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1.
It was shown recently [1] that the structural
-relaxation time
of supercooled o-terphenyl depends on a single control parameter
, which is the product of a function of density
, by the inverse temperature T
-1. We extend this finding to other fragile glassforming liquids using light scattering data. Available experimental results do not allow to discriminate between several analytical forms of the function
, the scaling arising from the separation of density and temperature in
. We also propose a simple form for
, which depends only on three material-dependent parameters, reproducing relaxation times over 12 orders of magnitude.Received: 16 July 2004, Published online: 23 December 2004PACS:
66.20. + d Viscosity of liquids; diffusive momentum transport - 78.35. + c Brillouin and Rayleigh scattering; other light scattering - 64.70.Pf Glass transitions 相似文献
2.
We compute the one-loop
-functions describing the renormalisation of the coupling constant
and the frequency parameter
for the real four-dimensional duality-covariant non-commutative
-model, which is renormalisable to all orders. The contribution from the one-loop four-point function is reduced by the one-loop wavefunction renormalisation, but the
-function remains non-negative. Both
and
vanish at the one-loop level for the duality-invariant model characterised by
. Moreover,
also vanishes in the limit
, which defines the standard non-commutative
-quantum field theory. Thus, the limit
exists at least at the one-loop level.Received: 19 March 2004, Published online: 5 May 2004 相似文献
3.
We study the stationary properties and the state transition of the tumor cell growth model (the logistic model) in presence of correlated noises for the case of nonzero correlation time. We derived an approximative Fokker-Planck equation and the stationary probability distribution (SPD) of the model. Based the SPD, we investigated the effects of both correlation strength (
) and correlation time (
) of cross-correlated noises on the SPD, the mean of the tumor cell population and the normalized variance (
) of the system, and calculated the state transition rate of the system between two stable states. Our results indicate that: (i)
and
play opposite roles in the stationary properties and the state transition of the system, i.e. increase of
can produce a smaller mean value of the cell population and slow down the state transition, but increase of
can produce a larger mean value of the cell population and enhance state transition; (ii) For large
, there a peak structure on both
-
plot and
-
plot. For the small
,
increases with increasing
, but
increases with decreasing
.Received: 26 June 2004, Published online: 30 September 2004PACS:
87.10. + e General theory and mathematical aspects - 05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion - 02.50.Ey Stochastic processes 相似文献
4.
We give a multiresolution partition of pure point parts of diffraction patterns of one-dimensional aperiodic sets. When an aperiodic set is related to the Golden Ratio, denoted by
, it is well known that the pure point part of its diffractive measure is supported by the extension ring of
, denoted by
. The partition we give is based on the formalism of the so called
-integers, denoted by
. The set of
-integers is a selfsimilar set obeying
,
. The pure point spectrum is then partitioned with respect to this Russian doll like sequence of subsets
. Thus we deduce the partition of the pure point part of the diffractive measure of aperiodic sets.Received: 24 March 2004, Published online: 12 July 2004PACS:
61.44.Br Quasicrystals - 61.10.Dp Theories of diffraction and scattering 相似文献
5.
Surface structures in the Te/Ni(111) system are revealed by using reflection high-energy electron diffraction combined with X-ray and ultraviolet photoelectron spectroscopies. At a 0.33 mono-layer (ML)-Te/Ni(111) surface, a reversible structural phase transition is observed with a transition temperature Tc of 380
C. The diffraction pattern from the low temperature phase is accompanied by streaks. The high and low temperature phases are characterized by
and
rectangle, respectively. The mechanism of the phase transition is explained by the order-disorder transition with a rumpled chain model. Both 0.51 ML- and 0.44 ML-Te/Ni(111) surfaces exhibit the complex diffraction patterns accompanied by diffuse streaks. These surface structures are characterized by the
rectangle and
, respectively. All diffuse streaks obtained at the above surfaces are consistently interpreted in the view of the ill-ordered arrangements of the well-ordered
linear chains. It is shown that the
linear structure is the key in the Te/Ni(111) system.Received: 1 December 2003, Published online: 20 April 2004PACS:
61.14.Hg Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED) - 68.65.-k Low-dimensional, mesoscopic, and nanoscale systems: structure and nonelectronic properties - 64.60.Cn Order-disorder transformations; statistical mechanics of model systems 相似文献
6.
Measurements of the time-dependent CP-asymmetry in the decay
and its charge conjugate by the BELLE and BABAR collaborations currently yield
and
, characterizing the direct and mixing-induced CP-asymmetries, respectively. We study the implication of these measurements on the CKM phenomenology taking into account the available information in the quark mixing sector. Our analysis leads to the results that the ratio |P
c
/T
c
| involving the QCD-penguin and tree amplitudes and the related strong phase difference
in the
decays are quite substantial. Using the isospin symmetry to constrain |P
c
/T
c
| and
, where
parameterizes the penguin-induced contribution, we present a fit of the current data including the measurements of
and
. Our best-fits yield
,
,
,
, and
. At 68% C.L., the ranges are
,
,
,
and
. Currently en vogue dynamical approaches to estimate the hadronic matrix elements in
decays do not provide a good fit of the current data.Received: 5 April 2004, Published online: 14 July 2004A.Ya. Parkhomenko: On leave of absence from Department of Theoretical Physics, Yaroslavl State University, Sovietskaya 14, 150000 Yaroslavl, Russia. 相似文献
7.
We investigate the phonon thermal conductivity
of doped
based on out-of-plane thermal conductivity measurements. When room temperature is approached the temperature dependence of
strongly deviates from the T-1-decrease which is usually expected for heat transport by acoustic phonons. Instead,
decreases much weaker or even increases with rising temperature. Simple arguments suggest that such unusual temperature dependencies of
are caused by heat transport via dispersive optical phonons.Received: 20 October 2003, Published online: 20 April 2004PACS:
66.70. + f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves - 74.72.Dn La-based cuprates - 44.10. + i Heat conduction 相似文献
8.
The effect of mixture lengths of vehicles on the asymmetric exclusion model is studied using numerical simulations for both open and periodic boundaries in deterministic parallel dynamics. The vehicles are filed according to their length, the small cars type 1 occupy one cell whereas the big ones type 2 takes two. In the case of open boundaries two cases are presented. The first case corresponds to a chain with two entries where densities are calculated as a function of the injecting rates
and
of vehicles type 1 and type 2 respectively, and the phase diagram (
) is presented for a fixed value of the extracting rate
. In this situation the first order transition from low to high density phases occurs at
and disappears for
. The second case corresponds to a chain with one entry, where
is the injecting rate of vehicles independent of their nature. Type 2 are injected with the conditional probability
, where
and n is the concentration of type 2. Densities are calculated as a function of the injecting rates
, and the phase diagrams (
,
) are established for different values of n. In this situation the gap which is a characteristic of the first order transition vanishes with increasing
for
. However, the first order transition between high and low densities exhibit an end point above which the global density undergoes a continuous passage. The end point coordinate depends strongly on the value of n. In the periodic boundaries case, the presence of vehicles type 2 in the chain leads to a modification in the fundamental diagram (current, density). Indeed, the maximal current value decreases with increasing the concentration of vehicles type 2, and occurs at higher values of the global density.Received: 13 May 2004, Published online: 3 August 2004PACS:
05.50. + q Lattice theory and statistics (Ising, Potts, etc.) - 64.60.Cn Order-disorder transformations; statistical mechanics of model systems - 75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.) - 82.20.Wt Computational modeling; simulation 相似文献
9.
Noiret I. Schamps J. Danede F. Odou G. Lamiot J. 《The European Physical Journal B - Condensed Matter and Complex Systems》2004,41(1):23-30
Structural properties of two RbCdCl3 samples grown either from the melt or from aqueous solution are studied via X-ray diffraction over a closed temperature cycle between 20
C and 300
C. During cooling step (300
C), the crystal grown from the melt undergoes a phase transition at 110
C that drives it from the cubic structure into a tetragonal structure that still persists at 20
C. It undergoes exactly the reverse phase transition at the same temperature during the heating (
C) step that immediately follows. The other crystal grows from aqueous solution at 20
C in an orthorhombic structure (i.e. not tetragonal as that of the crystal grown from the melt and cooled down to this temperature). During the heating (
C) step, it undergoes a direct orthorhombic-cubic phase transition at 240
C (without passing through the tetragonal phase) whereas, during subsequent cooling (300
C), it does not exhibit the corresponding reverse phase transition but rather exhibits exactly the same cubic-tetragonal phase transition at 110
C as the crystal grown from the melt. However, for both crystals, this tetragonal phase observed at room temperature is unstable and slowly converts into an orthorhombic phase over the course of time. Complementary Differential Scanning Calorimetry (D.S.C.) and Thermo Gravimetric Analysis (T.G.A.) measurements have been carried out over the range (
)
C in order to interpret diffraction experiments.Received: 19 May 2004, Published online: 30 September 2004PACS:
61.10.Nz X-ray diffraction - 64.70.Kb Solid-solid transitions - 65.40.Ba Heat capacity 相似文献
10.
The results of first-principles theoretical study of the structural, electronic and optical properties of beryllium monochalcogenides BeTe, BeSe and BeS, performed using the full potential linearized augmented plane wave (FP-LAPW) method are presented. The calculated structural parameters and band gaps compare very well with previous theoretical results. The trends of the band gap pressure coefficients and volume deformation potentials for these II-VI compounds are investigated. The linear pressure coefficients for the
X and
band gaps increase with decrease in anion atomic weight. The dependence of the direct and indirect band gaps on the relative change of lattice constant are found to follow almost the same type of trends in each of these compounds. The volume deformation potential (
) for the direct (
) and indirect (
) gaps are positive, but negative for the indirect (
) gap. Furthermore,
, for
transitions decreases with increase in anion atomic number whereas
, increases. The optical properties have also been calculated. From the reflectivity spectra, the compounds will be useful for optical applications. The variation of the band gaps with respect to the application of pressure and the origin of some of the peaks in the optical spectra are discussed in terms the calculated electronic structure.Received: 26 September 2003, Published online: 18 June 2004PACS:
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.) - 71.15.Mb Density functional theory, local density approximation, gradient and other corrections - 71.20.Nr Semiconductor compounds 相似文献
11.
A. N. Andreyev D. Ackermann F. P. Heßberger S. Hofmann M. Huyse I. Kojouharov B. Kindler B. Lommel G. Münzenberg R. D. Page K. Van de Vel P. Van Duppen K. Heyde 《The European Physical Journal A - Hadrons and Nuclei》2003,18(1):55-64
Alpha-decay of the new nuclide 184Bi has been studied in the complete-fusion reaction 93Nb(94Mo, 3n)184Bi at the velocity filter SHIP. The evaporation residues were separated in-flight and subsequently identified on the basis of recoil-
, recoil-
-
analysis and excitation functions measurements. Two
-decaying isomeric states in 184Bi with half-life values of 13(2) ms and 6.6(1.5) ms were identified. The
-branching ratio of 180Tl was deduced for the first time as
. Improved data on the fine-structure
-decay of 186Bi were obtained in the 93Nb(95Mo, 2n)186Bi reaction. A similarity of the decay energies and half-life values of 184,186Bi is pointed out and a possible explanation for this effect is suggested.Received: 14 March 2003, Revised: 29 April 2003, Published online: 2 September 2003PACS:
23.60.+e
decay - 27.70.+q
- 27.80.+w
K. Heyde: Present address: EP-ISOLDE, CERN, CH-1211, Geneva 23, Switzerland. 相似文献
12.
C.-M. Ghim E. Oh K.-I. Goh B. Kahng D. Kim 《The European Physical Journal B - Condensed Matter and Complex Systems》2004,38(2):193-199
We investigate a problem of data packet transport between a pair of vertices on scale-free networks without loops or with a small number of loops. By introducing load of a vertex as accumulated sum of a fraction of data packets traveling along the shortest pathways between every pair of vertices, it is found that the load distribution follows a power law with an exponent
. It is found for the Barabási-Albert-type model that the exponent
changes abruptly from
for tree structure to
as the number of loops increases. The load exponent seems to be insensitive to different values of the degree exponent
as long as
.Received: 4 February 2004, Published online: 14 May 2004PACS:
89.75.Fb Structures and organization in complex systems - 05.65. + b Self-organized systems - 02.10.Ox Combinatorics; graph theory 相似文献
13.
A presence of a Meissner-Ochsenfeld effect in a gas of spin 1/2 fermions with an interaction
, where
is a volume of a region
in real space which is taken by thesystem and
with
,
satisfying Fermi anticommutation relations, is investigated. The effect proves to be weaker than in BCS by a factor 3/4 at T = 0, implying a greater penetration depth
of external magnetic field. V
4 is nonzero only within a thin layer of 1-fermion energies around the chemical potential .Received: 14 June 2004, Published online: 12 October 2004PACS:
74.20.-z Theories and models of superconducting state - 74.20.Fg BCS theory and its development 相似文献
14.
By employing the QCD factorization approach, we calculated the next-to-leading order new physics contributions to the branching ratios, CP asymmetries, isospin and U-spin symmetry breaking of the exclusive decays
(
), induced by the charged Higgs penguins in general two-Higgs-doublet models. Within the considered parameter space, we found that (a) the new physics corrections to the observables are generally small in model I and model III-A, moderate in model II, but large in model III-B; (b) from the well measured branching ratios and upper limits, a lower bound of MH > 200 GeV in model II was obtained, while the allowed range of MH in model III-B is
GeV; these bounds are comparable with those from the inclusive
decay; (c) the NLO Wilson coefficient C7(mb) in model III-B is positive and disfavored by the measured value of isospin symmetry breaking
, but it still cannot be excluded if we take the large errors into account; (d) the CP asymmetry
in model III-B has an opposite sign to the one in the standard model (SM), which may be used as a good observable to distinguish the SM from model III-B; (e) the isospin symmetry breaking
is less than
in the region of
preferred by the global fit result, but it can be as large as 20 to
in the regions of
and
. The SM and model III-B predictions for
are opposite in sign for small or large values of the CKM angles; (f) the U-spin symmetry breaking
in the SM and the general two-Higgs-doublet models is generally small in size:
.Received: 9 October 2003, Revised: 11 November 2003, Published online: 18 February 2004 相似文献
15.
Brovchenko I. Geiger A. Oleinikova A. 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,44(3):345-358
The phase behavior of fluids near weakly attractive substrates is studied by computer simulations of the coexistence curve of a Lennard-Jones (LJ) fluid confined in a slitlike pore. The temperature dependence of the density profiles of the LJ fluid was used to study the surface critical behavior. A universal critical behavior of the local order parameter, defined as the difference between the local densities of the coexisting liquid and vapor phases at some distance
from the pore walls,
, is observed in a wide temperature range and found to be consistent with the surface critical behavior of the Ising model. Near the surface the dependence of the order parameter on the reduced temperature
obeys a scaling law ~1 with a critical exponent 1 of about 0.8, corresponding to the
surface transition. A crossover from bulk-like to surface-like critical behavior occurs, when the distance to the surface is about twice the correlation length at the given temperature. Relations between the
and
transitions in Ising systems and the surface critical behavior of fluids are discussed. 相似文献
16.
A resonance search has been made in the
invariant-mass spectrum with the ZEUS detector at HERA using an integrated luminosity of
. The decay channels
and
(and the corresponding antiparticle decays) were used to identify
mesons. No resonance structure was observed in the
mass spectrum from more than 60 000 reconstructed
mesons. The results are not compatible with a report of the H1 Collaboration of a charmed pentaquark,
.Received: 14 September 2004, Revised: 29 September 2004, Published online: 9 November 2004 相似文献
17.
R. L. Jaffe 《The European Physical Journal C - Particles and Fields》2004,35(2):221-222
In 1997 Diakonov, Petrov, and Polyakov, calculated the width of the exotic baryon that they called
. The prediction,
MeV, has received considerable attention, especially in light of the narrowness of the experimentally reported
resonance. However, there is an arithmetic error in their work: when corrected, the width estimate quoted in that paper should have been
MeV.Received: 29 January 2004, Published online: 5 May 2004 相似文献
18.
The Standard Model constraints on
which can be derived from the
decays are revisited in some depth. As experimental inputs, the
,
decays complemented by the
decays, the CP parameters
and
, and/or the value of
as determined by the global CKM fit are used. The constraints discussed here are model independent in the sense that they rely only on Isospin symmetry, following the Gronau-London proposal. A new bound on
and the function
are introduced. While another bound applied to BABAR results is shown to imply that
is negative. The Grossman-Quinn bound is rediscussed. A close form expression is given for
as a function of the measurements. Various scenarios for the future of the isospin analysis are explored. To probe the Standard Model the
plane is introduced.Received: 17 December 2004, Published online: 25 January 2005 相似文献
19.
We describe the spectra and decays of
and
atoms within a non-relativistic effective field theory. The evaluations of the energy shifts and widths are performed at next-to-leading order in isospin symmetry breaking. We provide general formulae for all S-states, and discuss the states with angular momentum one in some detail. The prediction for the lifetime of the
atom in its ground state yields
s.Received: 9 May 2004, Published online: 23 July 2004 相似文献
20.
V. Yu. Grishina L. A. Kondratyuk M. Büscher W. Cassing 《The European Physical Journal A - Hadrons and Nuclei》2004,21(3):507-520
Using an effective Lagrangian approach as well as the Quark-Gluon Strings Model, we analyze near-threshold production of a
0(980)-mesons in the reaction
as well as the background of non-resonant
-pair production. We argue that the reaction
at an energy release
MeV is dominated by the intermediate production of the a
0(980)-resonance. At larger energies the non-resonant
-pair production --where the kaons are produced in a relative P-wave-- becomes important. The effects of final-state interactions are evaluated in a unitarized scattering length approach and found to be in the order of a 20% suppression close to threshold. Thus, in present experiments at the Cooler Synchrotron COSY-Jülich for
MeV the a
0
+ signal can reliably be separated from the non-resonant
background.Received: 26 February 2004, Published online: 21 September 2004PACS:
25.10. + s Nuclear reactions involving few-nucleon systems - 13.75.-n Hadron-induced low- and intermediate-energy reactions and scattering (energy
GeV) 相似文献