Renormalization-group improved evolution of the meson distribution amplitude at the two-loop level

Abstract

We discuss the two-loop evolution of the flavor-nonsinglet meson distribution amplitude in perturbative QCD. After reviewing previous two-loop computations, we outline the incompatibility of these solutions with the group property of the renormalization-group transformations. To cure this deficiency, we compute a correction factor for the non-diagonal part of the meson evolution equation and prove that with this modification the two-loop solution conforms with the group properties of the renormalization-group transformations. The special case of a fixed strong coupling (no Q^2 dependence) is also discussed and comparison is given to previously obtained results.

23 pages, 9 figures, Revtex4 class. Discussion of relation to conformal symmetry enlarged and references added. Matches version to be published in Nucl. Phys. B

References in corpus (2)

• Pion form factor in QCD: From nonlocal condensates to NLO analytic perturbation theory
• Deep inside the pion. Reconciling QCD theory with data

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