paper

Dispersive evaluation of the D-term form factor in deeply virtual Compton scattering

arXiv:1407.5960 · doi:10.1016/j.physletb.2014.10.047

Abstract

We present a dispersive representation of the D-term form factor for hard exclusive reactions, using unsubtracted $t$ -channel dispersion relations. The $t$ -channel unitarity relation is saturated with the contribution of two-pion intermediate states, using the two-pion distributions amplitude for the $Î³^*Î³\rightarrow ÏÏ$ subprocess and reconstructing the $I ¨ I ¨ \to N N ˉ$ subprocess from available information on pion-nucleon partial-wave helicity amplitudes. Results for the D-term form factor as function of $t$ as well as at $t = 0$ are discussed in comparison with available model predictions and phenomenological parametrizations.

8 pages, 3 figures; improved presentation of the results; version to appear in Phys. Lett. B