Nuclear transparency and effective kaon-nucleon cross section from the A(e,e′K+) reaction

Abstract

We have determined the transparency of the nuclear medium to kaons from A(e,e[superscript ′]K+) measurements on [superscript 12]C, [superscript 63]Cu, and [superscript 197]Au targets. The measurements were performed at the Jefferson Laboratory and span a range in four-momentum-transfer squared Q[superscript 2]=1.1–3.0 GeV[superscript 2]. The nuclear transparency was defined as the ratio of measured kaon electroproduction cross sections with respect to deuterium (σ[superscript A]/σ[superscript D]). We further extracted the atomic number (A) dependence of the transparency as parametrized by T=(A/2)[superscript α-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 α 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.