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1.
The empirical equality of is noted, for the pomeron terms in NN, πN, KN, ?N, ωN, and φN scattering, where B is the elastic slope parameter and σt is the total cross section. This ratio increases slowly with energy, but remains the same in all channels. This is equivalent to a relation between the diffractive interaction radii and opacities; the opacity scales with the square of the radius. We conjecture that this systematics extends to ψN scattering. We contrast universaility with the slope predictions of an f-coupled pomeron model. Some other predictions of the f-dominance hypothesis are tested against data. 相似文献
2.
John Miles 《Physica D: Nonlinear Phenomena》1984,11(3):309-323
The weakly nonlinear, resonant response of a damped, spherical pendulum (length l, damping ratio δ, natural frequency ω0) to the planar displacement εl cos ωt (ε ? 1) of its point of suspension is examined in a four-dimensional phase space in which the coordinates are slowly varying amplitudes of a sinusoidal motion. The loci of equilibrium points and the corresponding bifurcation points in this space are determined. The control parameters are and . If α < 0.441 there is a finite interval of v within which no stable equilibrium points exist. As v decreases through the upper bound (a Hopf-bifurcation point) of this interval the motion in the phase space becomes periodic and then, following a period-doubling cascade, chaotic. There may be alternating sub-intervals of chaotic and periodic motion. The chaotic trajectories in the phase space appear to lie on fractal attractors. 相似文献
3.
C.R. Leavens 《Solid State Communications》1976,19(4):395-397
The Eliashberg gap equations relate the transition temperature Tc of an isotropic superconductor to its electron-phonon spectral function α2F(ω) and Coulomb pseudopotential parameter . Recently the Eliashberg theory has been used to derive some supposedly rigorous results bearing on the problem of attaining higher superconducting transition temperatures: Bergmann and Rainer derived an expression for the functional derivative ; Allen and Dynes showed that in the asymptotic limit of very large and Leavens proved that for any isotropic superconductor kBTc ?0.2309A, where A is the area under its electron-phonon spectral function. In this letter we show that the result of Allen and Dynes is not compatible with the other results and is, in fact, incorrect. 相似文献
4.
P. Halevi 《Surface science》1978,76(1):64-90
A review of polariton modes at interfaces composed of two semiinfinite, homogeneous, and isotropic media is given. Both media are characterized by frequency-dependent dielectric functions ?i(ω), i = 1, 2, and may become “interface-wave-active” in different frequency regions. The conditions for the existance of propagation windows are analyzed and applied to two particular cases: an interface composed of (a) two dielectrics with dielectric functions , where ?t8i are the dielectric constants for very large frequencies and ωTi and ωLi are the transverse and longitudinal phonon frequencies; (b) two conductors with dielectric functions , where ωiare the plasma frequencies. In the first case there exist two propagation windows in the infrared region, while in the second case there is one propagation window in the ultraviolet, visible, or infrared region. The dispersion relations of the modes and their decay distances into the two media are presented, and various damping effects are discussed. The review is concluded with theoretical results on the optical excitation and detection (ATR) of the interface modes. 相似文献
5.
We have obtained a least upper bound, , on the critical temperature Tc of an isotropic superconductor with paramagnetic impurities described by the scattering matrix t for fixed values of μ1. We have also obtained the corresponding optimal spectrum . The numerical results for the functions are presented for and 0.16 in the form of universal curves representing as functions of the reduced impurity concentration . We have also established an upper limit to the reduced critical concentration for an arbitrary shape of α2F(ω)1. 相似文献
6.
《Physica A》1995,216(4):445-451
7.
The deep inelastic structure function D(ω, q2) is calculated in the leading log approximation for . For larger ω up to ( the influence of reggeon cuts proves to slow down the growth of the structure function. A reggeon diagram technique is developed, and D is calculated up to a pre-exponent O(1), leading to D(ω, q2) ∝ q2 for . By assuming the reggeon diagrams when ω is still greater, one can expect to obtain a strong coupling behaviour: D(ω, q2) ∝ q2(ln ω)η (η <2). 相似文献
8.
We derive and compare with experimental data the bound , where α is the fine-structure constant, mp the proton mass, ν0 the photo-pion production threshold, σtot and are the unpolarized total hadronic photo-absorption cross section on protons and the unpolarized forward differential cross section for proton Compton scattering at photon-lab energy ν′, and λ and ν1 are any real numbers. We derive similar bounds on proton and neutron magnetic moments. 相似文献
9.
We consider the class of non-integrable, non-linear equations, in 1+1 dimensions. We seek rational solutions K(ω1,ω2), which we call bi-solitons, with exponential type variables ωi = exp(γix + ρit). In this paper, we restrict to q = 2 and 3, and investigate the general q case in the following paper. We find that these bi-solitons exist when the operator Lq (with ± ?) can be factorized as the product of smaller order differential operators. Besides the trivial factorized bi-solitons, we show that there exist non-trivial ones whenever K may be written as Σlmaxx ωl2Fl(Z = ω1 + ω2). In order to understand the origin of the factorization property, to any polynomial K = Σωl2Fl(Z) we associate a linear transformation such that LqK has only the power ωl2 of K2. For q = 2 and 3, we find that there exist particular polynomials of this type restraining Lq to be a product of smallr order operators. For the full non-linear equations we verify that all the bi-solitons can be obtained from these particular polynomials. 相似文献
10.
M.J. Corden J.D. Dowell J. Garvey M. Jobes I.R. Kenyon J. Mawson T. McMahon I.F. Corbett R.J. Esterling N.H. Lipman P.J. Litchfield K.C.T.O. Sumorok G. Alexander S. Dagan Y. Gnat E.H. Bellamy M.G. Green N. Harnew D.H. Thomas 《Nuclear Physics B》1978,138(2):235-252
Data on the reaction π?p → π+π?π0 have been taken at 12 and 15 GeV/c with the CERN Omega multiparticle spectrometer. In a 3-pion partial-wave analysis strong production of is observed. Total and differential cross sections are determined and density matrix elements presented as a function of t in the t- and s-channel frames. The energy dependence of A20 production is studied, and a comparison of production is made. 相似文献
11.
F.E. Close 《Physics letters. [Part B]》1973,43(5):422-426
The small ω′ behaviour of F2en/F2ep and the apparent difference in the q2 dependences of the magnetic form factor of the proton and of the transition to Δ+(1236) are quantitatively correlated in a model where nucleon consistes of a quarks and a scalar or vector core. The proton and Δ transition form factors suggest that only the scalar core contributes at large q2 and small ω′. As a result the ω′ dependence of is obtained for ω′ < 3 and predictions for the weak structure functions and polarisation asymmetries at smallω′ are presented. We predict asymmetries and also expect that as q2→∞. 相似文献
12.
P. Gregory D. Everett P. Grossmann P. Mason H. Muirhead G. Warren R. Carlsson G. Ekspong S.O. Holmgren S. Nilsson R. Stenbacka C. Walck 《Nuclear Physics B》1974,78(2):222-232
Relations have been derived between the invariant cross sections for various inclusive processes by assuming factorisation of the leading (pomeron) and non-leading (meson) trajectories. In this paper predictions for the invariant cross sections have been tested using data from interactions at 4.6 and 9.1 GeV/c.A large discrepancy between experiment and theory is apparent for the π? data: in the π+ case the discrepancy is less marked but still present. 相似文献
13.
The average multiplicity in deep inelastic electro- and neutrinoproduction at large ω(ω~s/Q2 + 1) is related in Feynman's version of the parton model to the average multiplicities in high-energy electron-positron annihilation and hadron-hadron scattering. The relation is: , where Ce+e? and Ch are, respectively, the coefficients of ln(s/M1⊥2) in the multiplicities from e+-e? and P-P in to hadrons, and M1⊥ is an average transverse mass. 相似文献
14.
P.R. Bunker 《Journal of Molecular Spectroscopy》1973,45(1):151-158
In the Born-Oppenheimer approximation the dipole moment of the vibrational levels of a 1Σ electronic state of a heteronuclear diatomic molecule can be expressed as a power series in [], where v is the vibrational quantum number, and to order this expression is Similarly the nuclear quadrupole coupling constant eQq of each nucleus in the molecule can be expressed as In this paper the effect of the breakdown of the Born-Oppenheimer approximation on the expressions for μv and eQq for an isolated 1Σ ground electronic state of a heteronuclear diatomic molecule is determined. The effect is to change only μc and eQqc and, therefore, to alter the relationship between the μv or eQq values of two isotopes of a molecule. The intensities of the lines in the rotation and rotation-vibration spectrum are also slightly modified by this effect.For the HCl molecule we find that where the second term (+164 D) would have the value ?4 D in the Born-Oppenheimer approximation. Similarly for the 35Cl nucleus of the HCl molecule we have where the second term (+2460 MHz) would be ?110 MHz in the Born-Oppenheimer approximation. 相似文献
15.
We show that the long time behaviour of the velocity correlation function in a two-dimensional classical system with pairwise repulsive potentials can be represented by a series expansion of the form , where t0 is mean free time between collisions. To lowest order in the density an exact expression has been obtained for d1 employing the kinetic theory ofsystems with hard-core interactions. The significance of the series is discussed at low and intermediate densities. 相似文献
16.
G.V. Dass 《Nuclear Physics B》1973,59(1):324-332
If resonance decaying into KS,L (the short- and long-lived kaon) and a neutral system So of pions, one can isolate the C-even and C-odd, crossed-channel contributions to by using the reactions whether So is a C-eigenstate, or a mixture of C-even and C-odd states. Applications to the production of K1(890) and the Q-meson are discussed, and simple numerical predictions made for QS,L production. Q-production data indicate approximate t-channel helicity conservation for the ω and P' exchanges at vertices involving a spin change, in similarity to the belief for the pomeron. QS,L production data can give information also on Q-decays. 相似文献
17.
The nuclear spin lattice relaxation rate in a quasi-two-dimensional (2-D) metal under strong magnetic fields is studied in a special case where the electronic cyclotron mass is small compared with the free electron mass. In the pure limit (ωcτ ? 1) and for sufficiently low temperatures () we find remarkable quantum oscillations of the relaxation rate as a function of the magnetic field. The period of these oscillations is identical to that of the de Haas-van Alphen oscillations and their amplitude grows linearly with the magnetic field. The possibility of observing such oscillations experimentally in the quasi-2-D mercury chain compound Hg3?δAsF6 is discussed. 相似文献
18.
Yu.M. Antipov V.A. Bessubov N.P. Budanov Yu.P. Gorin S.P. Denisov S.V. Klimenko A.A. Lebedev Yu.V. Mikhailov A.I. Petrukhin S.A. Polovnikov V.N. Roinishvili D.A. Stoyanova F.A. Yotch 《Physics letters. [Part B]》1978,76(2):235-236
The differential cross sections and of inclusive J/ψ production by 43 GeV/c π? off Be, Cu and W nuclei have been measured. Fitting we observed the increase of α with pt2. 相似文献
19.
We show that in QCD the production of high-pt hadrons in the pionization region is not a rare process, but a usual “soft” one. Its inclusive cross section ? behaves as . At ISABELLE energies and pt = 10 GeV we estimate this cross section to be at least an order larger than the value obtained by commonly used parametrizations. 相似文献
20.
Amit Sur 《Solid State Communications》1976,18(6):755-756
The first ten moments of the infinite-temperature space and frequency dependent two-spin correlation functions, and are obtained for the one-dimensional anisotropic Heisenberg model for r = 0 and r = 1. These are compared with those previously known. 相似文献