We report a measurement of the radiative decay of the K*- (890). The width for the transition K*- → K- γ is 62 ± 14 keV. The resulting ratio of decay probabilities (K*0 → K0γ)/(K*- → K-γ), while consistent with predictions of certain quark models, does not agree with expectations from unbroken SU(3) symmetry.
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Radiative decay transitions between meson states provide some of the most straight-forward tests of SU(3) and of the quark model. Predictions for K *f (890) ~ K-+7, p ~ rt7 and K*0(890) ~ K07 decays are independent of assumptions concerning mixing between the singlet and octet members of the vector and pseudoscalar meson nonets. In addition, the small mass differences between K *0 and K*-+, and between K 0 and K +-, make the ratio of the radiative widths P(K* 0 -~ K07)/F(K * ~ -~ K~7) essentially independent of any phase-space factors. In the simple quark model, this ratio can be expressed, using quark magnetic moments/~q, as Research supported by the US Department of Energy, The National Science Foundation and by funds from the Uni-versities of Minnesota and Rochester.