An Analysis of the Next-to-Leading Order Corrections to the g_T(=g_1+g_2) Scaling Function

We present a general method for obtaining the quantum chromodynamical radiative corrections to the higher-twist (power-suppressed) contributions to inclusive deep-inelastic scattering in terms of light-cone correlation functions of the fundamental fields of quantum chromodynamics. Using this procedure, we calculate the previously unknown ${\cal O}(\alpha_s)$ corrections to the twist-three part of the spin scaling function $g_T(x_B,Q^2) (=g_1(x_B,Q^2)+g_2(x_B,Q^2))$ and the corresponding forward Compton amplitude $S_T(\nu,Q^2)$. Expanding our result about the unphysical point $x_B=\infty$, we arrive at an operator product expansion of the nonlocal product of two electromagnetic current operators involving twist-two and -three operators valid to ${\cal O}(\alpha_s)$ for forward matrix elements. We find that the Wandzura-Wilczek relation between $g_1(x_B,Q^2)$ and the twist-two part of $g_T(x_B,Q^2)$ is respected in both the singlet and non-singlet sectors at this order, and argue its validity to all orders. The large-$N_c$ limit does not appreciably simplify the twist-three Wilson coefficients.Comment: 41 pages, 9 figures, corrected minor erro

Renormalon Model Predictions for Power-Corrections to Flavour Singlet Deep Inelastic Structure Functions

We analyze power corrections to flavour singlet deep inelastic scattering structure functions in the framework of the infrared renormalon model. Our calculations, together with previous results for the non-singlet contribution, allow to model the x-dependence of higher twist corrections to F_2, F_L and g_1 in the whole x domain.Comment: LaTeX, 25 pages, 8 eps figures included, one figure was added. Final version for publication in Nucl.Phys.