In the effort to understand the nature of dark matter, model building and both high- and low-energy phenomenology play a crucial role. These aim to determine the viable properties dark matter could possess while proposing new strategies to search for these elusive particles, whether in the laboratory or the sky. In this area, the Physics Department has made pivotal contributions across several domains. From a theoretical perspective, the department has pioneered the development of numerous viable dark matter models. One such example is the theory of composite dark matter, where the dark sector is stable due to an accidental symmetry, much like the stability of the proton within the Standard Model.
 

Our department is also a leader in the study of primordial black holes. Unlike traditional stellar black holes, these are macroscopic objects formed in the earliest moments of the Universe from large stochastic fluctuations in the matter density. Since they emit essentially no light, aside from possible Hawking radiation, they are considered excellent dark matter candidates. Finally, the department has contributed foundational results toward the understanding of wave dark matter, such as axions and dark photons. If characterized by sufficiently light masses, dark matter would cease to behave like a collection of point-like particles and would instead act as a classical field, sharing many properties with ordinary waves. Theorists within the department have greatly advanced the understanding of these candidates, from developing their underlying theoretical frameworks to studying their potential impact on astrophysics and both early- and late-time cosmology.
 

Another facet of dark matter theory is direct detection, consisting in the effort to observe dark matter in controlled laboratory experiments, by leveraging its potential non-gravitational interactions with ordinary matter. The Physics Department plays a leading role in these investigations. Our theorists have proposed a number of pioneering strategies to search for dark matter, often targeting previously unexplored regions of mass and couplings. These proposals are characterized by a stimulating interplay between particle physics and condensed matter physics. Among these innovative directions is the possibility of searching for light dark matter using advanced materials such as superconducting devices, superfluid helium-4, antiferromagnets, and hydrogenated carbon nanostructures, among other “exotic” detection media.

People:

• Andrea Caputo (constraining dark matter with astrophysics)

• Roberto Contino (theory of composite dark matter)

• Angelo Esposito (theory of existing and future direct detection strategies)

• Alessio Notari (theory of axions and their cosmology)

• Antonio D. Polosa (theory of future direct detection strategies)

• Alfredo Urbano (theory of primordial black holes)