Extraction of the KK-bar isovector scattering length from pp -> d K^+ K-bar^0 data near threshold

Abstract

The results of a recent experiment measuring the reaction pp -> dK^+ \bar K^0 near threshold are interpreted in terms of a spectator model that encapsulates the main features of the observed K^+ \bar K^0 invariant mass distribution. A chi^2 fit to this data leads to an imaginary part of the isovector scattering length in the K \bar K channel of Im(a_1) = -(0.63 \pm 0.24) fm. We then use the Flatte representation of the scattering amplitude to infer a value Re(a_1) = -(0.02 \pm 0.02) fm for the real part under the assumption that scaling is approximately satisfied. We show further that it is not possible to exclude the effects of \pi^+\eta to K^+ \bar K^0 channel coupling within the context of our model.