Few-body approach to the structure of (K)over-bar-nuclear quasibound states

The structure of light antikaon-nuclear quasibound states, which consist of an antikaon ((K) over barK= K-,(K) over bar (0)) and a few nucleons (N = p, n), such as (K) over bar NN, (K) over bar NNN, (K) over bar NNNN, and (K) over bar NNNNNN systems, is studied with full three- to seven-body calculations. Employing a realistic (K) over barN potential based on the chiral SU(3) effective field theory with the SIDDHARTA constraint, we show that the central nucleon densities of these systems increase when the antikaon is injected, by about factor of 2 at maximum. The (K) over bar NNNN system shows the largest central density, about 0.74 fm(-3) even with the phenomenological (K) over barN potential, which is not as high as those suggested in previous studies with approximate treatments of the few-body systems. We find that the spin of the ground state of the (K) over bar NNNNNN system depends on the strength of the (K) over barN attraction. Thus, the quantum number of the ground state can be another constraint on the (K) over barN interaction.