Muon puzzle in ultra-high energy EASs according to Yakutsk array and Auger experiment data

The lateral distribution of particles in extensive air showers from cosmic rays with energy above 1017 eV registered at the Yakutsk complex array was analyzed. Experimentally measured particle densities were compared to the predictions obtained within frameworks of three ultra-high energy hadron interaction models. The cosmic ray mass composition estimated from the readings of surface-based and underground detectors of the array is consistent with estimations obtained from measurements of lateral distribution of the air showers Cherenkov light emission. A comparison was made with the results of direct measurement of the muon component performed at the Pierre Auger Observatory. It is demonstrated that the densities of muon flux measured at Yakutsk array are consistent with results of fluorescent light measurements and disagree with results on muons obtained at the Auger array.