Faddeev approach to the reaction K- d → π Σn at pK=1GeV/c

The reaction K- d -> pi Sigma(n) is studied within a Faddeev-type approach, with emphasis on the specific kinematics of the E31 experiment at J-PARC, i.e., K-beam momentum of p(K) = 1 GeV/c and neutron angle of theta(n) = 0 degrees. The employed Faddeev approach requires as main input amplitudes for the two-body subsystems (K) over barN -> (K) over barN and (K) over barN -> pi Sigma. For the latter, results from recently published chiral unitary models of the (K) over barN interaction are utilized. The (K) over barN -> (K) over barN amplitude itself, however, is taken from a recent partial-wave analysis. Because of the large incoming momentum of the K-, the (K) over barN interaction is probed in a kinematical regime where those chiral potentials are no longer applicable. A comparison of the predicted spectrum for various pi Sigma charge channels with preliminary data is made and reveals a remarkable agreement as far as the magnitude and the line shape in general is concerned. Noticeable differences observed in the pi Sigma spectrum around the (K) over barN threshold, i.e. in the region of the Lambda (1405) resonance, indicate a sensitivity to the details of the employed (K) over barN -> pi Sigma amplitudes and suggest that pertinent high-precision data could indeed provide substantial constraints on the structure of the Lambda (1405).