Astroparticle physics at extreme energies and the muon puzzle
by
Sala de Conferências
Departamento de Física FCTUC
Astroparticle physics events at extreme energies, namely gamma-rays and ultra-high-energy cosmic rays, have been essential in the last years to understand our Universe and probe new physics. Due to the scarcity of these events, they can only be detected indirectly in large observatories by measuring the huge extensive air showers that they induce in the Earth's atmosphere. The intrinsic characteristics of the shower development are explored to infer the nature of the primary particle/radiation. These shower observables are identified recurring to shower simulations that attempt to describe the shower interactions, including high-energy hadronic interactions. The latter can only be expressed using phenomenological models tuned at accelerator energies and extrapolated to higher energies. However, it is known that air shower simulations have a deficit in predicting the number of muons at the ground - this is known as the muon puzzle.
In this presentation, I will present what we know about this puzzle, how it hampers the astroparticle physics field, and what are the experimental efforts being conducted to identify its origin.
Paulo Brás e Pedro Costa
