Dispersion relations of deeply virtual Compton scattering: Investigating twist-four kinematic power corrections

In this paper we include kinematic power corrections up to twist-four to the deeply virtual Compton scattering dispersion relation. We demonstrate that, both for (pseudo)scalar and spin- 1 / 2 targets, the formal expression of the n -subtracted leading-twist dispersion relations is preserved. However, the expression of the subtracted constants modified by the kinematic powers. Importantly, the minimal-subtracted dispersion relation for the helicity-conserving amplitude, previously thought to depend only on the Polyakov-Weiss D -term, now also depends on the double distributions F and K . These results are consistent with the ones obtained previously in the literature. Such a mixing may be critical for the Jefferson Lab kinematic range, as it is not suppressed for typical values of t and Q 2 in the valence region. We therefore expect a strong impact on the attempts to extract pressure forces from deeply virtual Compton scattering data.