Production of $\eta_c$ with two-photon decay in the GPM at the energies of NICA collider

The article discuss the production of $\eta_c$-mesons with decays into the photon pairs at the energy of the NICA collider, $\sqrt{s} =27$ GeV, in the generalized parton model and the leading order approximation of the perturbation theory of quantum chrodynamics. The hadronization of a $c\bar c$-pair into $\eta_c$-meson is described in the color singlet model and in the color evaporation model. In the calculation of the background process of two photon production with invariant mass near the mass of $\eta_c$-meson, we take into account direct as well as fragmentation mechanisms of the prompt photon production. The results of calculations are compared with predictions of the collinear parton model. We study the signal/background ratio as a function of the different kinematical variables.