Measurement of K^{-}p radiative capture to γΛ and γΣ^{0} for p_{K^{-}} between 514 and 750 MeV/c

Differential cross sections for K- radiative capture in flight on the proton, leading to the gamma Lambda and gamma Sigma(0) final states, have been measured at eight K- momenta between 514 and 750 MeV/c. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated K/pi beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Reggeplus- resonance approach. According to this analysis, the gamma Sigma(0) final state is dominated by hyperon- resonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the gamma Lambda final state, in contrast, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.