Study of the reaction ppbold-arrow-left-rightdπ+ at low pion energies

In the present paper we discuss the need to take into account off-mass-shell behavior of the s-wave πN amplitude with one pion off the mass shell in the calculations of the cross sections for pion production in nucleon--nucleon collisions near threshold and in the calculations of similar processes in nuclear matter in order to make it possible to interpret the parameters of the pion-nucleus optical potential. The total cross sections and angular distributions for the ppbold-arrow-left-rightdπ+ reaction, and also the analyzing power for the p-arrow-rightpbold-arrow-left-rightdπ+ reaction at low pion energies (eta = q/sub π//μ/sub π/<1), are calculated taking into account the one- and two-nucleon mechanisms of pion production (absorption). In the approximation of s- and p-wave pions, reasonable agreement with experimental data in the region eta≤0.5 is achieved