1,562 research outputs found

    Meta-stable Supersymmetry Breaking in an N=1 Perturbed Seiberg-Witten Theory

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    In this contribution, we discuss the possibility of meta-stable supersymmetry (SUSY) breaking vacua in a perturbed Seiberg-Witten theory with Fayet-Iliopoulos (FI) term. We found meta-stable SUSY breaking vacua at the degenerated dyon and monopole singular points in the moduli space at the nonperturbative level.Comment: Submitted for the SUSY08 proceedings, 3 pages, 4 figures, references added, minor change

    Neutrino self-interaction and MSW effects on the supernova neutrino-process

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    We calculate the abundances of 7^{7}Li, 11^{11}B, 92^{92}Nb, 98^{98}Tc, 138^{138}La, and 180^{180}Ta produced by neutrino (ν)(\nu) induced reactions in a core-collapse supernova explosion. We consider the modification by ν\nu self-interaction (ν\nu-SI) near the neutrinosphere and the Mikheyev-Smirnov-Wolfenstein effect in outer layers for time-dependent neutrino energy spectra. Abundances of 7^{7}Li and heavy isotopes 92^{92}Nb, 98^{98}Tc and 138^{138}La are reduced by a factor of 1.5-2.0 by the ν\nu-SI. In contrast, 11^{11}B is relatively insensitive to the ν\nu-SI. We find that the abundance ratio of heavy to light nucleus, 138^{138}La/11^{11}B, is sensitive to the neutrino mass hierarchy, and the normal mass hierarchy is more likely to be consistent with the solar abundances

    Pentaquark baryon production from photon-neuteron reactions

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    Extending the hadronic Lagrangians that we recently introduced for studying pentaquark Θ+\Theta^+ baryon production from meson-proton, proton-proton, and photon-proton reactions near threshold to include the anomalous interaction between γ\gamma and KKK^*K, we evaluate the cross section for Θ+\Theta^+ production from photon-neutron reactions, in which the Θ+\Theta^+ was first detected in the SPring-8 experiment in Japan and the CLAS experiment at Thomas Jefferson National Laboratory. With empirical coupling constants and form factors, and assuming that the decay width of Θ+\Theta^+ is 20 MeV, the predicted cross section is found to have a peak value of about 280 nb, which is substantially larger than that for Θ+\Theta^+ production from photon-proton reactions.Comment: 13 pages, 6 figure

    Pentaquark baryon production at the Relativistic Heavy Ion Collider

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    Production of pentaquark Θ+\Theta^+ baryons in central relativistic heavy ion collisions is studied in a kinetic model. Assuming that a quark-gluon plasma is produced in the collisions, we first determine the number of Θ+\Theta^+ produced from the quark-gluon plasma using a parton coalescence model, and then take into consideration its production and absorption in subsequent hadronic matter via the reactions KNΘKN\leftrightarrow\Theta, KNπΘKN\leftrightarrow\pi\Theta, and \piN\leftrightarrow\bar K\Theta. We find that although the final Θ+\Theta^+ number is affected by hadronic interactions, it remains sensitive to the initial number of Θ+\Theta^+ produced from the quark-gluon plasma, particularly in the case of a small Θ+\Theta^+ width as imposed by the K+NK^+N and K+dK^+d scattering data. Because of small baryon chemical potential in the hot dense matter produced in these collisions, the number of produced anti-Θ\Theta is only slightly smaller than that of Θ+\Theta^+.Comment: 6 pages, 2 figures, revised version, to appear in PL

    Net-charge probability distributions in heavy ion collisions at chemical freeze-out

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    We explore net charge probability distributions in heavy ion collisions within the hadron resonance gas model. The distributions for strangeness, electric charge and baryon number are derived. We show that, within this model, net charge probability distributions and the resulting fluctuations can be computed directly from the measured yields of charged and multi-charged hadrons. The influence of multi-charged particles and quantum statistics on the shape of the distribution is examined. We discuss the properties of the net proton distribution along the chemical freeze-out line. The model results presented here can be compared with data at RHIC energies and at the LHC to possibly search for the relation between chemical freeze-out and QCD cross-over lines in heavy ion collisions.Comment: 21 pages, 6 figure

    Comprehensive Analyses of the Neutrino-Process in the Core-collapsing Supernova

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    We investigate the neutrino flavor change effects due to neutrino self-interaction, shock wave propagation as well as matter effect on the neutrino process of the core-collapsing supernova. For the hydrodynamics, we use two models: a simple thermal bomb model and a specified hydrodynamic model for SN1987A. As a pre-supernova model, we take an updated model adjusted to explain the SN1987A employing recent development of the (n,γ)(n,\gamma) reaction rates for nuclei near the stability line (A100)(A \sim 100). As for the neutrino luminosity, we adopt two different models: equivalent neutrino luminosity and non-equivalent luminosity models. The latter is taken from the synthetic analyses of the CCSN simulation data which involved quantitatively the results obtained by various neutrino transport models. Relevant neutrino-induced reaction rates are calculated by a shell model for light nuclei and a quasi-particle random phase approximation model for heavy nuclei. For each model, we present abundances of the light nuclei (7^7Li, 7^7Be, 11^{11}B and 11^{11}C) and heavy nuclei (92^{92}Nb, 98^{98}Tc, 138^{138}La and 180^{180}Ta) produced by the neutrino-process. The light nuclei abundances turn out to be sensitive to the Mikheyev-Smirnov-Wolfenstein region around ONeMg region while the heavy nuclei are mainly produced prior to the MSW region. Through the detailed analyses of the numerical abundances, we find that neutrino self-interaction becomes a key ingredient in addition to the MSW effect for understanding the neutrino process and the relevant nuclear abundances. However, the whole results are shown to depend on the adopted neutrino luminosity scheme. Detailed evaluations of the nuclear abundances for the two possible neutrino mass hierarchies are performed with the comparison to the available meteorite analyses data. The normal mass hierarchy is shown to be more compatible with the meteoritic data
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