content_image/345192.jpg content_image/345193.jpg content_image/345195.jpg content_image/345194.jpg
where c q > 0 is the numerical constant. The value of the intercept in the relevant kinematical domain is α ( Q 2 = 4GeV $^{2}$) = 1 . 1 ÷ 1 . 2, The slope parameter α ′ can be fixed e.g. with the help of the form factor sum rule [39]: α ′ = 1 . $_{1 GeV}$− $^{2}$. 

The alluring possibility is to take advantage of the opportunities provided by the Abel transform tomography method and instead of modelling GPD quintessence function employ a model for the imaginary part of the elementary amplitude Im A ( ξ, t ). The real part of the elementary amplitude Re A ( ξ, t ) can be then computed with the help of GPD quintessence restored from Im A ( ξ, t ) using the tomography method. The important advantage of this approach is that the amplitude computed in this way possess proper analytic properties in ξ and automatically satisfies the fixed t dispersion relation with one subtraction in the variable ω = 1 ξ [33, 37]: 

<img src='content_image/345192.jpg'>

since the expression for Re A ( ξ, t ) in the dual parametrization through the GPD quintessence function is equivalent to the the dispersion relation (81). 

Let us introduce the following notations: Im A Q$_{0}$ and Im A N − Q$_{0}$ for the contributions to the imaginary part originating from Q$_{0}$ ( x, t ) and N ( x, t ) − Q$_{0}$ ( x, t ) respectively. Analogously for the D form factor we introduce the notations D Q$_{0}$ and D N − $^{Q$_{0}$}$. 

The leading singular behavior of Im A $^{Q$_{0}$}$( ξ, t ) computed from the Q$_{0}$ ( x, t ) corresponding to t -dependent PDF q ( x, t ) with the asymptotic behavior (80) is 

<img src='content_image/345193.jpg'>

where we define the function 

The contribution of Q$_{0}$ to the D form factor can be computed using 

<img src='content_image/345195.jpg'>

<img src='content_image/345194.jpg'>

The skewness effect in the model which includes only the contribution of Q$_{0}$ is given by the conformal ratio (75). In order to make skewness effect satisfy H1 measurements [41] we 

