Air shower genealogy for muon production

TL;DR

This paper investigates the origins of muons in extensive air showers by tracing their genealogy through all interaction stages, aiming to understand discrepancies between observed muon content and simulations.

Contribution

It introduces a method using CORSIKA 8 to analyze the entire cascade history of muons, providing new insights into their production mechanisms.

Findings

Muons originate from multiple cascade stages, not just the first interaction.

Interactions at all energies cumulatively affect muon numbers and distribution.

Comparison with models highlights areas for improving hadronic interaction descriptions.

Abstract

Measurements of the muon content of extensive air showers at the highest energies show discrepancies compared to simulations as large as the differences between proton and iron. This so-called muon puzzle is commonly attributed to a lack of understanding of the hadronic interactions in the shower development. Furthermore, measurements of the fluctuations of muon numbers suggest that the discrepancy is likely a cumulative effect of interactions of all energies in the cascade. A feature of the air shower simulation code CORSIKA 8 allows us to access all previous generations of final-state muons up to the first interaction. With this technique, we study the influence of interactions happening at any intermediate stage in the cascade on muons depending on their lateral distance in a quantitative way and compare our results with predictions of the Heitler-Matthews model.