CALCULATION OF THE FIXED LENGTH FUNDAMENTAL su(2) HIGGS MODEL

The phase diagram of the lattice system of SU(2) gauge field coupled with the fixed length Higgs field in fundamental representation has been calculated by the variational-cumulant expansion method to the third order approximation.The method of determining the variational parameter has been improved by using the free energy to the second order approximation.Thus calculated phase diagram is in good agreement with the Monte Carlo estimation and the order of the phase transition is clearly determined in the third order approximation.