28,222 research outputs found

    KN and KbarN Elastic Scattering in the Quark Potential Model

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    The KN and KbarN low-energy elastic scattering is consistently studied in the framework of the QCD-inspired quark potential model. The model is composed of the t-channel one-gluon exchange potential, the s-channel one-gluon exchange potential and the harmonic oscillator confinement potential. By means of the resonating group method, nonlocal effective interaction potentials for the KN and KbarN systems are derived and used to calculate the KN and KbarN elastic scattering phase shifts. By considering the effect of QCD renormalization, the contribution of the color octet of the clusters (qqbar) and (qqq) and the suppression of the spin-orbital coupling, the numerical results are in fairly good agreement with the experimental data.Comment: 20 pages, 8 figure

    Fulde-Ferrel-Larkin-Ovchinnikov Inhomogeneous Superconducting State and Phase Transitions Induced by Spin Accumulation in a Ferromagnet-dx2y2 d_{x^{2}-y^{2}}-Wave Superconductor-Ferromagnet Tunnel Junction

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    Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) inhomogeneous superconducting (SC) state, first- and second-order phase transitions, and quantum criticality induced by spin accumulation in a ferromagnet-dx2y2d_{x^{2}-y^{2}}-wave superconductor-ferromagnet tunnel junction are theoretically predicted. A complex phase diagram in the temperature-bias voltage plane is determined. It is found that the phase transitions from the homogeneous BCS state to the inhomogeneous FFLO state, and from the FFLO state with the momentum q\mathbf{% q}'s azimuthal angle θq=0\theta_{\mathbf{q}}=0 to that with θq=π/4\theta_{% \mathbf{q}}=\pi /4, are of the first-order; while the transitions from all SC states to the normal state at critical voltages are of the second-order. A Lifshitz point, a bicritical point and a quantum critical point are identified.Comment: 5 pages, 5 figure

    Lifshitz transitions in a heavy-Fermion liquid driven by short-range antiferromagnetic correlations in the two-dimensional Kondo lattice model

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    The heavy-Fermion liquid with short-range antiferromagnetic correlations is carefully considered in the two-dimensional Kondo-Heisenberg lattice model. As the ratio of the local Heisenberg superexchange JHJ_{H} to the Kondo coupling JKJ_{K} increases, Lifshitz transitions are anticipated, where the topology of the Fermi surface (FS) of the heavy quasiparticles changes from a hole-like circle to four kidney-like pockets centered around (π,π)(\pi ,\pi). In-between these two limiting cases, a first-order quantum phase transition is identified at JH/JK=0.1055J_{H}/J_{K}=0.1055 where a small circle begins to emerge within the large deformed circle. When JH/JK=0.1425J_{H}/J_{K}=0.1425, the two deformed circles intersect each other and then decompose into four kidney-like Fermi pockets via a second-order quantum phase transition. As JH/JKJ_{H}/J_{K} increases further, the Fermi pockets are shifted along the direction (π,π\pi,\pi) to (π/2,π/2\pi/2,\pi/2), and the resulting FS is consistent with the FS obtained recently using the quantum Monte Carlo cluster approach to the Kondo lattice system in the presence of the antiferrmagnetic order.Comment: 4 pages, 5 figure

    Analytical Results for Cold Asymmetrical Fermion Superfluids at the Mean-Field Level

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    We present the analytical results at the mean-field level for the asymmetrical fermion system with attractive contact interaction at the zero temperature. The results can be expressed in terms of linear combinations of the elliptic integrals of the first and second kinds. In the limit of small gap parameter, we discuss how the asymmetry in fermion species affects the phases of the ground state. In the limit of large gap parameter, we show that two candidate phases are competing for the system's ground state. The Sarma phase containing a pure Fermi fluid and a mixed condensate is favored at large degree of asymmetry. The separated phase consisting of a pure Fermi fluid and a boson condensate supports the system at smaller degree of asymmetry. The two phases are degenerate in the limit of infinite pairing gap.Comment: 23 pages, no figur

    Detection of a new methanol maser line with ALMA

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    Aims. We aimed at investigating the structure and kinematics of the gaseous disk and outflows around the massive YSO S255 NIRS3 in the S255IR-SMA1 dense clump. Methods. Observations of the S255IR region were carried out with ALMA at two epochs in the compact and extended configurations. Results. We serendipitously detected a new, never predicted, bright maser line at about 349.1 GHz, which most probably represents the CH3_3OH 14114014_{1} - 14_{0} A+^{- +} transition. The emission covers most of the 6.7 GHz methanol maser emission area of almost 1^{\prime\prime} in size and shows a velocity gradient in the same sense as the disk rotation. No variability was found on the time interval of several months. It is classified as Class II maser and probably originates in a ring at a distance of several hundreds AU from the central star.Comment: 4 pages, 4 figures, accepted by Astronomy and Astrophysic

    Consistency in Formulation of Spin Current and Torque Associated with a Variance of Angular Momentum

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    Stimulated generally by recent interest in the novel spin Hall effect, the nonrelativistic quantum mechanical conserved currents, taken into account of spin-orbit coupling, are rigorously formulated based on the symmetries of system and Noether' theorem. The quantum mechanical force on the spin as well as the torque associated with the variance of angular momentum are obtained. Consequently, the kinetic interpretation of the variances of spin and orbit angular momentum currents implies a torque on the "electric dipole" associated with the moving spin. The bearing of the force and the torque on the properties of spin current in a two-dimensional electron gas with the Rashba spin-orbit interaction is discussed.Comment: 4 pages, no figur

    The Cure: Making a game of gene selection for breast cancer survival prediction

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    Motivation: Molecular signatures for predicting breast cancer prognosis could greatly improve care through personalization of treatment. Computational analyses of genome-wide expression datasets have identified such signatures, but these signatures leave much to be desired in terms of accuracy, reproducibility and biological interpretability. Methods that take advantage of structured prior knowledge (e.g. protein interaction networks) show promise in helping to define better signatures but most knowledge remains unstructured. Crowdsourcing via scientific discovery games is an emerging methodology that has the potential to tap into human intelligence at scales and in modes previously unheard of. Here, we developed and evaluated a game called The Cure on the task of gene selection for breast cancer survival prediction. Our central hypothesis was that knowledge linking expression patterns of specific genes to breast cancer outcomes could be captured from game players. We envisioned capturing knowledge both from the players prior experience and from their ability to interpret text related to candidate genes presented to them in the context of the game. Results: Between its launch in Sept. 2012 and Sept. 2013, The Cure attracted more than 1,000 registered players who collectively played nearly 10,000 games. Gene sets assembled through aggregation of the collected data clearly demonstrated the accumulation of relevant expert knowledge. In terms of predictive accuracy, these gene sets provided comparable performance to gene sets generated using other methods including those used in commercial tests. The Cure is available at http://genegames.org/cure
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