8,721 research outputs found

    Neutron Stars with Bose-Einstein Condensation of Antikaons as MIT Bags

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    We investigate the properties of an antikaon in medium, regarding itas a MIT bag. We first construct the MIT bag model for a kaon withσ∗\sigma^* and ϕ\phi in order to describe the interaction ofss-quarks in hyperonic matter in the framework of the modifiedquark-meson coupling model. The coupling constant gσ′BKg'^{B_K}_\sigmain the density-dependent bag constant B(σ)B(\sigma) is treated as afree parameter to reproduce the optical potential of a kaon in asymmetric matter and all other couplings are determined by usingSU(6) symmetry and the quark counting rule. With various values ofthe kaon potential, we calculate the effective mass of a kaon inmedium to compare it with that of a point-like kaon. We thencalculate the population of octet baryons, leptons and K−K^- and theequation of state for neutron star matter. The results show thatkaon condensation in hyperonic matter is sensitive to the ss-quarkinteraction and also to the way of treating the kaon. The mass andthe radius of a neutron star are obtained by solving theTolmann-Oppenheimer-Volkoff equation.Comment: 14 figure

    Structure in Supersymmetric Yang-Mills Theory

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    We show that requiring sixteen supersymmetries in quantum mechanical gauge theory implies the existence of a web of constrained interactions. Contrary to conventional wisdom, these constraints extend to arbitrary orders in the momentum expansion.Comment: 22 pages, LaTe

    K*{\Lambda}(1116) photoproduction and nucleon resonances

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    In this presentation, we report our recent studies on the K∗Λ(1116)K^*\Lambda(1116) photoproduction off the proton target, using the tree-level Born approximation, via the effective Lagrangian approach. In addition, we include the nine (three- or four-star confirmed) nucleon resonances below the threshold sth≈2008\sqrt{s}_\mathrm{th}\approx2008 MeV, to interpret the discrepancy between the experiment and previous theoretical studies, in the vicinity of the threshold region. From the numerical studies, we observe that the S11(1535)S_{11}(1535) and S11(1650)S_{11}(1650) play an important role for the cross-section enhancement near the sth\sqrt{s}_\mathrm{th}. It also turns out that, in order to reproduce the data, we have the vector coupling constants gK∗S11(1535)Λ=(7.0∼9.0)g_{K^*S_{11}(1535)\Lambda}=(7.0\sim9.0) and gK∗S11(1650)Λ=(5.0∼6.0)g_{K^*S_{11}(1650)\Lambda}=(5.0\sim6.0).Comment: 2 pages, 2 figures, talk given at International Conference on the structure of baryons, BARYONS'10, Dec. 7-11, 2010, Osaka, Japa
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