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accurate determination of the longitudinal cross section needed for the extraction of the pion from factor feasible. 

In the π − channel the contribution of the tranverse and interference cross sections is predicted to be much smaller. As one can see in Figure 24 the π − electro- production cross section is largely longitudinal (dashed curves). If true this may provide a complimentary and probably more reliable access to the pion form factor from exclusive π − electroproduction off the deuteron target. 

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In summary, a description of exclusive charged pion electroproduction ( e, e ′ π ± ) off nucleons at high energies is proposed. Following a two-component hadron-parton picture of Refs. [25, 27] the model combines a Regge pole approach with residual effects of nucleon resonances. The contribution of nucleon resonances has been assumed to be dual to direct partonic interaction and therefore de- scribes the hard part of the model cross sections. The resonance/partonic effects are taken into account us- ing a Bloom-Gilman connection between the exclusive hadronic form factors and inclusive deep inelastic struc- ture functions. In the soft hadronic sector the exchanges of π (140), vector ρ (770) and axial-vector a$_{1}$ (1260) and b$_{1}$ (1235) Regge trajectories have been considered. 

We have shown that with only a few physical assump- tions a quantitative description of exclusive π + and π − electroproduction data can be achieved in a large range of ( Q $^{2}$, W ) from JLAB to DIS region at HERMES. In particular, the l/t partial longitudinal, transverse and interference cross sections measured at JLAB and DESY 

## XIV. SUMMARY 

