7,646 research outputs found

    Calculations of Branching Ratios for Radiative-Capture, One-Proton, and Two-Neutron Channels in the Fusion Reaction 209^{209}Bi+70^{70}Zn

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    We discuss the possibility of the non-one-neutron emission channels in the cold fusion reaction 70^{70}Zn + 209^{209}Bi to produce the element Z=113. For this purpose, we calculate the evaporation-residue cross sections of one-proton, radiative-capture, and two-neutron emissions relative to the one-neutron emission in the reaction 70^{70}Zn + 209^{209}Bi. To estimate the upper bounds of those quantities, we vary model parameters in the calculations, such as the level-density parameter and the height of the fission barrier. We conclude that the highest possibility is for the 2n reaction channel, and its upper bounds are 2.4% and at most less than 7.9% with unrealistic parameter values, under the actual experimental conditions of [J. Phys. Soc. Jpn. {\bf 73} (2004) 2593].Comment: 6 pages, 4 figure

    Critical Behavior of J/psi across the Phase Transition from QCD sum rules

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    We study behavior of J/psi in hot gluonic matter using QCD sum rules. Taking into account temperature dependences of the gluon condensates extracted from lattice thermodynamics for the pure SU(3) system, we find that the mass and width of J/psi exhibit rapid change across the critical temperature.Comment: 5 pages, 3 figures. Poster contribution for Quark Matter 2008. To be published in the proceeding

    Cluster Variation Approach to the Random-Anisotropy Blume-Emery-Griffiths Model

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    The random--anisotropy Blume--Emery--Griffiths model, which has been proposed to describe the critical behavior of 3^3He--4^4He mixtures in a porous medium, is studied in the pair approximation of the cluster variation method extended to disordered systems. Several new features, with respect to mean field theory, are found, including a rich ground state, a nonzero percolation threshold, a reentrant coexistence curve and a miscibility gap on the high 3^3He concentration side down to zero temperature. Furthermore, nearest neighbor correlations are introduced in the random distribution of the anisotropy, which are shown to be responsible for the raising of the critical temperature with respect to the pure and uncorrelated random cases and contribute to the detachment of the coexistence curve from the λ\lambda line.Comment: 14 pages (plain TeX) + 12 figures (PostScript, appended), Preprint POLFIS-TH.02/9

    A Simple n-Dimensional Intrinsically Universal Quantum Cellular Automaton

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    We describe a simple n-dimensional quantum cellular automaton (QCA) capable of simulating all others, in that the initial configuration and the forward evolution of any n-dimensional QCA can be encoded within the initial configuration of the intrinsically universal QCA. Several steps of the intrinsically universal QCA then correspond to one step of the simulated QCA. The simulation preserves the topology in the sense that each cell of the simulated QCA is encoded as a group of adjacent cells in the universal QCA.Comment: 13 pages, 7 figures. In Proceedings of the 4th International Conference on Language and Automata Theory and Applications (LATA 2010), Lecture Notes in Computer Science (LNCS). Journal version: arXiv:0907.382

    Imaginary in all directions: an elegant formulation of special relativity and classical electrodynamics

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    A suitable parameterization of space-time in terms of one complex and three quaternionic imaginary units allows Lorentz transformations to be implemented as multiplication by complex-quaternionic numbers rather than matrices. Maxwell's equations reduce to a single equation.Comment: 8 page

    BRST invariant Lagrangian of spontaneously broken gauge theories in noncommutative geometry

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    The quantization of spontaneously broken gauge theories in noncommutative geometry(NCG) has been sought for some time, because quantization is crucial for making the NCG approach a reliable and physically acceptable theory. Lee, Hwang and Ne'eman recently succeeded in realizing the BRST quantization of gauge theories in NCG in the matrix derivative approach proposed by Coquereaux et al. The present author has proposed a characteristic formulation to reconstruct a gauge theory in NCG on the discrete space M4×ZNM_4\times Z_{_N}. Since this formulation is a generalization of the differential geometry on the ordinary manifold to that on the discrete manifold, it is more familiar than other approaches. In this paper, we show that within our formulation we can obtain the BRST invariant Lagrangian in the same way as Lee, Hwang and Ne'eman and apply it to the SU(2)×\timesU(1) gauge theory.Comment: RevTeX, page

    Roundabout relaxation: collective excitation requires a detour to equilibrium

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    Relaxation to equilibrium after strong and collective excitation is studied, by using a Hamiltonian dynamical system of one dimensional XY model. After an excitation of a domain of KK elements, the excitation is concentrated to fewer elements, which are made farther away from equilibrium, and the excitation intensity increases logarithmically with KK. Equilibrium is reached only after taking this ``roundabout'' route, with the time for relaxation diverging asymptotically as KγK^\gamma with γ≈4.2\gamma \approx 4.2.Comment: 4 pages, 5 figure

    Role of the target orientation angle and orbital angular momentum in the evaporation residue production

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    The influence of the orientation angles of the target nucleus symmetry axis relative to the beam direction on the production of the evaporation residues is investigated for the 48^{48}Ca+154^{154}Sm reaction as a function of the beam energy. At low energies (Ec.m.<E_{\rm c.m.}<137 MeV), the yield of evaporation residues is observed only for collisions with small orientation angles (αT<450\alpha_T<45^0). At large energies (about Ec.m.=E_{\rm c.m.}=140--180 MeV) all the orientation angles αT\alpha_T can contribute to the evaporation residue cross section σER\sigma_{ER} in the 10--100 mb range, and at Ec.m.>E_{c.m.}>180 MeV σER\sigma_{ER} ranges around 0.1--10 mb because the fission barrier for a compound nucleus decreases by increasing its excitation energy and angular momentum.Comment: 20 pages, 10 figures, submitted to JPS

    Pattern-recalling processes in quantum Hopfield networks far from saturation

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    As a mathematical model of associative memories, the Hopfield model was now well-established and a lot of studies to reveal the pattern-recalling process have been done from various different approaches. As well-known, a single neuron is itself an uncertain, noisy unit with a finite unnegligible error in the input-output relation. To model the situation artificially, a kind of 'heat bath' that surrounds neurons is introduced. The heat bath, which is a source of noise, is specified by the 'temperature'. Several studies concerning the pattern-recalling processes of the Hopfield model governed by the Glauber-dynamics at finite temperature were already reported. However, we might extend the 'thermal noise' to the quantum-mechanical variant. In this paper, in terms of the stochastic process of quantum-mechanical Markov chain Monte Carlo method (the quantum MCMC), we analytically derive macroscopically deterministic equations of order parameters such as 'overlap' in a quantum-mechanical variant of the Hopfield neural networks (let us call "quantum Hopfield model" or "quantum Hopfield networks"). For the case in which non-extensive number pp of patterns are embedded via asymmetric Hebbian connections, namely, p/N→0p/N \to 0 for the number of neuron N→∞N \to \infty ('far from saturation'), we evaluate the recalling processes for one of the built-in patterns under the influence of quantum-mechanical noise.Comment: 10 pages, 3 figures, using jpconf.cls, Proc. of Statphys-Kolkata VI
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