Variational calculation of the ppK(-) system based on chiral SU(3) dynamics

The ppK(-) system, as a prototype for possible quasibound (K) over bar nuclei, is investigated using a variational approach. Several versions of energy-dependent effective (K) over barN interactions derived from chiral SU(3) dynamics are employed as input, together with a realistic NN potential (Av18). Taking into account theoretical uncertainties in the extrapolations below the (K) over barN threshold, we find that the antikaonic dibaryon ppK(-) is not deeply bound. With the driving s-wave (K) over barN interaction the resulting total binding energy is B(ppK(-)) = 20 +/- 3 MeV and the mesonic decay width involving (K) over barN -> pi Y is expected to be in the range 40-70 MeV. Properties of this quasibound ppK(-) system (such as density distributions of nucleons and antikaon) are discussed. The Lambda(1405), as an I = 0 quasibound state of (K) over bar and a nucleon, appears to survive in the ppK(-) cluster. Estimates are given for the influence of p-wave (K) over barN interactions and for the width from two-nucleon absorption ((K) over bar NN -> YN) processes. With inclusion of these effects and dispersive corrections from absorption, the ppK(-) binding energy is expected to be in the range 20-40 MeV, whereas the total decay width can reach 100 MeV but with large theoretical uncertainties.