Experimental Test of One-Pion Exchange and Partial Conservation of Axial-Vector Current in Proton-Nucleus Charge-Exchange Reactions at 144 MeV

Abstract

We have measured the differential cross sections of the ($p$,$n$) reaction on $^{6}\mathrm{Li}$, $^{12}\mathrm{C}$, and $^{14}\mathrm{N}$ to the ground state of the final nucleus ($\ensuremath{\Delta}J=1$, $\ensuremath{\Delta}I=1$, $\ensuremath{\Delta}P=0$) at ${E}_{p}=144$ MeV and $0\ifmmode^\circ\else\textdegree\fi{}<{\ensuremath{\theta}}_{\mathrm{lab}}<20\ifmmode^\circ\else\textdegree\fi{}$. We treat the nuclei as elementary particles, extract the initial-nucleus-pion-final-nucleus coupling constants, and compare them with predictions based on the partial conservation of axial-vector current hypothesis. The calculations, which have no free parameters, agree with the data for $^{6}\mathrm{Li}$ and $^{12}\mathrm{C}$, but not for $^{14}\mathrm{N}$.