Deeply inelastic pions in the exclusive reaction $p(e,e'π^+)n$ above the resonance region

Kaskulov, Murat M.; Gallmeister, Kai; Mosel, Ulrich

Deeply inelastic pions in the exclusive reaction $p(e,e'π^+)n$ above the resonance region

Authors

Kaskulov, Murat M.

Gallmeister, Kai

Mosel, Ulrich

Description

A model for the $p(e,e'π^+)n$ reaction which combines an improved treatment of gauge invariant meson--exchange currents and hard deep--inelastic scattering (DIS) of virtual photons off nucleons is proposed. It is shown that DIS dominates and explains the transverse response at moderate and high photon virtualities $Q^2$ whereas the longitudinal response is dominated by hadronic degrees of freedom and the pion electromagnetic form factor. This leads to a combined description of the longitudinal and transverse components of the cross section in a wide range of photon virtuality $Q^2$ and momentum transfer to the target $t$ and solves the longstanding problem of the observed large transverse cross sections. The latter are shown to be sensitive to the intrinsic transverse momentum distribution of partons.
6 pages, 4 figures. published version