Renormalization group approach to a functional formulation of a Bose system

The Wilson approach is applied to a functional formulation of a d-dimensional Bose system. At finite temperature T the classical Wilson-two-component behaviour is reproduced. When T goes to zero a dimensional crossover from d to d+2 arises. At T-0, surprisingly, the critical exponents associated to stable non Gaussian fixed point for d<2 result the same of the Gaussian ones at the first order in epsilon =2-d