18,697 research outputs found

    Real-time evolution method and its application to 3α\alpha cluster system

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    A new theoretical method is proposed to describe the ground and excited cluster states of atomic nuclei. The method utilizes the equation-of-motion of the Gaussian wave packets to generate the basis wave functions having various cluster configurations. The generated basis wave functions are superposed to diagonalize the Hamiltonian. In other words, this method uses the real time as the generator coordinate. The application to the 3α3\alpha system as a benchmark shows that the new method works efficiently and yields the result consistent with or better than the other cluster models. Brief discussion on the structure of the excited 0+0^+ and 11^- states is also made

    Diurnal variations from muon data at Takeyama underground station

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    An underground station, Takeyama, is introduced, and some results of the solar diurnal and semi-diurnal variations for the period between 1967 and 1984 are presented. There are clear tendencies of double and single solar cycle variations in the daily variations which are in good accord with those detected by other underground and neutron monitor observations

    Superconductivity in Pseudo-Binary Silicide SrNixSi2-x with AlB2-Type Structure

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    We demonstrate the emergence of superconductivity in pseudo-binary silicide SrNixSi2-x. The compound exhibits a structural phase transition from the cubic SrSi2-type structure (P4132) to the hexagonal AlB2-type structure (P6/mmm) upon substituting Ni for Si at approximately x = 0.1. The hexagonal structure is stabilized in the range of 0.1 < x < 0.7. The superconducting phase appears in the vicinity of the structural phase boundary. Ni acts as a nonmagnetic dopant, as confirmed by the Pauli paramagnetic behavior.Comment: 12 pages, 5 figure

    Quark tensor and axial charges within the Schwinger-Dyson formalism

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    We calculate the tensor and axial charges of the quark in the Schwinger-Dyson formalism of Landau gauge QCD. It is found that the dressed tensor and isovector axial charges of the quark are suppressed against the bare quark contribution, and the result agrees qualitatively with the experimental data. We show that this is due to the superposition of the spin flip of the quark arising from the successive emission of gluons which dress the vertex. For the isoscalar quark axial charge, we have analyzed the Schwinger-Dyson equation by including the leading unquenching quark-loop effect. It is found that the suppression is more significant, due to the axial anomaly effect.Comment: 5 pages, 4 figures, Contribution of proceedings of XV International Conference on Hadron Spectroscopy-Hadron 2013 (Hadron 2013

    Generalized Landau-Pollak Uncertainty Relation

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    The Landau-Pollak uncertainty relation treats a pair of rank one projection valued measures and imposes a restriction on their probability distributions. It gives a nontrivial bound for summation of their maximum values. We give a generalization of this bound (weak version of the Landau-Pollak uncertainty relation). Our generalization covers a pair of positive operator valued measures. A nontrivial but slightly weak inequality that can treat an arbitrary number of positive operator valued measures is also presented.Comment: Simplified the proofs. To be published in Phys.Rev.

    (63)Cu NQR Evidence for Spatial Variation of Hole Concentration in La(2-x)Sr(x)CuO(4)

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    We report experimental evidence for the spatial variation of hole concentration x_(hole) in the high Tc superconductor La(2-x)Sr(x)CuO(4) (0.04 <= x <= 0.16) by using (63)Cu NQR for (63)Cu isotope enriched samples. We demonstrate that the extent of the spatial variation of the local hole concentration D(x)_(hole) is reflected on (63)1/T1 and deduce the temperature dependence. D(x)_(hole) increases below 500 - 600K, and reaches values as large as D(x)_(hole)/x ~ 0.5 below ~ 150K. We estimate the length scale of the spatial variation in x_(hole) to be R_(hole) >~ 3nm from analysis of the NQR spectrum.Comment: Accepted for publication in Physical Review Letter

    What has NMR taught us about stripes and inhomogeneity?

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    The purpose of this brief invited paper is to summarize what we have (not) learned from NMR on stripes and inhomogeneity in La{2-x}Sr{x}CuO{4}. We explain that the reality is far more complicated than generally accepted.Comment: Accepted for publication in the Proceedings of the LT-23 Conference (invited

    Quark scalar, axial, and pseudoscalar charges in the Schwinger-Dyson formalism

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    We calculate the scalar, axial, and pseudoscalar charges of the quark in the Schwinger-Dyson formalism of Landau gauge QCD. It is found that the dressed quark scalar density of the valence quark is significantly enhanced against the bare quark contribution, and the result explains qualitatively the phenomenologically known value of the pion-nucleon sigma term and also that given by lattice QCD. Moreover, we show that the Richardson's interquark potential suppresses the quark scalar density in the Higashjima-Miransky approximation. This fact suggests that the quark scalar density is an observable that is sensitive to quark confinement. For the quark axial charge, we find that it is suppressed due to the gluon dynamics. The result of the quenched analysis agrees qualitatively with the experimental data of the isovector axial coupling constant gAg_A. We show that the suppression of the quenched axial charge is due to a mechanism similar to that of the quark tensor charge. In the Schwinger-Dyson equation with the leading unquenching quark-loop contribution the quark axial charge is more suppressed, due to the anomaly effect. The quark pseudoscalar density is found to be large, and is divergent as the bare quark becomes massless. This result is in agreement with the phenomenological current algebraic analysis, and explains well the dominance of the pion-pole contribution.Comment: 28 pages, 22 figure
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