6,047 research outputs found

    Critical phenomena in 1D Ising model with arbitrary spin

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    The aim of this work was to study critical phenomena taking place in 1D Ising model with different exchange interactions signs and arbitrary spin values in a magnetic field. Exact analytical formulas for frustration fields, zero temperature magnetization and entropy at these fields are obtained. The general behavior of pair spin correlation function with the accounting of only interactions between nearest neighbors is examined. © 2018 The Authors, published by EDP Sciences.The reflorted study was carried out within the state assignment of FASO of Russia (theme «Quantum» n. 01201463332) and was funded by RFBR according to the research flroject n. 16-32-00032

    Open Problems in α\alpha Particle Condensation

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    α\alpha particle condensation is a novel state in nuclear systems. We briefly review the present status on the study of α\alpha particle condensation and address the open problems in this research field: α\alpha particle condensation in heavier systems other than the Hoyle state, linear chain and α\alpha particle rings, Hoyle-analogue states with extra neutrons, α\alpha particle condensation related to astrophysics, etc.Comment: 12 pages. To be published in J. of Phys. G special issue on Open Problems in Nuclear Structure (OPeNST

    Density-of-states picture and stability of ferromagnetism in the highly-correlated Hubbard model

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    The problem of stability of saturated and non-saturated ferromagnetism in the Hubbard model is considered in terms of the one-particle Green's functions. Approximations by Edwards and Hertz and some versions of the self-consistent approximations based on the 1/z-expansion are considered. The account of longitudinal fluctuations turns out to be essential for description of the non-saturated state. The corresponding pictures of density of states are obtained. "Kondo" density-of-states singularities owing to spin-flip processes are analyzed. The critical electron concentrations for instabilities of saturated ferromagnetism and paramagnetic state are calculated for various lattices. Drawbacks of various approximations are discussed. A comparison with the results of previous works is performed.Comment: 16 pages, 7 eps figure

    Special features of the 9^9Be\to2He fragmentation in emulsion at an energy of 1.2~A~GeV

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    The results of investigations of the relativistic 9^9Be nucleus fragmentation in emulsion which entails the production of two He fragments of an energy of 1.2~A~GeV are presented. The results of the angular measurements of the 9^9Be\to2He events are analyzed. The 9^9Be8\to^8Be+n fragmentation channel involving the 8^8Be decay from the ground (0+^+) and the first excited (2+^+) states to two α\alpha particles is observed to be predominant.Comment: 10 pages, 6 figures, conference: Conference on Physics of Fundamental Interactions, Moscow, Russia, 5-9 Dec 2005 (Author's translation

    Fragmentation of relativistic nuclei in peripheral interactions in nuclear track emulsion

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    The technique of nuclear track emulsions is used to explore the fragmentation of light relativistic nuclei down to the most peripheral interactions - nuclear "white" stars. A complete pattern of therelativistic dissociation of a 8^8B nucleus with target fragment accompaniment is presented. Relativistic dissociation 9^{9}Be2α\to2\alpha is explored using significant statistics and a relative contribution of 8^{8}Be decays from 0+^+ and 2+^+ states is established. Target fragment accompaniments are shown for relativistic fragmentation 14^{14}N\to3He+H and 22^{22}Ne\to5He. The leading role of the electromagnetic dissociation on heavy nuclei with respect to break-ups on target protons is demonstrated in all these cases. It is possible to conclude that the peripheral dissociation of relativistic nuclei in nuclear track emulsion is a unique tool to study many-body systems composed of lightest nuclei and nucleons in the energy scale relevant for nuclear astrophysics.Comment: 15 pages, 4 figures, 4 tables, conference: Relativistic nuclear physics: from Nuclotron to LHC energies, Kiev, June 18-22, 200
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