Neutron spectra from the low-energy $\boldsymbol{K^{-} + d \to \pi + \Sigma + n}$ reaction and the shape of the $\boldsymbol{\Lambda(1405)}$ resonance

Abstract

Neutron spectra from the low-energy K − + d → π + + n reaction were calculated. This quantity should carry information on the (1405) resonance. We checked the possibility of extracting this information.Keywords Kaonic nuclear cluster · (1405) resonanceThe (1405) resonance plays a central role in low-energy kaon-nuclear physics. Being a manifestation of the assumed attraction between negative antikaons and nucleons, its observability and properties are crucial for the possible existence of antikaonic nuclear states (clusters). Its structure and origin are subject of sometimes passionate discussions among representatives of different opinions on this issue. This state can not be reached in two-body reactions due to the fact, that it lies below the K − p threshold. Therefore it can be observed only in reactions involving n ≥ 3 particles, the simplest of which is probably the following one:We investigated reaction (1) trying to find a signature of (1405) resonance in the neutron spectrum. The treatment is based on the coupled particle-channels Faddeev-AGS equations for theKNN ↔ π N three-body system. The equations for the system were discussed in detail earlier [1], however, it was necessary to write additional formulae forThe support from the OTKA grant T71989 is gratefully acknowledged.J. Révai (B)