Light scalars from compactified extra dimensions. Lattice results

The idea of studying 5 dimensional (5D) gauge theories to get some insights into new physics is very attractive. When the extra dimension is compactified and small, the theory provide a way to naturally obtain a light scalar particle in 4 dimensions. However, higher dimensional gauge theories are perturbatively non-renormalizable and can be used only in the framework of Effective Field Theories. Therefore, physical observables in a 5D theory can depend explicitly on the regularization procedure and on the actual value of the cut-off; using a sensible gauge-invariant cut-off regularization allow one to extract non-perturbative information out of these theories. As a simple non--trivial model, we started studying a non-abelian SU(2) gauge theory on a 5 dimensional euclidean lattice. I will present numerical results for the phase diagram of the lattice model and for the mass of the scalar in particular region of the parameter's space.