Abstract

In detailed air shower simulations, the uncertainty in the prediction of shower observables for different primary particles and energies is currently dominated by differences between hadronic interaction models. With the results of the first run of the LHC, the difference between post-LHC model predictions has been reduced to the same level as experimental uncertainties of cosmic ray experiments. At the same time new types of air shower observables, like the muon production depth, have been measured, adding new constraints on hadronic models. Currently no model is able to consistently reproduce all mass composition measurements possible within the Pierre Auger Observatory for instance. Comparing the different models, and with LHC and cosmic ray data, we will show that the remaining open issues in hadronic interactions in air shower development are now in the pion-air interactions and in nuclear effects.

Highlights

  • Knowing the elemental composition of cosmic ray particles arriving at Earth is of crucial importance to understand the production and propagation of cosmic rays

  • If the physics is well described by a given hadronic model, the masses obtained from different observables should be consistent

  • We will focus on the three high energy models which were updated to take into account Large Hadron Collider (LHC) data at 7 TeV: QGSJETII-03 [24, 25] changed into QGSJETII-04 [26], EPOS 1.99 [27, 28] replaced by EPOS LHC (V3400) [29], and Sibyll 2.1 [30,31,32] updated to Sibyll 2.3 [33] all available since CORSIKA V7.5600 [34]

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Summary

Introduction

Knowing the elemental composition of cosmic ray particles arriving at Earth is of crucial importance to understand the production and propagation of cosmic rays. If the physics is well described by a given hadronic model, the masses obtained from different observables should be consistent This constraint is much stronger than the traditional test limiting the results to the range between proton and iron induced showers. This is satisfied in most of the cases, but none of the current models is able to give a fully consistent picture of the different observable within a given experiment [20,21,22]. We will take the example of the muon production depth (MPD) measured by the Pierre Auger Observatory [20] to see how air shower measurements can constrain hadronic interaction physics and can be used to solve the remaining open issues

Hadronic interaction models
EPOS model
QGSJETII model
Sibyll model
Model comparison
Cross section
Multiplicity
Diffraction and elasticity
Baryon and resonance production
Depth of maximum shower development
Muons at ground level
Findings
Summary
Full Text
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