Faddeev approach to the reaction K−d→πΣn at pK=1GeV

Abstract

The reaction K − d → π 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 θ n = 0 •. The employed Faddeev approach requires as main input amplitudes for the two-body subsystemsKN →KN andKN → π. For the latter, results from recently published chiral unitary models of theKN interaction are utilized. TheKN →KN amplitude itself, however, is taken from a recent partial-wave analysis. Because of the large incoming momentum of the K − , theKN interaction is probed in a kinematical regime where those chiral potentials are no longer applicable. A comparison of the predicted spectrum for various π 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 π spectrum around theKN threshold, i.e. in the region of the (1405) resonance, indicate a sensitivity to the details of the employedKN → π amplitudes and suggest that pertinent high-precision data could indeed provide substantial constraints on the structure of the (1405).

Toward establishing low-lyingΛandΣhyperon resonances with theK¯+d→π+

“…We thus can make predictions for investigating low-lying Y * resonances, including the long-standing problem associated with Λ(1405) that was also the focus of Refs. [31][32][33][34]. The data from the J-PARC E31 experiment [30] can then be used to test our results.…”

“…In particular, we would like to examine how the predicted cross sections can be used to distinguish the resonance parameters extracted within Model A and Model B employed in our calculations. Following the previous works [31][32][33] and justified by the special kinematics mentioned above, we assume that the scattering amplitude forKd → πY N includes the singlescattering (impulse) term and theK-exchange term, as illustrated in Fig. 3.…”

“…Thus, it is reasonable to assume that our results as well as the results of Refs. [31][32][33] account for the main features of theKd → πY N reaction and can be used to explore the feasibility of using the experiment at J-PARC to investigate the low-lying hyperon resonances.…”

“…An essential difference between this work and the previous works [31][32][33][34] is that we employ the (off-shell)KN reaction amplitudes generated from the DCC model developed in Ref. [2].…”

“…However, the models for the meson-baryon subprocesses employed in Refs. [31][32][33][34] were constructed by fitting only the K − p reaction data just near theKN threshold. To see how theseKN models can be used in the calculations, it is instructive here to examine the kinematics of theK-exchange mechanism illustrated in Fig.…”