Primordial black holes production in Higgs inflation

The current observational data deriving from the CMB and large-scale structures only probes a limited range of cosmological scales, hence the majority of the inflationary dynamics is still unconstrained. It is possible that processes of cosmological relevance, such as the generation of dark matter, occurred during these unobserved stages. In this context, primordial black holes (PBHs) represent an interesting dark matter candidate. Higgs inflation is an interesting framework in which such phenomena may occur. Quantum corrections can flatten the effective potential in localized regions and induce an inflection point, leading to a temporary violation of the slow-roll conditions and to a transient phase of ultra–slow–roll. This phase amplifies the curvature perturbation spectrum on scales smaller than CMB scales, potentially triggering PBH formation at the end of inflation. This thesis presents a Higgs inflation model that includes higher–order operators in both the scalar potential and the non–minimal coupling, ensuring compatibility with CMB observations while allowing for a significant enhancement of the power spectrum at smaller scales. The enhancement is obtained by means of a quasi-inflection point in the Einstein frame potential, and the parameter space of the model is compatible with the current bounds on the value of the Higgs quartic self-coupling λ. The resulting mass and abundance of the produced PBHs are evaluated by means of a numerical analysis and compared with current observational bounds.