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Accueil du site > Formation > Thèses - Stages de M2

M2 Internship : Measurement of the double Higgs boson production in the bbγγ channel with Run 2 and Run 3 data

The measurement of the Higgs self-coupling at the LHC is of fundamental importance since it is the only way to experimentally assess the properties of the Higgs potential in a model-independent way. The most promising channel to perform such a measurement is HH → bbγγ process, that retains one of the largest sensitivities to the double Higgs production, and will be the focus of the ATLAS Higgs physics program at the LHC Run 3. The internship will focus on the development of the new ATLAS search for the HH → bbγγ process using the full LHC Run 2 and the partial Run 3 datasets, by exploring innovative analysis techniques such as a Kinematic Fit of the bbγγ system to improve the H → bb resolution ; novel Machine-Learning-based photon identification to increase the H → γγ signal efficiency especially for low transverse momentum photons ; and the Matrix Element Method to improve the global signal-to-background discrimination. The analysis will be performed with the joint Run 2 and (partial) Run 3 dataset. The internship will take place within the focus of to the current activities of the ATLAS LAPP Group dedicated to the Higgs and double-Higgs studies. It will require a regular presence at CERN, and could potentially evolve on a PhD thesis project.

The M2 internship can be expanded into a PhD project focused on the measurement and interpretation of the HH → bbγγ signal exploiting the full LHC Run 2 and Run 3 datasets.

The project will explore the separate treatment of various HH production modes to improve the analysis sensitiv- ity, and the final measurement will be designed to be robust against any deviation from the SM predictions, and to maximize sensitivity when interpreted in the context of Effective Field Theories (EFTs), such as the HEFT model. The analysis work will take place in the broader context of the ATLAS search for di-Higgs production in various decay channels, and a participation to Run 2 and Run 3 di-Higgs combination is foreseen. In parallel, the student will contribute to the improvement of the photon performance in ATLAS, with a strong connection to the understanding of the performance of the ATLAS Liquid Argon electromagnetic calorimeter with Run 3 data.

The duration of the PhD thesis is three years. The geographical proximity of LAPP and CERN, about 50 km and 35’ drive, will allow a strong involvement both with the data taking and detector operation and with the partici- pation in person to the working meetings of the ATLAS (di)Higgs Group. A period of several months of continuous presence at CERN is foreseen.

  • supervisor : Marco Delmastro
  • Phone Number : +33 4 50 09 17 85 (LAPP), +41 75 411 86 90 (CERN)
  • email