If the electroweak phase transition is of first order, it proceeds via bubble nucleation and it could explain the asymmetry between matter and antimatter and be a source of a stochastic background of gravitational waves. In this scenario, as the temperature of the Universe decreases, the Higgs field tunnels from a false vacuum to a lower true vacuum. The rate of this transition is determined by a solution of the field equations which minimises the Euclidean action called the bounce solution, which also gives the initial configuration of the nucleating bubble.

In this project, we aim to better understand where is the threshold that separates two regimes where the tunneling between the two vaccua is driven either by thermal fluctuations or purely by quantum tunneling. Using the code BSMPT, we will numerically find the two bounce solutions and minimise the respective actions for an extension of the Standard Model and find the tunneling temperature.