Energy dependence of color transparency

Abstract

A quantum-mechanical approach is used to study high-momentum-transfer reactions in which a nucleon is knocked out of a target nucleus. It is found that the nuclear interactions of the wave packet produced in such a hard interaction may cancel, so that the nuclear medium is transparent. Expressions for the effective wave-packet-nucleon interaction and the corresponding distorted waves are presented. An analysis of existing ($p, \mathrm{pp}$) data at beam momenta from about 5 to 12 GeV/c suggests that only the nucleon and Roper resonance components of the wave packet contribute to the scattering amplitude. The ($p, \mathrm{pp}$) data and our theory imply that color-transparency effects in the ($e, e^{\prime }p$) reaction may be significant at relatively low-momentum transfers of $Q^2\approx 3-6$ Ge${\mathrm{V}}^2$.