Parity Violating Photoproduction of $\pi^\pm$ on the $\Delta$ Resonance

Abstract

We analyze the real photon asymmetry $A^\pm_\gamma$ for the parity violating (PV) $\pi^\pm$ production on the $\Delta$ resonance via the reactions ${\vec \gamma} + p \to \Delta^+ \to \pi^+ + n$ and ${\vec \gamma} + d \to \Delta^0 + p \to \pi^- + p + p$. This asymmetry is nonvanishing due to a PV $\gamma N \Delta$ coupling constant, $d^\pm_\Delta$. We argue that an experimental determination of this coupling would be of interest for hadron dynamics, possibly shedding light on the S-wave/P-wave puzzle in the hyperon nonleptonic decays and the violation of Hara's theorem in weak radiative hyperon decays.