Z ' boson and electroweak phase transition

As a minimal extension to the standard model, the electroweak group SU(2) c ircle times U(1) circle times U ' (1) is considered to examine the possibil ity of an electroweak phase transition. The extended symmetry is broken by the doublet Higgs and isospin singlet bosons. An effective potential is pro posed which makes the Z ' boson enter into the standard model scenario due to radiative correction. Constraints on the masses of the Z ' and Higgs bos on due to perturbative expansion at zero and finite temperature as well as loop expansion are calculated. There is a strong first-order electroweak ph ase transition at T-c around 125 GeV for reasonable mass values of the Higg s and Z ' boson.