Starting from a recent model where the Kbar N amplitudes are evaluated from
the chiral Lagrangians using a coupled channel unitary method, we evaluate here
the scattering length for K^- deuteron scattering. We find that the double
scattering contribution is very large compared to the impulse approximation and
that the charge exchange contribution of this rescattering is as large as the
sequential K^- scattering on the two nucleons. Higher order rescattering
corrections are evaluated using coupled channels with K^- and Kbar^0 within the
integral form of the fixed centre approximation to the Faddeev equations. The
higher order corrections involving intermediate pions and hyperons are found
negligible.Comment: 16 pages, 4 figures, revised version to appear in Nucl. Phys.
