My research focuses on neutrinos, ghost particles with the potential to unlock the deepest secrets of Nature. Neutrinos play a key role in our life but they typically go unnoticed. They are extremely elusive and rarely interact with matter. They can travel for billions of light-years, flying through planets, stars, and even entire galaxies. This characteristic makes them a unique probe to study parts of the Universe otherwise inaccessible to us.

I studied all kinds of neutrinos produced by the nuclear fusion reactions occurring in the core of the Sun with the BOREXINO experiment. This has been extremely important to understand how a star shines. I now work on the Pacific Ocean Neutrino Experiment (P-ONE), a neutrino telescope for extragalactic ultrahigh-energy neutrinos. With P-ONE, I will study active galactic nuclei, blazers, and many other astrophysical systems in the most extreme energy and gravitational conditions. I am also exploring how a future planetary network of neutrino telescopes will lead us to ground-breaking discoveries in multi-messenger astronomy.

Neutrinos are important not only for understanding our Universe but also for uncovering the elementary laws of particle physics. During the last century, they led us to the discovery of the weak force and the postulation of modern quantum field theory. Nowadays, the observation that they are not massless particles provides the most compelling evidence that our standard model is incomplete. The mass of the neutrino can be explained assuming the existence of a new particle, the  “sterile” neutrino. The discovery of sterile neutrinos had been the goal of one of my past projects, the SOX short-baseline neutrino oscillation experiment.

Neutrino masses can also be explained assuming that the neutrino is its own antiparticle, i.e. a Majorana particle. This property emerges naturally in theories that explain why our Universe contains primarily matter. Neutrino masses and the matter-antimatter imbalance in our Universe could be both connected to the Majorana nature of neutrinos. I have been testing this exciting idea by searching for a nuclear transition called “neutrinoless double-beta decay”. I achieved the world-leading sensitivity to double-beta decay with the GERDA experiment. Based on this success, we founded LEGEND, a follow-up project that has very high discovery power. I am now preparing the first stage of LEGEND (LEGEND-200), which will start in 2021. I am also developing a global analysis to combine all available neutrino data and test theoretical models. This will be extremely important to postulate a theory of the neutrino masses after LEGEND has discovered the neutrinoless double-beta decay.