1,986 research outputs found

    Two-dimensional anyons and the temperature dependence of commutator anomalies

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    The temperature dependence of commutator anomalies is discussed on the explicit example of particular (anyonic) field operators in two dimensions. The correlation functions obtained show that effects of the non-zero temperature might manifest themselves not only globally but also locally.Comment: 11 pages, LaTe

    A String Approximation for Cooper Pair in High-Tc_{\bf c} superconductivity

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    It is assumed that in some sense the High-Tc_c superconductivity is similar to the quantum chromodynamics (QCD). This means that the phonons in High-Tc_c superconductor have the strong interaction between themselves like to gluons in the QCD. At the experimental level this means that in High-Tc_c superconductor exists the nonlinear sound waves. It is possible that the existence of the strong phonon-phonon interaction leads to the confinement of phonons into a phonon tube (PT) stretched between two Cooper electrons like a hypothesized flux tube between quark and antiquark in the QCD. The flux tube in the QCD brings to a very strong interaction between quark-antiquark, the similar situation can be in the High-Tc_c superconductor: the presence of the PT can essentially increase the binding energy for the Cooper pair. In the first rough approximation the PT can be approximated as a nonrelativistic string with Cooper electrons at the ends. The BCS theory with such potential term is considered. It is shown that Green's function method in the superconductivity theory is a realization of discussed Heisenberg idea proposed by him for the quantization of nonlinear spinor field. A possible experimental testing for the string approximation of the Cooper pair is offered.Comment: Essential changes: (a) the section is added in which it is shown that Green's function method in the superconductivity theory is a realization of discussed Heisenberg quantization method; (b) Veneziano amplitude is discussed as an approximation for the 4-point Green's function in High-T_c; (c) it is shown that Eq.(53) has more natural solution on the layer rather than on 3 dimensional spac

    Cosmological constant and Euclidean space from nonperturbative quantum torsion

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    Heisenberg's nonperturbative quantization technique is applied to the nonpertrubative quantization of gravity. An infinite set of equations for all Green's functions is obtained. An approximation is considered where: (a) the metric remains as a classical field; (b) the affine connection can be decomposed into classical and quantum parts; (c) the classical part of the affine connection are the Christoffel symbols; (d) the quantum part is the torsion. Using a scalar and vector fields approximation it is shown that nonperturbative quantum effects gives rise to a cosmological constant and an Euclidean solution.Comment: title is changed. arXiv admin note: text overlap with arXiv:1201.106

    Spherically Symmetric Solution for Torsion and the Dirac equation in 5D spacetime

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    Torsion in a 5D spacetime is considered. In this case gravitation is defined by the 5D metric and the torsion. It is conjectured that torsion is connected with a spinor field. In this case Dirac's equation becomes the nonlinear Heisenberg equation. It is shown that this equation has a discrete spectrum of solutions with each solution being regular on the whole space and having finite energy. Every solution is concentrated on the Planck region and hence we can say that torsion should play an important role in quantum gravity in the formation of bubbles of spacetime foam. On the basis of the algebraic relation between torsion and the classical spinor field in Einstein-Cartan gravity the geometrical interpretation of the spinor field is considered as ``the square root'' of torsion.Comment: 7 pages, REVTEX, essential changing of tex

    Semiclassical Calculation of Multiparticle Scattering Cross Sections in Classicalizing Theories

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    It has been suggested in arXiv:1010.1415 that certain derivatively coupled non-renormalizable scalar field theories might restore the perturbative unitarity of high energy hard scatterings by classicalization, i.e. formation of multiparticle states of soft quanta. Here we apply the semiclassical method of calculating the multiparticle production rates to the scalar Dirac-Born-Infeld (DBI) theory which is suggested to classicalize. We find that the semiclassical method is applicable for the energies in the final state above the cutoff scale of the theory L_*^{-1}. We encounter that the cross section of the process two to N ceases to be exponentially suppressed for the particle number in the final state N smaller than a critical particle number N_{crit} ~ (E L_*)^{4/3}. It coincides with the typical particle number produced in two-particle collisions at high energies predicted by classicalization arguments.Comment: 17 pages, 4 figures, v2. Minor changes to match the published versio

    Kinetic energy driven superconductivity, the origin of the Meissner effect, and the reductionist frontier

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    Is superconductivity associated with a lowering or an increase of the kinetic energy of the charge carriers? Conventional BCS theory predicts that the kinetic energy of carriers increases in the transition from the normal to the superconducting state. However, substantial experimental evidence obtained in recent years indicates that in at least some superconductors the opposite occurs. Motivated in part by these experiments many novel mechanisms of superconductivity have recently been proposed where the transition to superconductivity is associated with a lowering of the kinetic energy of the carriers. However none of these proposed unconventional mechanisms explores the fundamental reason for kinetic energy lowering nor its wider implications. Here I propose that kinetic energy lowering is at the root of the Meissner effect, the most fundamental property of superconductors. The physics can be understood at the level of a single electron atom: kinetic energy lowering and enhanced diamagnetic susceptibility are intimately connected. According to the theory of hole superconductivity, superconductors expel negative charge from their interior driven by kinetic energy lowering and in the process expel any magnetic field lines present in their interior. Associated with this we predict the existence of a macroscopic electric field in the interior of superconductors and the existence of macroscopic quantum zero-point motion in the form of a spin current in the ground state of superconductors (spin Meissner effect). In turn, the understanding of the role of kinetic energy lowering in superconductivity suggests a new way to understand the fundamental origin of kinetic energy lowering in quantum mechanics quite generally

    The Evolution of Universe with th B-I Type Phantom Scalar Field

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    We considered the phantom cosmology with a lagrangian L=1η[11+ηgμνϕ,μϕ,ν]u(ϕ)\displaystyle L=\frac{1}{\eta}[1-\sqrt{1+\eta g^{\mu\nu}\phi_{, \mu}\phi_{, \nu}}]-u(\phi), which is original from the nonlinear Born-Infeld type scalar field with the lagrangian L=1η[11ηgμνϕ,μϕ,ν]u(ϕ)\displaystyle L=\frac{1}{\eta}[1-\sqrt{1-\eta g^{\mu\nu}\phi_{, \mu}\phi_{, \nu}}]-u(\phi). This cosmological model can explain the accelerated expansion of the universe with the equation of state parameter w1w\leq-1. We get a sufficient condition for a arbitrary potential to admit a late time attractor solution: the value of potential u(Xc)u(X_c) at the critical point (Xc,0)(X_c,0) should be maximum and large than zero. We study a specific potential with the form of u(ϕ)=V0(1+ϕϕ0)e(ϕϕ0)u(\phi)=V_0(1+\frac{\phi}{\phi_0})e^{(-\frac{\phi}{\phi_0})} via phase plane analysis and compute the cosmological evolution by numerical analysis in detail. The result shows that the phantom field survive till today (to account for the observed late time accelerated expansion) without interfering with the nucleosynthesis of the standard model(the density parameter Ωϕ1012\Omega_{\phi}\simeq10^{-12} at the equipartition epoch), and also avoid the future collapse of the universe.Comment: 17 pages, 10 figures,typos corrected, references added,figures added and enriched, title changed, main result remaine

    Diffractive Vector Meson Photoproduction from Dual String Theory

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    We study diffractive vector meson photoproduction using string theory via AdS/CFT. The large ss behavior of the cross sections for the scattering of the vector meson VV on a proton is dominated by the soft Pomeron, σVs2ϵ2αP/B\sigma_V\sim s^{2\epsilon-2\alpha'_P/B}, where from the string theory model of \cite{nastase2}, ϵ\epsilon is approximately 1/7 below 10 GeV, and 1/11 for higher, but still sub-Froissart, energies. This is due to the production of black holes in the dual gravity. In ϕ\phi-photoproduction the mesonic Regge poles do not contribute, so that we deal with a pure Pomeron contribution. This allows for an experimental test. At the gauge theory "Planck scale" of about 1-2 GeV, the ratios of the soft Pomeron contributions to the photoproduction cross-sections of different vector mesons involve not only the obvious quark model factors, but also the Boltzmann factors e4MV/T0e^{-4 M_V/T_0}, with T0T_0 the temperature of the dual black hole. The presence of these factors is confirmed in the experimental data for ρ,ω,ϕ,J/ψ,\rho, \omega, \phi, J/\psi, and ψ(2S)\psi(2S) photoproduction and is compatible with the meager Υ\Upsilon photoproduction data. Throughout, we use vector meson dominance, and from the data we obtain T0T_0 of about 1.3GeV1.3 GeV, i.e. the gauge theory "Planck scale," as expected. The ratio of the experimental soft Pomeron onset scale E^R9\hat{E}_R\sim 9 GeV and of the gauge theory Planck scale, T01.3T_0 \sim 1.3 GeV conforms to the theoretical prediction of Nc2/Nc1/4N_c^2/N_c^{1/4}.Comment: 17 pages, 1 figure, late

    Remarks on the Extended Characteristic Uncertainty Relations

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    Three remarks concerning the form and the range of validity of the state-extended characteristic uncertainty relations (URs) are presented. A more general definition of the uncertainty matrix for pure and mixed states is suggested. Some new URs are provided.Comment: LaTex, 4 pages, no figure

    Proposal to improve the behaviour of self-energy contributions to the S-matrix

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    A simple modification of the definition of the S-matrix is proposed. It is expected that the divergences related to nonzero self-energies are considerably milder with the modified definition than with the usual one. This conjecture is verified in a few examples using perturbation theory. The proposed formula is written in terms of the total Hamiltonian operator and a free Hamiltonian operator and is therefore applicable in any case when these Hamiltonian operators are known.Comment: 24 pages, 1 figure; v2: revised version; v3: section 3 improved. Accepted for publication in Central European Journal of Physics; v4: minor text misprints correcte
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