共查询到20条相似文献,搜索用时 31 毫秒
1.
M. Al Jaghoub 《The European Physical Journal A - Hadrons and Nuclei》2001,11(2):175-183
A relation linking the normalized s-wave scattering and the corresponding bound state wave functions at bound state poles is derived. This is done in the case
of a non-local, velocity-dependent Kisslinger potential. Using formal scattering theory, we present two analytical proofs
of the validity of the theorem. The first tackles the non-local potential directly, while the other transforms the potential
to an equivalent local but energy-dependent one. The theorem is tested both analytically and numerically by solving the Schr?dinger
equation exactly for the scattering and bound state wave functions when the Kisslinger potential has the form of a square
well. A first order approximation to the deviation from the theorem away from bound state poles is obtained analytically.
Furthermore, a proof of the analyticity of the Jost solutions in the presence of a non-local potential term is also given.
Received: 3 March 2001 / Accepted: 9 June 2001 相似文献
2.
G. Sharma S.K. Ghosh 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(1):79-86
Using hydrodynamic model of semiconductor plasmas and coupled-mode theory of interacting waves, we have analytically investigated
parametric interaction in a magnetised piezoelectric semiconductor plasma in non-relativistic domain. The temperature dependence
of momentum transfer collision frequency of electrons due to their heating by the pump is assumed to induce nonlinearity in
the medium. We have derived a dispersion relation which finally gives four unstable acoustic modes; two forward amplifying
modes and two backscattered attenuating modes. We have also obtained an expression for the critical pump amplitude ( ) at and around which gains and phase velocities of amplifying acoustic modes become least dependent on the pump amplitude
and static magnetic field . The required can be readily obtained from a pulsed 10.6 μm CO2 laser. The magnetic field is found to shift the critical point towards lower pump amplitudes.
Received 5 September 2000 and Received in final form 5 March 2001 相似文献
3.
A model for scalar quarks and gluons that successfully gives rise to a ln s behavior in high-energy qq scattering and which contains a non-trivial three-gluon vertex is used to study collision theory with the following aspects:
i) A three-body interaction simulating QCD is present and ii) particle production and annihilation occur naturally. In this
paper, the collision term in the model is examined in detail in the quasiparticle approximation. The construction of cross-sections
in which self-energy terms are ordered according to a coupling constant expansion is undertaken. It is shown explicitly which
terms of second order are required to obtain the scattering amplitudes that are two body in nature. Additional ordering in
the number of colors shows that quark loop diagrams are suppressed and gluon production or scattering processes dominate.
It is also shown that a consistent calculation of the scattering graphs at the two-loop level also simultaneously yields terms
that renormalize one-loop level graphs. This can then be extended to arbitrary m↦n processes. We examine the constraint equation briefly, discussing the appearance of a width. The issue of pinch singularities
is also addressed, and examples of the elimination of such singularities in equilibrium are given explicitly.
Received: 7 November 2001 / Accepted: 12 June 2001 相似文献
4.
The formation of correlations due to collisions in an interacting nucleonic system is investigated. Results from one-time
kinetic equations are compared with the Kadanoff and Baym two-time equation with collisions included in Born approximation.
A reasonable agreement is found for a proposed approximation of the memory effects by a finite duration of collisions. This
form of collision integral is in agreement with intuitive estimates from Fermi's golden rule. The formation of correlations
and the build up time is calculated analytically for the high temperature and the low temperature limit. Different approximate
expressions are compared with the numerical results. We present analytically the time dependent interaction energy and the
formation time for Gau?- and Yukawa type of potentials.
Received: 25 November 1998 / Revised version: 11 January 1999 相似文献
5.
W. Y. Hwang D. Ahn S. W. Hwang Y. D. Han 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):129-132
We report that entangled pairs of quantum clocks (non-degenerate quantum bits) can be used as a specialized detector for precisely
measuring difference of proper-times that each constituent quantum clock experiences. We describe why the proposed scheme
would be more precise in the measurement of proper-time difference than a scheme of two-separate-quantum-clocks. We consider
possibilities that the proposed scheme can be used in precision test of the relativity theory.
Received 7 November 2001 相似文献
6.
We investigate the collision of two vortex lines moving with viscous dynamics and driven towards each other by an applied current. Using London theory in the approach phase we observe a nontrivial vortex conformation producing antiparallel segments; their attractive interaction triggers a violent collision. The collision region is analyzed using the time-dependent Ginzburg-Landau equation. While we find that vortices will always recombine through the exchange of segments, a crossing channel appears naturally through a double collision process. 相似文献
7.
R.-J. Tarento P. Joyes J. van de Walle M. Nakamura 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):111-114
We investigate the electron capture occurring in the collision between an ion A+ and a cluster An (n = 5). The process has been modelled within the Hubbard Hamiltonian,which takes into account the intrasite U electron correlation. An exact procedure has been numerically applied which involves all the excited states to examine the
time evolution of the system during the collision. We have applied the model to the sodium case. We have investigated the
time evolution of the electron population during the collision on the projectile versus the kinetic energy of the projectile. It displays some oscillations which means that the electron exchanges between the ion
and the cluster occurs alternatively in one direction and the other. We also vary U and examine its influence on the dynamics of the oscillation of the average population. Finally the cross section is derived
versus the energy and U.
Received 29 November 2000 相似文献
8.
J. Gidden M.T. Bowers 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):409-419
Ion mobility experiments and molecular modeling calculations were used to investigate the gas-phase conformations and folding
energetics of 16 deprotonated dinucleotides. [M-H]- ions were formed by MALDI and their collision cross-sections measured in helium using ion mobility based techniques. Cross-sections
of theoretical structures, generated by molecular mechanics/dynamics calculations, were compared to the experimental values
for conformational identification of the dinucleotides. Temperature dependent measurements and kinetic theory were also used
to obtain energetic and dynamic data concerning the folding properties of the dinucleotides. Three distinct families of conformations,
with significantly different collision cross-sections, were identified: a “stacked” family in which the two nucleobases stack;
an “H-bonded” family in which the two nucleobases stay in the same plane and are hydrogen-bonded to each other; and an “open”
family in which the two nucleobases are separated from each other. At temperatures ≥ 300 K these conformers rapidly interconvert
in most systems, but they can be separated and individually observed in the lower temperature (80-200 K) experiments. The
types and relative amounts of each conformer observed, and the temperature at which they can be separated, are base and sequence
dependent. Theoretical modeling of the temperature-dependent data was used to determine isomerization barrier heights between
the various conformers and yielded values between 0.8-12.9 kcal/mol, depending on the dinucleotide.
Received 17 May 2002
Published online 13 September 2002 相似文献
9.
Theoretical Prediction of Asymmetrical Jet Formation in Two-Metallic-Flow Collision 总被引:1,自引:0,他引:1 下载免费PDF全文
We develop a basic problem in ballistics and impact engineering, concerning the collision of two fluid streams with different widths. The geometrical theory of plane asymmetrical jet formation is presented and a closed form solution is given. The width and flow direction of the outgoing flows are predicted both analytically and numerically as a function of initial configuration of the incoming flows. The predictions are more accurate than the results of other analytic models and in agreement with the experimental data and numerical results over a wide range of flow widths ratio variation. 相似文献
10.
A. Alvarez F. R. Romero J. Cuevas J. F.R. Archilla 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(4):543-555
We investigate the collisions of moving breathers, with
the same frequency, in three different Klein-Gordon chains of
oscillators. The on-site potentials are: the asymmetric and
soft Morse potential, the symmetric and soft sine-Gordon
potential and the symmetric and hard φ4 potential. The
simulation of a collision begins generating two identical moving
breathers traveling with opposite velocities, they are obtained
after perturbing two identical stationary breathers which centers
are separated by a fixed number of particles. If this number is odd
we obtain an on-site collision, but if this number is even we obtain
an inter-site collision. Apart from this distinction, we have
considered symmetric collisions, if the colliding moving
breathers are vibrating in phase, and anti-symmetric
collisions, if the colliding moving breathers are vibrating in
anti-phase. The simulations show that the collision properties of
the three chains are different. The main observed phenomena are:
breather generation with trapping, with the appearance of two new
moving breathers with opposite velocities, and a stationary breather
trapped at the collision region; breather generation without
trapping, with the appearance of new moving breathers with opposite
velocities; breather trapping at the collision region, without the
appearance of new moving breathers; and breather reflection. For
each Klein-Gordon chain, the collision outcomes depend on the
lattice parameters, the frequency of the perturbed stationary
breathers, the internal structure of the moving breathers and the
number of particles that initially separates the stationary
breathers when they are perturbed. 相似文献
11.
12.
Chen SH Mallamace F Faraone A Gambadauro P Lombardo D Chen WR 《The European physical journal. E, Soft matter》2002,9(3):283-286
We detect in a tri-block co-polymer micellar system an ergodic-to-nonergodic-to-ergodic transition, as a function of temperature,
in a range of concentrations, by photon correlation measurements. The shear viscosity is also shown to jump two order of magnitude
at these transition temperatures. Surprisingly, the structure factor as measured by small angle neutron scattering shows a
marked narrowing at the structural arrest state. Rationalization of these results with the existence of an attractive branch
in the phase diagram of an attractive colloid system predicted by mode coupling theory is made.
Received 9 Aprile 2002 相似文献
13.
M.I. Jaghoub 《The European Physical Journal A - Hadrons and Nuclei》2002,13(3):349-354
Using formal scattering theory, the scattering wave functions are extrapolated to negative energies corresponding to bound-state
poles. It is shown that the ratio of the normalized scattering and the corresponding bound-state wave functions, at a bound-state
pole, is uniquely determined by the bound-state binding energy. This simple relation is proved analytically for an arbitrary
angular momentum quantum number l > 0, in the presence of a velocity-dependent Kisslinger potential. The extrapolation relation is tested analytically by solving
the Schr?dinger equation in the p-wave case exactly for the scattering and the corresponding bound-state wave functions when the Kisslinger potential has the
form of a square well. A numerical resolution of the Schr?dinger equation in the p-wave case and of a square-well Kisslinger potential is carried out to investigate the range of validity of the extrapolated
connection. It is found that the derived relation is satisfied best at low energies and short distances.
Received: 17 October 2001 / Accepted: 4 January 2002 相似文献
14.
J. Lages D.L. Shepelyansky 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(1):129-133
We study analytically and numerically the problem of two particles with a long range attractive interaction on a two-dimensional
(2d) lattice with disorder. It is shown that below some critical disorder the interaction creates delocalized coupled states
near the Fermi level. These states appear inside well localized noninteracting phase and have a form of two-particle ring
which diffusively propagates over the lattice.
Received 29 September 2000 and Received in final form 15 January 2001 相似文献
15.
R. D'Hulst G.J. Rodgers 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(3):447-453
A microscopic model of aggregation and fragmentation is introduced to investigate the size distribution of businesses. In
the model, businesses are constrained to comply with the market price, as expected by the customers, while customers can only
buy at the prices offered by the businesses. We show numerically and analytically that the size distribution scales like a
power-law. A mean-field version of our model is also introduced and we determine for which value of the parameters the mean-field
model agrees with the microscopic model. We discuss to what extent our simple model and its results compare with empirical
data on company sizes in the US and debt sizes in Japan. Finally, possible extensions of the mean-field model are discussed,
to cope with other empirical data.
Received 10 January 2001 and Received in final form 12 March 2001 相似文献
16.
M.F. El-Sayed 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):391-403
A linear analysis of the combined effect of viscosity, finite ion Larmor radius and suspended particles on Kelvin-Helmholtz
instability of two superposed incompressible fluids in the presence of a uniform magnetic field is carried out. The magnetic
field is assumed to be transverse to the direction of streaming. A general dispersion relation for such a configuration has
been obtained using appropriate boundary conditions. The stability analysis is discussed analytically, and the obtained results
are numerically confirmed. Some special cases are recovered and corrected. The limiting cases of absence of suspended particles
(or fluid velocities) and finite Larmor radius, absence of suspended particles are discussed in detail. In both cases, all
other physical parameters are found to have stabilizing as well as destabilizing effects on the considered system. In the
former case, the kinematic viscosity is found to has a stabilizing effect, while in the later case, the finite Larmor radius
is found to has a stabilizing influence for a vortex sheet. It is shown also that both finite Larmor radius and kinematic
viscosity stabilizations for interchange perturbations are similar to the stabilization effect due to a magnetic field for
non-interchange perturbations.
Received 13 January 2003 Published online 24 April 2003
RID="a"
ID="a"Also at: Department of Mathematics, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt. e-mail: m.elsayed@uaeu.ac.ae 相似文献
17.
F. Barranco P.F. Bortignon R.A. Broglia G. Colò E. Vigezzi 《The European Physical Journal A - Hadrons and Nuclei》2001,11(4):385-392
If neutrons are progressively added to a normal nucleus, the Pauli principle forces them into states of higher momentum. When
the core becomes neutron saturated, the nucleus expels most of the wave function of the last neutrons outside to form a halo,
which, because of its large size, can have a lower momentum. It is an open question how nature stabilizes such a fragile system
and provides the glue needed to bind the halo neutrons to the core. Here, we show that this problem is similar to that of
the instability of the normal state of an electron system at zero temperature solved by Cooper, a solution which is at the
basis of BCS theory of superconductivity. By mimicking this approach using, aside from the bare nucleon-nucleon interaction,
the long wavelength vibrations of the nucleus 11Li, the paradigm of halo nuclei, as tailored glues of the least bound neutrons, we are able to obtain a unified and quantitative
picture of the observed properties of 11Li.
Received: 9 May 2001 / Accepted: 17 November 2001 相似文献
18.
E.J.S. Fonseca E.A. Gouveia J.M. Hickmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):75-78
We propose a new technique to perform measurements of nonlinearities in optical waveguides based on the variation of an optical
pulse chirp. This technique is analogous to the z-scan technique in the time domain. We analyze the new experimental method analytically and numerically, obtaining an useful
expression relating the nonlinearity with a peak-valley structure. Practical ways to implement the technique are discussed.
Received 13 March 2001 相似文献
19.
A. Ralko T.T. Truong 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):335-338
We discuss the occurrence and properties of exact singular anyonic wave functions describing stationary states of two identical
charged particles moving on a plane and under the influence of a perpendicular uniform magnetic field.
Received 25 September 2001 / Received in final form 4 December 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: truong@u-cergy.fr 相似文献
20.
One soliton of particle velocity and its amplitude (maximum particle velocity of one soliton) in Toda lattice is given analytically. It has also been known numerically that the maximum particle velocity (when the collision of two solitons reaches their maximum, we define Vn at this time as its maximum particle velocity) during the collision of two solitons moving in the same direction is equal to the difference between the amplitudes of two solitons if the difference is large enough; however, the maximum particle velocity is equal to the adding up of the amplitudes of two solitons moving in the opposite directions. The relationship between the maximum value of e-(rn)-1 and their initial amplitude of e-(rn)-1 is also given analytically in Toda lattice if the amplitudes of the two solitons are the same and their moving directions are opposite. Compared with the Boussinesq equation, there are differences between the Toda lattice equation and the Boussinesq equation for solitons during the collision. 相似文献