S=-2 strangeness production in pbar-4He annihilations at rest

Events with production of two K+ are observed in (p) over bar He-4 annihilations at rest. They are detected in annihilation reactions with four and five prongs and are interpreted to proceed via the following intermediate states: 2K(+)Sigma(-)Sigma(-)p(s) -> 2K(+)2 pi(-)(2np(s)), 2K(+)Sigma(-)Sigma(+)n pi(-) -> 2K(+)pi(+)2 pi(-)(3n), 2K(+)Sigma(-)Lambda n -> 2K(+)p2 pi(-)(2n) and 2K(+)K(-)Lambda 2n -> 2K(+)K(-)p pi(-)(2n) with yields (lower limits) (0.17 +/- 0.04) x 10(-4), (2.71 +/- 0.47) x 10(-4), (1.21 +/- 0.29) x 10(-4) and (0.28 +/- 0.14) x 10(-4), respectively. They could be the signature of different production mechanisms like rescattering cascades and formation of quark-gluon plasma and of bound K-K--few nucleon systems. Even though the statistics is very small, signatures compatible with (K(-)K(-)nn) and (K(-)K(-)nnp) bound systems are discussed.