a very large pT, the backgrounds can be reduced and these channels may contribute for a low mass Higgs discovery. However, the current ATLAS jet trigger was not designed to select boosted jets with substructure, having therefore low efficiency. The feasible channels, usually require a high pT lepton for trigger. Some channels, like the pp->ZH->nu nu bb, can benefit clearly from the introduction of a dedicated trigger that selects efficiently boosted objects. Channels like pp->ZH->jet-jet bb, pp->WH->jet-jet bb, can only be possible with such a trigger.