Contributions of operators of twist two and higher in large n moments of structure functions

Abstract

Though high twist terms are becoming important as x→1, or equivalently, in large n moments, their detection in this regime in deep inelastic lepton scattering needs special caution. The high order terms in the twist two component are strongly dependent on n; one finds that at Q 2⪷Q 2 ∗∗≅Λ 2a k exp[α k( log n) 2−1 k ( 1+b k log n )] the perturbative expansion is invalid whereas higher twist terms are important at Q 2⪷Q ∗ 2 = Λ 2nC . Since Q ∗∗ 2 grows very fast with n the necessary requirement for any deep inelastic phenomenological analysis, namely Q ∗ 2⪢Q ∗∗ 2 , cannot hold for too large moments. The scheme dependence of a k , α k and b k is also discussed.