The Finite Temperature Effects on the Coleman Phase Transition in Double Sine-Gordon Model

By means of the finite temperature Gaussian effective potential (FTGEP) method, the (1+1) and (2+1) dimensional quantum double sine-Gordon (DsG) field theories are studied nonperturbatively for finite temperature. The explicitly FTGEP is obtained for both (1+1) and (2+1) dimensional DaG models. The temperature-dependent Coleman phase transition conditions obtained by us would reduce to the known results g_cr² when T→0. The alternative explanation of the Coleman phase transition at finite temperature is that for fixed coupling constantg² there is a critical temperature T_cr (whose value depends ong²) such that the theory becomes unstable when the temperature of the system exceeds the critical value T_cr.