Electroweak vacuum lifetime in two Higgs doublet models

The Two Higgs Doublet Model (2HDM) is an excellent candidate for physics Beyond the Standard Model, and it predicts the existence of extra scalar particles liable to be discovered in the coming years at the LHC. Unlike the Standard Model, however, the 2HDM scalar potential has a rich vacuum structure, with competing minima possible already at tree-level. Thus there is the possibility of the 2HDM electroweak vacuum not being the true minimum of the model, and tunneling to a deeper minimum could occur, with catastrophic consequences. In this talk I will review the theory and phenomenology of the 2HDM, analysing in detail its vacuum structure and explaining how the calculation of the tunnelling time to eventual lower minima is accomplished. This is then used to show how the parameter space of the model can be restricted, thus increasing its predicitive power.