$\rho -\omega$ Interference in the ${\pi }^{-}{\pi }^{+}$ Decay Mode of the Reaction ${\pi }^{-}+p\to (\rho ,\omega )+n$ at 2.3 $\frac{\mathrm{GeV}}{c}$

In a sample of 8300 events of the type ${\pi }^{-}+p\to {\pi }^{-}+{\pi }^{+}+n$ obtained from a hydrogen bubble chamber exposure, a strong sharp $\omega \to {\pi }^{-}+{\pi }^{+}$ peak is observed. Analysis indicates that this $\omega \to 2\pi$ decay interferes almost perfectly constructively with the prominent decay of ${\rho }^0\to {\pi }^{-}+{\pi }^{+}$. The interference phase is determined to be -15°±30°. This phase is consistent with predictions of $\pi -B$ degeneracy using Regge-pole methods.