Measurement ofπ−π+Ratios in Photoproduction from Deuterium: The Dip Test of an Isotensor Current

The angular distributions of $\frac{{\pi }^{-}}{{\pi }^{+}}$ ratios in photoproduction from deuterium were measured for fourteen photon energies between 260 and 800 MeV. The energy dependence of ${\sigma }^{-}-{\sigma }^{+}$ near the ${\Delta }_{33}\mathrm{}\left(1236\right)\mathrm{}$ resonance region shows no dip structure, consistent with an absence of the isotensor term. The differential cross sections of $\gamma n\to {\pi }^{-}p$ at $k=350\mathrm{}$ MeV are considerably larger than the ones obtained from the inverse reaction ${\pi }^{-}p\to \gamma n$, but the two are in fair agreement at $k=500\mathrm{}$ MeV.