Understanding the Forward Muon Deficit in Coherent Pion Production

L. M. Sehgal

For any inelastic process $v_{\ell }+I\to {\ell }^{-}+F$ with $m_{\ell }=0$, the cross section at ${\theta }_{\ell }=0$ is given by Adler's PCAC theorem. Inclusion of the lepton mass has…