New physics beyond the Standard Model: unified theories and extended Higgs sectors
In this project we study theories for physics beyond the standard model (SM) of particle physics given observations and constraints from the Large Hadron Collider (LHC) at CERN and from cosmology and astrophysics. There are many theoretical issues not explained by the SM, such as why it has its peculiar choice of gauge group, or why there is an asymmetry between matter and antimatter in the universe. Finally we need to understand better the physics of the Higgs boson, and whether there is more than one Higgs field. This question about the Higgs field(s) is intimately related to the matter-antimatter asymmetry and other cosmological issues, since the properties of the electroweak phase transition in the early universe and the stability of the ground state depend critically on the details of the Higgs sector. We are exploring the connection between observations of the newly discovered Higgs boson at the LHC and constraints on additional Higgs bosons on one hand and the electroweak phase transition on the other hand. We are also studying grand unified or partially unified theories with extended gauge groups and Higgs sectors, including the left-right symmetric model and SO(10) grand unified theories and the implications of such theories on the LHC and cosmology. For these investigations we now need to perform Monte Carlo simulations of particle collisions and Markov chain Monte Carlo studies of the many-dimensional parameter spaces of these theories.