dispersive evaluation of the d-term form factor in deeply virtual compton scattering
;B. Pasquini;M.V. Polyakov;M. Vanderhaeghen
ACS chemical biology2014Vol. 739pp. 133-138
177
pasquini2014physicsdispersive
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 γ⁎γ→ππ subprocess and reconstructing the ππ→NN¯ 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. Keywords: Dispersion relations, Deeply virtual Compton scattering, Generalized parton distributions