Dynamics of first-order phase transitions in the φ4–φ6 model caused by the parametric instability of the metastable vacuum

We suggest that the parametric resonance underlies the mechanism responsible for first-order phase transitions in non-dissipative systems. This conjecture is examined with the nonlinear Klein–Gordon equation describing a massive real scalar field with φ4–φ6 selfcoupling. The solutions for the unstable modes of the false vacuum fluctuations are constructed and the characteristic exponents are founded in both instability domains on the amplitude–wavevector chart. The growth of the vacuum oscillations, as well as the all stages of the subsequent phase transition, including the bubble formation and the appearance of a quasi-turbulent state of a new phase, were observed by us in the numerical experiment.