Thesis

Development of a parallel computing based search for the associated Higgs boson production with a top quark pair using LHC run-II data from ATLAS

• Call:

  IDPASC Portugal - PHD Programme 2015

• Academic Year:

  2015 / 2016

• Domain:

  Experimental Particle Physics

• Supervisor:

  Ricardo Gonçalo

• Co-Supervisor:

  José Soares Augusto

• Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  After the discovery of the Higgs boson at the ATLAS and CMS experiments of CERN’s LHC collider, the experimental focus has thus moved to the precise measurements of the Higgs boson properties. To do this, however, it is crucial to observe and study the production of the new boson in association with a pair of top quarks, ttH, which has not yet been achieved and will require data to be collected in the next few years. This production channel provides the only way to directly measure the top Yukawa coupling between Higgs and top. This is the largest coupling of the Higgs boson to matter particles in the Standard Model theories of particle physics, and there are reasons to believe it may show the way to the elusive physics beyond the current theories. Objectives of the PhD thesis: But the analysis of the ttH channel is far from easy. To observe it and extract the maximum information from it requires new analysis techniques that have been developed in the last few years. In this PhD project we propose to develop an analysis of the ttH channel using the Matrix Element Method to distinguish between the Higgs signal and the background processes. This method has many advantages over more standard techniques, but is also extremely computational intensive. To make its application feasible, we propose the parallelization of the ttH matrix element computation using Graphical Processing Units (GPUs). The evolution of computer hardware points to the trend of using graphical processing units containing hundreds of GPU cores to take up the load heavy and parallelizable tasks normally fulfilled by standard CPUs. It’s use in scientific computing, and particularly in particle physics, is emerging and promises to have an important impact. This PhD programme is therefore at the edge of both particle physics research and of computing technology, and the techniques developed will be extendable to other analyses and domains. The student will take part in ATLAS data taking operations and physics analysis activities, with frequent trips to CERN to participate in Control Room shifts and collaboration meetings. Contacts: jgoncalo@lip.pt, jasaugusto@gmail.com Further reading: http://arxiv.org/abs/1407.7595