Local muon density spectra at large zenith angles as a probe of high-energy hadronic interaction models

Experimental data on muon bundles at large zenith angles obtained with the Russian-Italian detector DECOR are analyzed in terms of a new phenomenological variable – local muon density at the observation point. Spectra of events in local muon density at various zenith angles are compared with CORSIKA-based simulations for different hadronic interaction models. The intensity of muon bundles near the horizon is significantly higher than expectations based on these models and fluorescence measurements of cosmic ray spectrum around .