Dynamical symmetry breaking of massless λφ 4 and renormalization scheme dependence ∗

Through two loop effective potential we demonstrate that the MS scheme of dimensional regularization and Jackiw's prescription in cutoff regularization allow for the dynamical breaking solution in massless λφ 4 theory, while the Coleman-Weinberg prescription does not. The beta function of the broken phase is negative, like in the one loop effective potential, but the UV fixed point is not zero, i.e., not an asymptotic freedom solution , unlike the one loop case. Some related issues were briefly discussed.