Electromagnetic and weak form factors of nucleon and charged quasielastic scatterings of neutrino (antineutrino) and nucleon

Abstract

The study of electromagnetic and weak form factors of nucleon (charged quasielastic scatterings of neutrino (antineutrino) and nucleon) done in $70^\prime s$ and published in Chinese journals is reviewed. In the approach of the study antiquark components are introduced to the wave functions of nucleon and the study shows that the antiquark components of nucleon play an essential role in the EM and weak form factors of nucleon. The SU(6) symmetric wave functions of baryons in the rest frame ( s-wave in the rest frame) have been constructed. In these wave functions there are both quark and antiquark components. Using Lorentz transformations these wave functions are boosted to moving frame. In terms of effective Lagrangian these wave functions are used to study the EM and weak form factors of nucleon and $p \rightarrow \Delta$. The ratio $\mu_p G^p_E/G^p_M$, $G^n_E$, $G^n_M$, $G^*_M$, $E1+$ and $S1+$ of $p \rightarrow \Delta$ are predicted. The axial-vector form factors of nucleon is predicted to be $G_A(q^2)/G_A(0) = F^p_1(q^2)$, where the $F^p_1$ is the first Dirac form factor of proton. This prediction agrees with data very well. The pseudoscalar form factor of nucleon is predicted. The model predicts there are three axial-form factors for $p\rightarrow\Delta$ and two of them play dominant roles. The cross sections of $\nu_\mu + n \rightarrow p + \mu^-\;\;\bar{\nu}_\mu + p \rightarrow n + \mu^+$, $\Delta S = 1$ quasielastic neutrino scatterings, and $\nu_\mu + p \rightarrow \Delta^{++} + \mu^-$ are predicted. Theoretical results are in agreement with data. The study shows that antiquark components of baryons play an essential role in understanding nucleon structure.