Helicity-flip off-forward parton distributions of the nucleon

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Abstract
We identify quark and gluon helicity-flip distributions defined between nucleon states of unequal momenta. The evolution of these distributions with a change of renormalization scale is calculated in the leading-logarithmic approximation. The helicity-flip gluon distributions do not mix with any quark distribution and are thus a unique signature of gluons in the nucleon. Their contribution to the generalized virtual Compton process is obtained both in the form of a factorization theorem and an operator product expansion. In deeply virtual Compton scattering, they can be probed through the distinct angular dependence of the cross section.