Test of the Quark Parton Model with Data from Electroproduction of Pions

We have measured the relative cross sections of ${\pi }^{+}$ and ${\pi }^{-}$ electroproduction from protons and neutrons, and combined them in a way which permits a new, detailed comparison with the quark parton model of the nucleon. We confirm the expected behavior with $\frac{1}{\omega }$ of the quark charge ratio and the quark fragmentation function.