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1.
Isoscalar and isovector nuclear matter properties
are investigated in the
Skyrme Hartree-Fock (SHF) and the relativistic mean field (RMF) models.
The Skyrme parameters are related analytically to the isoscalar and the
isovector nuclear matter properties of the Hamiltonian density.
Linear correlations are found among the isovector nuclear matter properties of
the Hamiltonian density in both the SHF and the RMF models.
We also discovered that the correlations between the isovector properties
and the incompressibility K show a singularity at the critical
incompressibility Kc=306 MeV.
It is shown that the neutron skin thickness gives crucial
information about not only
for the neutron EOS but also about the isovector nuclear matter properties and
about the parameterization of Skyrme interaction.
Charge exchange spin-dipole (SD) excitations are
proposed to determine the neutron skin thickness model independently. 相似文献
2.
J.E.S. Socolar D.G. Schaeffer P. Claudin 《The European physical journal. E, Soft matter》2002,7(4):353-370
A theory of stress fields in two-dimensional granular materials based on directed force chain networks is presented. A general
Boltzmann equation for the densities of force chains in different directions is proposed and a complete solution is obtained
for a special case in which chains lie along a discrete set of directions. The analysis and results demonstrate the necessity
of including nonlinear terms in the Boltzmann equation. A line of nontrivial fixed-point solutions is shown to govern the
properties of large systems. In the vicinity of a generic fixed point, the response to a localized load shows a crossover
from a single, centered peak at intermediate depths to two propagating peaks at large depths that broaden diffusively.
Received 16 January 2002 相似文献
3.
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
4.
5.
B. Audoly B. Roman A. Pocheau 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(1):7-10
We study the nonlinear deformations of a long rectangular elastic plate clamped along its edges and submitted to in-plane
biaxial compression. Using the F?ppl-von Kármán equations, we predict various secondary buckling modes according to the applied
longitudinal and transverse compressions. A model experiment is carried out in a thin polycarbonate film, and the observed
buckling patterns are found in good agreement with theory. Pattern selection in the delamination of compressed thin films
is discussed in the light of these results.
Received 22 January 2002 相似文献
6.
A. Michel V. Pierron-Bohnes J.P. Jay P. Panissod S. Lefebvre M. Bessière H.E. Fischer G. Van Tendeloo 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):225-239
Epitaxial Co/Mn multilayers (0.75 to 6 nm Co, 0.4 nm Mn layer thickness) have been grown on mica substrates covered by a (0002)
Ru buffer layer. The structural properties of these layers have been studied using X-ray diffraction, nuclear magnetic resonance
(NMR), and high resolution transmission electron microscopy (HRTEM). The Co layers, grown as face centred cubic (fcc), were
found to be stabilised by the very thin Mn layers. Data obtained using X-ray diffraction and NMR were analysed and found to
be in good agreement, while Monte-Carlo simulations were used to interpret the data and calculate the expected diffracted
intensity and NMR spectra. The HRTEM data show that the Mn layers give rise to a large strain contrast extending, in the growth
direction, over a distance which exceeds the thickness of the Mn layers. The superlattices could be described as having an
fcc structure containing randomly located stacking faults with varying densities. The results verify the presence of a dominant,
almost perfect phase of fcc stacking, and of a faulted hcp phase, while the number of defects increases with the Co layer
thickness.
Received 27 October 1999 and Received in final form 29 May 2000 相似文献
7.
Theenhaus T Allen MP Letz M Latz A Schilling R 《The European physical journal. E, Soft matter》2002,8(3):269-274
We investigate hard ellipsoids of revolution in a parameter regime where no long range nematic order is present but already
finite-size domains are formed which show orientational order. Domain formation leads to a substantial slowing down of a collective
rotational mode which separates well from the usual microscopic frequency regime. A dynamic coupling of this particular mode
into all other modes provides a general mechanism which explains an excess peak in spectra of molecular fluids. Using molecular
dynamics simulation on up to 4096 particles and on solving the molecular mode coupling equation we investigate dynamic properties
of the peak and prove its orientational origin.
Received 19 September 2001 and Received in final form 19 March 2002 相似文献
8.
J.-P. Bouchaud P. Claudin D. Levine M. Otto 《The European physical journal. E, Soft matter》2001,4(4):451-457
We investigate both numerically and analytically the effect of strong disorder on the large-scale properties of the hyperbolic
equations for stresses proposed in J.-P. Bouchaud, M.E. Cates, P. Claudin, J. Phys. I 5, 639 (1995), and J.P. Wittmer, P. Claudin, M.E. Cates, J.-P. Bouchaud, Nature 382, 336 (1996); J.P. Wittmer, P. Claudin, M.E. Cates, J. Phys. I 7, 39 (1997). The physical mechanism that we model is the local splitting of the force chains (the characteristics of the hyperbolic
equation) by packing defects. In analogy with the theory of light diffusion in a turbid medium, we propose a Boltzmann-like
equation to describe these processes. We show that, for isotropic packings, the resulting large-scale effective equations
for the stresses have exactly the same structure as those of an elastic body, despite the fact that no displacement field
needs to be introduced at all. Correspondingly, the response function evolves from a two-peak structure at short scales to
a broad hump at large scales. We find, however, that the Poisson ratio is anomalously large and incompatible with classical
elasticity theory that requires the reference state to be thermodynamically stable.
Received 13 November 2000 and Received in final form 3 January 2001 相似文献
9.
We present experimental evidence that the free-electron laser at the TESLA Test Facility has reached the maximum power gain
of 107 in the vacuum ultraviolet (VUV) region at wavelengths between 80 and 120 nm. At saturation the FEL emits short pulses with
GW peak power and a high degree of transverse coherence. The radiation pulse length can be adjusted between 30 fs and 100
fs. Radiation spectra and fluctuation properties agree with the theory of high gain, single-pass free-electron lasers starting
from shot noise.
Received 26 April 2002 Published online 28 June 2002 相似文献
10.
Gorce JP Bovey D McDonald PJ Palasz P Taylor D Keddie JL 《The European physical journal. E, Soft matter》2002,8(4):421-429
We present a systematic study of the vertical uniformity of water distribution during the drying of waterborne colloidal films,
testing the predictions of a Peclet number Pe defined for this system. Pe indicates the relative contributions of water evaporation and Brownian diffusion in determining the concentration profile
in the vertical direction (i.e. normal to the substrate). When Pe < 1, the water concentration in films cast from an alkyd emulsion is found via magnetic-resonance profiling to be uniform with depth, which is consistent with expectations. When Pe > 1, a gradient in the water concentration develops, with less water near the interface with air. The water profiles reveal
that the alkyd particles do not coalesce immediately upon contact in close-packing. At later times, a concentrated surface
layer develops, but particles are not coalesced in this layer to form a continuous “skin”, but rather the structure is likely
to be that of a biliquid foam.
Received 20 March 2002 and Received in final form 12 June 2002 相似文献
11.
E. Zhulina A.V. Dobrynin M. Rubinstein 《The European physical journal. E, Soft matter》2001,5(1):41-49
We develop a scaling theory for a single polyampholyte chain adsorbed on a charged spherical particle in a theta-solvent.
Adsorption of a polyampholyte molecule is due to its polarization in the electrostatic field of the particle. For large particles
with sizes exceeding the thickness of the adsorbed layer, the conformations of the chain are similar to the one found for
polyampholyte adsorption on charged planar surface. However, an adsorbed polyampholyte chain forms a self-similar flower-like
structure near the particles with sizes smaller than its Gaussian size. These self-similar structures result from the balance
of the polarization energy of loops and the excluded volume interactions between monomers. The structure of an adsorbed polyampholyte
in the flower-like conformation is similar to that of a neutral star polymer.
Received 3 March 2000 and Received in final form 5 July 2000 相似文献
12.
13.
14.
H. Toki 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):177-180
We critically review the present relativistic mean-field theory from the viewpoint of missing pions. We introduce the interesting
experimental data on pionic states taken at RCNP. These data seem to suggest the occurrence of pion condensation in the nuclear
surface. Qualitative discussion is made on the consequence of surface pion condensation on Gamow-Teller transitions and spin
response functions and others. The radioactive ion beams are the tools of studying the unstable nuclei, which have extended
nuclear surfaces. We shall start with radioactive ion beams the nuclear surface science, which includes the surface pion condensation
as the important ingredient in addition to spin-orbit splitting and surface pairing.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
15.
V. Bernard N. Kaiser U.-G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2001,11(2):209-216
We investigate near-threshold neutral pion photoproduction off protons to fourth order in heavy-baryon chiral perturbation
theory in the light of the new data from MAMI. We show that the unitarity cusp at the secondary π+
n threshold is in agreement with expectations from the final-state theorem. We also analyze the fourth-order corrections to
the P-wave low-energy theorems and show that potentially large Δ isobar contributions are cancelled by sizeable pion loop effects.
This solidifies the parameter-free third-order predictions, which are in good agreement with the data.
Received: 25 May 2001 / Accepted: 21 June 2001 相似文献
16.
17.
We develop a continuum theory of linear viscoelastic response in oriented monodomain nematic elastomers. The expression for
the dissipation function is analogous to the Leslie-Ericksen version of anisotropic nematic viscosity; we propose the relations
between the anisotropic rubber moduli and new viscous coefficients. A new dimensionless number is introduced, which describes
the relative magnitude of viscous and rubber-elastic torques. In an elastic medium with an independently mobile internal degree
of freedom, the nematic director with its own relaxation dynamics, the model shows a dramatic decrease in the dynamic modulus
in certain deformation geometries. The degree to which the storage modulus does not altogether drop to zero is shown to be
both dependent on frequency and to be proportional to the semi-softness, the non-ideality of a nematic network. We consider
the most interesting geometry for the implementation of the theory, calculating the dynamic response to an imposed simple
shear and making predictions for effective moduli and (exceptionally high) loss factors.
Received 16 October 2000 and Received in final form 10 December 2000 相似文献
18.
P. Sigmund A. Schinner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):165-172
Binary theory of electronic stopping, developed recently with the aim of quantifying stopping forces on swift heavy ions,
has been applied to antiproton stopping. Essential ingredients in the theory are inverse-Bloch and shell corrections. The
numerical input consists of the excitation spectrum of the stopping material, characterized by bundled oscillator strengths
extracted from tabulated optical properties. Predicted stopping forces for eight solid materials agree well with experimental
data, in particular for Si where measurements span over two decades of projectile energy. Large discrepancies were found with
stopping data for helium extracted from annihilation time measurements.
Received 22 February 2001 相似文献
19.
We have studied the effect of physical ageing in thin supported glassy polystyrene films by using ellipsometry to detect overshooting
in the expansivity-temperature curve upon heating of aged samples. Films with thickness 10-200 nm have been aged at 70°
C and 80°
C (below the bulk glass transition temperature). We observe clear relaxation peaks in the expansivity-temperature curve for
films thicker than 18 nm but not for the 10 nm film. The intensity of the relaxation peak is inversely proportional to the
film thickness, while the temperatures characteristic to the relaxation peak are almost independent of the film thickness.
These observations are successfully interpreted by the idea that the surface layer of the order of 10 nm has liquid-like thermal
properties.
Received 28 October 2002 / Published online: 1 April 2003
RID="a"
ID="a"Present address: Yokohama Research Center, Mitsubishi Chemical Corporation, 1000 Kamoshida-chou, Aoba-ku, Yokohama 227-8502, Japan; e-mail:
kawana@rc.m-kagaku.co.jp 相似文献
20.
C. von Ferber A. Jusufi C.N. Likos H. Löwen M. Watzlawek 《The European physical journal. E, Soft matter》2000,2(4):311-318
We analyze the effective triplet interactions between the centers of star polymers in a good solvent. Using an analytical
short-distance expansion inspired by scaling theory, we deduce that the triplet part of the three-star force is attractive
but only 11% of the pairwise part even for a close approach of three star polymers. We have also performed extensive computer
simulations for different arm numbers f to extract the effective triplet force. The simulation data show good correspondence with the theoretical predictions. Our
results justify the effective pair potential picture even beyond the star polymer overlap concentration.
Received 1 September 1999 and Received in final form 18 January 2000 相似文献