991 research outputs found

    Etaprime and Eta Mesons with Connection to Anomalous Glue

    Full text link
    We review the present understanding of etaprime and eta meson physics and these mesons as a probe of gluon dynamics in low-energy QCD. Recent highlights include the production mechanism of eta and etaprime mesons in proton-nucleon collisions from threshold to high-energy, the etaprime effective mass shift in the nuclear medium, searches for possible eta and etaprime bound states in nuclei as well as precision measurements of eta decays as a probe of light-quark masses. We discuss recent experimental data, theoretical interpretation of the different measurements and the open questions and challenges for future investigation.Comment: Review, 25 pages, 11 figures, to appear in Reviews of Modern Physic

    On Quasibound N* Nuclei

    Full text link
    The possibility for the existence of unstable bound states of the S11 nucleon resonance N^*(1535) and nuclei is investigated. These quasibound states are speculated to be closely related to the existence of the quasibound states of the eta mesons and nuclei. Within a simple model for the N N^* interaction involving a pion and eta meson exchange, N^*-nucleus potentials for N*-3^3He and N*-24^{24}Mg are evaluated and found to be of a Woods-Saxon like form which supports two to three bound states. In case of N*-3^3He, one state bound by only a few keV and another by 4 MeV is found. The results are however quite sensitive to the N N^* π\pi and N N^* η\eta vertex parameters. A rough estimate of the width of these states, based on the mean free path of the exchanged mesons in the nuclei leads to very broad states with Γ\Gamma \sim 80 and 110 MeV for N*-3^3He and N*-24^{24}Mg respectively.Comment: Presented at the Jagiellonian Symposium on Fundamental and Applied Subatomic Physics, Cracow, Poland, June 2015; to be published in Acta Physica Polonica B (2016

    Proton spin structure and the axial U(1) problem

    Get PDF
    We emphasise the relation between the spin structure of the proton and the axial U(1) problem. New experiments motivated by the proton spin problem which could shed light on the nature of U(1) symmetry breaking in QCD are discussed.Comment: Invited talk at the Workshop on the Spin Structure of the Proton and Polarized Collider Physics, Trento (July 23-28, 2001), 6 pages, 1 figur

    Project of the underwater system for chemical threat detection

    Get PDF
    In this article we describe a novel method for the detection of explosives and other hazardous substances in the marine environment using neutron activation. Unlike the other considered methods based on this technique we propose to use guides forneutron and gamma quanta which speeds up and simplifies identification. Moreover, it may provide a determination of the density distribution of a dangerous substance. First preliminary results of Monte Carlo simulations dedicated for design of a device exploiting this method are also presented.Comment: 9 pages, 6 figure

    Summary of the COSY-11 Measurements of Hyperon Production

    Full text link
    The studies of hyperon production performed at COSY-11 are summarized. The results of the experiments in the reaction channels pp-->pK+Lambda, pp-->pK+Sigma0, and pp-->nK+Sigma+ are shown. Excitation functions fromthreshold up to about 90MeV excess energies have been evaluated with high precision for the Lambda and Sigma0 production. The Lambdap and Sigma0p final state interactions were extracted. The Sigma+ production was measured at 13 and 60 MeV excess energies.Comment: 8 pages, 4 figures, Talk given at Symposium on Meson Physics at COSY-11 and WASA-at-COSY, Cracow, Poland, 17-22 Jun 200

    Design of the SABAT system for underwater detection of dangerous substances

    Get PDF
    We present status of simulations used to design a novel device for the detection of hazardous substances in the aquatic environment using neutron activation. Unlike the other considered methods based on this technique we propose to use guides for neutron and gamma quanta which speeds up and simplifies identification. First preliminary results show that both the neutron guide and the γ\gamma ray guide increase the performance of underwater threats detection.Comment: Presented at the Jagiellonian Symposium of Fundamental and Applied Subatomic Physics, Krak{\o}w, 11.06.201

    Measurement of the invariant mass distributions for the pp -> ppeta' reaction at excess energy of Q = 16.4 MeV

    Get PDF
    The proton-proton and proton-eta' invariant mass distributions have been determined for the pp -> ppeta' reaction at an excess energy of Q = 16.4 MeV. The measurement was carried out using the COSY-11 detector setup and the proton beam of the cooler synchrotron COSY. The shapes of the determined invariant mass distributions are similar to those of the pp -> ppeta reaction and reveal an enhancement for large relative proton-proton momenta. This result, together with the fact that the proton-eta interaction is much stronger that the proton-eta' interaction, excludes the hypothesis that the observed enhancement is caused by the interaction between the proton and the meson

    Study of the Low Energy Dynamics in the ppK+K- System with the Cosy-11 Magnetic Spectrometer

    Get PDF
    The near threshold production of K+K- pairs in proton-proton collisions has been investigated at the cooler synchrotron COSY below and above the threshold for the \phi meson production. The experimental excitation function determined for the pp-->ppK+K- reaction differs from theoretical expectations including proton-proton final state interaction. The discrepancy may be assigned to the influence of K+K- or pK interaction. In this article we present distributions of the cross section for the pp-->ppK+K- reaction as a function of the invariant masses of two and three particle subsystems at excess energies of Q=10 MeV and 28 MeV.Comment: Presented at the Symposium on Meson Physics, Cracow, 01-04 October 200

    Heavy Hyperon--Antihyperon Production

    Get PDF
    Based on the experience from the production of anti-Lambda Lambda and anti-Sigma Sigma pairs at LEAR (experiment PS185) it is suggested to continue the investigations towards the heavier antihyperon--hyperon pairs anti-Xi Xi and anti-Omega Omega in view of: (1) the production dynamics of the heavier antihyperon--hyperon out of the anti-p p annihilation (2) a comparison of the (3s 3anti-s quark system) anti-Omega Omega to the (3 (anti-s s)) 3 phi meson production, where both systems have similar masses (3.345 and 3.057, respectively) and identical valence quark content. A systematic study of the antihyperon--hyperon production with increasing strangeness content is interesting for the following reasons: The anti-Omega Omega production is the creation of two spin 3/2 objects out of the two spin 1/2 anti-p p particles. Results of the PS185 experiments prove a clear dominance of the spin triplet anti-s s dissociation. In the Omega anti-Omega the three s-quarks (three anti-s quarks) are aligned to spin 3/2 each. If the three anti-s s pairs are now all in spin triplet configurations when created out of the gluonic interaction they should have spin parity quantum number as 3^- as long as Omega anti-Omega is created with relative L=0 angular momentum. The comparison of the Omega anti-Omega baryon pair to the phi phi phi three meson production (where the three anti-s s quark pairs might not but can be produced without relative correlation) would provide a unique determination of the intermediate matter state. Measurements of excitation functions and polarization transfers should be used to examine these gluon rich anti-p p --> anti-Omega Omega and anti-p p --> phi phi phi reaction channels. Such experiments should be performed at the PANDA detector at the FAIR facility of the GSI.Comment: 4 pages, 2 figures, Presented at LEAP05: International Conference on Low Energy Antiproton Physics, Bonn - Juelich, Germany, May 16-22, 200

    Kaon pair production close to threshold

    Get PDF
    The total cross section of the reaction pp->ppK+K- has been measured at excess energies Q=10 MeV and 28 MeV with the magnetic spectrometer COSY-11. The new data show a significant enhancement of the total cross section compared to pure phase space expectations or calculations within a one boson exchange model. In addition, we present invariant mass spectra of two particle subsystems. While the K+K- system is rather constant for different invariant masses, there is an enhancement in the pK- system towards lower masses which could at least be partially connected to the influence of the Lambda(1405) resonance.Comment: accepted for publication in Phys. Lett.
    corecore