287 research outputs found

    A direct calculation of critical exponents of two-dimensional anisotropic Ising model

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    Using an exact solution of the one-dimensional (1D) quantum transverse-field Ising model (TFIM), we calculate the critical exponents of the two-dimensional (2D) anisotropic classical Ising model (IM). We verify that the exponents are the same as those of isotropic classical IM. Our approach provides an alternative means of obtaining and verifying these well-known results.Comment: 3 pages, no figures, accepted by Commun. Theor. Phys.(IPCAS

    Does the enhancement observed in γγDDˉ\gamma\gamma\to D\bar{D} contain two PP-wave higher charmonia?

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    Solved is a new puzzle raised by the observation of an enhancement structure Z(3930) in γγDDˉ\gamma\gamma\to D\bar{D}. If categorizing Z(3930) as χc2(2P)\chi_{c2}(2P) suggested by Belle and BaBar, we must explain why χc0(2P)\chi_{c0}(2P) dominantly decaying into DDˉD\bar{D} is missing in the DDˉD\bar{D} invariant mass spectrum. In this work, we propose that the Z(3930) enhancement structure may contain two PP-wave higher charmonia {χc0(2P)\chi_{c0}(2P)} and χc2(2P)\chi_{c2}(2P). We show that this assumption is supported by our analysis of the DDˉD\bar{D} invariant mass spectrum and cosθ\cos\theta^\ast distribution of γγDDˉ\gamma\gamma\to D\bar{D}. This observation would not only provide valuable information of two P-wave higher charmonia χc0(2P)\chi_{c0}(2P) and χc2(2P)\chi_{c2}(2P), but also serve as the crucial test of our novel proposal to the observed enhancement structure Z(3930), especially at the forthcoming BelleII and the approved SuperB.Comment: 5 pages, 2 tables, 3 figures. More contents and discussions adde

    Understanding the newly observed Y(4008) by Belle

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    Very recently a new enhancement around 4.05 GeV was observed by Belle experiment. In this short note, we discuss some possible assignments for this enhancement, i.e. ψ(3S)\psi(3S) and DDˉD^*\bar{D}^* molecular state. In these two assignments, Y(4008) can decay into J/ψπ0π0J/\psi\pi^0\pi^0 with comparable branching ratio with that of Y(4008)J/ψπ+πY(4008)\to J/\psi\pi^+\pi^-. Thus one suggests high energy experimentalists to look for Y(4008) in J/ψπ0π0J/\psi\pi^0\pi^0 channel. Furthermore one proposes further experiments to search missing channel DDˉD\bar{D}, DDˉ+h.c.D\bar{D}^*+h.c. and especially χcJπ+ππ0\chi_{cJ}\pi^+\pi^-\pi^0 and ηcπ+ππ0\eta_c\pi^+\pi^-\pi^0, which will be helpful to distinguish ψ(3S)\psi(3S) and DDˉD^*\bar{D}^* molecular state assignments for this new enhancement.Comment: 4 pages, 5 figures. Typos correcte

    The molecular systems composed of the charmed mesons in the HSˉ+h.c.H\bar{S}+h.c. doublet

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    We study the possible heavy molecular states composed of a pair of charm mesons in the H and S doublets. Since the P-wave charm-strange mesons Ds0(2317)D_{s0}(2317) and Ds1(2460)D_{s1}(2460) are extremely narrow, the future experimental observation of the possible heavy molecular states composed of Ds/DsD_s/D_s^\ast and Ds0(2317)/Ds1(2460)D_{s0}(2317)/D_{s1}(2460) may be feasible if they really exist. Especially the possible JPC=1J^{PC}=1^{--} states may be searched for via the initial state radiation technique.Comment: 42 pages, 4 tables, 31 figures. Improved numerical results and Corrected typos

    The open-charm radiative and pionic decays of molecular charmonium Y(4274)

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    In this work, we investigate the decay widths and the line shapes of the open-charm radiative and pionic decays of Y(4274) with the DsDˉs0(2317)D_s\bar{D}_{s0}(2317) molecular charmonium assignment. Our calculation indicates that the decay widths of Y(4274)Ds+DsγY(4274)\to D^{+}_{s}D^{*-}_{s}\gamma and Y(4274)Ds+Dsπ0Y(4274)\to D^+_{s}D^-_{s}\pi^0 can reach up to 0.05 keV and 0.75 keV, respectively. In addition, the result of the line shape of the photon spectrum of Y(4274)Ds+DsγY(4274)\to D_s^+ {D}_s^{*-} \gamma shows that there exists a very sharp peak near the large end point of photon energy. The line shape of the pion spectrum of Y(4274)Ds+Dsπ0Y(4274)\to D_s^+ {D}_s^{*-} \pi^0 is similar to that of the pion spectrum of Y(4274)Ds+DsγY(4274)\to D_s^+ {D}_s^{*-} \gamma, where we also find a very sharp peak near the large end point of pion energy. According to our calculation, we suggest further experiments to carry out the search for the open-charm radiative and pionic decays of Y(4274).Comment: 7 pages, 6 figures, 1 table. Published versio

    Quasiparticle spectra in the vicinity of a d-wave vortex

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    We discuss the evolution of the local quasiparticle spectral density and the related tunneling conductance measurable by the scanning tunneling microscope, as a function of distance r and angle \theta from the vortex core in a d_{x^2-y^2} superconductor. We consider the effects of electronic disorder and of a strongly anisotropic tunneling matrix element, and show that in real materials they will likely obscure the ~1/r asymptotic tail in the zero-bias tunneling conductance expected from the straightforward semiclassical analysis. We also give a prediction for the tunneling conductance anisotropy around the vortex core and establish a connection to the structure of the tunneling matrix element.Comment: 9 pages REVTeX + 5 PostScript figures. For related work and info visit http://www.pha.jhu.edu/~fran

    Conditional generation of arbitrary multimode entangled states of light with linear optics

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    We propose a universal scheme for the probabilistic generation of an arbitrary multimode entangled state of light with finite expansion in Fock basis. The suggested setup involves passive linear optics, single photon sources, strong coherent laser beams, and photodetectors with single-photon resolution. The efficiency of this setup may be greatly enhanced if, in addition, a quantum memory is available.Comment: 7 pages, 5 figure

    Three-Component Mixture Model-Based Adverse Drug Event Signal Detection for the Adverse Event Reporting System

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    The US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) is an important source for detecting adverse drug event (ADE) signals. In this article, we propose a three-component mixture model (3CMM) for FAERS signal detection. In 3CMM, a drug-ADE pair is assumed to have either a zero relative risk (RR), or a background RR (mean RR = 1), or an increased RR (mean RR >1). By clearly defining the second component (mean RR = 1) as the null distribution, 3CMM estimates local false discovery rates (FDRs) for ADE signals under the empirical Bayes framework. Compared with existing approaches, the local FDR's top signals have noninferior or better sensitivities to detect true signals in both FAERS analysis and simulation studies. Additionally, we identify that the top signals of different approaches have different patterns, and they are complementary to each other

    Anomalous Heat Conduction and Anomalous Diffusion in Low Dimensional Nanoscale Systems

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    Thermal transport is an important energy transfer process in nature. Phonon is the major energy carrier for heat in semiconductor and dielectric materials. In analogy to Ohm's law for electrical conductivity, Fourier's law is a fundamental rule of heat transfer in solids. It states that the thermal conductivity is independent of sample scale and geometry. Although Fourier's law has received great success in describing macroscopic thermal transport in the past two hundreds years, its validity in low dimensional systems is still an open question. Here we give a brief review of the recent developments in experimental, theoretical and numerical studies of heat transport in low dimensional systems, include lattice models, nanowires, nanotubes and graphenes. We will demonstrate that the phonon transports in low dimensional systems super-diffusively, which leads to a size dependent thermal conductivity. In other words, Fourier's law is breakdown in low dimensional structures
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