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Cosmological model with variable vacuum pressure

Scenarios of cosmological evolution having inflationary stages are studied by using equations of state (EoS) inspired by the quark bag model. A crucial point is the existence of states where the specific enthalpy of the cosmological fluid vanishes. A large class of barotropic EoS admits, depending upon initial conditions, for a concrete equation of state, analogs of the "Big Rip" as well as solutions describing an exponential inflation followed by the usual matter dominance. We found scalar field potentials that mimic the behavior of the cosmological scale factor in case of special EoS from the above class. Extensions to more general two-parametric EoS are discussed that describe a pre-inflationary evolution.