PRISMA Colloquium

Thanks to their extremely weak interaction with matter and neutral electric charge, neutrinos travel vast cosmic distances without deflection, providing a unique and complementary approach to investigating the most energetic events in the Universe. Neutrino telescopes are designed to detect Cherenkov light inferred by neutrino interactions. After more than fifteen years of data collection, the pioneering ANTARES detector has been successfully dismantled, making way for its next-generation successor, KM3NeT, deployed at two sites in the Mediterranean Sea. Near the former ANTARES location, off the coast of Toulon (France), KM3NeT/ORCA is dedicated to studying the intrinsic properties of atmospheric neutrinos through their oscillations within the Earth. Further southeast, off the coast of Sicily, KM3NeT/ARCA is monitoring the high-energy sky in search of cosmic neutrinos. In this presentation, I will highlight the latest insights in neutrino (astro)physics emerging from the depths of the Mediterranean. Particular attention will be given to the recent detection of an ultra-high-energy neutrino event, designated KM3-230213A, by KM3NeT/ARCA. The observed particle is a muon with an estimated energy of 120+110−60 PeV. Its exceptionally high energy and nearly horizontal trajectory suggest that its parent neutrino originated from a cosmic accelerator or could potentially be the first detected cosmogenic neutrino—produced when ultra-high-energy cosmic rays interact with background photons in the Universe. This groundbreaking observation underscores the remarkable capabilities of deep-sea neutrino telescopes in unveiling new astrophysical phenomena. To also view graphic content, follow the link: https://www.thep.physik.uni-mainz.de/files/2025/04/Title_Abstract_Mainz_AK_16.04.2025.pdf

Neutrinos, though nearly massless and weakly interacting, play a central role in modern physics—from the origin of mass and the nature of matter–antimatter asymmetry to the search for physics beyond the Standard Model. Yet one of the main obstacles to fully realising their potential lies in our limited understanding of how neutrinos interact with matter. These interactions are complex, often involving nuclear effects that are difficult to model and challenging to measure. As a result, they introduce significant systematic uncertainties in precision experiments, including those aiming to determine mixing parameters and explore CP violation. This talk will provide an accessible overview of why neutrino interaction physics is both essential and challenging, and how it connects nuclear and particle physics. I will outline current experimental limitations and discuss the key requirements for future progress: well-characterised neutrino beams, dedicated measurements, and new experimental strategies. These advances are not only crucial for interpreting results from current and future experiments, but also for enabling discoveries that may reshape our understanding of fundamental physics. As an illustrative example, I will introduce nuSTORM—a proposed facility based on stored muons—as a next-generation platform for precision neutrino scattering and searches for new physics.