Muon problem in UHECR investigations. Journal of Physics: Conference Series Volume 409, Issue 1, 2013, Article number 012103

In many UHECR experiments, some excess of muons is observed, which cannot be explained in frame of the existing theoretical models of hadron interaction. Attempts of its explanation through a heavy mass composition of PCR contradict the results of Xmax measurements. Really, the excess of muons appears already at lower energies (1016 - 1017 eV), but in this domain it may be explained by the trend to a heavier mass composition, which is in a qualitative agreement with the galactic model of CR origin. The absence of heavy nuclei at energies of the order of 1018 eV requires to consider other possibilities of the appearance of muon excess, including changes of hadron interaction model. The actuality of the considered problem is connected with plans of future experiments in UHECR physics, in which the necessity of its solution must be taken into account.



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Indexed keywords

Heavy nucleus; Interaction model; Lower energies; Mass composition; Theoretical models