No abstract available

No abstract available

No abstract available

[en] In an experiment in the CERN SPS charged hyperon beam, a sample of 16,000 Ω^- decays was collected at an Ω^- momentum of 131 GeV/c. The Ω^- lifetime, the branching ratios and decay asymmetry parameters for the main decay modes were measured, giving: tausub(Ω^-) =(0.823 +- 0.015) x 10^-10s. For the rare decay modes the branching ratios were obtained. A sample of 32,000 Ψ^- decays collected under the same experimental conditions gave a new measurement of the Ψ^- lifetime: tausub(Ψ^-) = (1.652 +- 0.051) X 10^-10s. Combining the measurements of the present experiment with those obtained in a previous experiment in the SPS hyperon beam gives: tausub(Ω^-) = (0.823 +- 0.013) X 10^-10s. The experimental results are compared with theoretical calculations

[en] Short communication. 3 figs

[en] We will begin with the H particle, stranglets and strange matter since these proposed objects are a strong motivation for studying hypernuclei containing two strange quarks. The data on ΛΛ and Ξ hypernuclei will then be reviewed, as well as experiments in progress or scheduled. Many have contributed to the work that will be discussed, which took place primarily at KEK and BNL. At this time of transition, and anticipation of new experimental results and facilities, we take time to remember Carl Dover and Hiro Bando who contributed so much to this field

[en] In a diquark-diquark-antiquark picture of pentaquarks, we use two interpolating currents to calculate the mass of the recently measured Ξ^- state in the framework of QCD sum rules. We show that, even though yielding similar values for m _Ξ^- (and close to the experimental value), these currents differ from each other in what concerns the strength of the pole, convergence of the OPE and sensitivity to the continuum threshold parameter

[en] The calculation of the asymmetry parameter α_h in Ξ^-→Σ^-γ is argued to be less model dependent than in other similar decays. Including short- and long-distance contributions, we find α_h=-0.13±0.15

[en] We present the first measurements of the absolute branching fractions of ${\mathrm{\Xi }}_c^{+}$ decays into ${\mathrm{\Xi }}^{-}{\pi }^{+}{\pi }^{+}$ and $p{K}^{-}{\pi }^{+}$ final states. Our analysis is based on a data set of $(772\pm 11)\times {10}^{6}B\overline{B}$ pairs collected at the $\mathrm{{\rm Y}}(4S)$ resonance with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. We measure the absolute branching fraction of ${\overline{B}}^0\to {\overline{\mathrm{\Lambda }}}_c^{-}{\mathrm{\Xi }}_c^{+}$ with the ${\mathrm{\Xi }}_c^{+}$ recoiling against ${\overline{\mathrm{\Lambda }}}_c^{-}$ in ${\overline{B}}^0$ decays resulting in $\mathcal{B}({\overline{B}}^0\to {\overline{\mathrm{\Lambda }}}_c^{-}{\mathrm{\Xi }}_c^{+})=[1.16\pm 0.42(\mathrm{stat}.)\pm 0.15(\mathrm{syst}.)]\times {10}^{-3}$. We then measure the product branching fractions $\mathcal{B}({\overline{B}}^0\to {\overline{\mathrm{\Lambda }}}_c^{-}{\mathrm{\Xi }}_c^{+})\mathcal{B}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Xi }}^{-}{\pi }^{+}{\pi }^{+})$ and $\mathcal{B}({\overline{B}}^0\to {\overline{\mathrm{\Lambda }}}_c^{-}{\mathrm{\Xi }}_c^{+})\mathcal{B}({\mathrm{\Xi }}_c^{+}\to p{K}^{-}{\pi }^{+})$. Dividing these product branching fractions by ${\overline{B}}^0\to {\overline{\mathrm{\Lambda }}}_c^{-}{\mathrm{\Xi }}_c^{+}$ yields $\mathcal{B}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Xi }}^{-}{\pi }^{+}{\pi }^{+})=[2.86\pm 1.21(\mathrm{stat}.)\pm 0.38(\mathrm{syst}.)]\%$ and $\mathcal{B}({\mathrm{\Xi }}_c^{+}\to p{K}^{-}{\pi }^{+})=[0.45\pm 0.21(\mathrm{stat}.)\pm 0.07(\mathrm{syst}.)]\%$. Our result for $\mathcal{B}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Xi }}^{-}{\pi }^{+}{\pi }^{+})$ can be combined with ${\mathrm{\Xi }}_c^{+}$ branching fractions measured relative to ${\mathrm{\Xi }}_c^{+}\to {\mathrm{\Xi }}^{-}{\pi }^{+}{\pi }^{+}$ to set the absolute scale for many ${\mathrm{\Xi }}_c^{+}$ branching fractions.

[en] We review recent advances in the understanding of rare decays of particles in the (s,d,u) sector, with emphasis on the radiative decays of Kaons and Hyperons. From among the K-decays we concentrate on K_L^o→γ1⁺1^-, K_L^o→μ⁺μ^-, K_L^o→π^oe⁺e^- and K⁺→π⁺1⁺1^-, each of these having some particularly characteristic feature. After a general overview of radiative hyperon decays, we discuss the transitions Ω^-→ Ξ ^-γ and Ξ ^-→ Σ^-γ which are singled out for their potential in the verification of the flavour-changing s→dγ transition of the Standard Model. (author)