Inflation, the Standard Model Higgs and the nature of gravity
PT-CERN Call 2020/2
Instituto Superior Técnico (Universidade de Lisboa)
CENTRA - Center for astrophysics and gravitation
The properties of the recently discovered Higgs boson together with the absence of new physics at the Large Hadron Collider (LHC) allows us to speculate about consistently extending the Standard Model (SM) all the way up to the Planck scale while staying in the perturbative regime. In this context, the SM Higgs non-minimally coupled to gravity could be responsible for the symmetry properties of the Universe at large scales and the generation of the primordial spectrum of temperature fluctuations seen in the Cosmic Microwave Background (CMB). Interestingly enough, the detailed predictions of this general paradigm are sensitive to the different incarnations of gravity, opening the door to test its fundamental nature with collider experiments and future cosmological probes such as the Simon Observatory or LiteBIRD. This thesis will carry out a systematic exploration of the relation between the Higgs field and gravity. In particular, we will attempt to identify a set of self-consistent Einstein-Cartan theories able to describe the whole evolution of the Universe in the absence of new degrees of freedom above the electroweak scale. To this end, we will follow a multidisciplinary approach combining theoretical and particle physics requirements such as unitarity and radiative stability with cosmological and astrophysical observations.