Abstract
The Standard Model (SM) is a theory in particle physics that unifies three fundamental forces and gives accurate experimental predictions. It has many unsolved problems including the hierarchy problem and the unknown dark matter. Supersymmetry is an extension of the SM that provides theoretical solutions to these problems. To find evidence of supersymmetry in the real world, proton-proton collisions were conducted at the LHC at CERN. These collisions can produce super particles such as charginos, neutralinos and sleptons theoretically. The decay products from these particles include SM particles and super particles which result in missing energy in detection. This project collaborates with the ATLAS detector at the LHC, aiming to find evidence of superparticles and thereby prove supersymmetry. In particular, the decay modes of pair production of squarks or gluinos with two same-sign or three leptons final states are investigated to test whether there are significant signals of particles beyond the SM. As the LHC Run 3 started with higher collision energy at 13.6 TeV and upgraded detectors, larger data samples with higher quality are used in this project than in previous studies. New machine learning techniques and data binning and fitting are also applied aiming for greater signal significance and lower background contamination. This presentation will discuss the theory and analysis methods used in the project.
Anyone interested is welcome to attend.