An effective field theory calculation of the parity violating asymmetry in (n)over-right-arrow+p→d+γ

Weak interactions are expected to induce a parity violating pion-nucleon coupling, h(pi-NN)((1)). This coupling should be measurable in a proposed experiment to study the parity violating asymmetry A(gamma) in the process (n)over-right-arrow + p --> d + gamma, We compute the leading dependence of A(gamma) on the coupling h(pi-NN)((1)) using recently developed effective field theory techniques and find an asymmetry of A(gamma) = +0.17 h(pi-NN)((1)) at leading order. This asymmetry has the opposite sign to that given by Desplanques and Missimer. (C) 1999 Published by Elsevier Science B.V. All rights reserved.