15 0 0.2 0.4 0.6 0.8 -t [GeV$^{2}$] 0 1 2 3 4 5 6 7 8 9 10 11 12 d U  /dt [ b/GeV 2 ] 0 0.2 0.4 0.6 0.8 1 -t [GeV$^{2}$] 0 1 2 3 Q$^{2 }$= 1.1 GeV 2 Q$^{2 }$= 2.17 GeV 2  = 0.55 Q$^{2 }$= 4 GeV 2  = 0.25 Q$^{2 }$= 2.2 GeV 2  = 0.27 Q$^{2 }$= 3 GeV 2  = 0.44 Q$^{2 }$= 4.7 GeV 2  = 0.26  = 0.49 W = 2.26 GeV W = 2.22 GeV W = 2.14 GeV W = 2.2 GeV W = 2.13 GeV W = 2.25 GeV  = 0.39 W = 2.25 GeV Q$^{2 }$= 3.9 GeV 2 JLAB JLAB FIG. 9: (Color online) The differential cross sections dσ$_{U}$/dt = dσ$_{T}$/dt + εdσ$_{L}$/dt in exclusive reaction p ( γ $^{∗}$, π $^{+}$) n in the kinematics of the π -CT experiment at JLAB [52]. The square symbols connected by solid lines describe the model results. The discontinuities in the curves result from the different values of ( Q $^{2}$, W, ε ) for the various − t bins. The dash-dotted and dashed curves describe the contributions of the longitudinal εdσ$_{L}$ and transverse dσ$_{T}$ cross sections, respectively, to the total unseparated cross sections (solid curves) for the the lowest and highest average values of Q 2 = 1 . 1 GeV 2 and Q 2 = 4 . 7 GeV $^{2}$. formed for values of ( Q $^{2}$, W ) corresponding to the first − t bin [2, 4]. The notations for the curves are the same as in Figure 6. In these calculations we used the value of Λ 2 γππ = 0 . 4 GeV $^{2}$. Also here we find a pronounced resonance contribution in dσ$_{T}$/dt , dσ$_{TT}$/dt and dσ$_{LT}$/dt . The slope and magnitude of dσ$_{L}$/dt at forward angles are also affected by the resonances. of the π -exchange and dash-dotted curves do not account for the resonances. The upper set of solid, dashed and dash-dotted curves belongs to the higher value of ε . In Figure 9 we confront the result of our calculations with the new JLAB p ( γ ∗ , π $^{+}$) n data [52] for unsepa- rated cross sections dσ$_{U}$/dt , see Eq. (6), at values of W ≃ 2 . 2 ÷ 2 . 4 GeV and for different values of ( Q $^{2}$, ε ) bins. The square symbols connected by solid lines describe the model results. The discontinuities in the curves result from the different values of ( Q $^{2}$, W, ε ) for the various − t bins. The data are very well reproduced by the present model in the measured Q 2 range from Q 2 ≃ 1 GeV 2 up to 5 GeV $^{2}$. In Figure 9 we also show the contribu- tions of the longitudinal εdσ$_{L}$ (dash-dotted curves) and transverse dσ$_{T}$ (dashed curves) cross sections to the to- tal unseparated cross sections (solid curves) for the low- est and highest average values of Q 2 = 1 . 1 GeV 2 and Q 2 = 4 . 7 GeV $^{2}$. The cross sections at high values of Q 2 are flat and totally transverse. At forward angles a strong An extraction of l/t partial differential cross sections requires besides the Rosenbluth separation a fit of dif- ferent harmonics in the azimuthal φ -angle distribution of the measured unseparated double differential cross sec- tions. In the actual experiment one measures d $^{2}$σ/dtdφ for two different ε bins. In Figure 8 we show the φ de- pendence of 2 πd $^{2}$σ/dtdφ in the reaction p ( γ ∗ , π $^{+}$) n at fixed − t and two (high and low) values of ε . This is a representative example of φ -dependent exclusive cross sections. In Figure 8 the solid curves are the model re- sults and experimental data are from [1–3]. As in Fig- ures 6 the dashed curves correspond to the contribution