A new mechanism for the pion production in high energy reactions is suggested. It is related to a possibility for the direct production of the pions induced by instantons, topologically nontrivial gluonic excitations of the QCD vacuum. This mechanism does not require any fragmentation functions for the production of pseudoscalar mesons in high energy reactions with hadrons. We calculate the contribution of the new mechanism to the inclusive ${\pi }^0$-meson production in high energy proton-proton collisions. It is shown that it gives the dominant contribution to the inclusive cross sections in the few GeV region for the transverse momentum of the final pion with large rapidity. We discuss the possible applications of the new mechanism to the phenomenon of large spin effects observed in numerous high energy reactions and to particle productions in the relativistic heavy ion collisions.

• Received 24 March 2015

DOI:https://doi.org/10.1103/PhysRevD.92.034025