From Higgs Compositeness to Higher Dimensions

While the Standard Model posits that the Higgs boson is an elementary particle, there are good reasons to explore the possibility that it is a composite of more fundamental constituents. However, the paradigm of Higgs compositeness is notoriously difficult to model theoretically as the basis for experimental tests, necessarily involving new strong binding forces that go beyond perturbative analysis, and bringing in the complex structure of couplings to the other known particles. I will review the surprising manner in which the Randall-Sundrum I model has evolved to address these challenges, trading a frontal attack on strong coupling for a weakly-coupled description set in higher-dimensional “warped” spacetime, in which the extra-dimensional excitations secretly describe new composites beyond the Higgs itself. We thereby obtain a theoretically controlled and comprehensive framework for particle physics and compositeness, with implications ranging from LHC searches to  flavor/neutrino physics to dark matter   to gravitational wave cosmology.