Determination of nucleon effective number in reactions like photoproduction of charged pions on nuclei by absorption and inelastic cross sections

Incoherent inclusive processes like photoproduction of charged pions on nuclei A(γ, π±), A(π±, γ), and A(π±, e+e-) are considered. The minimum and maximum values of the effective number of nucleons in these reactions (corresponding to ''good'' and ''bad'' energy resolution) are shown to be determined in the region of Δ(1236)-resonance by the total inelastic cross section for interaction of pions with the given nucleus and by the absorption part of this cross section, respectively. Values of the effective number of nucleons, calculated in this way for 7Li and 12C nuclei at the kinetic pion energy 125-380 MeV, are compared with the available experimental values. One of the calculated values is used to find the cross section for the reaction π+n → e+e-p and the isovector nucleon form factor F1v via the cross section for the reaction 7Li(π+, e+e-)X at the 380 MeV kinetic pion energy