The study of possible new physics beyond the standard model proceeds through a variety of different approaches. The traditional approach is to construct new perturbative models involving extra particles and gauge symmetries (grand unification), extra space-time symmetries (supersymmetry) and extra dimensions. Alternatively, one can study novel dynamics of simpler systems. In particular, we study candidate models for dynamical electroweak symmetry breaking, providing insights on the existence of near-conformal theories.
We have also studied quantitatively the 1/N corrections to the orientifold planar equivalence between supersymmetric and non-supersymmetric theories. Our calculations have combined string techniques and lattice computations in extra-dimensional theories. The work is a first step to define four-dimensional massless scalar-gauge theories on the lattice as the low-energy limit of extra-dimensional pure gauge theories.