共查询到20条相似文献,搜索用时 343 毫秒
1.
P.G. Kevrekidis B.A. Malomed Z. Musslimani 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):421-436
A model including two nonlinear chains with linear and nonlinear couplings between them, and opposite signs of the discrete
diffraction inside the chains, is introduced. In the case of the cubic [ χ(3)] nonlinearity, the model finds two different interpretations in terms of optical waveguide arrays, based on the diffraction-management
concept. A continuum limit of the model is tantamount to a dual-core nonlinear optical fiber with opposite signs of dispersions
in the two cores. Simultaneously, the system is equivalent to a formal discretization of the standard model of nonlinear optical
fibers equipped with the Bragg grating. A straightforward discrete second-harmonic-generation [ χ(2)] model, with opposite signs of the diffraction at the fundamental and second harmonics, is introduced too. Starting from
the anti-continuum (AC) limit, soliton solutions in the χ(3) model are found, both above the phonon band and inside the gap. Solitons above the gap may be stable as long as they exist,
but in the transition to the continuum limit they inevitably disappear. On the contrary, solitons inside the gap persist all
the way up to the continuum limit. In the zero-mismatch case, they lose their stability long before reaching the continuum
limit, but finite mismatch can have a stabilizing effect on them. A special procedure is developed to find discrete counterparts
of the Bragg-grating gap solitons. It is concluded that they exist at all the values of the coupling constant, but are stable
only in the AC and continuum limits. Solitons are also found in the χ(2) model. They start as stable solutions, but then lose their stability. Direct numerical simulations in the cases of instability
reveal a variety of scenarios, including spontaneous transformation of the solitons into breather-like states, destruction
of one of the components (in favor of the other), and symmetry-breaking effects. Quasi-periodic, as well as more complex,
time dependences of the soliton amplitudes are also observed as a result of the instability development.
Received 14 September 2002 / Received in final form 4 February 2003 Published online 24 April 2003
RID="a"
ID="a"e-mail: malomed@eng.tau.ac.il 相似文献
2.
A.K. Chattopadhyay 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):567-576
We study the dynamics of a growing crystalline facet where the growth mechanism is controlled by the geometry of the local
curvature. A continuum model, in (2+1) dimensions, is developed in analogy with the Kardar-Parisi-Zhang (KPZ) model is considered
for the purpose. Following standard coarse graining procedures, it is shown that in the large time, long distance limit, the
continuum model predicts a curvature independent KPZ phase, thereby suppressing all explicit effects of curvature and local
pinning in the system, in the “perturbative” limit. A direct numerical integration of this growth equation, in 1+1 dimensions,
supports this observation below a critical parametric range, above which generic instabilities, in the form of isolated pillared
structures lead to deviations from standard scaling behaviour. Possibilities of controlling this instability by introducing
statistically “irrelevant" (in the sense of renormalisation groups) higher ordered nonlinearities have also been discussed.
Received 23 April 2002 / Received in final form 24 July 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: akc@mpipks-dresden.mpg.de 相似文献
3.
R. Dandoloff A. Saxena 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):265-267
For a spin-polarized electron gas on an elastic cylinder in an external axial magnetic field and an axial electric field we
find that the corresponding Euler-Lagrange equation is the double sine-Gordon (DSG) equation with an exact 2π-skyrmion solution.
The DSG skyrmion is stabilized, without Coulomb repulsion, by the curvature of the cylinder. It adopts a characteristic length
ξ which is smaller than the radius of the cylinder. For an elastic cylinder this mismatch of length scales causes a deformation
of the cylinder in the region of the skyrmion.
Received 23 October 2001 / Received in final form 8 March 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: rossen.dandoloff@ptm.u-cergy.fr 相似文献
4.
R. Anni 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):361-374
A simple recipe for revealing classical-like properties of optical-potential cross-sections is proposed. The recipe is based
on the fact that the classical properties are not expected to depend on the actual value of . This allows us to identify
the classical-like characteristics of an optical-potential cross-section by simply repeating the calculation with different
values of , and observing which properties of the cross-section are invariant. The method is applied to the cross-sections
of a few optical potentials used to describe the recent data of light heavy-ion elastic scattering. An improved near-side/far-side
decomposition is used to separate the near-side and far-side components of the optical-potential cross-sections.
Received: 4 September 2001 / Accepted: 3 June 2002 / Published online: 26 November 2002
RID="a"
ID="a"e-mail: anni@le.infn.it
Communicated by V. Vento 相似文献
5.
W.J. Zakrzewski 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):217-219
In this talk we introduce a Weierstrass-like system of equations corresponding to CP
N
-1 fields in two dimensions. Then using this representation we introduce a vector in R
N
2-1 and treating this vector as the radius vector of a surface immersed in R
N
2-1 we discuss to what extent the associated metric describes the geometry of the CP
N
-1 maps. We show that for the holomorphic maps - the correspondence is exact; while for the more general fields we have to go
beyond the Weierstrass system and add extra terms.
Received 1st August 2001 / Received in final form 18 October 2001 Published online 2 October 2002
RID="a"
ID="a"Work done in collaboration with M. Grundland e-mail: w.j.zakrzewski@durham.ac.uk 相似文献
6.
J. Uhlig J.C. Lemm A. Weiguny 《The European Physical Journal A - Hadrons and Nuclei》1998,2(4):343-354
Abstact: Three variants of mean field methods for atomic and nuclear reactions are compared with respect to both conception and applicability:
The time–dependent Hartree–Fock method solves the equation of motion for a Hermitian density operator as initial value problem,
with the colliding fragments in a continuum state of relative motion. With no specification of the final state, the method
is restricted to inclusive reactions. The time–dependent mean field method, as developed by Kerman, Levit and Negele as well
as by Reinhardt, calculates the density for specific transitions and thus applies to exclusive reactions. It uses the Hubbard–Stratonovich
transformation to express the full time-development operator with two–body interactions as functional integral over one–body
densities. In stationary phase approximation and with Slater determinants as initial and final states, it defines non–Hermitian,
time–dependent mean field equations to be solved self–consistently as boundary value problem in time. The time–independent
mean field method of Giraud and Nagarajan is based on a Schwinger–type variational principle for the resolvent. It leads to
a set of inhomogeneous, non-Hermitian equations of Hartree–Fock type to be solved for given total energy. All information
about initial and final channels is contained in the inhomogeneities, hence the method is designed for exclusive reactions.
A direct link is established between the time–dependent and time–independent versions. Their relation is non–trivial due to
the non–linear nature of mean field methods.
Received: 7 January 1998 / Revised version: 20 April 1998 相似文献
7.
E. Mergel C.M. Petrache G. Lo Bianco H. Hübel J. Domscheit D. Roßbach G. Schönwaßer N. Nenoff A. Neußer A. Görgen F. Becker E. Bouchez M. Houry A. Hürstel Y. Le Coz R. Lucas Ch. Theisen W. Korten A. Bracco N. Blasi F. Camera S. Leoni F. Hannachi A. Lopez-Martens M. Rejmund D. Gassmann P. Reiter P.G. Thirolf A. Astier N. Buforn M. Meyer N. Redon O. Stezowski 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):417-420
The even-even nucleus 136Nd was studied via in-beam γ-ray spectroscopy using the 16O + 125Te reaction at 100 MeV and the EUROBALL array. One new dipole band was observed. Together with a previously identified dipole
band, whose position in the level scheme is revised, the new band forms a doublet structure similar to the recently observed
chiral bands in the odd-odd neighboring nuclei. This would be the first case of a chiral doublet in an even-even nucleus.
Received: 23 May 2002 / Accepted: 30 September 2002 / Published online: 27 November 2002
RID="a"
ID="a"e-mail: costel.petrache@unicam.it
RID="b"
ID="b"Present address: Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
RID="c"
ID="c"Present address: Gesellschaft für Schwerionenforschung D-64291 Darmstadt, Germany.
Communicated by C. Signorini 相似文献
8.
A.A. Zvyagin 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(3):351-360
The behavior of charge and spin persistent currents in an integrable lattice ring of strongly correlated electrons with a
magnetic impurity is exactly studied. Our results manifest that the oscillations of charge and spin persistent currents are
similar to the ones, earlier obtained for integrable continuum models with a magnetic impurity. The difference is due to two
(instead of one) Fermi velocities of low-lying excitations. The form of oscillations in the ground state is “saw-tooth”-like,
generic for any multi-particle coherent one-dimensional models. The integrable magnetic impurity introduces net charge and
spin chiralities in the generic integrable lattice system, which determine the initial phase shifts of charge and spin persistent
currents. We show that the magnitude of the charge persistent current in the generic Kondo situation does not depend on the
parameters of the magnetic impurity, unlike the (magneto)resistivity of transport currents.
Received 30 January 2003 / Received in final form 12 March 2003 Published online 11 April 2003
RID="a"
ID="a"e-mail: zvyagin@fy.chalmers.se 相似文献
9.
J. Westergren S. Nordholm A. Rosén 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(1):81-97
The cooling of the metal cluster Pd13 in an atmosphere of rare gas has been studied by means of computer simulation. By simulation, the average energy transfer
in collisions between one cluster and one gas atom has been obtained. Emphasis has been placed on conditions when the temperatures
of the colliding species are almost equal. All modes of motion, inclusive the translation, must be considered in order to
obtain vanishing energy transfer at equilibrium. A simulation scheme is presented by which the energy transfer is zero to
the cluster when the gas and the cluster temperatures are equal. At equilibrium the energy transfer does however not vanish
for all impact parameters. In the collisions with Pd13, the cluster is heated by collisions with a small impact parameter but equally cooled by collisions with a large impact parameter.
Argon and krypton are found to cool Pd13 equally efficiently while neon and helium are less efficient cooling agents.
Received 28 September 2001 / Received in final form 8 August 2002 Published online 12 November 2002
RID="a"
ID="a"e-mail: JanW@phc.gu.se 相似文献
10.
Tasinkevych M Silvestre NM Patrício P Telo da Gama MM 《The European physical journal. E, Soft matter》2002,9(4):341-347
The interaction between two disks immersed in a 2D nematic is investigated i) analytically using the tensor order parameter
formalism for the nematic configuration around isolated disks and ii) numerically using finite-element methods with adaptive
meshing to minimize the corresponding Landau-de Gennes free energy. For strong homeotropic anchoring, each disk generates
a pair of defects with one-half topological charge responsible for the 2D quadrupolar interaction between the disks at large
distances. At short distance, the position of the defects may change, leading to unexpected complex interactions with the
quadrupolar repulsive interactions becoming attractive. This short-range attraction in all directions is still anisotropic.
As the distance between the disks decreases, their preferred relative orientation with respect to the far-field nematic director
changes from oblique to perpendicular.
Received 1 October 2002 and Received in final form 12 November 2002
RID="a"
ID="a"e-mail: miko@cii.fc.ul.pt 相似文献
11.
H.F. Lü J. Meng S.Q. Zhang S.-G. Zhou 《The European Physical Journal A - Hadrons and Nuclei》2003,17(1):19-24
Properties of single- Λ and double- Λ hypernuclei for even-N Ca isotopes ranging from the proton dripline to the neutron dripline are studied using the relativistic continuum Hartree-Bogoliubov
theory with a zero-range pairing interaction. Compared with ordinary nuclei, the addition of one or two Λ-hyperons lowers
the Fermi level. The predicted neutron dripline nuclei are, respectively, 75
ΛCa and 76
2ΛCa, as the additional attractive force provided by the Λ-N interaction shifts nuclei from outside to inside the dripline.
Therefore, the last bound hypernuclei have two more neutrons than the corresponding ordinary nuclei. Based on the analysis
of two-neutron separation energies, neutron single-particle energy levels, the contribution of continuum and nucleon density
distribution, giant halo phenomena due to the pairing correlation, and the contribution from the continuum are suggested to
exist in Ca hypernuclei similar to those that appear in ordinary Ca isotopes.
Received: 21 October 2002 / Accepted: 11 January 2003 / Published online: 8 April 2003 相似文献
12.
Adhikari R 《The European physical journal. E, Soft matter》2002,9(2):127-134
We calculate the elastic-field-mediated interaction between macroscopic particles in a columnar hexagonal phase. The interaction
is found to be long-ranged and non-central, with both attractive and repulsive parts. We show how the interaction modifies
the particle correlations and the column fluctuations. We also calculate the interaction of particles with the topological
defects of the columnar phase. The particle-defect interaction reduces the mobility of the defects.
Received 14 March 2002 and Received in final form 13 August 2002
RID="a"
ID="a"e-mail: rjoy@physics.iisc.ernet.in 相似文献
13.
K. Broderix M. Weigt A. Zippelius 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(3):441-455
We consider the gelation of particles which are permanently connected by random crosslinks, drawn from an ensemble of finite-dimensional
continuum percolation. To average over the randomness, we apply the replica trick, and interpret the replicated and crosslink-averaged
model as an effective molecular fluid. A Mayer-cluster expansion for moments of the local static density fluctuations is set
up. The simplest non-trivial contribution to this series leads back to mean-field theory. The central quantity of mean-field
theory is the distribution of localization lengths, which we compute for all connectivities. The highly crosslinked gel is
characterized by a one-to-one correspondence of connectivity and localization length. Taking into account higher contributions
in the Mayer-cluster expansion, systematic corrections to mean-field can be included. The sol-gel transition shifts to a higher
number of crosslinks per particle, as more compact structures are favored. The critical behavior of the model remains unchanged
as long as finite truncations of the cluster expansion are considered. To complete the picture, we also discuss various geometrical
properties of the crosslink network, e.g. connectivity correlations, and relate the studied crosslink ensemble to a wider class of ensembles, including the Deam-Edwards
distribution.
Received on 24 April 2002 Published online 14 October 2002
RID="a"
ID="a"deceased
RID="b"
ID="b"e-mail: weigt@theorie.physik.uni-goettingen.de 相似文献
14.
Sheng-Feng Cheng Guo-Jun Jin 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(3):291-296
We investigate coupled optical interface modes in Thue-Morse (TM) dielectric superlattices composed of two kinds of materials
with frequency-dependent dielectric functions. Four basic transfer matrices are derived in the dielectric continuum approximation.
By a standard matrix operation method, the trace map of the global transfer matrix in this configuration is obtained. Under
Born-von Kármán boundary conditions, the frequency spectra are calculated and their branching rules together with the quartet property are elucidated. It is further proved rigorously that nearly all eigenmodes in this framework have extended nature. The quartet of the eigenmodes is illuminated analytically. The common features and pronounced differences compared
with coupled optical interface modes in periodic and Fibonacci dielectric superlattices as well as with other collective elementary
excitations in TM structures are also revealed.
Received 24 September 2002 / Received in final form 11 January 2003 Published online 11 April 2003
RID="a"
ID="a"e-mail: gjin@nju.edu.cn 相似文献
15.
Ribeiro AC Heinrich B Cruz C Nguyen HT Diele S Schröder MW Guillon D 《The European physical journal. E, Soft matter》2003,10(2):143-151
We present the structural study of a biforked compound exhibiting a Colr-Colh phase transition. This study was performed by means of DSC, optical microscopy, X-ray diffraction, dilatometry and molecular
modelling. The molecular packing within the two columnar mesophases of this compound is discussed. For the first time, it
is shown that the clusters of adjacent molecules which form the elementary section of a column are tilted with respect to
the columnar axis in the rectangular mesophase. From the whole set of experimental data, the number of molecules in a columnar
section is found to be about 5 in the rectangular mesophase, and 4 in the hexagonal one. The transition between the two columnar
mesophases is discussed with respect to its slow kinetics.
Received 1st October 2002 Published online: 16 April 2003
RID="a"
ID="a"e-mail: ribeiro@cii.fc.ul.pt
RID="b"
ID="b"UMR 7504 相似文献
16.
R. Lucas M.-G. Porquet Ts. Venkova I. Deloncle M. Houry Ch. Theisen A. Astier A. Bauchet S. Lalkovski G. Barreau N. Buforn T.P. Doan L. Donadille O. Dorvaux J. Durell Th. Ethvignot B.P.J. Gall D. Grimwood W. Korten Y. Le Coz M. Meyer A. Minkova A. Prévost N. Redon A. Roach N. Schulz A.G. Smith O. Stézowski B.J. Varley 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):315-323
The 115, 117, 119, 121In nuclei have been produced as fission fragments in three reactions induced by heavy ions: 12C + 238U at 90MeV bombarding energy, 18O + 208Pb reaction at 85MeV, and 31P + 176Yb at 152MeV. Their level schemes have been built from gamma-rays detected using the EUROBALL III and IV arrays. High-spin
states of 117, 119, 121In nuclei have been identified for the first time. Moreover, isomeric states lying around 2.5MeV have been established in
119, 121In from the delayed coincidences between the fission fragment detector SAPhIR and the gamma array. Most of the observed states
can be described by coupling a proton g
9/2 hole to a Sn core, while the intruder band based on an orbital from the π[g
7/2/d
5/2] sub-shells behaves as the ground-state band of neighbouring Cd isotopes.
Received: 24 May 2002 / Accepted: 11 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: porquet@csnsm.in2p3.fr
RID="b"
ID="b"Present address: CEA-DIF, DAM/DCRE/SDE/LDN, 91680 Bruyères-le-Chatel, France.
RID="c"
ID="c"Present address: CSNSM IN2P3-CNRS and Université Paris-Sud 91405 Orsay, France.
RID="d"
ID="d"Present address: CEA/Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette Cedex, France.
Communicated by D. Schwalm 相似文献
17.
B. Macke B. Ségard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):125-141
This paper deals with the apparent superluminal propagation of electromagnetic pulses in a linear dispersive medium. One specifically
examines the possibility that the pulse leaving the medium may be nearly identical to the incident one (low distortion) and
in significant advance of it (strongly negative group-delays). Favourable conditions are obtained in a dilute medium where
the required anomalous dispersion originates in an ensemble of narrow absorption or gain lines. Analytical expressions of
the advancement of the pulse centre-of-gravity and of the lowest order distortion are established from the transfer-function
of the medium. The experiments already achieved with arrangements involving a single absorption-line or a gain-doublet are
analysed in detail and compared. The considerable difficulties to overcome in order to attain advancements comparable to the
pulse width without important distortion are pointed out. New and promising schemes involving a narrow dip in a gain profile
or absorption-doublets are proposed.
Received 4 July 2002 / Received in final form 8 November 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: bruno.macke@univ-lille1.fr
RID="b"
ID="b"Unité Mixte de Recherche de l'Université et du CNRS (UMR 8523) 相似文献
18.
Ch. Lisdat N. Vanhaecke D. Comparat P. Pillet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):299-309
Two-photon photoassociation spectra in a Λ-type excitation scheme are analysed under the systematically varied experimental conditions of frequency detunings and laser
intensities. Line shape fits are presented as well as the investigation of intensity and detuning dependent line shifts. From
both we determine the attained spectroscopic precision, that is corrected for a systematic line shift due to the thermal distribution
of atoms in the trap. An energy correction for this effect is given. Information about the feasibility of generating translationally
cold molecules in a well defined rotational and vibrational level by the photoassociation process is derived from the analysis.
Received 21 May 2002 Published online 15 October 2002
RID="a"
ID="a"Current address e-mail: christian.lisdat@ptb.de
RID="b"
ID="b"e-mail: pierre.pillet@lac.u-psud.fr 相似文献
19.
K.-M. Källman M. Brenner V.Z. Goldberg T. Lönnroth P. Manngård A.E. Pakhomov V.V. Pankratov 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):159-169
The excitation function and angular distributions of elastic α-particle scattering on 28Si have been measured in the laboratory energy range 6-28 MeV using a backscattering technique on a thick target, yielding
a continuous energy distribution. More than 200 narrow states are observed, with widths in the range ∼ 30-100 keV at excitation
energies E
* = 13-32 MeV. Angular distributions at backward angles were measured, and angular momentum values of more than 83 states have
been deduced. The analysis gives spin-parities J
π, α-partial widths Γα and reduced widths of the narrow high-lying resonant states in 32S. The experimentally observed states display both the negative- and the positive-parity rotational-like sequences with seemingly
no parity splitting, a finding which is at variance with most potential-model predictions. The deduced effective moment of
inertia indicates a more extended structure than the ground-state configuration. The observed strength of each ℓ-value is
analyzed in terms of an underlying split doorway state of Lorentzian form, which yields an interpretation as fragmented rotational
α + 28Si states.
Received: 26 June 2000 / Accepted: 16 September 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: kkallman@abo.fi
RID="b"
ID="b"Present address: Swedish Polytechnic, FIN-65200 Vasa, Finland.
Communicated by D. Guerreau 相似文献
20.
J.V. Jovanović S.B. Vrhovac Z.Lj. Petrović 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):335-342
Transport properties of ion swarms in presence of Resonant Charge Transfer (RCT) collisions are studied using Momentum Transfer
Theory (MTT). It was shown that, not surprisingly, RCT collisions may be represented as a special case of elastic scattering.
Using the developed MTT we tested a previously available anisotropic set of cross-sections for Ar+Ar
+ collisions by making the comparisons with the available data for the transverse diffusion coefficient. We also developed
an anisotropic set of Ne+Ne
+ integral cross-sections based on the available data for mobility, longitudinal and transverse diffusion. Anisotropic sets
of cross-sections are needed for Monte Carlo simulations of ion transport and plasma models.
Received 16 June 2002 / Received in final form 2nd August 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: vrhovac@phy.bg.ac.yu
RID="b"
ID="b"e-mail: zoran@phy.bg.ac.yu 相似文献