One-loop matching for the twist-3 parton distribution $g_T(x)$

Perturbative matching relates the parton quasidistributions, defined by Euclidean correlators at finite hadron momenta, to the light-cone distributions which are accessible in experiments. Previous matching calculations have exclusively focused on twist-2 distributions. In this work, we address, for the first time, the one-loop matching for the twist-3 parton distribution function $g_T(x)$. The results have been obtained using three different infrared regulators, while dimensional regularization has been adopted to deal with the ultraviolet divergences. We present the renormalized expressions of the matching coefficient for $g_T(x)$ in the $\overline{\mathrm{MS}}$ and modified $\overline{\mathrm{MS}}$ schemes. We also discuss the role played by a zero-mode contribution. Our results have already been used for the extraction of $g_T(x)$ from lattice QCD calculations.

Figure 1

One-loop real diagrams contributing to both $g_T$ and $g_{T,\mathrm{Q}}$.

Figure 2

One-loop virtual diagrams contributing to both $g_T$ and $g_{T,\mathrm{Q}}$. The Hermitean conjugate diagrams of (2a) and (2d) are not shown.