Δi=12 rule and right-handed currents: Heavy-quark expansion and limitation on Zweig's rule

We reexamine and extend the analysis of the effects of right-handed currents on the ΔI=12 rule in nonleptonic decays. The Wilson coefficients and anomalous dimensions of new operators generated by right-handed currents are computed. We apply the recently developed techniques of heavy-quark expansion to the resulting effective weak Hamiltonian. We point out that the short-distance-enhanced operator (N̄LγμcLc̄Rγμ λR) is expected to have large matrix elements, contrary to the naive implication of Zweig's rule. This may well account for the ΔI=12 rule, if right-handed currents exist.