80 research outputs found

    Dispersion Relations for Waves propagating in Composite Fermion Gases

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    The discrete Uehling-Uhlenbeck equations are solved to study the propagation of plane (sound) waves in a system of composite fermionic particles with hard-sphere interactions and the filling factor (ν\nu) being 1/2. The Uehling-Uhlenbeck collision sum, as it is highly nonlinear, is linearized firstly and then decomposed by using the plane wave assumption. We compare the dispersion relations thus obtained by the relevant Pauli-blocking parameter BB which describes the different-statistics particles for the quantum analog of the discrete Boltzmann system when BB is positive (Bose gases), zero (Boltzmann gases), and negative (Fermi Gases). We found, as the effective magnetic field being zero (ν\nu=1/2 using the composite fermion formulation), the electric and fluctuating (induced) magnetic fields effect will induce anomalous dispersion relations.Comment: 13 pages with 2 figure

    Possible Orientation Effects to Phase Diagram of Strange Matter

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    We obtain possibly valuable information about the orientation-tuning of phase diagram of superdense nuclear matter at high fermion as well as boson number density but low temperature, which is not accessible to relativistic heavy ion collision experiments. Our results resemble those proposed before by Alford. Possible observational signatures associated with the theoretically proposed states of matter inside compact stars are discussed as well.Comment: 3 Figures; 2006-Jan. work

    Stability of Quantum Fluids : Wavy Interface Effect

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    A numerical investigation for the stability of the incompressible slip flow of normal quantum fluids (above the critical phase transition temperature) inside a microslab where surface acoustic waves propagate along the walls is presented. Governing equations and associated slip velocity and wavy interface boundary conditions for the flow of normal fluids confined between elastic wavy interfaces are obtained. The numerical approach is an extension (with a complex matrix pre-conditioning) of the spectral method. We found that the critical Reynolds number (RecrRe_{cr} or the critical velocity) decreases significantly once the slip velocity and wavy interface effects are present and the latter is dominated (RecrRe_{cr} mainly depends on the wavy interfaces).Comment: 4 Figures; 2004-Jan work

    Possible Pressure Effect for Superconductors

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    We make an estimate of the possible range of ΔTc\Delta T_c induced by high-pressure effects in post-metallic superconductors by using the theory of {\it extended irreversible/reversible thermodynamics} and Pippard's length scale. The relationship between the increment of the superconducting temperature and the increase of the pressure is parabolic.Comment: 6 pages; 1999-March result

    Comments on "Attainable conditions and exact invariant for the time-dependent harmonic oscillator"

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    We make remarks on Fern\'{a}ndez Guasti's paper [{\it J. Phys. A: Math. Gen.} 39 (2006) 11825-11832] by pointing out some mistakes Fern\'{a}ndez Guasti derived therein.Comment: Comments for ; 2 Pages in tota

    Phantom Thermodynamics Revisited

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    Although generalized Chaplygin phantom models do not show any big rip singularities, we investigated k-essence models together with noncanonical kinetic energy for which there might be a big rip future singularity in the phantom region. We present our results by finely tuning the parameter (β\beta) which is closely related to the canonical kinetic term in kk-essence formalism. The scale factor a(t)a(t) could be negative and decreasing within a specific range of β\beta during the initial evolutional period. There will be no singularity for the scale factor for all times once β\beta is carefully selected.Comment: 4 pages; 1 figur

    Possible Enhanced Flux of Glassy Solid Helium in Cylindrical Corrugated Nanopores

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    By using the glassy (helium-)fluid model and boundary perturbation method, we can obtain the velocity fields (as well as the flow rate; up to the second order) inside the wavy-rough cylindrical nanopores which are of the same size as those samples prepared by Kim and Chan as well as Day {\it et al.} Our results show that the velocities measured in porous Vycor samples could be reproduced by carefully selecting relevant parameters but those in glass capillaries are difficult to obtain.Comment: 2 figure

    Possible Zero-Flux Transport induced by Density Waves in a Tube filled with Solid Helium

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    Macroscopic derivation of the entrainment in a supersolid cylinder induced by a surface elastic wave (of small amplitude) propagating along the flexible interface is conducted by considering the nonlinear coupling between the interface and the rarefaction effect. We obtain the critical bounds for zero-volume-flow-rate states corresponding to specific rarefaction measure and wave number which is relevant to the rather small critical velocity or disappearance of supersolid flows reported by Rittner and Reppy.Comment: 13 pages with one Table and 3 figure

    Comments on "Evidence for Quantized Displacement in Macroscopic Nanomechanical Oscillators"

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    We make comments on Gaidarzhy {\it et al.}'s [{\it Phys. Rev. Lett.} 94, 030402 (2005)] letter.Comment: 3 page

    Note on the 818_{18}-Knot

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    We define some physical variables associated with the traversing sequences of electrons along the orbit which is a 2D projection of 818_{18}-knot. The configuration is regular but the resulting contributions, which are related to the physical variable, of those combinations from all the possible states to the fixed spatial sites show certain irregular behavior near the over- or under-crossing points of this knot. The possible explanation for this kind of direct geometric consequences is made to linked to the physical insight.Comment: One Table and Two Figures; 1999-Feb. complete
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