In models of real scalar fields with degenerate double-well potentials , spherically symmetric , large amplitude fluctuations away from the vacuum are unstable .
Neglecting interactions with an external environment , the evolution of such configurations may entail the development of an oscillon ; a localized , non-singular , time-dependent configuration which is extremely long-lived .
In the present study we investigate numerically how the coupling to a heat bath influences the evolution of collapsing bubbles .
We show that the existence and lifetime of the oscillon stage is extremely sensitive to how strongly the field is coupled to the heat bath .
By modeling the coupling through a Markovian Langevin equation with viscosity coefficient \gamma , we find that for \gamma \gtrsim 5 \times 10 ^ { -4 } m , where m is the typical mass scale in the model , oscillons are not observed .

PACS : 11.10.Lm , 05.70.Lm , 98.80.Cq