  Using some techniques of conformal field theories, we find a closed
expression for the contribution of leading twist operators and their
descendants, obtained by adding total derivatives, to the operator product
expansion (OPE) of two electromagnetic currents in QCD. Our expression resums
contributions of all twists and to all orders in perturbation theory up to
corrections proportional to the QCD $\beta$-function. At tree level and to
twist-four accuracy, our result agrees with the expression derived earlier by a
different method. The results are directly applicable to deeply-virtual Compton
scattering and, e.g., $\gamma\gamma^\ast$ annihilation in two mesons. As a
byproduct, we derive a simple representation for the OPE of two scalar currents
that is convenient for applications.
