Light scalar spectrum in extra-dimensional gauge theories.
Extra dimensional theories have been around for almost a century and they provide interesting new ideas both in particle physics and cosmology. In this talk I will show how a simple five dimensional gauge theory can be studied using lattice Monte Carlo simulations. The phase diagram of this five-dimensional SU(2) gauge theories with one compactified dimension on anisotropic lattices has a rich structure. It is important to control non-perturbatively the scale hierarchy between the cutoff and the compactification scale in the bare parameter space, in order to obtain the desired physical scenario. It exists a region of values fir the bare coupling for which the the five-dimensional lattice theory can be described by an effective four-dimensional theory coupled to a scalar field in the adjoint representation. I will present a detailed study of the light scalar spectrum as it arises from the non-perturbative dynamics of the full lattice theory. Cutoff effects and finite-size effects are studied and the results are favourably compared to perturbative results.