Quantum-chromodynamic corrections to meson-photon transition form factors

We calculate corrections to the hard-scattering amplitude for meson-photon transition form factors using dimensional regularization. Special attention is paid to the pseudoscalar case in which there is an ambiguity associated with ${\gamma }_5$. We resolve this ambiguity by appealing to axial-vector Ward identities and check the answer by using a four-dimensional regularization.