121,832 research outputs found

    Baryon Masses in the 1/N Expansion

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    The masses of baryons and heavy quark baryons are studied analytically in an expansion in 1/N, SU(3) flavor symmetry breaking and heavy-quark symmetry breaking. The measured baryon masses are in striking agreement with the 1/N hierarchy.Comment: Lattice 2000 (Spectrum

    Charm and Bottom Baryon Masses in the 1/N Expansion

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    The masses of heavy quark baryons are studied in an expansion in 1/N_c, SU(3) flavor symmetry breaking, and heavy-quark symmetry breaking. Very accurate model-independent mass relations are obtained for charm and bottom baryons.Comment: Proceedings of ICHEP2002, Amsterda

    Hyperfine Mass Splittings of Baryons Containing a Heavy Quark in Large N QCD

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    The hyperfine mass splittings of baryons containing a heavy quark are derived at leading order in large NN QCD. Hyperfine splittings either preserve or violate heavy quark spin symmetry. Previous work proves that the splittings which preserve heavy quark spin symmetry are proportional to J2{\bf J}^2 at order 1/N1/N, where JJ is the angular momentum of the light degrees of freedom of the baryon. This work proves that the splittings which violate heavy quark spin symmetry are proportional to J⋅SQ{\bf J} \cdot {\bf S_Q} at order 1/(NmQ)1/(N m_Q) in the 1/N1/N and 1/mQ1/m_Q expansions.Comment: (8 pages, no figures, uses harvmac), UCSD/PTH 93-2

    Baryon-Pion Couplings from Large-N QCD

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    We derive a set of consistency conditions for the pion-baryon coupling constants in the large-N limit of QCD. The consistency conditions have a unique solution which are precisely the values for the pion-baryon coupling constants in the Skyrme model. We also prove that non-relativistic SU(2Nf)SU(2N_f) spin-flavor symmetry (where NfN_f is the number of light flavors) is a symmetry of the baryon-pion couplings in the large-N limit of QCD. The symmetry breaking corrections to the pion-baryon couplings vanish to first order in 1/N1/N. Consistency conditions for other couplings, such as the magnetic moments are also derived.Comment: (12 pages, 2 figs, uses harvmac and uufiles), UCSD/PTH 93-1

    Light Quark Spin-Flavor Symmetry for Baryons Containing a Heavy Quark in Large N QCD

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    The couplings and interactions of baryons containing a heavy quark are related by light quark spin-flavor symmetry in the large NN limit. The single pion coupling constant which determines all heavy quark baryon-pion couplings is equal to the pion coupling constant for light quark baryons. Light quark symmetry relations amongst the baryon couplings are violated at order 1/N21/N^2. Heavy quark spin-flavor symmetry is used in conjunction with large NN light quark spin-flavor symmetry to determine the couplings of the degenerate doublets of heavy quark baryons.Comment: (14 pages, 2 figs, uses harvmac and uufiles), UCSD/PTH 93-1

    Large-N Baryons, Chiral Loops, and the Emergence of the Constituent Quark

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    Meson loop corrections to baryon axial currents are computed in the 1/N expansion. It is already known that the one-loop corrections are suppressed by a factor 1/N; here it is shown that the two-loop corrections are suppressed by (1/N)^2. To leading order, these corrections are exactly what would be calculated in the constituent quark model. Some applications are discussed

    Naturalness of the Coleman-Glashow Mass Relation in the 1/N_c Expansion: an Update

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    A new measurement of the Xi^0 mass verifies the accuracy of the Coleman-Glashow relation at the level predicted by the 1/N_c expansion. Values for other baryon isospin mass splittings are updated, and continue to agree with the 1/N_c hierarchy.Comment: 6 pages, revte

    Semiclassical Meson-Baryon Dynamics from Large-Nc QCD

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    The large-NcN_c limit of the meson-baryon effective Lagrangian is shown to reduce to a semiclassical field theory. A chiral bag structure emerges naturally in the Nc→∞N_c\rightarrow \infty limit. A possible connection between the chiral bag picture and the Skyrme model is discussed. The classical meson-baryon theory is used to reproduce the Mπ3M_\pi^3 non-analytic correction to the baryon mass obtained previously as a loop correction in chiral perturbation theory.Comment: (13 pages, 1 figure, uses harvmac and uufiles), UCSD/PTH 94-1

    Incidence of the WTO Anti-Discrimination Rules on Corporation Income Taxation

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    Many countries with free trade zones or export processing zones now exempt from corporate income taxation the income of firms exporting from these areas. The WTO has attempted to eliminate this exemption through its rules to promote the non-discrimination of fiscal systems with respect to export production. In particular, these rules do not allow countries to exempt the income of firms exporting from Free Trade Zones from corporate income taxation. This paper examines both theoretically as well as empirically the incidence of removing this corporate income tax exemption. The empirical analysis is carried out for the case of the Dominican Republic. The findings indicate that in the case of the Dominican Republic the removal of the corporate income tax exemption would inflict a burden on labour equal to about 6 times the amount of additional corporate tax revenue collected from the companies operating in its free trade zones.WTO, tax incidence, Free Trade Zones, corporate taxation

    Latin America and China—a new dependency?

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