Photoproduction of charm and production of muons in electromagnetic showers

In the literature there are large discrepancies in estimation of the contribution of charm to the production of muons by γ rays in the Earth's atmosphere. We have made detailed calculations of this process with allowance for the chain of reactions γN→c→D→μ, where c and D are the charmed quark and the D meson. The uncertainties of the calculation are estimated. It is shown that even according to an exaggerated estimate the contribution of charm does not exceed a few percent of the combined contribution of the processes γ+Z→Z+μ++μ-, γA→π→μ, γA→K→μ