48,948 research outputs found

    Level-One Representations and Vertex Operators of Quantum Affine Superalgebra Uq[gl(NN)^]U_q[\hat{gl(N|N)}]

    Get PDF
    Level-one representations of the quantum affine superalgebra Uq[gl(NN)^]U_q[\hat{gl(N|N)}] associated to the appropriate non-standard system of simple roots and qq-vertex operators (intertwining operators) associated with the level-one modules are constructed explicitly in terms of free bosonic fields.Comment: Errors in the cocycle factors of the vertex operators and some typos are corrected. LaTex file 17 page

    Space Alignment Based on Regularized Inversion Precoding in Cognitive Transmission

    Get PDF
    For a two-tier Multiple-Input Multiple-Output (MIMO) cognitive network with common receiver, the precoding matrix has a compact relationship with the capacity performance in the unlicensed secondary system. To increase the capacity of secondary system, an improved precoder based on the idea of regularized inversion for secondary transmitter is proposed. An iterative space alignment algorithm is also presented to ensure the Quality of Service (QoS) for primary system. The simulations reveal that, on the premise of achieving QoS for primary system, our proposed algorithm can get larger capacity in secondary system at low Signal-to-Noise Ratio (SNR), which proves the effectiveness of the algorithm

    B_s decays at Belle

    Full text link
    We report recent results obtained with the Belle detector using a 23.6 fb^{-1} data sample collected on the Y(5S) resonance at the KEKB asymmetric energy e^+ e^- collider. Inclusive semileptonic B_s^0 -> X^+ l^- \nu decays are studied for the first time and the branching fraction is measured. Combining the electron and muon channels, we obtain Bf(B_s^0 -> X^+ l^- \nu) = (10.2 \pm 0.8 \pm 0.9)%. Also, the radiative penguin decay B_s^0 -> \phi \gamma is observed for the first time, and an improved upper limit for the decay B_s^0 \to \gamma \gamma is obtained.Comment: Proceedings of the EPS/HEP 2007 Conference, Manchester, England, July 2007 (on behalf of the Belle collaboration), 3 pages, 2 figure

    Quantum Affine Lie Algebras, Casimir Invariants and Diagonalization of the Braid Generator

    Full text link
    Let Uq(G^)U_q(\hat{\cal G}) be an infinite-dimensional quantum affine Lie algebra. A family of central elements or Casimir invariants are constructed and their eigenvalues computed in any integrable irreducible highest weight representation. These eigenvalue formulae are shown to absolutely convergent when the deformation parameter qq is such that q>1|q|>1. It is proven that the universal R-matrix RR of Uq(G^)U_q(\hat{\cal G}) satisfies the celebrated conjugation relation R=TRR^\dagger=TR with TT the usual twist map. As applications, the braid generator is shown to be diagonalizable on arbitrary tensor product modules of integrable irreducible highest weight Uq(G^)U_q(\hat{\cal G})-modules and a spectral decomposition formula for the braid generator is obtained which is the generalization of Reshetikhin's and Gould's forms to the present affine case. Casimir invariants acting on a specified module are also constructed and their eigenvalues, again absolutely convergent for q>1|q|>1, computed by means of the spectral decomposition formula.Comment: 22 pages (many changes are made

    New insights into the Ds0(2317)D^{*}_{s0}(2317) and other charm scalar mesons

    Get PDF
    Through the scattering of light-pseudoscalar mesons (π,K,η,η\pi,K,\eta,\eta') off charmed mesons (D,DsD, D_s), we study the Ds0(2317)D^{*}_{s0}(2317) state and other relevant charm scalar mesons in a unitarized chiral effective field theory approach. We investigate the charm scalar meson poles with different strangeness (SS) and isospin (II) quantum numbers as well as their corresponding residues, which provide the coupling strengths of the charm scalar mesons. Both the light-quark mass and NCN_C dependences of the pole positions of the Ds0(2317)D^{*}_{s0}(2317) and the poles with (S,I)=(0,1/2)(S,I)=(0,1/2) are analyzed in detail in this work. Interestingly we observe quite similar pion mass trajectories for the resonance pole at around 2.1 GeV with (S,I)=(0,1/2)(S,I)=(0,1/2) to those of the f0(500)f_0(500) given in the literature. When increasing the values of NCN_C we find that a bound state and a virtual state in the (S,I)=(1,0)(S,I)=(1,0) channel asymmetrically approach the DKD K threshold for NC<6N_C<6, and they meet at this threshold at NC=6N_C=6. When NC>6N_C>6, the bound and virtual states move into the complex plane on the second Riemann sheet and become a symmetric pair of resonance poles. For large enough values of NCN_C, neither the Ds0(2317)D^{*}_{s0}(2317) pole nor the poles with (S,I)=(0,1/2)(S,I)=(0,1/2) tend to fall down to the real axis, indicating that they do not behave like a standard quark-antiquark meson at large NCN_C.Comment: 26 pages, published version in PR

    The rare decay B --> X_s l^+ l^- to NNLL precision for arbitrary dilepton invariant mass

    Full text link
    We present a new phenomenological analysis of the inclusive rare decay BXs+B \to X_s \ell^+\ell^-. In particular, we present the first calculation of the NNLL contributions due to the leading two-loop matrix elements, evaluated for arbitrary dilepton invariant mass. This allows to obtain the first NNLL estimates of the dilepton mass spectrum and the lepton forward-backward asymmetry in the high M+2 M^2_{\ell^+ \ell^-} region, and to provide an independent check of previously published results in the low M+2 M^2_{\ell^+ \ell^-} region. The numerical impact of these NNLL corrections in the high-mass region (M+2>14.4GeV2 M^2_{\ell^+ \ell^-} > 14.4 GeV^2) amounts to -13% in the integrated rate, and leads to a reduction of the scale uncertainty to ±3\pm 3%. The impact of non-perturbative contributions in this region is also discussed in detail.Comment: 40 pages, 12 figures. v2: extended phenomenological discussion; results unchanged; published versio
    corecore