Parity-violating pion-nucleon coupling h(pi NN)((1)) from pi(+)-electroproton production near the threshold

We study the possibility of measuring parity-violating pion-nucleon couplin g h(pi NN)((1)) from pi (+)-electroproton production in the threshold regio n. We calculate the electron-helicity asymmetry in terms of h(pi NN)((1)) a nd the Z-boson exchange between the electron and proton in leading-order he avy-baryon chiral perturbation theory. From the result, we demonstrate that the coupling can be determined to an accuracy of similar to 2 x 10(-7) in an experiment with incident electron energy 250 MeV, luminosity 10(38) s(-1 ) cm(-2), and a running time of 10(7) s. (C) 2001 Published by Elsevier Sci ence B.V.