Consequences of a charge-symmetry breaking mechanism for the charge-asymmetry parameter Aπ(θ) of low-energy elastic πD scattering

The consequences of a charge-symmetry breaking mechanism provided by a gauge-generated three-body πd term involving Coulombic interaction for the asymmetry parameter Aπ(θ) of low-energy elastic πd scattering are studied in the form-factor formulation of the impulse approximation. Theory and experimental data are compared at Tπ = 65 MeV where several sets of experimental data exist. It is found that the effect of charge-symmetry breaking is of the same order of magnitude as that of Δ- and target-baryon mass differences and of the same sign, thus bringing theory and experiment into closer agreement. That agreement is more marked if one uses Weinbergʹs chiral lagrangian formulation of S-wave π- nuclear interaction rather than the phenomenological S-wave theory.