My research interests lie in theoretical cosmology and its connections with high energy physics. The leading paradigm of primordial cosmology is the theory of inflation, which describes how, during the very first moments of its existence, the universe underwent a rapid, quasi-exponential expansion, naturally reaching an extremely flat and homogeneous configuration. During this phase, quantum fluctuations were stretched to macroscopic scales, becoming the seeds of the large-scale structure we observe today. These conditions not only make inflation phenomenologically rich, but also provide a natural setting to study quantum field theory in curved spacetime and its connection with general relativity. Some of my works on inflation and on formal aspects of quantum field theory are presented below. More recently, my research interests have also extended to the study of black holes. In particular, I am currently working on a project that studies dynamical black holes in slow-roll inflation, where the metric evolves quasi-statically through a sequence of Schwarzschild–de Sitter metrics.
Research on Axion Inflation
Axion inflation is a class of models in which the inflaton is a pseudo Nambu–Goldstone boson with a broken shift symmetry, allowing couplings to gauge and fermionic fields. Within this framework, I have studied the generation of gravitational waves, the anisotropies of the primordial stochastic gravitational wave background they produce, as well as aspects of backreaction.
Related papers:
Sofia P. Corbà, Lorenzo Sorbo, "Correlated scalar perturbations and gravitational waves from axion inflation", arXiv: 2403.03338 [astro-ph.CO] (2024), JCAP 10 (2024), 024.
Sofia P. Corbà, "Gravitational wave anisotropies from axion inflation", arXiv:2504.13156 [astro-ph.CO] (2025),
JCAP 01 (2026), 029.
Sofia P. Corbà, Lorenzo Sorbo, "Study of backreaction from fermion production during axion inflation". In preparation (2025).
Research on Formal Aspects of Curved Spacetimes
Making predictions in quantum field theory requires a consistent method of renormalizing observables. In the presence of gravity, this becomes more complicated than in flat spacetime due to particle creation. My work has focused on studying the limitations of the existing method of renormalization of observables in curved spacetime, the adiabatic renormalization, and suggesting ways to overcome them. I have then applied this alternative approach to the analysis of observables such as the power spectrum and the energy-momentum tensor in inflationary models.
Related papers:
Sofia P. Corbà, Lorenzo Sorbo, "On adiabatic subtraction in an inflating Universe", arXiv:2209.14362 [hep-th] (2022), JCAP 07 (2023), 005.
Sofia P. Corbà, Lorenzo Sorbo, "Calculation of the conformal anomaly using adiabatic renormalization". In preparation (2025).
In slow-roll inflationary cosmologies, dynamical black holes can be studied within a metric that evolves quasi-statically through a sequence of Schwarzschild–de Sitter like metrics, with slowly varying mass and effective cosmological constant. In this framework, both the black hole and cosmological horizon areas grow as the inflaton rolls. I am currently working with Prof. Jennie Traschen to extend this model in order to better understand primordial black holes during inflation and their potential cosmological signatures.
Research on String Theory Inflation and Magnetogenesis
In my Master’s thesis, Backreaction from Magnetogenesis in String Inflation, supervised by Michele Cicoli, I studied Kähler Inflation and Fibre Inflation, two string-theory inflationary models arising from Type IIB flux compactifications. In these models, the inflaton couples to gauge fields, which in turn backreact by slowing the inflationary evolution. This mechanism could help reconcile the requirement of sufficient e-foldings of inflation with the geometric constraints imposed by the extra dimensions on the inflaton. Within this framework, I also investigated the production of primordial magnetic fields that could serve as seeds for the large-scale magnetic fields observed today.
List of publications
Sofia P. Corbà, Lorenzo Sorbo, "On adiabatic subtraction in an inflating Universe", arXiv:2209.14362 [hep-th] (2022), JCAP 07 (2023), 005.
Sofia P. Corbà, Lorenzo Sorbo, "Correlated scalar perturbations and gravitational waves from axion inflation", arXiv: 2403.03338 [astro-ph.CO] (2024), JCAP 10 (2024), 024.
Sofia P. Corbà, "Gravitational wave anisotropies from axion inflation", arXiv:2504.13156 [astro-ph.CO] (2025). Accepted for publication in JCAP.
Sofia P. Corbà, Lorenzo Sorbo, "Study of backreaction from fermion production during axion inflation". In preparation (2025).
Sofia P. Corbà, Lorenzo Sorbo, "Calculation of the conformal anomaly using adiabatic renormalization". In preparation (2025).