Thesis

Observation and measurement of a boosted Higgs boson decaying to b quarks using jet substructure techniques

• Call:

  IDPASC Portugal - PHD Programme 2017

• Academic Year:

  2017 / 2018

• Domain:

  Experimental Particle Physics

• Supervisor:

  Patricia Conde Muino

• Co-Supervisor:

  Ricardo Gonçalo

• Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  The measurement of Higgs boson properties in LHC experiments has already produced amazing results, including a Higgs mass measurement with a 0.2% precision. But most of these measurements used the decays to vector bosons (two photons, WW, ZZ), comparatively easy to observe but not directly sensitive to some of the most interesting properties of the Higgs boson. The Higgs boson decay to quarks, in particular, has not been observed so far, and may yet produce some very meaningful surprises. Measurement of the tensor structure of the Higgs coupling to heavy quarks, for example, can lead to answers for some of the deepest pending questions in particle physics, such as the matter-antimatter asymmetry in the Universe. In the proposed PhD project, the successful candidate will contribute to the ATLAS search for H ?bb decays in the associated production channel with a W or Z boson (WH/ZH). The data accumulated by the ATLAS experiment early during the PhD will lead to the observation of this decay. The focus of the project will be the development of an analysis to identify highly boosted Higgs bosons in H?bb decays, using novel jet substructure techniques. In this topology, Higgs bosons have a large transverse momentum and decay into two b quarks, which are identified as part of the same hadronic jet. Focusing on this kinematic region leads to a comparatively cleaner selection, ideal for precise measurements of the Higgs to b-quark coupling. The student will be integrated in the Portuguese ATLAS team and will take part in ATLAS data taking operations and physics analysis activities. Frequent trips to CERN may be required to participate in Control Room shifts and collaboration meetings.