Decomposition of non-local light-cone operators into harmonic operators of definite twist Original Research Article

Bilocal light-ray operators which are Lorentz scalars, vectors or antisymmetric tensors, and which appear in various hard QCD scattering processes, are decomposed into operators of definite twist. These operators are harmonic tensor functions and their Taylor expansion consists of (traceless) local light-cone operators which span irreducible representations of the Lorentz group with definite spin j and common (geometric) twist (= dimension - spin). Some applications concerning the non-forward matrix elements of these operators and the generalization to conformal light-cone operators of definite twist is considered. The group theoretical background of the method has been made clear.