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1.
《Nuclear Physics A》1988,481(3):531-541
This paper contains off-shell generalizations of the standard (on-shell) Born series. Both Fredholm and Volterra integral equations are derived for the half-off-shell wave functions. Fully off-shell matrix elements of the transition operator are then developed by iteration. Convergence and truncation problems are also discussed. An alternative approach via the explicit form of the T-operator is also indicated.  相似文献   

2.
The two-body density matrix for 4He,16O and 40Ca within the Low-order approximation of the Jastrow correlation method is considered. Closed analytical expressions for the two-body density matrix, the center of mass and relative local densities and momentum distributions are presented. The effects of the short-range correlations on the two-body nuclear characteristics are investigated. Received: 11 September 1999 / Revised version: 20 December 1999  相似文献   

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Using the Green function techniques we express the wave solutions of the radial inhomogeneous Schrödinger equation by means of the on-shell Jost and regular solutions. Making use of their boundary behaviour atr = andr = 0 we reexpress them alternatively in terms of the off-shell Jost and regular solutions. Relations among the different generalized (fully off the energy shell) Jost functions are derived and the radial matrix elements of the transition and reaction (reactance) operators are given in terms of these Jost functions. The relations reflect the principle of detailed balance.  相似文献   

5.
The s-wave part of the T-matrix on the mass shell was obtained from the well-known solution of the s-wave Schrödinger equation for the Morse potential. The result is expressed in terms of the confluent hypergeometric function.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 27–29, May, 1975.  相似文献   

6.
The EVDM and factorization technique are extended to the case of two tagged photons. The results obtained from both methods are remarkably close, and in very good agreement with the recent measurements made by the PLUTO collaboration at PETRA. Predictions are made for higher values ofQ 2 andP 2, where future experiments are planned, and these are compared with the relevant QCD calculations.  相似文献   

7.
The Jost functions and the T-matrix outside an energy surface are obtained by applying the method of van Leeuwen and Reiner to scattering by a nonlocal separable potential.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 27–30, 1980.  相似文献   

8.
We show that, under reasonable hypotheses, it is possible to study two-body non-leptonic weak decays in numerical simulations of lattice QCD. By assuming that final-state interactions are dominated by the nearby resonances and that the couplings of the resonances to the final particles are smooth functions of the external momenta, it is possible indeed to overcome the difficulties imposed by the Maiani-Testa no-go theorem and to extract the weak decay amplitudes, including their phases. Under the same assumptions, results can be obtained also for time-like form factors and quasi-elastic processes.  相似文献   

9.
The two-center shell model of two equal overlapping spheroids is combined with Lawrence's liquid-drop shapes. Within this framework, potential energy surfaces for nuclei from different mass regions are calculated. In particular, the transition of the ground state deformation from spherical to deformed is investigated for a sequence of ruthenium isotopes.  相似文献   

10.
We predictl=0 nucleons in12C to have a negative (binding) energy centered around –22 MeV with a full width at half-maximum of 5.3 MeV. Thel=1 (P 3/2 nucleons) are predicted to have a much narrower spectral energy function centered around –10.6 MeV. A strongly correlated translational invariant wave function was used to describe the ground state nucleus. A central two-nucleon potential was utilized in the hyperspherical harmonic method to approximately solve the Schrödinger equation for the ground state wave function. Both confirmation and failings of the independent particle shell model are exposed.  相似文献   

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The range of applicability of the T-matrix method and its modifications for solving the problem if the scattering of electromagnetic radiation by nonspherical, axially symmetric particles is investigated analytically and numerically. The use of this method for calculating the characteristics of scattered radiation in the farfield region (the extinction and scattering cross sections, the scattering indicatrix, etc.) is shown to be appropriate for “weak-Rayleigh-type” particles. This condition is met when the intersection of the analytic continuations of the scattered and internal fields contains a ring with the center at the origin of coordinates. For a reliable calculation of the scattered field in the near-field region, it is necessary that a particle be a “Rayleigh-type” one (i.e., the Rayleigh hypothesis be valid for it). In this case, the singularities of the scattered field must occur inside a sphere lying inside a scatterer. Spheroidal particles are weak-Rayleigh-type ones if their semiaxes ratio is $a/b < (\sqrt {2 + 1} )The range of applicability of the T-matrix method and its modifications for solving the problem if the scattering of electromagnetic radiation by nonspherical, axially symmetric particles is investigated analytically and numerically. The use of this method for calculating the characteristics of scattered radiation in the farfield region (the extinction and scattering cross sections, the scattering indicatrix, etc.) is shown to be appropriate for “weak-Rayleigh-type” particles. This condition is met when the intersection of the analytic continuations of the scattered and internal fields contains a ring with the center at the origin of coordinates. For a reliable calculation of the scattered field in the near-field region, it is necessary that a particle be a “Rayleigh-type” one (i.e., the Rayleigh hypothesis be valid for it). In this case, the singularities of the scattered field must occur inside a sphere lying inside a scatterer. Spheroidal particles are weak-Rayleigh-type ones if their semiaxes ratio is , and they are Rayleigh-type ones if . Numerical calculations for spheroids and Chebyshev particles corroborate these conclusions. However, the indicated boundaries are “ spread” (toward the expansion), because the expansion coefficients for the fields are determined with the use of the reduced (i.e., finite) systems. The limiting sizes of the particles for which the T-matrix method gives plausible results are primarily determined by their geometry (shape). __________ Translated from Optika i Spektroskopiya, Vol. 92, No. 5, 2002, pp. 813–825. Original Russian Text Copyright ? 2002 by Farafonov.  相似文献   

13.
We suggest a new approach to calculate the inverse matrix in scattering calculations using the T-matrix method. Instead of inversion of the full matrix, we suggest the inversion of two matrices, each of which contains half the number of rows. This approach allows significant time savings and a noticeable increase of the precision of scattering calculations due to fewer arithmetical operations. An iterative method can be applied to matrices whose dimension is also divisible by factors of 2, which can further increase the time savings and accuracy.  相似文献   

14.
The Newman-Penrose nonlinear asymptotic field equations are separated in terms of spin weight spherical harmonics (s.w.s.h.). As an example, the results are used to study the radiation effects on a two-body system. The presence of radiation is manifest through the nonlinear terms in the asymptotic equations. If these terms are assumed to be small, the asymptotic equations can be formally solved by an iteration procedure. For the above example the first step of the iteration procedure is implemented to an accuracy that includes the effects of radiation up to octopole order. The results illustrate the usual internal decay of the orbit as well as an acceleration of the system's center of mass. In favorable cases, the two-body source can reach significant velocities due to the radiation reaction.  相似文献   

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The valence shell binding energy spectrum of carbonyl sulphide (10–45 eV) has been measured using both binary (e,2e) and dipole (e,2e) electron impact spectroscopy and calculated by the 2ph-TDA many body Green's function technique. The spectrum shows extensive structure above 20 eV, indicating a major breakdown of the quasi-particle picture for ionization of COS. The calculation is in good agreement with the present experimental and literature ESCA binding energy spectra. Binary (e,2e) spectra at two azimuthal angles support the theoretical prediction that this extensive final ion state structure arises primarily from ionization of the COS 6σ and 7σ inner valence electrons.  相似文献   

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The relativistic analogon of a procedure demonstrating the link between theS-wave off-the-mass- shellN/D equations (variables: the momentum, energy and radial coordinate of a scattered particle) and the Marchenko equations of the inversion problem is presented in the static scattering. For the Klein-Gordon formalism the transition from the former type of the equations to the latter requires: a decomposition of theN/D equation quantities into the components without theE-branch points, a suitable deformation of the integration path in theN/D equations and an assumption on the regular behaviour of the off-the-mass-shellN function discontinuities.  相似文献   

19.
The probability that photoionization of the caged atom in an endohedral system is accompanied by excitation of the fullerene shell is shown to be close to unity in broad intervals of the photoelectron energies. This is obtained by summation of the perturbative series for the interaction between the photoelectron and the fullerene shell. The result can be verified in experiments. As an outcome, interaction between the photoelectron ejected from the caged atom and the fullerene shell cannot be described by a static potential, since inelastic processes become decisively important.  相似文献   

20.
Hadronic two body decays of the 3.1 GeV resonance were measured and the following branching ratios were obtained: Γπ+π?μμ <0.0046, ΓK+K?μμ <0.0084, and Γpp/ Γμμμ = 0.036 ± 0.010 assuming the pp decay distribution is ≈ + cos2θ.  相似文献   

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