Evidence for the Lorentz-Lorenz Effect in Low-Energy Pion-Nucleus Scattering

Abstract

We point out the relatively clean geometrical aspect of the Lorentz-Lorenz effect and use it to extract the strength of the effect from an analysis of the elastic scattering of 50-MeV ${\ensuremath{\pi}}^{+}$ on $^{16}\mathrm{O}$. We find that for a finite-range $\ensuremath{\pi}\ensuremath{-}N$ interaction there is strong evidence for the effect with a value $0.2<~\ensuremath{\xi}<~0.6$.