We have determined the transparency of the nuclear medium to kaons from $A(e,e{}^{\prime }{K}^{+})$ measurements on ${}^{12}\mathrm{C}$, ${}^{63}\mathrm{Cu}$, and ${}^{197}\mathrm{Au}$ targets. The measurements were performed at the Jefferson Laboratory and span a range in four-momentum-transfer squared $Q^2=1.1–3.0\hspace{0.5em}{\mathrm{GeV}}^2$. The nuclear transparency was defined as the ratio of measured kaon electroproduction cross sections with respect to deuterium (${\sigma }^A/{\sigma }^D$). We further extracted the atomic number ($A$) dependence of the transparency as parametrized by $T=(A/2){}^{\alpha -1}$ and, within a simple model assumption, the in-medium effective kaon-nucleon cross sections. The effective cross sections extracted from the electroproduction data were found to be smaller than the free cross sections determined from kaon-nucleon scattering experiments, and the parameter $\alpha$ was found to be significantly larger than those obtained from kaon-nucleus scattering. We have included similar comparisons between pion- and proton-nucleon effective cross sections as determined from electron-scattering experiments and pion-nucleus and proton-nucleus scattering data.

• Received 21 March 2011

DOI:https://doi.org/10.1103/PhysRevC.84.015210