Study of the properties of pions in the fragmentation region of the target nucleon at a primary momentum 69 GeV/c

Characteristics of charged pions emitted backward (theta > or = 90/sup 0/) in the lab in proton-proton interactions recorded in the liquid-hydrogen bubble chamber Mirabelle at a primary momentum 69 GeV/c are analyzed. The experimental results on the value of the average transverse momentum, angular distributions, and distributions in the Feynman variable x for these pions indicate that they are generated in the decay of isobars. A new method of estimation of the upper limit of the cross section for production of baryon resonances in inclusive reactions is discussed.