Gauging the cosmic ray muon puzzle with the Forward Physics Facility

TL;DR

This paper proposes a phenomenological model to address the muon deficit in air shower simulations by linking it to strangeness production enhancements observed in collider data, and discusses future experimental tests at the FPF.

Contribution

It introduces a new model based on $ ext{pi} ext{--} ext{K}$ swapping probability to resolve the muon puzzle and outlines how FPF data can test this model.

Findings

The model can fit UHECR data with appropriate $F_s$ parametrization.

FPF experiments will be sensitive to the proposed $ ext{pi} ext{--} ext{K}$ swapping effects.

The approach connects collider strangeness data to cosmic ray shower modeling.

Abstract

We investigate the observed muon deficit in air shower simulations when compared to ultrahigh-energy cosmic ray (UHECR) data. Gleaned from the observed enhancement of strangeness production in ALICE data, the associated $\pi \leftrightarrow K$ swap is taken as a cornerstone to resolve the muon puzzle via its corresponding impact on the shower evolution. We develop a phenomenological model in terms of the $\pi \leftrightarrow K$ swapping probability $F_s$. We provide a parametrization of $F_s (E^{\rm (proj)}, \eta)$ that can accommodate the UHECR data, where $E^{\rm (proj)}$ is the projectile energy and $\eta$ the pseudorapidity. We also explore a future game plan for model improvement using the colossal amount of data to be collected by LHC neutrino detectors at the Forward Physics Facility (FPF). We calculate the corresponding sensitivity to $F_s$ and show that the FPF experiments will be able to probe the model phase space.