UC Irvine

For decades, the leading examples of new physics targets at particle colliders were particles with TeV-scale masses and O(1) couplings to the standard model. More recently, however, there is a growing and complementary interest in new particles that are much lighter and more weakly coupled. I review the motivations for this shift and the importance of renormalizable portals. I then present FASER, a proposed LHC experiment that is specifically designed to discover light and weakly interacting particles, including those that interact through renormalizable portal interactions.