23,731 research outputs found

    The development of local government financial vehicles in China: A case study of Jiaxing Chengtou

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    Financial intermediaries have been widely used in urban development. Since the global financial crisis, it has been an urgent task to understand their operation and implications for financial risks. This paper examines emerging local government financial vehicles (LGFVs) in China. We review their history, current status and underlying financial mechanisms. Confronting the global financial crisis, China has taken a stimulus plan to invest four-trillion Yuan in urban development to stimulate the economy. The plan has been largely fulfilled by the LGFVs. This paper investigates the case of Jiaxing City Construction Investment Corporation (Jiaxing Chengtou), which plays a role of LGFVs. We find that it mainly uses bank loans and bonds to finance land and infrastructure development. To borrow from the capital market, Jiaxing Chengtou collateralizes allocated state-owned land and enhances credits by build and transfer protocols with the city government. However, the enterprise did not manage to pay back its loans, which has led to further borrowing. Due to the central government’s control, Jiaxing Chengtou has been nominally detached from the municipal government since 2012, but it maintains a financial role. It has been re-packaged with other LGFVs to access foreign bond markets. The paper reveals how LGFVs act as financial conduits to connect local governments with the financial market in China

    Charmless decays B->pipi, piK and KK in broken SU(3)symmetry

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    Charmless B decay modes Bππ,πKB \to \pi \pi, \pi K and KKKK aresystematically investigated with and without flavor SU(3) symmetry. Independent analyses on ππ\pi \pi and πK\pi K modes both favor a large ratio between color-suppressed tree (CC) and tree (T)T) diagram, which suggests that they are more likely to originate from long distance effects. The sizes of QCD penguin diagrams extracted individually from ππ\pi\pi, πK\pi K and KKKK modes are found to follow a pattern of SU(3) breaking in agreement with the naive factorization estimates. Global fits to these modes are done under various scenarios of SU(3)relations. The results show good determinations of weak phase γ\gamma in consistency with the Standard Model (SM), but a large electro-weak penguin (P_{\tmop{EW}}) relative to T+CT + C with a large relative strong phase are favored, which requires an big enhancement of color suppressed electro-weak penguin (P_{\tmop{EW}}^C) compatible in size but destructively interfering with P_{\tmop{EW}} within the SM, or implies new physics. Possibility of sizable contributions from nonfactorizable diagrams such as WW-exchange (EE), annihilation(AA) and penguin-annihilation diagrams(PAP_A) are investigated. The implications to the branching ratios and CP violations in KKK Kmodes are discussed.Comment: 27 pages, 9 figures, reference added, to appear in Phy.Rev.

    TeV Scale Lee-Wick Fields out of Large Extra Dimensional Gravity

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    We study the gravitational corrections to the Maxwell, Dirac and Klein-Gorden theories in the large extra dimension model in which the gravitons propagate in the (4+n)-dimensional bulk, while the gauge and matter fields are confined to the four-dimensional world. The corrections to the two-point Green's functions of the gauge and matter fields from the exchanges of virtual Kaluza-Klein gravitons are calculated in the gauge independent background field method. In the framework of effective field theory, we show that the modified one-loop renormalizable Lagrangian due to quantum gravitational effects contains a TeV scale Lee-Wick partner of every gauge and matter field as extra degrees of freedom in the theory. Thus the large extra dimension model of gravity provides a natural mechanism to the emergence of these exotic particles which were recently used to construct an extension of the Standard Model.Comment: 17 pages, 3 figures, references added, to appear in Phys. Rev.

    Seasonal and spatial variations of heavy metalsin surface sediments collected from the BaoxiangRiver in the Dianchi Watershed, China

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    To explore potential ecological hazards due to heavy metals in the Dianchi Lake Watershed, a three-stage European Community Bureau of Reference (BCR) sequential extraction procedure was applied to examine the spatial distributions and relative speciation ratios of Zn, Cu, Ni, Pb, and Cr in Baoxiang River sediments during wet and dry seasons. The metal species have similar spatial variations during different seasons. In the upstream reaches of the Baoxiang River, heavy metals reside primarily in the non-extractable residual fraction (72&ndash;90%). In the midstream, the residual fraction (35&ndash;89%) remains dominant, but the extractable fraction increases, featuring especially notable increases in the reducible fraction (5&ndash;40%). Downstream, the Cu, Ni, Pb, and Cr residual fractions remain high (46&ndash;80%) and the extractable fractions increase rapidly; the Zn extractable fraction is quite high (65.5%). Anthropogenic sources drive changes in heavy metal speciation. Changes in the river environment, such as pH and oxidation-reduction potential, also affect speciation. The reducible fraction of heavy metals in Baoxiang River sediments is most sensitive to pH. Potential ecological risk assessments for these five elements indicate that risks from Zn and Pb are mild to moderate in the middle and lower reaches of the river.<br style="line-height: normal; text-align: -webkit-auto; text-size-adjust: auto;" /

    A Language and Hardware Independent Approach to Quantum-Classical Computing

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    Heterogeneous high-performance computing (HPC) systems offer novel architectures which accelerate specific workloads through judicious use of specialized coprocessors. A promising architectural approach for future scientific computations is provided by heterogeneous HPC systems integrating quantum processing units (QPUs). To this end, we present XACC (eXtreme-scale ACCelerator) --- a programming model and software framework that enables quantum acceleration within standard or HPC software workflows. XACC follows a coprocessor machine model that is independent of the underlying quantum computing hardware, thereby enabling quantum programs to be defined and executed on a variety of QPUs types through a unified application programming interface. Moreover, XACC defines a polymorphic low-level intermediate representation, and an extensible compiler frontend that enables language independent quantum programming, thus promoting integration and interoperability across the quantum programming landscape. In this work we define the software architecture enabling our hardware and language independent approach, and demonstrate its usefulness across a range of quantum computing models through illustrative examples involving the compilation and execution of gate and annealing-based quantum programs

    Superstructure-induced splitting of Dirac cones in silicene

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    Atomic scale engineering of two-dimensional materials could create devices with rich physical and chemical properties. External periodic potentials can enable the manipulation of the electronic band structures of materials. A prototypical system is 3x3-silicene/Ag(111), which has substrate-induced periodic modulations. Recent angle-resolved photoemission spectroscopy measurements revealed six Dirac cone pairs at the Brillouin zone boundary of Ag(111), but their origin remains unclear [Proc. Natl. Acad. Sci. USA 113, 14656 (2016)]. We used linear dichroism angle-resolved photoemission spectroscopy, the tight-binding model, and first-principles calculations to reveal that these Dirac cones mainly derive from the original cones at the K (K') points of free-standing silicene. The Dirac cones of free-standing silicene are split by external periodic potentials that originate from the substrate-overlayer interaction. Our results not only confirm the origin of the Dirac cones in the 3x3-silicene/Ag(111) system, but also provide a powerful route to manipulate the electronic structures of two-dimensional materials.Comment: 6 pages, 3 figure
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