Orateur
Description
A bosonic particle with a mass equals to 125GeV was observed in 2012, by ATLAS and CMS collaborations at the Large Hadron Collider (LHC). This particle was associated with the Higgs Boson or BEH boson, predicted fifty years before its discovery by François Englert, Robert Brout and Peter Higgs. This particle validates the BEH mechanism, explaining the origin of the mass of known particles and the electroweak symmetry breaking.
Since this discovery, physicists have been trying to probe the various properties of the Higgs boson such as the Higgs self-coupling. The success in probing Higgs self-coupling will bring another probe of the standard model and will give a direct measurement of the Higgs field potential in the vacuum. This measure is performed through a global analysis of the di-Higgs (HH) production at LHC, decaying into various channels.The aim of this work is to build a discriminant variable to maximise the distinction between the signal (HH) and the background (all processes ending in the same signature).
In this study, the analysis has been done through the signature 2$\ell$SS, it represents around 10% of the leptonic decays of the Higgs pair. Given this signature, the main backgrounds will be Di-boson production, ttbar production and single boson production. The distinction could be measured through the significance. In order to maximise this last named, multivariate techniques targeting the main background processes have been used. The study has been realised using Monte Carlo simulations and data from the Run II. Finally the main instrumental backgrounds, especially the contribution from misidentified leptons, are derived from data.
