Resonances in radiative hyperon decays - art. no. 054019

The importance of resonances for the radiative hyperon decays is examined i n the framework of chiral perturbation theory. Low lying baryon resonances are included into the effective theory and tree contributions to these deca ys are calculated. We find significant contributions to both the parity-con serving and parity-violating decay amplitudes and a large negative value fo r the asymmetry parameter in polarized Sigma(+) --> p gamma is found, in ag reement with the experimental result alpha(gamma)(p Sigma+) = -0.76 +/- 0.0 8. [S0556-2821(99)05305-9].