13,962 research outputs found

    Baryonic Resonances from the Interactions of the Baryon Decuplet and Meson Octet

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    We study SS-wave interactions of the baryon decuplet with the octet of pseudoscalar mesons using the lowest order chiral Lagrangian. We find two bound states in the SU(3) limit corresponding to the octet and decuplet representations. These are found to split into eight different trajectories in the complex plane when the SU(3) symmetry is broken gradually. Finally, we are able to provide a reasonable description for a good number of 4-star 3/2{{3/2}}^- resonances listed by the Particle Data Group. In particular, the Ξ(1820)\Xi(1820), the Λ(1520)\Lambda(1520) and the Σ(1670)\Sigma(1670) states are well reproduced. We predict a few other resonances and also evaluate the couplings of the observed resonances to the various channels from the residues at the poles of the scattering matrix from where partial decay widths into different channels can be evaluated.Comment: Contribution to the HADRON05 Conference, Rio de Janeiro, September 200

    The role of macroeconomic variables in sovereign risk

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    We use a dynamic term structure model with default and observable factors to study the interaction between macro variables and the Brazilian sovereign yield curve. We also calculate the default probabilities implied from the estimated model and the impact of macro shocks on those probabilities. Our results indicate that the VIX is the most important macro factor affecting short-term bonds and default probabilities, while the American short-term rate is the most important factor affecting the long-term default probabilities. Regarding the domestic variables, only the slope of the local yield curve presents significant explanatory power for the sovereign rates and default probabilities.

    Application of a Fractional Order Integral Resonant Control to increase the achievable bandwidth of a nanopositioner

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    The congress program will essentially include papers selected on the highest standard by the IPC, according to the IFAC guidelines www.ifac-control.org/publications/Publications-requirements-1.4.pdf, and published in open access in partnership with Elsevier in the IFAC-PapersOnline series, hosted on the ScienceDirect platform www.sciencedirect.com/science/journal/24058963. Survey papers overviewing a research topic are also most welcome. Contributed papers will have usual 6 pages length limitation. 12 pages limitation will apply to survey papers.Publisher PD

    Meson Exchange Currents in Kaon Scattering on the Lightest Nuclei

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    The K^+ scattering on the lightest nuclei, d, 3He and 4He is studied in the framework of multiple scattering theory. Effects from MEC tied to the K^+N-->KNpi reaction are evaluated. We found that at momentum transfers Q^2<0.5 (GeV/c)^2 contributions from MEC are much smaller than kaon rescattering corrections. This makes the conventional multiple scattering picture a reliable tool to study these reactions in this kinematical domain and to extract the K^+n scattering amplitude from the K^+d data. At larger transferred momentum MEC can become more relevant.Comment: revtex, 16 pages, 6 figure
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