Role of negative-parity resonances in the electromagnetic weakΣ+→pγdecay

Contributions from ${1/2}^{-}$ resonance poles to the parity-violating amplitude for ${\Sigma }^{+}\to p\gamma$ have been estimated. Two-quark weak transitions have been described in the framework of the Weinberg-Salam model including quantum-chromodynamics corrections. Weak matrix elements and photon emissions have been calculated using the MIT bag model. It has been shown that ${1/2}^{-}$ resonance poles give sizable contributions, which might provide an explanation of the experimental results.