N16(O−) beta decay and weak axial vector meson exchange currents

We have measured the branching ratio for beta decay of the $J^{\pi }=0^{-}$ state at 120 keV in ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$ allowing us to infer a beta decay probability of ${\Lambda }_{\beta }=(0.45\mathrm{}\pm 0.05)$ ${\sec }^{-1\mathrm{}}$, in excellent agreement with recent calculations which include pion exchange corrections to the axial vector time component as an essential feature. When combined with the muon capture rate for the inverse reaction, our result implies $\frac{g_p}{g_A}=11\mathrm{}\pm 2$.