1. For a recent review of lepton-hadron scattering, seeF. J. Gilman:Proceedings of the XVII International Conference on High-Energy Physics (London, 1974), p. IV-149.
2. S. D. Drell andT. M. Yan:Phys. Rev. Lett.,24, 181 (1970);G. B. West:Phys. Rev. Lett.,24, 1206 (1970).
3. For a review of this expansion, seeS. Ferrara, R. Gatto andA. Grillo:Springer Tracts in Modern Physics, Vol.67 (Berlin, 1973);S. Ferrara, R. Gatto, A. Grillo andG. Parisi:Scale and Conformal Symmetry in Hadron Physics, edited byR. Gatto (New York, N. Y., 1973). In the above articles the conformal covariant light-cone expansion is formulated purely in an algebraic method which is independent of the special models of the Lagrangian field theory. However it is well known that, when the Lagrangian is scale invariant, it is also conformal invariant if there are no derivative couplings.
4. K. Bitar:Phys. Rev. D,6, 2250 (1972).
5. R. J. Crewther:Phys. Rev. Lett.,28, 1421 (1972).