A new observable in extensive air showers

TL;DR

This paper introduces a new observable, r_{mu e}, in extensive air showers that correlates with the shower maximum depth and can distinguish primary particle types with high accuracy, independent of hadronic models.

Contribution

The study demonstrates that the muon to electromagnetic component ratio at ground level serves as a reliable, model-independent indicator of shower development and primary particle identity.

Findings

r_{mu e} correlates with X_{max} in air showers

r_{mu e} distinguishes proton from iron primaries with 98% efficiency

Heavy quark production may cause anomalous r_{mu e} values

Abstract

We find that the ratio r_{mu e} of the muon to the electromagnetic component of an extended air shower at the ground level provides an indirect measure of the depth X_{max} of the shower maximum. This result, obtained with the air-shower code AIRES, is independent of the hadronic model used in the simulation. We show that the value of r_{mu e} in a particular shower discriminates its proton or iron nature with a 98% efficiency. We also show that the eventual production of forward heavy quarks inside the shower may introduce anomalous values of r_{mu e} in isolated events.