0 1 2 3 4 5 6 7 8 9 10 Q$^{2}$ [GeV$^{2}$] 0 0.2 0.4 0.6 0.8 1 | F s (Q 2 , s) | 10 The dash-dotte d curves correspond to the gauged electric model with the on-shell Dirac form factor, see Eq. (15), and exchange of ρ (770) /a$_{2}$ (1320) and a$_{1}$ (1260) Regge trajectories. In Eq. (42) the electric form factor G p E decreases linea rly as a function of Q 2 with respect to the magnetic f orm factor G p M with a node around Q 2 0 ≃ 8 GeV 2 [49] pr ovided µ$_{p}$G p $_{E}$/G p M = 1 − Q $^{2}$/Q2$_{0}$. On the other hand up t o ≃ 5 GeV 2 the magnetic form factor is a dipole G p M = µ$_{p}$ / (1 + Q $^{2}$/ 0 . 71GeV $^{2}$) 2 where µ$_{p}$ = 2 . 793 is the magnetic moment of the proton. F p $_{1}$( Q $^{2}$) = G p $_{E}$( Q $^{2}$) /G p $_{M}$( Q $^{2}$) + Q $^{2}$/ 4 M 2 p 1 + Q $^{2}$/ 4 M 2 p G p $_{M}$( Q $^{2}$) , (42) FIG. 5: (Color online) The Q 2 dependence of the absolute value of the transition form factor | F$_{s}$ ( Q $^{2}$, s ) | (dashed curve), Eq. (43), at √$_{s}$ = 2 . 2 GeV. The solid curve describes the proton Dirac form factor, Eq (42), in comparison with data. As one can see, this model (dash-dotted curves) with the nucle on-pole (gauge invariance), vector and axial-vector me son-exchange Regge trajectories describes dσ$_{L}$/dt well an d grossly underestimates dσ$_{T}$/dt . Varia- tions of the cut -offs in the vector and axial-vector meson transition form factors do not improve the description. This preliminary comparison with data shows that being consistent with photoproduction the above simple exten- sion of the Regge model to electroproduction is not able to describe the data already at values of Q 2 as low as Q 2 ≃ 1 GeV $^{2}$. The discrepancies with data increase with increasing value of Q 2 [4]. experimental data here. An extension of the model to electroproduction is straightforward provided the Q $^{2}$-dependent transition form factors are defined. In Figure 4 we plot the trans- verse dσ$_{T}$/dt (left panel) and longitudinal dσ$_{L}$/dt (right panel) π + electroproduction data from JLAB and DESY (old data) scaled to the same values of Q 2 = 0 . 7 GeV 2 and W = 2 . 19 GeV [4]. The value of the momentum cut-off Λ$_{γππ}$ in the pion form factor, Eq. (14), is largely constrained by the magnitude of dσ$_{L}$/dt at forward an- gles. In the following the JLAB data are considered to be a guideline for fixing the model parameters. The dashed curves correspond to Λ 2 γππ = 0 . 46 GeV 2 and describe the contribution of the π -reggeon exchange only. The exchange of π dominates in dσ$_{L}$/dt at forward angles. However, in dσ$_{T}$/dt the π -exchange is not compatible with data and also vanishes in the forward direction. Next, consider the resonance contributions using the transition form factors as defined in Eq. (31). We have two parameters at hand: the parameter β which is related to the level density of states and a parameter ξ describ- ing the average cut-off in the resonance transition form factors. All the exclusive p ( γ ∗ , π $^{+}$) n and n ( γ ∗ , π − ) p elec- troproduction data considered in this work from JLAB, DESY and Cornell to DIS region at HERMES can be well described by the choice β = 3 and ξ = 0 . 4. The formulae for the transition form factors given in (31) and (32) can be integrated and yield (for β = 3) F$_{s}$ ( Q $^{2}$, s ) = s ln [ ξQ 2 M 2 p + 1 ] (2 ξQ 2 + s ) ( ξQ $^{2}$)2 − s ( ξQ 2 + s ) ξQ $^{2}$( ξQ 2 + M 2 $_{p}$) + ln [ s − M 2 p M 2 p ] − iπ ( ξQ 2 s + 1 ) $^{2}$( s 2 + 2 sM 2 p 2 M 4 p + ln [ s − M 2 p M 2 p ] − iπ ) , (43) F$_{u}$ ( Q $^{2}$, u ) = u ln [ ξQ 2 M 2 p + 1 ] (2 ξQ 2 + u ) ( ξQ $^{2}$)2 − u ( ξQ 2 + u ) ξQ $^{2}$( ξQ 2 + M 2 $_{p}$) + ln [ M 2 p − u M 2 p ] ( ξQ 2 u + 1 ) $^{2}$( u 2 + 2 uM 2 p 2 M 4 p + ln [ M 2 p − u M 2 p ]) . (44) In Figure 5 we plot the Q 2 dependence of the absolute value of the transition form factor | F$_{s}$ ( Q $^{2}$, s ) | (dashed