Evidence for sharper than expected transition between metastable and unstable states

In mean-field theory, i.e. infinite-range interactions, the transition between metastable and unstable states of a thermodynamic system is sharp. The metastable and the unstable states are separated by a spinodal curve. For systems with short-range interaction the transition between metastable and unstable states has been thought of as gradual. We show evidence, that one can define a sharp border between the two regions. We have analysed the lifetimes of states by considering the relaxation trajectories following a quench. The average lifetimes, as a function of the quench depth into the two-phase region, shows a very sharp drop defining a limit of stability for metastable states. Using the limit of stability we define a line similar to a spinodal in the two-phase region.