The CMS group at CEA-Saclay/IRFU/DPhP proposes a thesis on the search for double Higgs boson production in the decay channel with a pair of bottom quarks and a pair of tau leptons. The study of this production gives a direct access to the Higgs boson self-coupling, parameter still to be measured. The selected student will take part to research activities well established within CMS, within the CEA group, in link with other institutes in France and abroad. He or she will have to develop an analysis using the Run 3 data of LHC, and in particular to optimise the trigger strategy with regard to previous such analyses. Several publications are foreseen: a first one using the data collected in 2022 and 2023, combined with Run 2 if the sensitivity gain is as large as expected, and a second one using the full Run 2 and Run 3 data. A contribution to the combination of HH results in the different sensitive channels is also foreseen. In parallel, the student will be able to also take part in activities related to detector upgrades, in particular in calorimetry, benefiting from the great expertise of the group in this domain.