Scaling of single photon production in hadronic collisions

Scaling of single photon production in $pp$ and $p\overline{p}$ collisions is studied. It is empirically observed the available data scales $\sim \sqrt{s}/p_T^5$ for $x_T=2p_T/\sqrt{s} \leq 0.1$ and $\sim (\sqrt{s})^{3.3}/p_T^9$ for larger $x_T$. The NLO pQCD predictions for $pp$ collisions at $\sqrt{s}$ of 200 and 5500 GeV, relevant for RHIC and LHC energies are seen to closely follow this scaling behaviour. Implications for single photon production in heavy ion collisions are discussed.