$\Sigma$ Like Term in Pion Electroproduction Near Threshold

Abstract

Sum of the time component of $\Sigma$ term and the induced pseudo scalar term in axial current is shown to be the t-channel pion pole in Born terms for pion electroproduction near threshold. We also show that this $\Sigma$ term represents the charged pseudo scalar quark density matrix elements in nucleon and manifests itself in the $L_0^{+}$ amplitude on this reaction.

Comments: 16pages, latex, no figures, submitted to Nucl. Phys. A