Erlangen 2026 – scientific programme

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T: Fachverband Teilchenphysik

T 85: Cosmic Rays IV

T 85.2: Talk

Thursday, March 19, 2026, 16:30–16:45, KS 00.006

Pythia 8/Angantyr and CORSIKA 8: Muon Puzzle and tuning* — •Chloé Gaudu for the CORSIKA8 collaboration — Bergische Universität Wuppertal, Gaußstraße 20, 42119 Wuppertal

The field of air-shower physics seeks to understand the development of cosmic-ray interactions with the Earth’s atmosphere. A key challenge in this field is the discrepancy in the muon content of extensive air showers (EAS), widely referred to as the “Muon Puzzle”, observed by cosmic-ray experiments when comparing to predictions from commonly used hadronic interaction models. This puzzle might stem from limitations in modeling high-energy hadronic interactions, arising as model parameters are tuned to accelerator data probing lower energies than those relevant to EAS, thus requiring extrapolations into unmeasured phase space. With Pythia 8/Angantyr now fully integrated into the Corsika 8 particle-shower simulation code, analyses of EAS are feasible. Initial studies indicate that its default configuration fails to reproduce key measurements from the Pierre Auger Observatory. The Pythia 8/Angantyr model remains a promising candidate for shedding light on the Muon Puzzle, owing to its user-friendly tunability.
In this work, the first dedicated efforts to tune Pythia 8/Angantyr for air-shower physics using fixed-target measurements are presented. The tuned Pythia configuration is compared to its default configuration, to other hadronic interaction models used in cosmic-ray physics, and to existing experimental data, highlighting the impact of tuning on muon production and other relevant shower properties.*Supported by DFG (SFB 1491)

Keywords: Pythia; hadronic interaction; CORSIKA; muon puzzle; air shower