55,748 research outputs found

    Recent progress in random metric theory and its applications to conditional risk measures

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    The purpose of this paper is to give a selective survey on recent progress in random metric theory and its applications to conditional risk measures. This paper includes eight sections. Section 1 is a longer introduction, which gives a brief introduction to random metric theory, risk measures and conditional risk measures. Section 2 gives the central framework in random metric theory, topological structures, important examples, the notions of a random conjugate space and the Hahn-Banach theorems for random linear functionals. Section 3 gives several important representation theorems for random conjugate spaces. Section 4 gives characterizations for a complete random normed module to be random reflexive. Section 5 gives hyperplane separation theorems currently available in random locally convex modules. Section 6 gives the theory of random duality with respect to the locally L0L^{0}-convex topology and in particular a characterization for a locally L0L^{0}-convex module to be L0L^{0}-pre-barreled. Section 7 gives some basic results on L0L^{0}-convex analysis together with some applications to conditional risk measures. Finally, Section 8 is devoted to extensions of conditional convex risk measures, which shows that every representable LL^{\infty}-type of conditional convex risk measure and every continuous LpL^{p}-type of convex conditional risk measure (1p<+1\leq p<+\infty) can be extended to an LF(E)L^{\infty}_{\cal F}({\cal E})-type of σϵ,λ(LF(E),LF1(E))\sigma_{\epsilon,\lambda}(L^{\infty}_{\cal F}({\cal E}), L^{1}_{\cal F}({\cal E}))-lower semicontinuous conditional convex risk measure and an LFp(E)L^{p}_{\cal F}({\cal E})-type of Tϵ,λ{\cal T}_{\epsilon,\lambda}-continuous conditional convex risk measure (1p<+1\leq p<+\infty), respectively.Comment: 37 page

    QCD Factorization in BB Decays into ρπ\rho \pi

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    Based on the QCD factorization approach we analyse the branching ratios for the channel BρπB \to \rho \pi. From the comparisons with experimental data provided by CLEO, BELLE and BABAR we constrain the form factor FBπ(mρ2)F^{B \to \pi}(m_{\rho}^{2}) and propose boundaries for this form factor depending on the CKM matrix element parameters ρ\rho and η\eta.Comment: 11 pages, 9 figures. Talk presented at Fourth Tropical Workshop, Cairns, Australia, 9--13 June 2003. Proceedings to be published by AI

    Spectra of Baryons Containing Two Heavy Quarks in Potential Model

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    In this work, we employ the effective vertices for interaction between diquarks (scalar or axial-vector) and gluon where the form factors are derived in terms of the B-S equation, to obtain the potential for baryons including a light quark and a heavy diquark. The concerned phenomenological parameters are obtained by fitting data of B()B^{(*)}-mesons instead of the heavy quarkonia. The operator ordering problem in quantum mechanics is discussed. Our numerical results indicate that the mass splitting between B3/2(V),B1/2(V)B_{3/2}(V), B_{1/2}(V) and B1/2(S)B_{1/2}(S) is very small and it is consistent with the heavy quark effective theory (HQET).Comment: 16 page

    Chiral extrapolation of lattice data for the hyperfine splittings of heavy mesons

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    Hyperfine splittings between the heavy vector (D*,B*) and pseudoscalar (D,B) mesons have been calculated numerically in lattice QCD, where the pion mass (which is related to the light quark mass) is much larger than its physical value. Naive linear chiral extrapolations of the lattice data to the physical mass of the pion lead to hyperfine splittings which are smaller than experimental data. In order to extrapolate these lattice data to the physical mass of the pion more reasonably, we apply the effective chiral perturbation theory for heavy mesons, which is invariant under chiral symmetry when the light quark masses go to zero and heavy quark symmetry when the heavy quark masses go to infinity. This leads to a phenomenological functional form with three parameters to extrapolate the lattice data. It is found that the extrapolated hyperfine splittings are even smaller than those obtained using linear extrapolation. We conclude that the source of the discrepancy between lattice data for hyperfine splittings and experiment must lie in non-chiral physics.X.-H. Guo and A. W. Thoma

    Radio light curves during the passage of cloud G2 near Sgr A*

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    We calculate radio light curves produced by the bow shock that is likely to form in front of the G2 cloud when it penetrates the accretion disk of Sgr A*. The shock acceleration of the radio-emitting electrons is captured self-consistently by means of first-principles particle-in-cell simulations. We show that the radio luminosity is expected to reach maximum in early 2013, roughly a month after the bow shock crosses the orbit pericenter. We estimate the peak radio flux at 1.4 GHz to be 1.4 - 22 Jy depending on the assumed orbit orientation and parameters. We show that the most promising frequencies for radio observations are in the 0.1<nu<1 GHz range, for which the bow shock emission will be much stronger than the intrinsic radio flux for all the models considered.Comment: 15 pages, 10 figures, accepted for publication in MNRA

    Nonequilibrium thermal entanglement in three-qubit XXXX model

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    Making use of the master equation and effective Hamiltonian approach, we investigate the steady state entanglement in a three-qubit XXXX model. Both symmetric and nonsymmetric qubit-qubit couplings are considered. The system (the three qubits) is coupled to two bosonic baths at different temperatures. We calculate the steady state by the effective Hamiltonian approach and discuss the dependence of the steady state entanglement on the temperatures and couplings. The results show that for symmetric qubit-qubit couplings, the entanglements between the nearest neighbor are equal, independent of the temperatures of the two baths. The maximum of the entanglement arrives at TL=TRT_L=T_R. For nonsymmetric qubit-qubit couplings, however, the situation is totally different. The baths at different temperatures would benefit the entanglement and the entanglements between the nearest neighbors are no longer equal. By examining the probability distribution of each eigenstate in the steady state, we present an explanation for these observations. These results suggest that the steady entanglement can be controlled by the temperature of the two baths.Comment: Comments are welcom

    p63, cellular senescence and tumor development

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    Deficiency of p63, a p53-related protein, causes severe defects in epithelial morphogenesis. Studies of p63-compromised mouse models reveal that p63 deficiency induces cellular senescence both in cultured cells and in vivo, through regulation p19(Arf)/p53 and p16(Ink4a)/Rb pathways. An extensive tumor study of p63-compromised mice demonstrated that p63 deficiency does not predispose to, but rather protects from, tumor development. These findings further implicate p63 as a negative regulator of the tumor suppressive mechanism of cellular senescence

    Performance of Photosensors in the PandaX-I Experiment

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    We report the long term performance of the photosensors, 143 one-inch R8520-406 and 37 three-inch R11410-MOD photomultipliers from Hamamatsu, in the first phase of the PandaX dual-phase xenon dark matter experiment. This is the first time that a significant number of R11410 photomultiplier tubes were operated in liquid xenon for an extended period, providing important guidance to the future large xenon-based dark matter experiments.Comment: v3 as accepted by JINST with modifications based on reviewers' comment

    Bethe-Salpeter equation for doubly heavy baryons in the covariant instantaneous approximation

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    In the heavy quark limit, a doubly heavy baryon is regarded as composed of a heavy diquark and a light quark. We establish the Bethe-Salpeter (BS) equations for the heavy diquarks and the doubly heavy baryons, respectively, to leading order in a 1/mQ1/m_{Q} expansion. The BS equations are solved numerically under the covariant instantaneous approximation with the kernels containing scalar confinement and one-gluon-exchange terms. The masses for the heavy diquarks and the doubly heavy baryons are obtained and the non-leptonic decay widths for the doubly heavy baryons emitting a pseudo-scalar meson are calculated within the model.Comment: Corrections to the text, two references added, version accepted for publication in Physical Review

    Plasmon assisted transmission of high dimensional orbital angular momentum entangled state

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    We present an experimental evidence that high dimensional orbital angular momentum entanglement of a pair of photons can be survived after a photon-plasmon-photon conversion. The information of spatial modes can be coherently transmitted by surface plasmons. This experiment primarily studies the high dimensional entangled systems based on surface plasmon with subwavelength structures. It maybe useful in the investigation of spatial mode properties of surface plasmon assisted transmission through subwavelength hole arrays.Comment: 7 pages,6 figure
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