Electroweak Phase Transition in the U(1)' MSSM
  In this work, we have investigated the nature of the electroweak phase
transition in the U(1) extended minimal supersymmetric standard model without
introducing any exotic fields. The effective potential has been estimated
exactly at finite temperature taking into account the whole particle spectrum.
For reasonable values of the lightest Higgs and neutralino, we found that the
electroweak phase transition could be strongly first order due to: (1) the
interactions of the singlet with the doublets in the effective potential, and
(2) the evolution of the wrong vacuum that delays the transition.
