236,187 research outputs found

    Observations of Cygnus X-1 in the MeV band by the INTEGRAL imager

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    The spectrum of the MeV tail detected in the black-hole candidate Cygnus X-1 remains controversial as it appeared much harder when observed with the INTEGRAL Imager IBIS than with the INTEGRAL spectrometer SPI or CGRO. We present an independent analysis of the spectra of Cygnus X-1 observed by IBIS in the hard and soft states. We developed a new analysis software for the PICsIT detector layer and for the Compton mode data of the IBIS instrument and calibrated the idiosyncrasies of the PICsIT front-end electronics. The spectra of Cygnus X-1 obtained for the hard and soft states with the INTEGRAL imager IBIS are compatible with those obtained with the INTEGRAL spectrometer SPI, with CGRO, and with the models that attribute the MeV hard tail either to hybrid thermal/non-thermal Comptonisation or to synchrotron emission.Comment: 6 pages, 7 figure

    Large scale behaviour of 3D continuous phase coexistence models

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    We study a class of three dimensional continuous phase coexistence models, and show that, under different symmetry assumptions on the potential, the large-scale behaviour of such models near a bifurcation point is described by the dynamical Φ3p\Phi^p_3 models for p∈{2,3,4}p \in \{2,3,4\}. This result is specific to space dimension 33 and does not hold in dimension 22

    Low Energy Effective Field Theories of Sp(4) Spin systems

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    We study the classical and quantum phase transitions of Sp(4) spin systems on three dimensional stacked square and triangular lattices. We present general Ginzburg-Landau field theories for various types of Sp(4) spin orders with different ground state manifolds such as CP(3), S^7/Z_2, Grassmann manifold G_{2,5}, G_{2,6} and so on, based on which the nature of the classical phase transitions are studied, and a global phase diagram is presented. The classical phase transitions close to quantum phase transitions toward spin liquid states are also discussed based on renormalization group (RG) flow. Our results can be directly applied to the simplest Sp(4) and SU(4) Heisenberg models which can be realized using spin-3/2 atoms and Alkaline earth atoms trapped in optical lattice.Comment: 8 pages, 4 figure

    Triple-Gluon and Triple-Quark Elastic Scatterings and Early Thermalization

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    Three-gluon to three-gluon scatterings lead to rapid thermalization of gluon matter created in central Au-Au collisions at RHIC energies. Thermalization of quark matter is studied from three-quark to three-quark scatterings.Comment: 8 pages, 5 figures, talk presented at the workshop on quark-gluon-plasma thermalization, TU Wien, Vienna, Austria, Aug. 2005. v2: add two figures and relevant discussion

    Chromo-dynamic multi-component lattice Boltzmann equation scheme for axial symmetry

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    We validate the chromo-dynamic multi-component lattice Boltzmann equation (MCLBE) simulation for immiscible fluids with a density contrast against analytical results for complex flow geometries, with particular emphasis on the fundamentals of the method, i.e. compliance with inter-facial boundary conditions of continuum hydrodynamics. To achieve the necessary regimes for the chosen validations, we develop, from a three-dimensional, axially-symmetric flow formulation, a novel, two-dimensional, pseudo Cartesian, MCLBE scheme. This requires the inclusion in lattice Boltzmann methodology of a continuously distributed source and a velocity-dependent force density (here, the metric force terms of the cylindrical Navier–Stokes equations). Specifically, we apply our model to the problem of flow past a spherical liquid drop in Re = 0, Ca regime and, also, flow past a lightly deformed drop. The resulting simulation data, once corrected for the simulation’s inter-facial micro-current (using a method we also advance herein, based on freezing the phase field) show good agreement with theory over a small range of density contrasts. In particular, our data extend verified compliance with the kinematic condition from flat (Burgin et al 2019 Phys. Rev. E 100 043310) to the case of curved fluid–fluid interfaces. More generally, our results indicate a route to eliminate the influence of the inter-facial micro-current
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