13,059 research outputs found

    Additional Acceleration of Protons and Energetic Neutrino Production in a Filamentary Jet of the Blazar Markarian 501

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    Blazars have been regarded as one of the most powerful sources of the highest energy cosmic rays and also their byproducts, neutrinos. Provided that a magnetized filamentary system is established in a blazar jet as well, we could apply the mechanism of multi-stage diffusive shock acceleration to a feasible TeV emitter, Mrk 501 to evaluate the achievable maximum energy of protons. Taking conceivable energy restriction into account systematically, it seems adequate to say that EeV-protons are produced at this site by our present model. We also estimate neutrino fluxes generated by these accelerated protons and discuss the detectability based on an updated kilometre-scale telescope such as IceCube.Comment: 17 pages, 3 Postscript figure

    Program logics for homogeneous meta-programming.

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    A meta-program is a program that generates or manipulates another program; in homogeneous meta-programming, a program may generate new parts of, or manipulate, itself. Meta-programming has been used extensively since macros were introduced to Lisp, yet we have little idea how formally to reason about metaprograms. This paper provides the first program logics for homogeneous metaprogramming – using a variant of MiniMLe by Davies and Pfenning as underlying meta-programming language.We show the applicability of our approach by reasoning about example meta-programs from the literature. We also demonstrate that our logics are relatively complete in the sense of Cook, enable the inductive derivation of characteristic formulae, and exactly capture the observational properties induced by the operational semantics

    False Vacuum in the Supersymmetric Mass Varying Neutrinos Model

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    We present detailed analyses of the vacuum structure of the scalar potential in a supersymmetric Mass Varying Neutrinos model. The observed dark energy density is identified with false vacuum energy and the dark energy scale of order (10−3eV)4(10^{-3}eV)^4 is understood by gravitationally suppressed supersymmetry breaking scale, F(TeV)2/MPlF({TeV})^2/M_{Pl}, in the model. The vacuum expectation values of sneutrinos should be tiny in order that the model works. Some decay processes of superparticles into acceleron and sterile neutrino are also discussed in the model.Comment: 7 pages, 5 figures, revtex, typos correcte

    Field-induced commensurate long-range order in the Haldane-gap system NDMAZ

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    High-field neutron diffraction studies of the new quantum-disordered S=1 linear-chain antiferromagnet Ni(C5_5H14_{14}N2_2)2_2N3_3(ClO4_4) (NDMAZ) are reported. At T=70 mK, at a critical field Hc=13.4H_c=13.4 T applied along the (013) direction, a phase transition to a commensurate N\'{e}el-like ordered state is observed. The results are discussed in the context of existing theories of quantum phase transitions in Haldane-gap antiferromagnets, and in comparions with previous studies of the related system Ni(C5_5H14_{14}N2_2)2_2N3_3(PF6_6)

    Deformation of LeBrun's ALE metrics with negative mass

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    In this article we investigate deformations of a scalar-flat K\"ahler metric on the total space of complex line bundles over CP^1 constructed by C. LeBrun. In particular, we find that the metric is included in a one-dimensional family of such metrics on the four-manifold, where the complex structure in the deformation is not the standard one.Comment: 20 pages, no figure. V2: added two references, filled a gap in the proof of Theorem 1.2. V3: corrected a wrong statement about Kuranishi family of a Hirzebruch surface stated in the last paragraph in the proof of Theorem 1.2, and fixed a relevant error in the proof. Also added a reference [24] about Kuranishi family of Hirzebruch surface

    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

    On Asynchronous Session Semantics

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    This paper studies a behavioural theory of the π-calculus with session types under the fundamental principles of the practice of distributed computing — asynchronous communication which is order-preserving inside each connection (session), augmented with asynchronous inspection of events (message arrivals). A new theory of bisimulations is introduced, distinct from either standard asynchronous or synchronous bisimilarity, accurately capturing the semantic nature of session-based asynchronously communicating processes augmented with event primitives. The bisimilarity coincides with the reduction-closed barbed congruence. We examine its properties and compare them with existing semantics. Using the behavioural theory, we verify that the program transformation of multithreaded into event-driven session based processes, using Lauer-Needham duality, is type and semantic preserving

    Atmospheric neutrino flux at INO, South Pole and Pyh\"asalmi

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    We present the calculation of the atmospheric neutrino fluxes for the neutrino experiments proposed at INO, South Pole and Pyh\"asalmi. Neutrino fluxes have been obtained using ATMNC, a simulation code for cosmic ray in the atmosphere. Even using the same primary flux model and the interaction model, the calculated atmospheric neutrino fluxes are different for the different sites due to the geomagnetic field. The prediction of these fluxes in the present paper would be quite useful in the experimental analysis.Comment: 12Pages,9Fig

    Effects of mirror reflection versus diffusion anisotropy on particle acceleration in oblique shocks

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    Cosmic ray particles are more rapidly accelerated in oblique shocks, with the magnetic field inclined with respect to the shock normal direction, than in parallel shocks, as a result of mirror reflection at the shock surface and slower diffusion in the shock normal direction. We investigate quantitatively how these effects contribute to reducing the acceleration time over the whole range of magnetic field inclinations. It is shown that, for quasi-perpendicular inclination, the mirror effect plays a remarkable role in reducing the acceleration time; whereas, at relatively small inclination, the anisotropic diffusion effect is dominant in reducing that time. These results are important for a detailed understanding of the mechanism of particle acceleration by an oblique shock in space and heliosphereic plasmas.Comment: 6 pages, 2 figure
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