The isovector time-reversal-and parity-violating pion-nucleon coupling g_π~((1)) is uniquely sensitive to dimension-six interactions between right-handed light quarks and the Standard Model Higgs doublet that naturally arises in left-right symmetric models. Recent work has used the g_π~((1))-induced one-loop contribution to the neutron electric dipole moment d_n, together with the present experimental d_n bound，to constrain the CP-violating parameters of the left-right symmetric model. We show that this and related analyses are based on an earlier meson theory d_n computation that is not consistent with the powercounting appropriate for an effective field theory. We repeat the one-loop calculation using heavy baryon chiral perturbation theory and find that the resulting d_n sensitivity to g_π~((1)) is suppressed, implying more relaxed constraints on the parameter space of the left-right symmetric model. Assuming no cancellations between this loop contribution and other contributions, such as the leading order EDM low-energy constant, the present limit on dn implies |g_π~((1))| ?1.1× 10~(-10).
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