共查询到20条相似文献,搜索用时 15 毫秒
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V. R. Kudashev
S. E. Sharapov
《Physics letters. A》1991,160(6):559-563The effective structure of the hydrodynamic symmetries for the Whitham equations, derived for simplest one-phase solutions of the sine-Gordon equation, is presented. This structure is analogous to the one, that was obtained for the Whitham equations for the KdV equation and the nonlinear Schrödinger equation (NSE). The hydrodynamic symmetries for the gas dynamic equations are described. 相似文献
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G. S. AgarwalR. Simon 《Optics Communications》1993,100(5-6):411-414
An experiment is proposed for the study of the Gouy effect associated with the wave function for the squeezed vacuum state of light. The proposed experiment relies on the connection between the phase of the wave function and the phase of an appropriately defined field amplitude. 相似文献
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Spline algorithms are evaluated for the non-linear, integro-differential equation describing the Hartree-Fock approximation for the He 1s21S ground state. The error in the energy decreases as h2K−2, where h is a grid parameter and K is the order of the spline. It is shown that for higher order splines, the method is fast and accurate, and contrary to the conclusion reached by Altenberger-Siczek and Gilbert, that spline methods are suitable for SCF atomic structure calculations. Accuracy and timing studies are presented as well as comparisons with other accurate procedures. 相似文献
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The roughness exponent for fracture surfaces in the fuse model has been thought to be universal for narrow threshold distributions and has been important in the numerical studies of fracture roughness. We show that the fuse model gives a disorder dependent roughness exponent for narrow disorders when the lattice is influencing the fracture growth. When the influence of the lattice disappears, the local roughness exponent approaches zeta(local)=0.65+/-0.03 for distribution with a tail toward small thresholds, but with large jumps in the profiles giving corrections to scaling on small scales. For very broad disorders the distribution of jumps becomes a Lévy distribution and the Lévy characteristics contribute to the local roughness exponent. 相似文献
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Herbert Weigel 《Czechoslovak Journal of Physics》2002,52(3):C65-C78
In these lectures the three flavor soliton approach for baryons is reviewed. Effects of flavor symmetry breaking in the baryon wave functions on axial current matrix elements are discussed. A bosonized chiral quark model is considered to outline the computation of spin dependent nucleon structure functions in the soliton picture. 相似文献
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An approximate stochastic model for the topological dynamics of the periodic triangular Lorentz gas is constructed. The model, together with an extremum principle, is used to find a closed form approximation to the diffusion coefficient as a function of the lattice spacing. This approximation is superior to the popular Machta and Zwanzig result and agrees well with a range of numerical estimates. 相似文献
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Luca Fabbri 《International Journal of Theoretical Physics》2011,50(11):3616-3620
We consider a geometric approach to field theory in which torsion is present beside gravity and also electrodynamics for the
matter field equations, and we develop the consequences of the torsion-spin coupling for the spinor fields; we show that these
interactions have the structure of the weak interactions acting among leptons: we discuss the implications for the standard
model of fundamental interactions of elementary fields in the perspective of the foundations of unification in theoretical
physics. 相似文献
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We present a new method for the evaluation of the RKR potential-integrals for diatomic molecules. This method is straightforward
and fast, and the calculations can be performed to an accuracy better than any other method. 相似文献
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A. Pellegrinotti 《Journal of statistical physics》1988,53(5-6):1327-1336
A transformation on the two-dimensional torus which is related to the problem of limit distribution for the distance between the levels in the kicked-rotator model is considered. The first four moments of the r.w. which describe the numbers of visits of a point in a rectangle of measure are calculated. It is shown that when 0 they converge to the first four moments of a Poisson r.w. 相似文献
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We address the question of determining the eigenvalues \({\lambda_{n}}\) (listed in nondecreasing order, with multiplicities) for which Courant’s nodal domain theorem is sharp i.e., for which there exists an associated eigenfunction with \({n}\) nodal domains (Courant-sharp eigenvalues). Following ideas going back to Pleijel (1956), we prove that the only Courant-sharp eigenvalues of the flat equilateral torus are the first and second, and that the only Courant-sharp Dirichlet eigenvalues of the equilateral triangle are the first, second, and fourth eigenvalues. In the last section we sketch similar results for the right-angled isosceles triangle and for the hemiequilateral triangle. 相似文献
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We present a formalism for calculating the absorption coefficient of a pair of coaxial tubules. A spatially nonlocal, dynamical self-consistent field theory is obtained by calculating the electrostatic potential produced by the charge density fluctuations as well as the external electric field. There are peaks in the absorption spectrum arising from plasma excitations corresponding either to plasmon or particle-hole modes. In this Letter, we numerically calculate the plasmon contribution to the absorption spectrum when an external electric field is applied. The number of peaks depends on the radius of the inner as well as outer tubule. The height of each peak is determined by the plasmon wavelength and energy. For a chosen wave number, the most energetic plasmon has the highest peak corresponding to the largest oscillator strength of the excited modes. Some of the low-frequency plasmon modes have such weak coupling to an external electric field that they are not seen on the same scale as the modes with larger energy of excitation. We plot the peak positions of the plasmon excitations for a pair of coaxial tubules. The coupled modes on the two tubules are split by the Coulomb interaction. The energies of the two highest plasmon branches increase with the radius of the outer tubule. On the contrary, the lowest modes decrease in energy as this radius is increased. No effects due to inter-tubule hopping are included in these calculations. 相似文献
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Matt Visser 《General Relativity and Gravitation》1998,30(12):1717-1728
Can we give the graviton a mass? Does it even make sense to speak of a massive graviton? In this essay I shall answer these questions in the affirmative. I shall outline an alternative to Einstein Gravity that satisfies the Equivalence Principle and automatically passes all classical weakfield tests (GM/r ≈ 10-6). It also passes medium-field tests (GM/r ≈ 1/5), but exhibits radically different strong-field behaviour (GM/r ≈ 1). Black holes in the usual sense do not exist in this theory, and large-scale cosmology is divorced from the distribution of matter. To do all this we have to sacrifice something: the theory exhibits prior geometry, and depends on a non-dynamical background metric. 相似文献
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Matthew P. Richey 《Nuclear Physics B》1990,330(2-3):681-704
We calculate the polynomial relationships P(, z) = 0 and P(, κ) = 0 in both the ordered and disordered regimes for the hard hexagon model. We start with Baxter's exact solution which gives the physical quantities κ, , and z parametrically as a function of a variable τ and exploit the modular properties of Baxter's solution. Using elementary Riemann surface theory, the computation can be reduced to algorithms involving only linear algebra. These algorithms are implemented using a computer algebra system. The method will be applicable to other exactly solvable models in which cusp expansions can be computed. 相似文献