The Standard Model of particle physics is the most robust formalism built so far to explain the interactions between elementary particles. The Higgs boson, the last particle discovered in 2012, is a key element of this theory, explaining simultaneously the origin of the mass of the bosons mediating interactions, and the fermions constituting matter. However, its existence is a heuristic formulation that needs to be better understood. In addition, its coupling, or interaction, with any massive particle makes it an excellent probe for the discovery of new particles, postulated in Beyond the Standard Model theories.

For all these reasons, the study of Higgs boson production is at the heart of the research program of the ATLAS experiment, exploiting the proton-proton collisions of the Large Hadron Collider (LHC) located at CERN. After having discovered and measured the main couplings to the most massive particles, the main focus of the collaboration is today on the production of a pair of Higgs boson, which remains, to date, unobserved. This search is particularly

complex experimentally due to its reduced probability of occurrence and the multitude of final states available. Its observation, by the end of the high luminosity phase of the LHC (HL-LHC), is one of the most awaited result by the community.

The work expected during the thesis will mainly focus on the analysis of the data collected during Run 2 and 3 by ATLAS, developing advanced analysis methods, including sophisticated machine learning models, and by refining the statistical methods to measure the expected accuracy of signal rates. The tools and methods developed will mix C++ and Python languages, for which a minimum knowledge base is required, and will be part of a strong international collaborative environment.

The doctoral student will also work on the development of the High Granularity Timing Detector (HGTD) for the HL-LHC. This detector, designed to provide a measurement of the time of arrival of charged particles and thus better identify interesting interactions in each collision, is being developed with strong participation from the Clermont ATLAS team. An active role in the evaluation of its performance is therefore expected.

The LPCA ATLAS team has 11 members specialized in the study of final states with Top quarks and Higgs bosons. The team is also involved in the operation and development of particle detectors (hadronic calorimeter, time detector).

The selected person will have to travel regularly to CERN to participate in collaboration meetings and in the detector operation or study.

This position should go through the selection of the École Doctorale, centralised with the ADUM website: https://adum.fr/as/ed/voirproposition.pl?langue=&site=casf&matricule_prop=55309

It will start on the 1st of October 2024, with a net salary of roughly 1,400 euros/month (see https://www.campusfrance.org/en/FAQ-Doctorate-France-questions) lasting for 3 years.

Please contact the relevant contact for more information: louis.deramo@clermont.in2p3.fr