Constraining the energy-momentum tensor through the DVCS dispersion relation beyond leading power

Abstract

In this paper, we analyze and interpret the kinematic power corrections to deeply virtual Compton scattering dispersion relation. We show that the kinematic corrections at twist-four can be connected to other form factors of the energy-momentum tensor beyond the pressure distribution involved at leading power, namely the ones related to momentum and total angular momentum distributions. In the nucleon case, these corrections are not negligible at presently accessible virtualities. The deeply virtual Compton scattering (DVCS) subtraction constant becomes an experimental constraint on momentum distributions, pressure forces distributions, and total angular momentum distributions. Finally, we use continuum and lattice-QCD results to predict the expected size of the DVCS subtraction constant, and conclude that momentum distributions are responsible of roughly one-third of the experimental signal at Q2 = 2 GeV2.