[en] Scientists from the LHCb experiment at the large hadron collider (LHC) in CERN have announced the discovery of a new particle named Ξ_cc⁺⁺. This particle being made up of 3 quarks is a baryon but it is the first baryon ever discovered containing 2 charmed quarks. Its mass equals 3261 MeV which is almost 4 times the proton mass. (A.C.)

[en] We describe the various techniques developed in the Fermilab Wideband Experiments, E687 and FOCUS, to reconstruct long-lived states. The techniques all involve modifications to standard tracking techniques and are useful to report for future experiments

[en] We present a minimal statistical model designed for the description of rare- hadron multiplicities in nucleus-nucleus collisions at energies below the threshold of the particle production in binary elementary collisions. Differences to more conventional canonical statistical model are explained. The minimal statistical model is applied to the description of multiplicity ratios involving Ξ hyperons, which are measured by the HADES collaboration at GSI-SIS. It is argued that the HADES data cannot be reproduced by the model based on the statistical equilibrium and the strangeness conservation. The data remain underpredicted even when inmedium potentials acting on hadrons are taken into account. This hints to non-equilibrium production of the Ξ hyperons and their continuous freeze-out. (paper)

No abstract available

[en] A scenario is given for the formation of Ξ^- states and the transitions to states with double-Λ in anticipation of observations, especially in the KEK-E224 experiment. First, the production cross sections of Ξ^- hypernuclear states by (K^-, K⁺) reactions are calculated within the framework of the distorted-wave impulse approximation. Next, the transition rates from Ξ^- hypernuclear states to possible double-Λ states are obtained, which are closely related to single- and double-Λ emissions after the Ξ^-p→ΛΛ conversion in nuclei. (author)

[en] The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the Ξ₅ pentaquarks and investigate the excited Ξ states. Specifically, the exotic Ξ₅^-- pentaquark will be sought by first reconstructing the Ξ^- particle through its weak decays, Ξ^- → π^-Λ and Λ → π^-. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction γD → ppπ^- was studied in order to correct the track measurements and covariance matrices of the charged particles. The Λ → pπ^- and Ξ^- → π^-Λ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly

[en] The strange hadronic matter with nucleon, Λ-hyperon and Ξ-hyperon is studied by using a chiral symmetry model in a mean-field approximation. The saturation properties and stabilities of the strange hadronic matter are discussed. The result indicates a quite large strangeness fraction (fs) region where the strange hadronic matter is stable against particle emission. In the large fs region, the Ξ component dominates, resulting in a deep minimum in the curve of the binding energy per baryon E_B versus the strangeness fraction fs will (E_B, fs) ≅ (-26.0 MeV, 1.23)

[en] We perform theoretical analysis on the structure and decay of a double-strangeness five-body system which consists of _ΛΛ⁵H and _≡⁵H states. In this S=-2 five-body system the thresholds of the tΛΛ channel and the α≡^- channel come closer with only 8.51 MeV difference. We treat both bound and resonant states of the three-body channels tΛΛ and tp≡^- by applying a complex rotation method. It is found that there is a bound _ΛΛ⁵H state with 6.3 MeV below the threshold of t+Λ+Λ. In the ≡^- channel a resonant _≡⁵H state appears at 1.7 MeV below the threshold of α+≡^-. Though the existence of this state is ensured by the Coulomb interaction, it is a 'halo' nuclear state rather than an atomic state as judged from its size. The conversion width of this state is 0.2 MeV which is extremely narrow. It is also found that ≡ mixing into the _ΛΛ⁵H ground state is small with 1.0 %. For the _ΛΛ⁵H state, the weak decay to the α+Σ^- final state produces a high mono-energetic Σ^- with branching ratio of 5.5 %. Thus the Σ^- with discrete energy would become a clear signature of the forming of the ΛΛ hypernucleus. (author)

[en] In these proceedings we discuss recent developments in the microscopic description of strange particle production in nuclear collisions. We put a special emphasis on the production of hypernuclei at the upcoming FAIR and NICA facilities as well as the deep sub threshold, ϕ and Ξ"- production yields measured with the HADES experiment. Employing new resonance decay channels we obtain a satisfactory description of ϕ and Ξ"- production in deep sub threshold Ar+KCl reactions. Our results implicate that no new medium effects are required to describe the rare strange particle production data from low energy nuclear collisions. (paper)

[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