Abstract

The stability condition of the electroweak (EW) vacuum, clearly connected with the stability of the universe as a whole, has been investigated for decades. Within the usual analysis, and for the present experimental values of M_H and M_t (the Higgs boson and top quark masses), the EW vacuum (and then our universe) turns out to be metastable and very long lived, with a lifetime much larger than the age of the universe itself. The usual analysis, however, misses an important effect. It was previously thought that if New Physics lives at very high energy scales, its presence cannot affect the stability condition. Contrary to this expectation, it has been recently shown that the stability condition of the EW vacuum crucially depends on the presence of New Physics at very high scales. In this talk I will show why previous analyses failed in finding this effect and I will present the consequences of these results on model building beyond the Standard Model. Moreover, I will show that, despite claims to the contrary, more precise determinations of the top and Higgs masses will not allow to decide whether our universe lives in a metastable or in a stable state. The Higgs inflation scenario and the so called “Higgs Criticality” will also be discussed in the light of these results.