10.1007/s11450-008-3016-1

Abstract

It is shown that, under kinematical conditions of quasielastic knockout, the differential cross section for the exclusive process p(e, e'{pi}{sup +})n induced by longitudinal virtual photons {gamma}*{sub L} changes its physical nature as the recoil momentum vertical bar k vertical bar of the spectator nucleon grows from values in the range vertical bar k vertical bar {approx} 0.1-0.4 GeV/c, which are typical in studying the pion cloud of the nucleon, to values around vertical bar k vertical bar {approx} 1 GeV/c. Calculations within the {sup 3}P{sub 0} quark microscopic model reveal that the amplitudes for the deexcitation of vector and pseudovector mesons via the processes {rho}{sup +} + {gamma}*{sub L} {sup {yields}} {pi}{sup +} and b{sub 1}{sup +} + {gamma}*{sub L} {sup {yields}} {pi}{sup +} become dominant here. Concurrently, the effective momentum distributions develop a substantial angular anisotropy of about 50% with respect to the angle between the momentum of the photon {gamma}*{sub L} and the recoil momentum of the spectator nucleon, the longitudinal differential cross sections undergoing respective changes. In this region, the energy of knock-on pions is expected to be about 5 GeV under conditions of quasielastic kinematics.