Next-to-leading order Q^2-evolution of the transversity distribution h_1(x, Q^2)

Abstract

We present a calculation of the two-loop anomalous dimension for the transversity distribution h_1(x,Q^2), ${\gamma }_n^{h(1)}$, in the MS scheme of the dimensional regularization. Due to the chiral-odd nature, h_1 does not mix with the gluon distributions, and thus our result is the same for the flavor-singlet and nonsinglet distributions. At small n (moment of h_1), ${\gamma }_n^{h(1)}$ is significantly larger than ${\gamma }_n^{f(1)}$ (the anomalous dimension for the nonsinglet f_1), but approaches ${\gamma }_n^{f(1)}$ very quickly at large n, keeping the relation ${\gamma }_n^{h(1)}>{\gamma }_n^{f(1)}$. This feature is in parallel to the relation between the one-loop anomalous dimension for f_1 and h_1.

Comments: 28 pages, Latex. 10 figures. Submitted for publication some time ago