Aspects of Neutrino Interactions (Scattering at small $Q^2$- Region)

Abstract

The article begins with a description of chiral symmetry and its application to neutrino induced reactions. For small $Q^2$ (forward direction) the process is dominated by the amplitute with helicity zero where the pion pole disappears when multiplied with the polarization vector. The remaining part of the amplitude is determined by PCAC. For $E_\nu > 2$ GeV the computed cross sections are in good agreement with data. In coherent pion production we expect equal yields for neutrinos and antineutrinos a relation which for $E_\nu > 2$ GeV is fulfilled. We discuss specific features of the data and suggest methods for improving them by presenting new estimates for the incoherent background.