On the relation between the proton-air cross section and fluctuations of the shower longitudinal profile

TL;DR

This paper discusses how to infer the proton-air cross section from fluorescence measurements of air showers, highlighting the challenges due to indirect observables, model dependence, and uncertainties in the analysis.

Contribution

It analyzes the relationship between shower profile fluctuations and the proton-air cross section, emphasizing the impact of model assumptions and measurement uncertainties.

Findings

Model dependence affects cross section estimates.

Reconstruction methods introduce systematic uncertainties.

Non-proton contamination impacts measurement accuracy.

Abstract

The current status and prospects of deducing the proton-air cross section from fluorescence telescope measurements of extensive air showers are discussed. As it is not possible to observe the point of first interaction, $X_ {\rm 1}$, directly, other observables closely linked to $X_{\rm 1}$ must be inferred from the measured longitudinal profiles. This introduces a dependence on the models used to describe the shower development. Systematic uncertainties arising from this model dependence, from the reconstruction method itself and from a possible non-proton contamination of the selected shower sample are discussed.