Whereas muon in extensive air shower is an observable sensitive to the primary composition and to the hadron interaction properties, the discrepancy between measured and estimated values has not been solved.
Using the new data of forward hadron from an accelerator experiment, a hadron interaction model (QGSJET II-04) is modified.
Air shower simulated with the modified interaction model develops quickly and produces more muons.
But these changes are not enough to solve the discrepancy.