Astroparticle and Cosmology
There are a number of important gaps in our current understanding of the Universe. For instance, the Dark Matter problem: we know from astronomical and cosmological observations that around 80% of the total matter content of the Universe is made of a substance that does not correspond to any of the known elementary particles, and whose nature is unknown. Or cosmic rays: this highly energetic radiation (of different species) coming from space has been discovered more than 100 years ago but its origin is still unknown and its properties still largely not understood. Or the recently discovered acceleration of the Universe: it is attributed to another mysterious substance dubbed Dark Energy, whose nature is even more elusive than Dark Matter. Or the properties of neutrinos, e.g. as messengers of astronomical phenomena (supernova explosions, very high energy events…). Or the reason for the imbalance between matter (which makes up essentially everything) and antimatter (which is extremely rare in the Universe), as opposed to an assumed initial perfect symmetry.
By their very nature, these problems sit at the interface between particle physics, astrophysics and cosmology, a domain of research which is usually broadly defined as “Astroparticle physics".
The activity at the LPTHE currently focuses in particular on the Dark Matter problem, along the following canonical directions:
- Phenomenology of Indirect Detection: the study of how possible signals of annihilations or decays of Dark Matter particles in the Galaxy (and beyond) can be searched for in cosmic rays (electrons, positrons, antiprotons, gamma rays, X rays, neutrinos…).
- Phenomenology of Direct Detection: the study of possible manifestations of DM particles via their scattering on ordinary atoms, within ultra-clean and ultra-shielded experiments.
- Study of Dark Matter searches at accelerators and colliders (most notably the Large Hadron Collider at CERN, but also future machines), where DM particles can be produced by ordinary particle collisions.
- Theoretical model building: the search for the theory embedding the DM particle and the study of its consequences in other subfields of physics and cosmology.