Higher-twist contributions, quantum chromodynamics, and inclusive meson photoproduction at highpT

We investigate higher-twist contributions to inclusive meson photoproduction in the context of perturbative QCD, demonstrating that the higher-twist subprocess $\gamma q\to \mathrm{Mq}$ contributes significantly to the inclusive cross section at large transverse momenta. The normalization of the subprocess is determined entirely by the meson electromagnetic form factor. We show that higher-twist effects are especially dramatic for $\rho$ production.