Longitudinal and transverse contributions to the threshold cross-section slope of single-pion electroproduction by a proton

The cross sections of inelastic electron scattering are measured near the threshold of single-pion production by a proton at k2=2.5, 3.5, 5.0 and 8.0 fm-2 in the polarization range of the virtual photon epsilon=0.3-0.9. The separation of the mod(Esub(0+))2 and k2mod(Ssub(0+))2 contributions to the cross-section slope at threshold is carried out and thus a new method of determining the Fsub(A) and Fsub(π) form factors is realized. The values for the axial mass and mean square radius of the pion are obtained. (Auth.)