Shedding light on new physics with Effective Field Theories
Ilaria Brivio (Niels Bohr Institute, Kopenhagen)

Effective Field Theories (EFTs) are a powerful tool for investigating the presence of new physics beyond the Standard Model. We will first consider the Standard Model Effective Field Theory and discuss, in a “bottom-up” approach, how its parameters can be constrained with global fit analyses without making assumptions on the UV physics.
As a case study I will present the results of a fit to electroweak data. The latter exhibits instructive features, among which the presence of two combinations of Wilson coefficients that remain unconstrained when the analysis is restricted to 2 -> 2 scattering processes and whose origin can be understood in terms of a reparameterization invariance.
The second part of the talk will follow a “top-down” perspective: considering the type-I seesaw model for neutrino masses, EFT techniques will be employed to discuss the possibility that the Higgs potential and electroweak scale are generated radiatively in this scenario. This framework represents an alternative approach to the hierarchy problem: here the Higgs mass is not stabilized around the TeV scale, but rather determined by radiative corrections at higher energies.