4,540 research outputs found

    Half quantum vortex in superfluid 3^3He-A phase in parallel plate geometry

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    The half quantum vortex(HQV) in condensate has been studied, since it was predicted by Salomaa and Volovik in superfluid 3^3He-A phase. However, an experimental evidence for its existence has not been reported so far. Motivated by a recent experimental report by Yamashita et al\cite{yamashita}, we study the HQVs in superfluid 3^3He confined between two parallel plates with a gap D \sim 10 μ\mum in the presence of a magnetic field H \sim 26 mT perpendicular to the parallel plates. We find that the bound HQVs are more stable than the singular vortices and free pairs of HQVs, when the rotation perpendicular to the parallel plates is below the critical speed, Ωc\Omega_c \sim 2 rad/s. The bound pair of HQVs accompanies the tilting of d^{\hat d}-vector out of the plane, which leads to an additional absorption in NMR spectra. Our study appears to describe the temperature and rotation dependence of the observed satellite NMR signal, which supports the existence of the HQVs in 3^3He.Comment: 5 pages, 5 figure

    The small mixing angle θ13\theta_{13} and the lepton asymmetry

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    We present the correlation of low energy CP phases, both Dirac and Majorana, and the lepton asymmetry for the baryon asymmetry in the universe, with a certain class of Yukawa matrices that consist of two right-handed neutrinos and include one texture zero in themselves. For cases in which the amount of the lepton asymmetry YLY_L turns out to be proportional to θ132\theta_{13}^2, we consider the relation between two types of CP phases and the relation of YLY_L versus the Jarlskog invariant or the amplitude of neutrinoless double beta decay as θ13\theta_{13} varies.Comment: 17 pages, 14 figures, information for figures added, version published in PR

    Possible f-wave superconductivity in Sr2_2RuO4_4?

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    Until recently it has been believed that the superconductivity in Sr2_2RuO4_4 is described by p-wave pairing. However, both the recent specific heat and the magnetic penetration depth measurements on the purest single crystals of Sr2_2RuO4_4 appear to be explained more consistently in terms of f-wave superconductivity. In order to further this hypothesis, we study theoretically the thermodynamics and thermal conductivity of f-wave superconductors in a planar magnetic field. We find the simple expressions for these quantities when HHc2H \ll H_{c2} and TTcT \ll T_{c}, which should be readily accessible experimentally.Comment: 6 pages, 2 figure

    LWR fuel performance analysis : fuel cracking and relocation

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    "Final report for research project sponsored by Northeast Utilities Service Company, Yankee Atomic Electric Co. under the MIT Energy Laboratory Electric Utility Program.

    Gap Symmetry an Thermal Conductivity in Nodal Superconductors

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    There are now many nodal superconductors in heavy fermion (HF) systems, charge conjugated organic metals, high Tc cuprates and ruthenates. On the other hand only few of them have a well established gap function. We present here a study of the angular dependent thermal conductivity in the vortex state of some of the nodal superconductors. We hope it will help to identify the nodal directions in the gap function of UPd_2Al_3, UNi_2Al_3, UBe_13 and URu_2Si_2.Comment: 4 pages, 5 figure

    Gap Anisotropy and de Haas-van Alphen Effect in Type-II Superconductors

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    We present a theoretical study on the de Haas-van Alphen (dHvA) oscillation in the vortex state of type-II superconductors, with a special focus on the connection between the gap anisotropy and the oscillation damping. Numerical calculations for three different gap structures clearly indicate that the average gap along extremal orbits is relevant for the magnitude of the extra damping, thereby providing a support for experimental efforts to probe gap anisotropy through the dHvA signal. We also derive an analytic formula for the extra damping which gives a good fit to the numerical results.Comment: 5 pages, 1 figure, changes in Introductio

    Abnormal systolic blood pressure response during exercise is related to subendocardial hypoperfusion detected by exercise 201Tl myocardial scintigraphy in patient with hypertrophic cardiomyopathy

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    Balcells, EugèniaPla general, d'alguns dels elements que formen la taula periòdica. Cadascun dels 112 elements és representat pel seu espectre de color. Es van produir diverses còpies de l'obra, aquesta està a la Biblioteca de la Facultat de Química

    Sound propagation in density wave conductors and the effect of long-range Coulomb interaction

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    We study theoretically the sound propagation in charge- and spin-density waves in the hydrodynamic regime. First, making use of the method of comoving frame, we construct the stress tensor appropriate for quasi-one dimensional systems within tight-binding approximation. Taking into account the screening effect of the long-range Coulomb interaction, we find that the increase of the sound velocity below the critical temperature is about two orders of magnitude less for longitudinal sound than for transverse one. It is shown that only the transverse sound wave with displacement vector parallel to the chain direction couples to the phason of the density wave, therefore we expect significant electromechanical effect only in this case.Comment: revtex, 14 pages (in preprint form), submitted to PR

    Half-quantum vortex and d-soliton in Sr2_2RuO4_4

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    Assuming that the superconductivity in Sr2_2RuO4_4 is described by a planar p-wave order parameter, we consider possible topological defects in Sr2_2RuO4_4. In particular, it is shown that both of the d^{\hat d}-soliton and half-quantum vortex can be created in the presence of the magnetic field parallel to the aa-bb plane. We discuss how one can detect the d^{\hat d}-soliton and half-quantum vortex experimentally.Comment: 8 pages, 3 figure

    Unconventional spin density wave in Bechgaard salt (TMTSF)2NO3

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    Among many Bechgaard salts, TMTSF2NO3 exhibits very anomalous low temperature properties. Unlike conventional spin density wave (SDW), TMTSF2NO3 undergoes the SDW transition at \T_SDW\approx 9.5 K and the low temperature quasiparticle excitations are gapless. Also, it is known that TMTSF2NO3 does not exhibit superconductivity even under pressure, while FISDW is found in TMTSF2NO3 only for P=8.5 kbar and B>20 T. Here we shall show that both the angle dependent magnetoresistance data and the nonlinear Hall resistance of TMTSF2NO3 at ambient pressure are interpreted satisfactory in terms of unconventional spin density wave (USDW). Based on these facts, we propose a new phase diagram for Bechgaards salts.Comment: 4 pages, 4 figs, RevTe
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