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T: Fachverband Teilchenphysik

T 37: Neutrino Astronomy II

T 37.7: Talk

Tuesday, March 17, 2026, 17:45–18:00, KS H C

Tau neutrino appearance with KM3NeT/ORCA — •Sebastian Weissbrod for the KM3NET-ERLANGEN collaboration — Friedrich-Alexander-Universität Erlangen-Nürnberg, ECAP, Erlangen, Germany

KM3NeT/ORCA is a water-Cherenkov neutrino telescope currently under construction in the Mediterranean Sea. Due to its modular design, based on strings of Digital Optical Modules (DOMs), data taking is possible already during the construction phase. In the last year, the KM3NeT collaboration has presented a multitude of physics results obtained with a 433 kt-yr data-set recorded with the six-string ORCA6 sub-array. Among these results is the analysis of tau neutrino appearance in the atmospheric neutrino flux through neutrino oscillations, providing insight into the tau neutrino cross section, as well as probing non-unitary neutrino mixing.

The analysis is based on the minimization of a binned log-likelihood ratio comparing model predictions with observed event counts. The detector response is estimated using detailed Monte Carlo simulations that are specific to the present detector geometry.

A new analysis is currently in preparation, harnessing the further deployment of more strings, providing an expanded detector sub-array and increasing the exposure to up to 1.7 Mt-yr. This update introduces new challenges, such as the characterization of the larger data-set and the transition to a new software framework for the statistical calculations. In my talk I will be presenting preliminary insights on atmospheric tau neutrino appearance using the expanded data-set.

Keywords: KM3NeT; Neutrino Oscillation; Tau Neutrino