Determination of the bar K⁰ d scattering length from the reaction pp to d bar K⁰ K^+

The real and imaginary parts of the \bar K^0 d scattering length are extracted from the \bar K^0 d mass spectrum obtained from the reaction pp \to d \bar K^0 K^+ measured recently at the Cooler Synchrotron COSY at J\"ulich. We extract a new limit on the K^- d scattering length, namely Im a \le 1.3 fm and |Re a| \le 1.3 fm. The limit for the imaginary part of the K^- d scattering length is supported by data on the total K^- d cross sections.