Using results from the now-operational Large Hadron Collider, this project will probe the physics of electroweak symmetry breaking and test the twin theoretical ideas of the Higgs mechanism and supersymmetry. By examining extensions of the Higgs sector, the group will find ways to test the minimal models of supersymmetry and to distinguish among various models using data. This will also tie into tests of lepton flavor violation through Higgs decays, a phenomenon deeply connected to the ongoing efforts to study neutrino masses and mixings. Finally, connections will be explored between the physics of the Higgs boson, supersymmetry and the astrophysical problems of dark matter and the baryon asymmetry of the universe. In so doing, the group seeks to increase our understanding of physics which is not readily measured in experiment, such as the source of the neutrino masses and the properties of the dark matter correlated with experimental signatures for SUSY at the LHC.
Simultaneously, this project includes continued outreach to the Notre Dame academic community through new and innovative courses in modern physics for non-science majors, work on improving academic advising throughout the university, and programs designed to increase the number of Notre Dame students pursuing graduate studies in science, technology, engineering and mathematics. This is coupled to continued outreach to the greater Northern Indiana community through public lectures and planetarium shows on the Notre Dame campus, and interactions with local high schools through the QuarkNet program.
The discovery of the Higgs boson seems to validate the basic structure of the Standard Model of particle physics and our understanding of how nature works at very small distance scales. However, the Standard Model makes no clear prediction about the mass of the Higgs boson, and it is only in extensions of the Standard Model, such as supersymmetry (SUSY), that the mass takes on some predicted value. The mass found for the Higgs boson is consistent with minimal SUSY, but requires that SUSY particles are heavy enough to escape detection to date at the LHC. However minimal SUSY is well studied and new ideas are needed for how to extend the minimal model of SUSY while maintaining its successful predictions. My collaborators and I created a new next-to-minimal version of SUSY we called the Singlet-Modified SUSY Standard Model (SMSSM). This model has one additional new particle in it which can be used to raise the Higgs mass and/or to provide an alternative phenomenology for SUSY. The model itself is important as an extension of minimal SUSY that had too often been overlooked by previous theorists, providing intellectual merit to the study. In fact, we would argue that it is the most general next-to-minimal implementation of SUSY possible. The model also provides alternative signals for experimentalists at the LHC as they work to find SUSY. In particular these models contained a new singlet state which could be discovered, for example, in the decays of the Higgs boson; and it provided an alternative dark matter candidate which could explain much of the missing matter in the universe. Whether this model is correct is a question that nature will ultimately decide, with help from the LHC. But the broader impact of the model is through its alternative set of signals and signatures that these experimentalists can use to hone their own discovery techniques.
