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We perform the calculations for the average ( Q $^{2}$, x ) val- ues in a given Q 2 and x$_{B}$ bin [57]. In Figure 14 instead of t , the quantity − t + t$_{min}$ is again used, where − t$_{min}$ 

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denotes the minimum value of − t for a given Q 2 and x$_{B}$ . The different panels in Figure 14 correspond to the differ- ent Q 2 and x bins. In the calculations we use the cut-off Λ 2 γππ = 0 . 46 GeV 2 in the pion form factor, Eq. (14). This is an optimal va lue needed for the description of high Q 2 data at JLAB. I n Figure 14 the model results which in- clude both the meson-exchange and r/p -contributions are shown by th e solid curves. The dash-dotted and the dashed curves co rrespond to the longitudinal ϵdσ$_{L}$/dt and to the transverse dσ$_{T}$/dt components of the cross section, respectively. T he dash-dash-dotted curves describe the results without the r/p -contributions. 

Interestingly, the physics of p ( γ ∗ , π $^{+}$) n in the DIS re- gion at HERM ES is essentially the same as at JLAB where the value of W is smaller (2 GeV vs. 4 GeV). Just contrary to the situation in the JLAB experiment the longitudinal cro ss section at HERMES determines the total differential cross section at small − t . As at JLAB the transverse cr oss section at HERMES is dominated by the r/p -mecha nism. At JLAB the transverse cross sec- tion is somewhat larger and at forward angles comparable with the longitu dinal cross section. In deeply virtual pro- duction of π + at HERMES the transverse cross section gets smaller at forward angles and the cross section is dominated by th e exchange of Regge trajectories, with π being the domin ant trajectory. The π -reggeon exchange contributes ma inly to the longitudinal response σ$_{L}$ and at low momentum transfer − t the variation of the forward cross section with Q 2 falls down as the electromagnetic form factor of the pion σ$_{L}$ ∝ ( F$_{γππ}$ ( Q $^{2}$))$^{2}$. In the off- forward region, − t > 1 GeV $^{2}$, because of the exponential 

