Linking parton distributions to form factors and Compton scattering

Abstract

We relate ordinary and skewed parton distributions to soft overlap contributions to elastic form factors and large angle Compton scattering, using light-cone wave functions in a Fock state expansion of the nucleon. With a simple ansatz for the wave functions of the three lowest Fock states we achieve a good description of unpolarised and polarised parton distributions at large x, and of the data for the Dirac form factor and for Compton scattering, both of which can be saturated with soft contributions only. Large angle Compton scattering appears as a good case to investigate the relative importance of soft and hard contributions in exclusive processes which are sensitive to the end point regions of the nucleon wave function.

Continuity of generalized parton distributions for the pion virtual Compton scattering

“…8(b), we show the ζ dependence of Re(|M IJ | 2 ) for the gaussian type gauge boson wave function. In our model calculations, the DVCS squared amplitude 7 The skewedness parameter ξ in Ref. [21] is related to ζ by ξ = ζ 1− ζ 2 .…”

“…Although many recent theoretical endeavors [7][8][9][10][11][12] have been made in describing the GPDs in terms of LF wave functions, the task has not yet been satisfactory enough for practical calculations. In Refs.…”

Angular correlations in the double Drell-Yan process

“…The corresponding wave function depending on transverse momenta is a Gaussian with exponent −a 2 i k 2 i /x i , which was long ago proposed in [65] and is often used for the phenomenology of valence dominated quantities, see e.g. [66]. The relation between the light-cone wave functions in transverse momentum and transverse position representation can be found in [67].…”

Generalized Parton Distributions – theoretical review –

“…It was also argued that the amplitudes of the photon and meson photoproduction at large s and −t factorize to LO in terms of the inverse GPD moments 1 −1 dx q(x, ξ, t)/x [ 44,45,46]. For these processes also a perturbative treatment is used in which all valence partons are resolved via hard gluon exchanges [ 37].…”

“…Unfortunately, no factorization theorem could be established, since power corrections are uncontrolled. This problem has been attempted to resolve by the assumption that the virtuality of the partons in the initial and final state is always small [ 45].…”