K anti-K N molecule state with I=1/2 and J^P=1/2^+ studied with three-body calculation

Abstract

A K \bar{K} N system with I=1/2 and J^P=1/2^+ is investigated with non-relativistic three-body calculations by using effective \bar K N, K \bar K and KN interactions. The \bar K N interaction describes the Lambda(1405) as a \bar K N molecule, and the K\bar K interaction is adjusted to give f_0(980) and a_0(980) states as K \bar K molecules. The present investigation suggests that a bound K \bar K N state can be formed below the K \bar K N threshold (1930 MeV) with a 90 ~ 100 MeV width of three-hadron decays, which are dominated by K bar K N -> K pi Sigma and pi eta N. It is found that the K \bar K N state is a weakly bound hadron molecular state with a size larger than an alpha particle because of the repulsive KN interactions.