8,251 research outputs found

    Large-N reduction for N=2 quiver Chern-Simons theories on S^3 and localization in matrix models

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    We study reduced matrix models obtained by the dimensional reduction of N=2 quiver Chern-Simons theories on S^3 to zero dimension and show that if a reduced model is expanded around a particular multiple fuzzy sphere background, it becomes equivalent to the original theory on S^3 in the large-N limit. This is regarded as a novel large-N reduction on a curved space S^3. We perform the localization method to the reduced model and compute the free energy and the vacuum expectation value of a BPS Wilson loop operator. In the large-N limit, we find an exact agreement between these results and those in the original theory on S^3.Comment: 46 pages, 11 figures; minor modification

    Bending and springback prediction method based on multi-scale finite element analyses for high bendability and low springback sheet generation

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    In this study, a sheet bendability and springback property evaluation technology through bending test simulations is newly developed using our multi-scale finite element analysis code, which is based on the crystallographic homogenization method

    Right-veering diffeomorphisms of compact surfaces with boundary II

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    We continue our study of the monoid of right-veering diffeomorphisms on a compact oriented surface with nonempty boundary, introduced in [HKM2]. We conduct a detailed study of the case when the surface is a punctured torus; in particular, we exhibit the difference between the monoid of right-veering diffeomorphisms and the monoid of products of positive Dehn twists, with the help of the Rademacher function. We then generalize to the braid group B_n on n strands by relating the signature and the Maslov index. Finally, we discuss the symplectic fillability in the pseudo-Anosov case by comparing with the work of Roberts [Ro1,Ro2].Comment: 25 pages, 5 figure

    Transitive X-ray spectrum and PeV gamma-ray cutoff in the M87 jet: Electron "Pevatron"

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    We propose a modified version of the X-ray spectral index and an intrinsic cutoff frequency of inverse Compton radiation from the brightest knot of the M87 jet, in conjunction with an application of the new conceptions of injection and diffusive shock acceleration (DSA) of electrons in magnetized filamentary plasma to the specified source. The drop of the X-ray flux density in a transitive frequency region is associated with the interplay of ordinary synchrotron cooling and weaker magnetic fields concomitant with the smaller scale filaments that allow the electron injection, while the radio-optical synchrotron continuum is dominantly established by the major electrons that are quasi-secularly bound to larger filaments. With reference to, particularly, the updated external Compton model, we demonstrate that in the Klein-Nishina regime fading inverse Comptonization, the injected electrons can be stochastically energized up to a Lorentz factor as high as 5×10105\times 10^{10} in the temporal competition with diffuse synchrotron cooling; this value is larger than that attainable for a simple DSA scenario based on the resonant scattering diffusion of the gyrating electrons bound to a supposed magnetic field homogeneously pervading the entire knot. The upper limits of the photon frequency boosted via conceivable inverse Compton processes are predicted to be of the common order of 1030\sim 10^{30} Hz. The variability of the broadband spectrum is also discussed in comparison to the features of a blazar light curve. The present scenario of a peta-eV (PeV; 101510^{15} eV) electron accelerator, the "Pevatron," might provide some guidance for exploring untrod hard X-ray and gamma-ray bands in forthcoming observations.Comment: 34 pages, 6 figures, matches version published in Ap

    Half-ordered state in the anisotropic Haldane-gap antiferromagnet NDMAP

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    Neutron diffraction experiments performed on the Haldane gap material NDMAP in high magnetic fields applied at an angle to the principal anisotropy axes reveal two consecutive field-induced phase transitions. The low-field phase is the gapped Haldane state, while at high fields the system exhibits 3-dimensional long-range Neel order. In a peculiar phase found at intermediate fields only half of all the spin chains participate in the long-range ordering, while the other half remains disordered and gapped.Comment: 4 pages, 2 figures, submitted to Phys. Rev.

    Implementing Session Centered Calculi

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    Recently, specific attention has been devoted to the development of service oriented process calculi. Besides the foundational aspects, it is also interesting to have prototype implementations for them in order to assess usability and to minimize the gap between theory and practice. Typically, these implementations are done in Java taking advantage of its mechanisms supporting network applications. However, most of the recurrent features of service oriented applications are re-implemented from scratch. In this paper we show how to implement a service oriented calculus, CaSPiS (Calculus of Services with Pipelines and Sessions) using the Java framework IMC, where recurrent mechanisms for network applications are already provided. By using the session oriented and pattern matching communication mechanisms provided by IMC, it is relatively simple to implement in Java all CaSPiS abstractions and thus to easily write the implementation in Java of a CaSPiS process

    Oscillons in Scalar Field Theories: Applications in Higher Dimensions and Inflation

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    The basic properties of oscillons -- localized, long-lived, time-dependent scalar field configurations -- are briefly reviewed, including recent results demonstrating how their existence depends on the dimensionality of spacetime. Their role on the dynamics of phase transitions is discussed, and it is shown that oscillons may greatly accelerate the decay of metastable vacuum states. This mechanism for vacuum decay -- resonant nucleation -- is then applied to cosmological inflation. A new inflationary model is proposed which terminates with fast bubble nucleation.Comment: 11 pages, 4 figures, to appear in Int. J. Mod. Phys.

    Observation of a Transient Magnetization Plateau in a Quantum Antiferromagnet on the Kagome Lattice

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    The magnetization process of an S=1/2 antiferromagnet on the kagome lattice, [Cu_3(titmb)_2(OCOCH_3)_6]H_2O {titmb= 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6 trimethylbenzene} has been measured at very low temperatures in both pulsed and steady fields. We have found a new dynamical behavior in the magnetization process: a plateau at one third of the saturation magnetization appears in the pulsed field experiments for intermediate sweep rates of the magnetic field and disappears in the steady field experiments. A theoretical analysis using exact diagonalization yields J_1=-19K and J_2=6K, for the nearest neighbor and second nearest neighbor interactions, respectively. This set of exchange parameters explains the very low saturation field and the absence of the plateau in the thermodynamic equilibrium as well as the two-peak feature in the magnetic heat capacity. Supported by numerical results we argue that a dynamical order by disorder phenomenon could explain the transient appearance of the 1/3 plateau in pulsed field experiments.Comment: 7 pages, 5 figure
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