Searching and Discovering New Physics with Run-2 on ATLAS Experiment of LHC

California State University-Fresno Foundation, Fresno CA

Investigators

Abstract

The Standard Model (SM) of elementary particle physics gives an excellent description of the strong and electroweak interactions, the forces that influence the structure and behavior of elementary particles such as the proton and neutron. The SM also describes most of what we know about the visible matter in the Universe. The Higgs Boson, discovered at the Large Hadron Collider (LHC) in Switzerland, was the last ingredient in this theory. Yet the overwhelming success of the SM seems only to emphasize its limitations. There are many open questions remaining. Why are there three families of quarks, elementary particles that make up the proton and neutron, and leptons, elementary particles such as the electron and muon? What is the nature of space-time itself? Do the extra dimensions suggested by string theories and string- inspired models really exist? Where do dark energy and dark matter fit into our current picture of the universe? Answers to these key questions can only be found by including new physics beyond the SM. This group will work with the ATLAS experiment at the LHC to look for this new physics by searching for new particles emerging from proton-proton collisions. An exciting feature of this program is that a number of undergraduate and Masters students from Fresno and other Cal State institutions will be involved. They will participate not only in this analysis thrust but will also gain hands-on experience helping in a variety of hardware projects from other ATLAS collaborators. In this proposed research plan, Professor Gao and his group at California State University, Fresno will continue to search for particles from new physics in di-jet events. The use of di-jet data as a way to search for new physics is a classic approach with a long history, and requires precise understanding of the jet energy scales expected from the SM. The PI has considerable experience in jet physics and is well aware of the challenges this presents. He intends to build on successful prior work in which new variables were identified that should discriminate a potential new physics signal from QCD. Such variables, by construction, use the radiation patterns from partons in a multi-variate analysis of the structures observed.