186 research outputs found

    Deflection of coronal rays by remote CMEs: shock wave or magnetic pressure?

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    We analyze five events of the interaction of coronal mass ejections (CMEs) with the remote coronal rays located up to 90^\circ away from the CME as observed by the SOHO/LASCO C2 coronagraph. Using sequences of SOHO/LASCO C2 images, we estimate the kink propagation in the coronal rays during their interaction with the corresponding CMEs ranging from 180 to 920 km/s within the interval of radial distances form 3 R. to 6 R. . We conclude that all studied events do not correspond to the expected pattern of shock wave propagation in the corona. Coronal ray deflection can be interpreted as the influence of the magnetic field of a moving flux rope related to a CME. The motion of a large-scale flux rope away from the Sun creates changes in the structure of surrounding field lines, which are similar to the kink propagation along coronal rays. The retardation of the potential should be taken into account since the flux rope moves at high speed comparable with the Alfven speed.Comment: Accepted for Publication in Solar Physic

    Research of Gravitation in Flat Minkowski Space

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    In this paper it is introduced and studied an alternative theory of gravitation in flat Minkowski space. Using an antisymmetric tensor, which is analogous to the tensor of electromagnetic field, a non-linear connection is introduced. It is very convenient for studying the perihelion/periastron shift, deflection of the light rays near the Sun and the frame dragging together with geodetic precession, i.e. effects where angles are involved. Although the corresponding results are obtained in rather different way, they are the same as in the General Relativity. The results about the barycenter of two bodies are also the same as in the General Relativity. Comparing the derived equations of motion for the nn-body problem with the Einstein-Infeld-Hoffmann equations, it is found that they differ from the EIH equations by Lorentz invariant terms of order c2c^{-2}.Comment: 28 page

    THE TIGHT-BINDING APPROACH TO THE DIELECTRIC RESPONSE IN THE MULTIBAND SYSTEMS

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    Starting from the random phase approximation for the weakly coupled multiband tightly-bounded electron systems, we calculate the dielectric matrix in terms of intraband and interband transitions. The advantages of this representation with respect to the usual plane-wave decomposition are pointed out. The analysis becomes particularly transparent in the long wavelength limit, after performing the multipole expansion of bare Coulomb matrix elements. For illustration, the collective modes and the macroscopic dielectric function for a general cubic lattice are derived. It is shown that the dielectric instability in conducting narrow band systems proceeds by a common softening of one transverse and one longitudinal mode. Furthermore, the self-polarization corrections which appear in the macroscopic dielectric function for finite band systems, are identified as a combined effect of intra-atomic exchange interactions between electrons sitting in different orbitals and a finite inter-atomic tunneling.Comment: 20 pages, LaTeX, no figure

    High frequency sound in superfluid 3He-B

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    We present measurements of the absolute phase velocity of transverse and longitudinal sound in superfluid 3He-B at low temperature, extending from the imaginary squashing mode to near pair-breaking. Changes in the transverse phase velocity near pair-breaking have been explained in terms of an order parameter collective mode that arises from f-wave pairing interactions, the so-called J=4- mode. Using these measurements, we establish lower bounds on the energy gap in the B-phase. Measurement of attenuation of longitudinal sound at low temperature and energies far above the pair-breaking threshold, are in agreement with the lower bounds set on pair-breaking. Finally, we discuss our estimations for the strength of the f-wave pairing interactions and the Fermi liquid parameter, F4s.Comment: 15 pages, 8 figures, accepted to J. Low Temp. Phy

    Thermal correction to the Casimir force, radiative heat transfer, and an experiment

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    The low-temperature asymptotic expressions for the Casimir interaction between two real metals described by Leontovich surface impedance are obtained in the framework of thermal quantum field theory. It is shown that the Casimir entropy computed using the impedance of infrared optics vanishes in the limit of zero temperature. By contrast, the Casimir entropy computed using the impedance of the Drude model attains at zero temperature a positive value which depends on the parameters of a system, i.e., the Nernst heat theorem is violated. Thus, the impedance of infrared optics withstands the thermodynamic test, whereas the impedance of the Drude model does not. We also perform a phenomenological analysis of the thermal Casimir force and of the radiative heat transfer through a vacuum gap between real metal plates. The characterization of a metal by means of the Leontovich impedance of the Drude model is shown to be inconsistent with experiment at separations of a few hundred nanometers. A modification of the impedance of infrared optics is suggested taking into account relaxation processes. The power of radiative heat transfer predicted from this impedance is several times less than previous predictions due to different contributions from the transverse electric evanescent waves. The physical meaning of low frequencies in the Lifshitz formula is discussed. It is concluded that new measurements of radiative heat transfer are required to find out the adequate description of a metal in the theory of electromagnetic fluctuations.Comment: 19 pages, 4 figures. svjour.cls is used, to appear in Eur. Phys. J.

    Elastic double diffractive production of axial-vector \chi_c(1^{++}) mesons and the Landau-Yang theorem

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    We discuss exclusive elastic double diffractive axial-vector \chi_c(1^{+}) meson production in proton-antiproton collisions at the Tevatron. The amplitude for the process is derived within the k_t-factorisation approach with unintegrated gluon distribution functions (UGDFs). We show that the famous Landau-Yang theorem is not applicable in the case of off-shell gluons. Differential cross sections for different UGDFs are calculated. We compare exclusive production of \chi_c(1^+) and \chi_c(0^+). The contribution of \chi_c(1^+) to the J/\Psi + \gamma channel is smaller than that of the \chi_c(0^+) decay, but not negligible and can be measured. The numerical value of the ratio of the both contributions is almost independent of UGDFs modeling.Comment: 14 pages, 5 figures, a numerical error corrected, discussions extended, conclusions unchange

    On non-local variational problems with lack of compactness related to non-linear optics

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    We give a simple proof of existence of solutions of the dispersion manage- ment and diffraction management equations for zero average dispersion, respectively diffraction. These solutions are found as maximizers of non-linear and non-local vari- ational problems which are invariant under a large non-compact group. Our proof of existence of maximizer is rather direct and avoids the use of Lions' concentration compactness argument or Ekeland's variational principle.Comment: 30 page

    Small BGK waves and nonlinear Landau damping

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    Consider 1D Vlasov-poisson system with a fixed ion background and periodic condition on the space variable. First, we show that for general homogeneous equilibria, within any small neighborhood in the Sobolev space W^{s,p} (p>1,s<1+(1/p)) of the steady distribution function, there exist nontrivial travelling wave solutions (BGK waves) with arbitrary minimal period and traveling speed. This implies that nonlinear Landau damping is not true in W^{s,p}(s<1+(1/p)) space for any homogeneous equilibria and any spatial period. Indeed, in W^{s,p} (s<1+(1/p)) neighborhood of any homogeneous state, the long time dynamics is very rich, including travelling BGK waves, unstable homogeneous states and their possible invariant manifolds. Second, it is shown that for homogeneous equilibria satisfying Penrose's linear stability condition, there exist no nontrivial travelling BGK waves and unstable homogeneous states in some W^{s,p} (p>1,s>1+(1/p)) neighborhood. Furthermore, when p=2,we prove that there exist no nontrivial invariant structures in the H^{s} (s>(3/2)) neighborhood of stable homogeneous states. These results suggest the long time dynamics in the W^{s,p} (s>1+(1/p)) and particularly, in the H^{s} (s>(3/2)) neighborhoods of a stable homogeneous state might be relatively simple. We also demonstrate that linear damping holds for initial perturbations in very rough spaces, for linearly stable homogeneous state. This suggests that the contrasting dynamics in W^{s,p} spaces with the critical power s=1+(1/p) is a trully nonlinear phenomena which can not be traced back to the linear level

    Two-body ZZ' decays in the minimal 331 model

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    The two-body decays of the extra neutral boson Z_2 predicted by the minimal 331 model are analyzed. At the three-level it can decay into standard model particles as well as exotic quarks and the new gauge bosons predicted by the model. The decays into a lepton pair are strongly suppressed, with Br(Z2>l+l) 102Br(Z_2 --> l^+l^-) ~ 10^{-2} and Br(Z2>νˉlν) 103Br(Z_2 --> \bar{\nu}_l \nu) ~ 10^{-3}. In the bosonic sector, Z_2 would decay mainly into a pair of bilepton gauge bosons, with a branching ratio below the 0.1 level. The Z_2 boson has thus a leptophobic and bileptophobic nature and it would decay dominantly into quark pairs. The anomaly-induced decays Z2>Z1γZ_2 --> Z_1\gamma and Z2>Z1Z1Z_2 --> Z_1Z_1, which occurs at the one-loop level are studied. It is found that Br(Z2>Z1γ) 109Br(Z_2 --> Z_1\gamma) ~ 10^{-9} and Br(Z2>Z1Z1) 106Br(Z_2 --> Z_1Z_1) ~ 10^{-6} at most. As for the Z2>W+WZ_2 --> W^+W^- and Z2>Z1HZ_2 --> Z_1H decays, with H a relatively light Higgs boson, they are induced via Z'-Z mixing. It is obtained that Br(Z2>W+W) 102Br(Z_2 --> W^+W^-) ~ 10^{-2} and Br(Z2>Z1H) 105Br (Z_2 --> Z_1H) ~ 10^{-5}. We also examine the flavor changing neutral current decays Z2>tcZ_2 --> tc and Z2>tuZ_2 --> tu, which may have branching fractions as large as 10310^{-3} and 10510^{-5}, respectively, and thus may be of phenomenological interest.Comment: 14 pages, 3 figures, submitted to Physical Review

    Resonance- and Chaos-Assisted Tunneling

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    We consider dynamical tunneling between two symmetry-related regular islands that are separated in phase space by a chaotic sea. Such tunneling processes are dominantly governed by nonlinear resonances, which induce a coupling mechanism between ``regular'' quantum states within and ``chaotic'' states outside the islands. By means of a random matrix ansatz for the chaotic part of the Hamiltonian, one can show that the corresponding coupling matrix element directly determines the level splitting between the symmetric and the antisymmetric eigenstates of the pair of islands. We show in detail how this matrix element can be expressed in terms of elementary classical quantities that are associated with the resonance. The validity of this theory is demonstrated with the kicked Harper model.Comment: 25 pages, 5 figure
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