An optimisation based algorithm for finding the nucleation temperature of cosmological phase transitions

We present the OptiBounce algorithm, a new and fast method for finding bounce action cosmological phase transitions. This is done by direct solution of “reduced” minimisation problem proposed Coleman, Glaser, Martin. Using formula action, our avoids rescaling step used in other algorithms based on this formulation. The path represented using pseudo-spectral Gauss-Legendre collocation scheme leading to non-linear optimisation over coefficients. Efficient enabled recent advances automatic differentiation, sparse matrix representation large scale programming. algorithm optimised nucleation temperatures sharing model initialisation work between instances calculation when operating at different temperatures. numerical results range potentials with up 20 scalar fields, demonstrating O(1%) agreement existing codes highly favourable performance characteristics.