26,075 research outputs found

    The Measure of the Orthogonal Polynomials Related to Fibonacci Chains: The Periodic Case

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    The spectral measure for the two families of orthogonal polynomial systems related to periodic chains with N-particle elementary unit and nearest neighbour harmonic interaction is computed using two different methods. The interest is in the orthogonal polynomials related to Fibonacci chains in the periodic approximation. The relation of the measure to appropriately defined Green's functions is established.Comment: 19 pages, TeX, 3 scanned figures, uuencoded file, original figures on request, some misprints corrected, tbp: J. Phys.

    Polaronic slowing of fermionic impurities in lattice Bose-Fermi mixtures

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    We generalize the application of small polaron theory to ultracold gases of Ref. [\onlinecite{jaksch_njp1}] to the case of Bose-Fermi mixtures, where both components are loaded into an optical lattice. In a suitable range of parameters, the mixture can be described within a Bogoliubov approach in the presence of fermionic (dynamic) impurities and an effective description in terms of polarons applies. In the dilute limit of the slow impurity regime, the hopping of fermionic particles is exponentially renormalized due to polaron formation, regardless of the sign of the Bose-Fermi interaction. This should lead to clear experimental signatures of polaronic effects, once the regime of interest is reached. The validity of our approach is analyzed in the light of currently available experiments. We provide results for the hopping renormalization factor for different values of temperature, density and Bose-Fermi interaction for three-dimensional 87Rb40K^{87}\rm{Rb}-^{40}\rm{K} mixtures in optical lattice.Comment: 13 pages, 5 figure

    Potential competitive effects on U.S. bank credit card lending from the proposed bifurcated application of Basel II

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    This paper analyzes the potential competitive effects of the proposed bifurcated application of Basel II capital regulations in the United States on bank credit card lending activities. For this purpose, the authors consider the Basel II regulations as stated in the June 2004 Basel Committee Framework Agreement. ; Also issued as Payment Cards Center Discussion Paper No. 05-21 ; Superseded by Working Paper 07-09Basel capital accord ; Credit cards

    Scaling of gauge balls and static potential in the confinement phase of the pure U(1) lattice gauge theory

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    We investigate the scaling behaviour of gauge-ball masses and static potential in the pure U(1) lattice gauge theory on toroidal lattices. An extended gauge field action P(βcosΘP+γcos2ΘP)-\sum_P(\beta \cos\Theta_P + \gamma \cos2\Theta_P) is used with γ=0.2\gamma= -0.2 and -0.5. Gauge-ball correlation functions with all possible lattice quantum numbers are calculated. Most gauge-ball masses scale with the non-Gaussian exponent νng0.36\nu_{ng}\approx 0.36. The A1++A_1^{++} gauge-ball mass scales with the Gaussian value νg0.5\nu_{g} \approx 0.5 in the investigated range of correlation lengths. The static potential is examined with Sommer's method. The long range part scales consistently with νng\nu_{ng} but the short range part tends to yield smaller values of ν\nu. The β\beta-function, having a UV stable zero, is obtained from the running coupling. These results hold for both γ\gamma values, supporting universality. Consequences for the continuum limit of the theory are discussed.Comment: Contribution to the Lattice 97 proceedings, LaTeX, 3 pages, 3 figure
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