with results of the INC simulation (pink hatched areas). Separately shown are INC predictions for the number of protons and charged pions in the C-arm. There is a qualitative agreement of the INC simulation with the experimental data for the case of the subthreshold beam energy, $E_e=650$ MeV. Meanwhile, in the case of $E_e=850$ MeV there is a clear excess of the experimentally observed events over the simulation results in two velocity regions closely corresponding to the kinematics of $\eta$-mesic nuclei decays with emission of $\pi N$ and $NN$ correlated pairs, Eqs. (\[kinema-piN\]) and (\[kinema-NN\]).

Knowing from the INC simulations that the ”normal” (without $\eta$-mesic nuclei) dynamics of the considered reaction does not yield a sufficient amount of protons and pions with the velocities of about $\beta_C\sim 0.7$, we interpret the found anomaly at $\beta_C\sim 0.7$ as a result of production of low-energy $\eta$-mesons followed by their two-nucleon annihilation.

The energy resolution of the experimental setup is not sufficient to say whether an essential part of these $\eta$-mesons is produced in the bound state, but theoretical arguments discussed in above make such a statement plausible.

Concerning the excess of pions with $\beta_C\simeq 0.95$, this feature is in agreement with our 