Target Mass Effects in Polarized Virtual Photon Structure Functions

Abstract

We study target mass effects in the polarized virtual photon structure functions $g_1^{\gamma }(x,Q^2,P^2)$, $g_2^{\gamma }(x,Q^2,P^2)$ in the kinematic region ${\Lambda }^2\ll P^2\ll Q^2$, where $-Q^2(-P^2)$ is the mass squared of the probe (target) photon. We obtain the expressions for $g_1^{\gamma }(x,Q^2,P^2)$ and $g_2^{\gamma }(x,Q^2,P^2)$ in closed form by inverting the Nachtmann moments for the twist-2 and twist-3 operators. Numerical analysis shows that target mass effects appear at large $x$ and become sizable near $x_{\max }(=1/(1+\frac{P^2}{Q^2}))$, the maximal value of $x$, as the ratio $P^2/Q^2$ increases. Target mass effects for the sum rules of $g_1^{\gamma }$ and $g_2^{\gamma }$ are also discussed.

Comments: 24 pages, LaTeX, 9 eps figures