Subleading corrections to parity violating pion photoproduction

Abstract

We compute the photon asymmetry $B_{\gamma }$ for near threshold parity violating (PV) pion photoproduction through sub-leading order. We show that sub-leading contributions involve a new combination of PV couplings not included in previous analyses of hadronic PV. We argue that existing constraints on the leading order contribution to $B_{\gamma }$ -- obtained from the PV $\gamma$-decay of ${}^{18}$F -- suggest that the impact of the subleading contributions may be more significant than expected from naturalness argumen

Comments: latex, 10 pages + 2 figures