Thermodynamic Instability of Splitting Thin Shell Solutions in Braneworld Einstein-Gauss-Bonnet Gravity

The thermodynamic stability of braneworld cosmological solutions in five-dimensional Einstein-Gauss-Bonnet gravity is addressed, particularly in the context of the splitting vacuum thin shells in which the shells represent either an ephemeral or a branch-changing false vacuum bubble spontaneously emerging from the braneworld and there is more than one possible solution for the same distributional initial data set. The free energy associated with the competing solutions is computed. It is shown that the criterion to decide which solution is preferred coincides with the criterion of the possibility of having a splitting solution. This result suggests an equivalence between a thermodynamic and a dynamic selection criteria among possible classical solutions that deserve further consideration.