共查询到20条相似文献,搜索用时 15 毫秒
1.
t-channel unitarity equations are derived for n-particle overlap functions. Together with s-channel unitarity they lead to scaling laws for the inelastic s-channel partial-wave amplitudes in the limits . Assuming the validity of the scaling law in the whole range, allowed by s-channel unitarity — i.e. for we obtain constant production cross sections σ(n)(s) at high energies s → ∞ up to s factors. 相似文献
2.
Necessary and sufficient conditions for the existence of the Lagrangian associated with given field equations of motion are investigated. For the quasi-linear equations Aabμν(xλ, φc, φ?c)φμνb + Ba(xμ, φb, φνb) = 0, the complete necessary and sufficient conditions are obtained, resorting to the formalism of an exterior derivative. It is emphasized that, to find expressions of these conditions, the anti-symmetric parts of the second derivatives of a Lagrangian, , which disappear in the field equations, take an important role. The procedure to construct the Lagrandian associated with the field equations is also presented. 相似文献
3.
Nuclear spectroscopic quadrupole moments of the radioactive isotopes 131Cs, 132Cs, and 136Cs have been determined from the hyperfine structure of the state by the level crossing method. The results including a Sternheimer correction are: , , . The quadrupole moments of all the Cs isotopes from A = 131 to A = 137 are recalculated. It is shown, that nuclear quadrupole moments of a specific isotope obtained from different atomic P-states only agree within the limits of error after application of the Sternheimer correction. The increase of Qs with decreasing neutron number conforms with other observations and theoretical calculations stating that for elements around Z = 55 nuclear deformation develops below N = 82. The staggering of the sign of Qs may be interpreted as consequence of an oblate-prolate degeneracy of the nuclear energy surface. Some magnetic moments have been slightly improved: , (corrected for diamagnetism). 相似文献
4.
We studied the energy width and the width in reciprocal space Δq of the central mode of SrTiO3 above Tc. At Tc+4° we observed an energy width of about 6×10?7 eV. If the measured Δq is interpreted by a correlation length we obtain . 相似文献
5.
We have carried out a high-resolution X-ray critical scattering experiment in the isotropic phase connected with the isotropic-smectic-B transition in 4,4-di-n-hexyl-biphenyl. The measurements yield the following parameter values: , and the critical exponents γ = 1.51 ± 0.12, ν∥ = 0.65 ± 0.06, ν⊥ = 0.70 ± 0.08. At the temperature t = 10?3 () the correlation lengths are and . 相似文献
6.
Jean-Paul Jurzak 《Reports on Mathematical Physics》1975,8(2):203-228
Let be a decomposable von Neumann algebra, ? a faithful strictly semi-finite weight on , σ?! the modular automorphism group associated with ?; if admits a cyclic and separating vector (or if π?()′ is countably decomposable, (π?, H?) being the representation of , given by ?), then we get (the ?ξ being faithful strictly semi-finite weights) and (σ?! is the modular automorphism group in (ξ), associated with ?).These results are obtained by developing the functional calculus for decomposable operators. More precisely, let be a Hermitian (bounded) decomposable operators, and f a complex essentially bounded function on R; then .Extensions of these results are given for nonessentially bounded measurable fields of bounded operators and for unbounded self-adjoint operators commuting with diagonalizable operators. 相似文献
7.
Jan T. łopuszański 《Reports on Mathematical Physics》1976,9(3):301-307
It is shown that for spinorial charges Q(L))α (α = 1, 2, L = 1, …, S) satisfying the commutation relations where Q is a scalar charge commuting with the spinor charges as well aswith the energy- momentum vector Pμ, there can exist several different multiplets for free massive scalar and spinor fields. 相似文献
8.
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
9.
The analysing power of the reaction for vector and tensor polarization of an 800 keV deuteron beam, as well as the relative cross section for the unpolarized beam were measured at 7 to 9 angles between 0° and 160°, using a thick target. Analysis in terms of (l, s, Jπ) matrix elements shows that two intermediate states with and present, strongly interfering with each other. Assignments to known 9Be levels and to threshold resonances as suggested by Hackenbroich and Seligman are briefly discussed. The magnitude of the vector analysing power makes the reaction interesting as a monitor for the vector polarization of low-energy deuteron beams. 相似文献
10.
J. Leotin R. Barbaste S. Askenazy M.S. Skolnick R.A. Stradling J. Tuchendler 《Solid State Communications》1974,15(4):693-697
The first observation of cyclotron resonance in p-type InP is reported. The holes were thermally excited at 110 K and the resonance was observed at 337μm wavelength (HCN laser) using a pulsed magnetic field of 0–350 kG. The effective masses of the light and heavy holes in the 〈111〉 direction were found to be , and in the 〈100〉 direction , . We obtain an estimate of the Dresselhaus parameters A = ?5.04, |B| = 3.12, C2 = 6.57. We also report the effective masses for p-type GaP in the 〈111〉 direction as , . 相似文献
11.
We prove that the generalized eigenfunctions of the Schrödinger operator are continuous for potentials obeing the following assumptions: V=V+?V?,V±≥0,, ,. 相似文献
12.
Starting with a Hilbert space we introduce the dense subspace where is a positive self-adjoint Hilbert–Schmidt operator on 2(R,μ). For the space a measure-theoretical Sobolev lemma is proved. The results for the spaces of type are applied to nuclear analyticity spaces , where e?t is a Hilbert–Schmidt operator on the Hilbert space X for each t>0. We solve the so-called generalized eigenvalue problem for a general self-adjoint operator in X. 相似文献
13.
A. Possoz Ph. Deschepper L. Grenacs P. Lebrun J. Lehmann L. Palffy A. De Moura Gonçalves C. Samour V.L. Telegdi 《Physics letters. [Part B]》1977,70(2):265-268
The helicity, h?, of μ? in π-decay has been determined as positive (h??+0.90) from the average polarization, Pav≡〈JB·sμ〉, of 12B produced in the reaction. We obtain also dynamical information on μ-capture: (i) the weak magnetism form factor, μ=4.5±1.1, and (ii) the sum of the induced pseudoscalar (gp) and the 2nd class induced tensor (gT) couplings versus gA, (. The latter result, adopting the “canonical” value of , leads to which is compatible with zero and in strong contradiction with the value ?—6 recently advocated by Kubodera, Delorme and Rho. 相似文献
14.
An analysis of dynamic and nonlocal longitudinal dielectric response properties of a two-dimensional Landau-quantized plasma is carried out, using a thermodynamic Green's function formulation of the RPA with a two-dimensional thermal Green's function for electron propagation in a magnetic field developed in closed form. The longitudinal-electrostatic plasmon dispersion relation is discussed in the low wavenumber regime with nonlocal corrections, and Bernstein mode structure is studied for arbitrary wavenumber. All regimes of magnetic field strength and statistics are investigated. The class of integrals treated here should have broad applicability in other two-dimensional and finite slab plasma studies.The two-dimensional static shielding law in a magnetic field is analyzed for low wavenumber, and for large distances we find . The inverse screening length (? = density, ξ = chemical potential) is evaluated in all regimes of magnetic field strength and all statistical regimes. k0 exhibits violent DHVA oscillatory behavior in the degenerate zero-temperature case at higher field strengths, and the shielding is complete when , but there is no shielding when . A careful analysis confirms that there is no shielding at large distances in the degenerate quantum strong field limit . Since shielding does persist in the nondegenerate quantum strong field limit , there should be a pronounced change in physical properties that depend on shielding if the system is driven through a high field statistical transition. (It should be noted that the static shielding law of semiclassical and classical models has no dependence on magnetic field in two dimensions, as in three dimensions.) Finally, we find that the zero field two-dimensional Freidel-Kohn “wiggle” static shielding phenomenon is destroyed by the dispersal of the zero field continuum of electron states into the discrete set of Landau-quantized orbitals due to the imposition of the magnetic field. 相似文献
15.
Evans M. Harrell 《Annals of Physics》1977,105(2):379-406
This is a perturbative analysis of the eigenvalues and eigenfunctions of Schrödinger operators of the form ?Δ + A + λV, defined on the Hilbert space L2(Rn), where , A is a potential function and V is a positive perturbative potential function which diverges at some finite point, conventionally the origin. λ is a small real or complex parameter. The emphasis is on one-dimensional or separable problems, and in particular the typical example is the “spiked harmonic oscillator” Hamiltonian, , where α is a positive constant. When this kind of perturbation is very singular, the first-order Rayleigh-Schrödinger perturbative correction, (u0, Vu0), where u0 is the unperturbed eigenfunction, diverges. This analysis constructs explicitly calculable terms in a modified perturbation series to a finite order, by using linear operator theory in concert with approximation methods for differential equations. Along the way a connection between a W-K-B type approximation and Bessel functions is exploited. 相似文献
16.
17.
Consider an instantaneous severing interaction which at t = ts transforms is given N-soliton solution q0 into two new solutions, qL and qR, with discontinuous anitial conditions at t = ts such that qL(qR) is equal to q0 to the left (right) of the severing point xs and vanishes to the right (left) of xs. The soliton content of qL and qR is studied in the context of the cubic Schrödinger equation and the sine-Gordon equation by solving the direct scattering problem. It is shown that the motion constants Cn, n = 1, 2 …, are related by , Furthermore, if q0 contains N solitons and no contribution from the continuous spectrum, then qL(qR) contains NL(NR) solitons with 0 ? NL, NR ? N and NL + NR = N. The slicing puts a soliton into qL or qR, respectively as the slicing point xs is taken to the right or left of the soliton's “center” at t = ts. 相似文献
18.
Masuo Suzuki 《Physics letters. A》1985,113(6):299-300
It is proved that the trace of the generalized Trotter formula is an even function of n, when all Aj are symmetric, namely Atj = Aj, togethern with some generalizations. This yields a new extrapolatio n method of the form for large n in quanntum Monte Carlo simulations. 相似文献
19.
V. Privman 《Physica A》1984,129(1):220-224
We employ the recently proposed scaling theory for first-order transitions to derive a detailed prediction for the large-argument behaviour of the critical-point scaling function of the reduced fourth order cumulant correct up to a term exponentially small in L/ξ(T). 相似文献
20.
The volt-ampere curves and their second derivatives were studied for niobium point contacts at low temperatures in the voltage range corresponding to the characteristic phonon energies. It was found that while for the dirty contacts in the normal state no PC spectra of phonons could be detected, in the superconducting state there were singularities in the I–V curves corresponding to maxima either in the first or in the second derivatives. The singularities observed were due to the energy dependence of the excess current. We suppose that the origin of these singularities is due to the inelastic transitions of electrons between chemical potentials of Cooper pairs at both sides of the contact, which differ in energy by eV. These transitions are possible if ξ(0) ? d ≈ Λ?, (ξ(0) being the coherence length; d, the contact diameter; , where li and l? being the elastic and inelastic electron mean free paths, respectively). 相似文献