Observation of Color-Transparency in Diffractive Dissociation of Pions

Abstract

We have studied the diffractive dissociation into dijets of $500\mathrm{GeV}/c$ pions scattering coherently from carbon and platinum targets. Extrapolating to asymptotically high energies (where ${t}_{\mathrm{min}}\ensuremath{\rightarrow}0$), we find that when the per-nucleus cross section for this process is parametrized as $\ensuremath{\sigma}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}{\ensuremath{\sigma}}_{0}{A}^{\ensuremath{\alpha}}$, $\ensuremath{\alpha}$ has values near 1.6, the exact result depending on jet transverse momentum. These values are in agreement with those predicted by theoretical calculations of color-transparency.