New Measurements of the European Muon Collaboration Effect in Very Light Nuclei

Abstract

New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from $^{2}\mathrm{H}$, $^{3}\mathrm{He}$, $^{4}\mathrm{He}$, $^{9}\mathrm{Be}$ and $^{12}\mathrm{C}$ for $0.3<x<0.9$, ${Q}^{2}\ensuremath{\approx}3--6\text{ }\text{ }{\mathrm{GeV}}^{2}$. These data represent the first measurement of the EMC effect for $^{3}\mathrm{He}$ at large $x$ and a significant improvement for $^{4}\mathrm{He}$. The data do not support previous $A$-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment.