Fitting DVCS amplitude in moment-space approach to GPDs
We describe small-x_Bj deeply virtual Compton scattering measurements at HERA in terms of generalized parton distributions at leading order of perturbation series.
hep-ph↗
arXiv subjects
Dieter Mueller
Publications and source records attributed to Dieter Mueller.
Sum rules and dualities for generalized parton distributions: is there a holographic principle?
To leading order approximation, the physical content of generalized parton distributions (GPDs) that is accessible in deep virtual electroproduction of photons or mesons is contained in their value on the cross-over trajectory. This trajectory separates the t-channel and s-channel dominated GPD regions. The underlying Lorentz covariance implies correspondence between these two regions through their relation to GPDs on the cross-over trajectory. This point of view leads to a family of GPD sum rules which are a quark analogue of finite energy sum rules and it guides us to a new phenomenological GPD concept. As an example, we discuss the constraints from the JLab/Hall A data on the dominant u-quark GPD H. The question arises whether GPDs are governed by some kind of holographic principle.
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Refined analysis of photon leptoproduction off spinless target
We calculate the differential cross section for real photon electroproduction off spinless hadron which sevres as a main probe of the hadrons structure via the concept of generalized parton distributions. Compared to previously available computations performed with twist-three power accuracy, we exactly accounted for all kinematical effects in hadron mass and momentum transfer which arise from leptonic helicity amplitudes. We performed numerical studies of these kinematical effects and demonstrated that in the valence quark region and rather low virtualities of the hard photon which sets the factorization scale, the available approximate results significantly overestimate the cross section rates in comparison to exact formulas.
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