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Cosmological first-order phase transitions beyond the standard inflationary scenario

Motivated by cosmological first-order phase transitions we examine the nucleation and evolution of vacuum bubbles in non-vacuum environments. Non-standard backgrounds can be relevant in the context of rapid tunneling processes on the landscape. Utilising complex time methods, we show that tunneling rates can be notably modified in the case of dynamical FRW backgrounds. We give a classification of the importance of the effect in terms of the relevant dynamical time scales. For both the bubble nucleation and evolution analysis we make use of the thin-wall approximation. From the classical bubble evolution on homogeneous matter backgrounds via the junction method, we find that the inflation of vacuum bubbles is very sensitive to the presence of ambient matter and quantify this statement. We also employ inhomogeneous matter models (LTB) and models that undergo a rapid phase transition (FRW) as a background and discuss in which cases potentially observable imprints on the bubble trajectory can remain.