Thesis

Measuring di-Higgs production at ATLAS to probe the electroweak vacuum

• Call:

  IDPASC Portugal - PHD Programme 2019

• Academic Year:

  2019 / 2020

• Domain:

  Experimental Particle Physics

• Supervisor:

  Ricardo Gonçalo

• Co-Supervisor:

  Filipe Veloso

• Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  Since its discovery, the Higgs boson became a prime tool to search for physics beyond the Standard Model (SM). With the current level of precision, LHC data indicates a Higgs boson compatible with SM expectations, but we have only just begun to scratch the surface. The wealth of new results on the Higgs boson properties since the discovery have only probed the region around the minimum of the potential, and no experimental constrain has been made on the shape of the Higgs potential. This is intimately intertwined with the breaking of the electro-weak gauge symmetry, and so with the nature of the fundamental forces we experience today. To experimentally constrain this shape we must measure the triple Higgs coupling parameter. This is accessible through the simultaneous production of two Higgs bosons, HH. The selected student will join the Portuguese ATLAS team, working in close collaboration with theorists and foreign experimental groups. The two related aims of this project are to contribute to ongoing ATLAS analyses in this channel and to develop sensitivity studies for future analyses. To achieve optimal results in this challenging analysis, the student will employ the latest theory developments and the most recent advances in reconstruction techniques: from boosted object identification to machine learning. As part of the work, the student will also take part in experimental developments towards the LHC upgrade, in particular the development of the Hardware Tracking Trigger co-processor, one of the most advanced parts of the ATLAS upgrade programme. The work programme will include at least one year at LIP Lisbon and one year at the University of Coimbra, where both supervisors are based. The student will be able to participate in the operation of the ATLAS experiment during the LHC Run 3 to start in 2021 Frequent trips to CERN may be required to participate in Control Room shifts and collaboration meetings.