Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering

We present the first measurements of the $\overrightarrow{e}p\to ep\gamma$ cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The $Q^2$ dependence (from 1.5 to $2.3{\mathrm{GeV}}^2$) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate $Q^2$. The helicity-independent cross section is also measured at $Q^2=2.3{\mathrm{GeV}}^2$. We present the first model-independent measurement of linear combinations of GPDs and GPD integrals up to the twist-3 approximation.