Application of renormalization-group techniques to a homogeneous Bose gas at finite temperature

A homogeneous Bose gas is investigated at finite temperature using renormalization-group techniques. A nonperturbative flow equation for the effective potential is derived using sharp and smooth cutoff functions. Numerical solutions of these equations show that the system undergoes a second-order phase transition in accordance with universality arguments. We obtain the critical exponent $\nu =\mathrm{0.73.}\mathrm{}$