Jw. Chen et Xd. Ji, Measuring the p-odd pion-nucleon coupling h(pi NN)((1)) in pi(+)-photoproton production near threshold, PHYS REV L, 86(19), 2001, pp. 4239-4242
We show that <(<gamma>)over right arrow>p --> pi (+)n in the threshold regi
on is an excellent candidate fur measuring the leading parity-violating pio
n-nucleon coupling h(pi NN)((1)) to an uncertainty of 20% if it has a natur
al size from dimensional analysis. The conclusion is based on a large unpol
arized cross section, a new low-energy theorem for the photon polarization
asymmetry at the threshold A(gamma)\(th) = root2 f(pi)(mu (p) - mu (n))h(pi
NN)((1))/g(A)m(N) similar to h(pi NN)((1))/2 and its strong dominance at f
orward and backward angles in the threshold region.