Angular Dependence of High-pTπ0Production

The ${\pi }^0$ inclusive cross section for c.m. production angles $\theta =90\mathrm{}°$ and $22°>~\theta >~5°$ at c.m. energies of $\sqrt{s}=23\mathrm{} \mathrm{and} 53$ GeV has been measured. This cross section is strongly dependent on both $\theta$ and $\sqrt{s}$ at small angles. The hypothesis of radial scaling is shown to be incapable of incorporating both $\theta$ and $\sqrt{s}$ dependence of the cross section. A recent quantum-chromodynamics calculation is in qualitative agreement with our results.