Non-perturbative chiral approach to K(-)p ->gamma Y reactions

A recently developed nonperturbative chiral approach to describe the S=-1 meson-baryon reactions has been extended to investigate the near threshold K−p→γΛ,γΣ0 reactions. With the parameters governed by chiral SU(3) symmetry, we show that the predicted branching ratios ΓK−p→γΛ/ΓK−p→all and ΓK−p→γΣ0/ΓK−p→all are close to the experimental values. The coupling with the η channels, which was shown to be important in the S=−1 meson-baryon reactions, is also found to be significant here. Our results are consistent with the interpretation of the Λ(1405) as a quasi-bound meson-baryon state as found in other similar chiral approaches.