共查询到20条相似文献,搜索用时 250 毫秒
1.
L.L. Salcedo 《The European Physical Journal A - Hadrons and Nuclei》2003,16(1):71-94
The multiscattering problem is studied in the matrix density formalism. We study how to isolate the quasi-classical degrees
of freedom in order to connect them with a cascade approach. The different problems that arise, as well as their possible
solutions, are discussed and exemplified with a pion-nucleus model.
Received: 24 May 2002 / Accepted: 25 July 2002 / Published online: 17 January 2003
RID="a"
ID="a"e-mail: salcedo@ugr.es
Communicated by A. Sch?fer 相似文献
2.
V.P. Zhdanov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(3):485-489
To illustrate complex spatio-temporal effects which are possible in cellular reactions with a small number of particles, we
present Monte Carlo simulations of the formation of oscillatory spark-like patterns in a model completely stochastic Ca+2 oscillator. Our analysis shows that in order to observe such patterns the minimum average number of Ca+2 ions in the cytosol may be as low as about 50.
Received 21 April 2002 / Received in final form 19 June 2002 Published online 14 October 2002
RID="a"
ID="a"e-mail: zhdanov@catalysis.nsk.su 相似文献
3.
The intranuclear cascade model is generally considered to be valid when the incident particle has a sufficiently small de
Broglie wavelength to interact with individual nucleons. On this basis, a lower limit of 200 MeV is usually quoted for the
incident energy in nucleon-induced reactions. Here this statement is questioned. A pragmatic approach is used, which compares
the predictions of the Liège intranuclear cascade model with available data at incident energy between 40 and 250 MeV. It
is found that this model gives surprisingly good results at energies well below the limit mentioned above. Results are also
compared with the predictions of other models commonly used in this energy range.
Received: 2 September 2002 / Accepted: 22 October 2002 / Published online: 6 March 2003
RID="a"
ID="a"e-mail: cugnon@plasma.theo.phys.ulg.ac.be
RID="b"
ID="b"e-mail: P.Henrotte@ulg.ac.be
Communicated by G. Orlandini 相似文献
4.
D. Davesne M. Oertel H. Hansen 《The European Physical Journal A - Hadrons and Nuclei》2003,16(1):35-42
In this paper, we develop a consistent extension of RPA for bosonic systems. In order to illustrate the method, we consider
the case of the anharmonic oscillator. We compare our results with those obtained in mean-field and standard RPA approaches
with the exact ones and show that they are very close to these ones.
Received: 17 June 2002 / Accepted: 14 September 2002 / Published online: 17 January 2003
RID="a"
ID="a"e-mail: davesne@ipnl.in2p3.fr
Communicated by A. Molinari 相似文献
5.
B. Leblanc E. Lutton F. Axel 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):619-628
We present the first application of Genetic Algorithms to the analysis of data from an aperiodically ordered system, high
resolution X-Ray diffraction spectra from multilayer heterostructures arranged according to a deterministic or random scheme.
This method paves the way to the solution of the “inverse problem”, that is the retrieval of the generating disorder from
the investigation of the spectra of an unknown sample having non crystallographic, non quasi-crystallographic order.
Received 18 March 2002 / Received in final form 3 July 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: Evelyne.Lutton@inria.fr
RID="b"
ID="b"CNRS UMR 8502 相似文献
6.
P.O. Hess A. Algora M. Hunyadi J. Cseh 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):449-454
The procedure of Jarrio et al. (Nucl. Phys. A 528, 409 (1991)) for the determination of the effective SU(3) symmetry of nuclear states is extended to small deformations and to oblate nuclei. Self-consistency checks are carried
out both for light and for heavy nuclei.
Received: 23 April 2002 / Accepted: 25 July 2002 / Published online: 10 December 2002
RID="a"
ID="a"e-mail: hess@nuclear.unam.mx
Communicated by A. Molinari 相似文献
7.
G. Montagnoli S. Beghini F. Scarlassara A.M. Stefanini L. Corradi C.J. Lin G. Pollarolo Aage Winther 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):351-356
The two systems 40Ca + 90,96Zr have been studied by measuring nucleon transfer reactions at two energies near the Coulomb barrier, thus complementing
the available sub-barrier fusion cross-sections. Angular distributions for various transfer channels have been determined.
Significantly larger neutron transfer cross-sections are found for the target 96Zr that exhibits the larger enhancement in the sub-barrier fusion cross-sections. All data have been analyzed with a new model
for heavy-ion collisions that calculates simultaneously transfer cross-sections, fusion excitation functions and barrier distributions.
The model gives a good account of both transfer and fusion data.
Received: 2 May 2002 / Accepted: 4 June 2002 / Published online: 26 November 2002
RID="a"
ID="a"e-mail: montagnoli@pd.infn.it, Fax +39049 8277102, Tel. +39049 8277117.
RID="b"
ID="b"On leave from the China Institute for Atomic Energy, 102413 Beijing, China.
Communicated by C. Signorini 相似文献
8.
The $-game 总被引:1,自引:0,他引:1
J. Vitting Andersen D. Sornette 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(1):141-145
We propose a payoff function extending Minority Games (MG) that captures the competition between agents to make money. In
contrast with previous MG, the best strategies are not always targeting the minority but are shifting opportunistically between
the minority and the majority. The emergent properties of the price dynamics and of the wealth of agents are strikingly different
from those found in MG. As the memory of agents is increased, we find a phase transition between a self-sustained speculative
phase in which a “stubborn majority” of agents effectively collaborate to arbitrage a market-maker for their mutual benefit
and a phase where the market-maker always arbitrages the agents. A subset of agents exhibit a sustained non-equilibrium risk-return
profile.
Received 5 June 2002 / Received in final form 21 November 2002 Published online 27 January 2003
RID="a"
ID="a"e-mail: sornette@unice.fr
RID="b"
ID="b"CNRS UMR7536
RID="c"
ID="c"CNRS UMR6622 相似文献
9.
I.M. Mladenov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):327-330
The general shape equation describing the forms of vesicles is a highly nonlinear partial differential equation for which
only a few explicit solutions are known. These solvable cases are briefly reviewed and a new analytical solution which represents
the class of the constant mean curvature surfaces is described. Pearling states of the tubular fluid membranes can be explained
as a continuous deformation preserving membrane mean curvature.
Received 2 February 2002 / Received in final form 4 February 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: mladenov@obzor.bio21.bas.bg 相似文献
10.
E. Caurier F. Nowacki A. Poves 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):145-150
Recent shell model calculations for the neutron-rich nuclei around the magic numbers N = 20, N = 28 and N = 40 are reviewed. We stress two points: i) The crucial role played by the monopole part of the effective interaction that
determines the evolution of the spherical mean field. In particular, the reduction in the quasiparticle gaps at the magic
numbers can erode or even erase the shell closures. ii) The rich variety of structures that can be found in these situations,
with coexisting deformed and spherical states, rapid changes of behaviour with N or Z, and the massive occurrence of intruder states as ground states.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: alfredo.poves@uam.es 相似文献
11.
A. Hürstel M. Rejmund E. Bouchez P.T. Greenlees K. Hauschild S. Juutinen H. Kettunen W. Korten Y. Le Coz P. Nieminen Ch. Theisen A.N. Andreyev F. Becker T. Enqvist P.M. Jones R. Julin H. Kankaanpää A. Keenan P. Kuusiniemi M. Leino A.-P. Leppänen M. Muikku J. Pakarinen P. Rahkila J. Uusitalo 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):329-334
Prompt and delayed gamma-ray spectroscopy of very neutron-deficient bismuth isotopes 187, 189Bi has been performed using the Recoil Decay Tagging (RTD) method. The isomeric i
13/2 states have been identified and their lifetimes have been measured. The systematics of these long-lived M2 isomers has been extended to the proton-unbound isotopes. The general behaviour of single-proton states is discussed within
the systematics and interpreted within the shell-model framework.
Received: 2 May 2002 / Accepted: 3 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: wkorten@cea.fr
RID="b"
ID="b"Present address: GANIL, Caen, France.
RID="c"
ID="c"Present address: Radiation and Nuclear Safety Authority, P.O. Box 14, FIN-00881 Helsinki.
Communicated by D. Schwalm 相似文献
12.
M.B. Sheftel 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):203-206
Using the heavenly equation as an example, we propose the method of group foliation as a tool for obtaining non-invariant
solutions of PDEs with infinite-dimensional symmetry groups. The method involves the study of compatibility of the given equations
with a differential constraint, which is automorphic under a specific symmetry subgroup and therefore selects exactly one
orbit of solutions. By studying the integrability conditions of this automorphic system, i.e. the resolving equations, one can provide an explicit foliation of the entire solution manifold into separate orbits. The
new important feature of the method is the extensive use of the operators of invariant differentiation for the derivation
of the resolving equations and for obtaining their particular solutions. Applying this method we obtain exact analytical solutions
of the heavenly equation, non-invariant under any subgroup of the symmetry group of the equation.
Received 13 September 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: sheftel@gursey.gov.tr 相似文献
13.
J.E. Amaro M.B. Barbaro J.A. Caballero T.W. Donnelly A. Molinari 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):421-427
The impact of Hartree-Fock correlations on the nuclear momentum distribution is studied in a fully relativistic one-boson-exchange
model. Hartree-Fock equations are exactly solved to first order in the coupling constants. The renormalization of the Dirac
spinors in the medium is shown to affect the momentum distribution, as opposed to what happens in the non-relativistic case.
The unitarity of the model is shown to be preserved by the present renormalization procedure.
Received: 7 June 2002 / Accepted: 24 September 2002 / Published online: 10 December 2002
RID="a"
ID="a"e-mail: juan@nucle.us.es
Communicated by G. Orlandini 相似文献
14.
We study the quark mass expansion of the magnetic moments of the nucleon in a chiral effective field theory including nucleons,
pions and delta-resonances as explicit degrees of freedom. We point out that the usual power counting applied so far to this
problem misses important quark mass structures generated via an intermediate isovector M1 nucleon-delta transition. We propose a modified power counting and compare the resulting chiral extrapolation function to
available (quenched) lattice data. The extrapolation is found to work surprisingly well, given that the lattice data result
from rather large quark masses. Our calculation raises the hope that extrapolations of lattice data utilizing chiral effective
field theory might be applicable over a wider range in quark masses than previously thought, and we discuss some open questions
in this context. Furthermore, we observe that within the current lattice data uncertainties the extrapolations presented here
are consistent with the Padé fit ansatz introduced by the Adelaide group a few years ago.
Received: 23 April 2002 / Accepted: 18 July 2002 / Published online: 17 December 2002
RID="c"
ID="c"e-mail: themmert@physik.tu-muenchen.de
RID="d"
ID="d"e-mail: weise@ect.it
Communicated by A. Sch?fer 相似文献
15.
V.S. Gerdjikov G.G. Grahovski N.A. Kostov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):243-248
The class of nonlinear evolution equations (NLEE) - gauge equivalent to the N-wave equations related to the simple Lie algebra are derived and analyzed. They are written in terms of (x, t) ∈ satisfying r = rank nonlinear constraints. The corresponding Lax pairs and the time evolution of the scattering data are found. The Zakharov-Shabat
dressing method is appropriately modified to construct their soliton solutions.
Received 20 October 2001 / Received in final form 30 April 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: gerjikov@inrne.bas.bg 相似文献
16.
17.
Y. Pavlyukh W. Hübner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(2):239-246
We present a method for the numerical investigation of the electron dynamics in small metallic clusters in intense laser fields.
We obtain information about collective excitations and relaxation processes in the Na
9
+
and Pt3 clusters analyzing the power spectrum of the dipole moment within a mean-field approach. The power spectrum is computed for
various laser pulse parameters as well as for the limit of an infinitely short laser pulse. Due to the basis set expansion
of the wave function our method is capable to follow the dynamics not only of the whole electron cloud, but of any particular
molecular orbital.
Received 28 March 2002 / Received in final form 31 May 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: pavlyukh@mpi-halle.de 相似文献
18.
Th. Desaive M. Hennenberg G. Lebon 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):641-647
In this work, we study the problem of onset of thermal convection in a rotating saturated porous medium heated from below.
The effect of rotation is restricted to the Coriolis force, neglecting thus the centrifugal effects, the porous medium is
described by Brinkman's model. The linear eigenvalue problem is solved by means of a modified Galerkin method. The behavior
of the critical temperature gradient is discussed in terms of various parameters of the system for both stationary and overstable
convections. Finally a weakly nonlinear analysis is provided to derive amplitude equations and to study the onset of Küppers-Lortz
instability.
Received 24 June 2002 / Received in final form 11 September 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: tdesaive@ulg.ac.be 相似文献
19.
G. Benenti G. Casati S. Montangero D.L. Shepelyansky 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(2):285-293
We investigate the transition to quantum chaos, induced by static imperfections, for an operating quantum computer that simulates
efficiently a dynamical quantum system, the sawtooth map. For the different dynamical regimes of the map, we discuss the quantum
chaos border induced by static imperfections by analyzing the statistical properties of the quantum computer eigenvalues.
For small imperfection strengths the level spacing statistics is close to the case of quasi-integrable systems while above
the border it is described by the random matrix theory. We have found that the border drops exponentially with the number
of qubits, both in the ergodic and quasi-integrable dynamical regimes of the map characterized by a complex phase space structure.
On the contrary, the regime with integrable map dynamics remains more stable against static imperfections since in this case
the border drops only algebraically with the number of qubits.
Received 19 June 2002 / Received in final form 30 September 2002 Published online 17 Decembre 2002
RID="a"
ID="a"e-mail: dima@irsamc.ups-tlse.fr
RID="b"
ID="b"UMR 5626 du CNRS 相似文献
20.
Ch. Nacke H. Stolz G. Manzke K. Henneberger 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(3):303-312
The influence of thermalized non-coherent carriers on the dielectric function of GaAs/AlAs quantum wells is investigated by
reflection spectroscopy. Experiments are performed using the method of spectral interferometry, where both amplitude and phase
of reflected pulses can be determined. For low excitation density the complex coefficient of reflection can be described using
as dielectric function a broadened Elliot formula. With increasing carrier density pronounced nonlinearities appear in both
amplitude and phase due to many-body effects between excited carriers. The nonlinear behavior fits very well to the results
of a many-body theory based on the Semiconductor Bloch equations including memory effects in the scattering processes between
carriers and the polarization induced by the probe pulse.
Received 29 May 2002 / Received in final form 23 September 2002 Published online 19 December 2002
RID="a"
ID="a"e-mail: manzke@physik3.uni-rostock.de 相似文献