Higgs Cosmology

The discovery of the Standard Model (SM) Higgs boson has triggered a quest for understanding its cosmological implications.
It has been recently understood that, on general grounds, the Higgs field is always expected to be largely excited during or immediately after inflation. By studying the phenomenology of this excitation, we can attempt to address many relevant questions that remain yet unanswered: Was the Higgs responsible for inflation? What is the connection between the Higgs and the inflationary sector? How did the Higgs decay after inflation? Did it decay into SM particles only, or also into Beyond the SM species? What are the cosmological consequences in each case? What can we learn about the Higgs properties from them? What are the observable signals?

The main objective of this part is to obtain an accurate description of the Higgs excitation and subsequent later decay, in as many cases as possible, classified by symmetry arguments. We will study also the subsequent evolution of the decay products.

As the connection between inflation and the Higgs is not known, we will scan systematically over possibilities, studying three main circumstances: a) the case when the Higgs is responsible for inflation, b) the case when it is merely a spectator field, and c) the cases in between when the Higgs is coupled to the inflaton, to BSM sectors, and/or non-minimally to gravity.

We will investigate the potential cosmological implications of the Higgs excitation in each case, which range from the realization of reheating and baryogenesis, to magnetic fields and dark matter generation. This research will require the use of analytical techniques of quantum field theory and particle physics, as well as numerical lattice simulations, depending on the aspect to be studied.