共查询到20条相似文献,搜索用时 296 毫秒
1.
David Dereudre 《Journal of statistical physics》2008,131(1):127-151
In this paper, we prove the existence of infinite Gibbs Delaunay tessellations on ℝ2. The interaction depends on the local geometry of the tessellation. We introduce a geometric hardcore condition on small
and large cells, consequently we can construct more regular infinite random Delaunay tessellations. 相似文献
2.
Linsen Zhang Puxun Wu Hongwei Yu 《The European Physical Journal C - Particles and Fields》2011,71(3):1588
In this paper, two modified Ricci models are considered as the candidates of unified dark matter–dark energy. In model one,
the energy density is given by rMR=3Mpl(aH2+b[(H)\dot])\rho_{\mathrm{MR}}=3M_{\mathrm{pl}}(\alpha H^{2}+\beta\dot{H}), whereas, in model two, by
rMR=3Mpl(\fraca6 R+g[(H)\ddot]H-1)\rho_{\mathrm{MR}}=3M_{\mathrm{pl}}(\frac{\alpha}{6} R+\gamma\ddot{H}H^{-1}). We find that they can explain both dark matter and dark energy successfully. A constant equation of state of dark energy
is obtained in model one, which means that it gives the same background evolution as the wCDM model, while model two can give an evolutionary equation of state of dark energy with the phantom divide line crossing
in the near past. 相似文献
3.
Yong Luo Shirong Ge Zhongmin Jin John Fisher 《Applied Physics A: Materials Science & Processing》2010,98(4):765-768
Micro-porous titanium carbide coating was successfully synthesized in a vacuum gas carburizing furnace by using a sequential
diffusion technology. The composition and structure of the as-synthesized TiC were examined by X-ray diffraction, X-ray photoelectron
spectroscopy (XPS) and glow discharge mass spectrometry (GDMS), and scanning electron microscopy (SEM). All of the XRD, XPS
and GDMS analysis results indicate that carbon atoms effectively diffused into the titanium alloys and formed a uniform acicular
TiC coating with micro-porous structure. 相似文献
4.
R. G. C. Oldeman M. Meloni B. Saitta 《The European Physical Journal C - Particles and Fields》2010,65(1-2):81-87
Antineutrino induced electron capture is a resonant process that can have a large cross-section for beams of monochromatic antineutrinos. We calculate the cross-section of this process and investigate an experimental setup where monochromatic antineutrinos are produced from the bound-beta decay of fully ionized radioactive atoms in a storage ring. If the energy between the source and the target is well matched, the cross-sections can be significantly larger than the cross-sections of commonly used non-resonant processes. The rate that can be achieved at a small distance between the source and two targets of 103?kg is up to one interaction per 8.3?1018 decaying atoms. For a source-target distance corresponding to the first atmospheric neutrino oscillation maximum, the largest rate is one interaction per 3.2?1021 decaying atoms, provided that extremely stringent monochromaticity conditions (10?7 or better) are achieved in future ion beams. 相似文献
5.
Song He Mei Huang Qi-Shu Yan Yi Yang 《The European Physical Journal C - Particles and Fields》2010,66(1-2):187-196
By matching the predictions of the Dp–Dq soft-wall model in type II superstring theory with the spectra of vector and axial-vector mesons, we show the dependence of the Regge trajectories parameters on the metric parameters of the model. From the experimental results of Regge parameters for vector mesons, it is found that the D3 background brane with both q=5 and q=7 probe brane and D4 background brane with q=4 probe brane are close to the realistic holographic QCD. We also discuss how to realize chiral symmetry breaking in the vacuum and asymptotic chiral symmetry restoration in high excitation states. We find that the constant component of the 5-dimension mass square of axial-vector mesons plays an efficient role to realize the chiral symmetry breaking, and a small negative z 4 correction in the 5-dimension mass square is helpful to realize the chiral symmetry restoration in high excitation states. 相似文献
6.
Shuvendu Chakraborty Ujjal Debnath 《International Journal of Theoretical Physics》2010,49(8):1693-1698
We have considered N-dimensional Einstein field equations in which four-dimensional space-time is described by a FRW metric and that of extra
dimensions by an Euclidean metric. We have supposed that the higher dimensional anisotropic universe is filled with only normal
scalar field or tachyonic field. Here we have found the nature of potential of normal scalar field or tachyonic field. From
graphical representations, we have seen that the potential is always decreases with field φ increases. 相似文献
7.
Xudong Wang Yong-Hong Ye Chao Zheng Wen Xuan Tang Tie Jun Cui 《Applied Physics A: Materials Science & Processing》2010,100(4):1029-1033
Metamaterials with large-scale freestanding Ag-SU-8-Ag sandwich configuration, perforated with a square periodic array of
circular holes, are fabricated. The transmittance spectra of both experiment and simulation have shown the existence of two
transmittance peaks in the middle-infrared region. Numerical simulations based on the effective media method and the effective
parameter retrieval procedure verify that the low-frequency transmittance peak results from the electric and the magnetic
resonance associated with the negative refractive index. The influence of dielectric loss of the interlayer on transmission
and negative refractive response is discussed. Numerical simulations indicate that the transmission within the negative refractive
index region decreases, while the dielectric loss of interlayer increase, mainly due to the enhanced reflection. Moreover,
the electric resonance mode further increases the absorption resulted from the dielectric loss of interlayer. 相似文献
8.
This paper focuses on the study of existence and uniqueness of distributional and classical solutions to the Cauchy Boltzmann problem for the soft potential case assuming S n?1 integrability of the angular part of the collision kernel (Grad cut-off assumption). For this purpose we revisit the Kaniel–Shinbrot iteration technique to present an elementary proof of existence and uniqueness results that includes the large data near local Maxwellian regime with possibly infinite initial mass. We study the propagation of regularity using a recent estimate for the positive collision operator given in (Alonso et al. in Convolution inequalities for the Boltzmann collision operator. arXiv:0902.0507 [math.AP]) , by E. Carneiro and the authors, that allows us to show such propagation without additional conditions on the collision kernel. Finally, an L p -stability result (with 1≤p≤∞) is presented assuming the aforementioned condition. 相似文献
9.
Ekaterina Turilova 《International Journal of Theoretical Physics》2009,48(11):3083-3091
Let ℳ be a von Neumann algebra acting on a Hilbert space H and let S be a dense lineal in H that is affiliated with a von Neumann algebra ℳ. The “topological” definition of measures on the classes of orthoclosed and
splitting subspaces of S affiliated with a von Neumann algebra ℳ is given and results on the relationships of these measures to measures on orthoprojections
of the algebra ℳ are presented. 相似文献
10.
Gilberto Colangelo Emanuel Nikolidakis Christopher Smith 《The European Physical Journal C - Particles and Fields》2009,59(1):75-98
We revisit the formulation of the principle of minimal flavor violation (MFV) in the minimal supersymmetric extension of the
standard model, both at moderate and large tan β, and with or without new CP-violating phases. We introduce a counting rule which keeps track of the highly hierarchical structure
of the Yukawa matrices. In this manner, we are able to control systematically which terms can be discarded in the soft SUSY
breaking part of the Lagrangian. We argue that for the implementation of this counting rule, it is convenient to introduce
a new basis of matrices in which both the squark (and slepton) mass terms as well as the trilinear couplings can be expanded.
We derive the RGE for the MFV parameters and show that the beta functions also respect the counting rule. For moderate tan β, we provide explicit analytic solutions of these RGE and illustrate their behavior by analyzing the neighborhood (also switching
on new phases) of the SPS-1a benchmark point. We then show that even in the case of large tan β, the RGE remain valid and that the analytic solutions obtained for moderate tan β still allow us to understand the most important features of the running of the parameters, as illustrated with the help of
the SPS-4 benchmark point. 相似文献
11.
We consider the dimer problem on a planar non-bipartite graph G, where there are two types of dimers one of which we regard as impurities. Computer simulations reveal a reminiscence of
the Cheerios effect, that is, impurities are attracted to the boundary, which is the motivation to study this particular graph.
Our main theorem is a variant of the Temperley bijection: a bijection between the set of dimer coverings and the set of spanning
forests with certain conditions. We further discuss some implications of this theorem: (1) the local move connectedness yielding
an ergodic Markov chain on the set of all possible dimer coverings, and (2) a rough bound for the number of dimer coverings
and that for the probability of finding an impurity at a given edge, which is an extension of a result in (Nakano and Sadahiro
in ). 相似文献
12.
We in this paper provide a sine-Gordon model of (1+1)-dimensions in which macroscopic quantum coherence of domain walls may
be observed. The tunneling amplitude in field models of (1+1)-dimensions, such as sine-Gordon, is negligible small at zero
temperature. In the long, but finite-length chain at finite temperature it is possible to have a finite, but still very small one. In the present model of the antiferromagnetic spin chain with biaxial anisotropy in an external magnetic field, in which
the height of the sine-Gordon barrier can be tuned, the tunneling amplitude is shown to be enhanced by adjusting the external
parameter. 相似文献
13.
A. Bolshakova I. Boyko G. Chelkov D. Dedovitch A. Elagin M. Gostkin A. Grishin A. Guskov Z. Kroumchtein Yu. Nefedov K. Nikolaev A. Zhemchugov F. Dydak J. Wotschack A. De Min V. Ammosov V. Gapienko V. Koreshev A. Semak Yu. Sviridov E. Usenko V. Zaets 《The European Physical Journal C - Particles and Fields》2008,56(3):323-332
Hadron generation in the Geant4 simulation tool kit is compared with inclusive spectra of secondary protons and pions from
the interactions with beryllium nuclei of +8.9 GeV/c protons and pions, and of −8.0 GeV/c pions. The data were taken in 2002 at the CERN Proton Synchrotron with the HARP spectrometer. We report on significant disagreements
between data and Monte Carlo simulation especially in the polar-angle distributions of secondary protons and pions.
On leave of absence at Ecole Polytechnique Fédérale, Lausanne, Switzerland. 相似文献
14.
Ana R. Hortal Paola Hurtado Bruno Martínez-Haya Andrés Arregui Luis Bañares 《Applied Physics A: Materials Science & Processing》2008,92(4):859-863
Matrix-assisted laser desorption ionization (MALDI) was applied to determine the relative efficiencies for attachment of alkali
cations to poly(ethylene glycol) polymers. The solvent-free sample preparation method was employed in order to discriminate
the gas-phase polymer-cation complex formation mechanism from solubility and co-crystallization effects. We show that the
cohesion energy of the cation precursor has a strong influence on the outcome of the MALDI measurements. This potential drawback
is circumvented by the simultaneous use of alkali salts of similar lattice energy. The experiments include chain polymers
of different length (PEG600 and PEG1000) and alkali cations of different size (Na+, K+, Cs+). We found that the attachment efficiencies decrease with growing cation size. This decrease is significantly more rapid
for the shorter PEG600 polymers. These results corroborate the general trends observed in earlier studies, but correct the
dependence on alkali cation size assessed in previous MALDI experiments with the conventional dried-droplet sample preparation
method. 相似文献
15.
We study the dynamics of the thermal momentum distribution function for an interacting, homogeneous Fermi gas on ℤ3 in the presence of an external weak static random potential, where the pair interactions between the fermions are modeled
in dynamical Hartree-Fock theory. We determine the Boltzmann limits associated to different scaling regimes defined by the
size of the random potential, and the strength of the fermion interactions. 相似文献
16.
We describe the application of a long-wavelength vertical-cavity surface-emitting laser (VCSEL) with extended tuning range
to the detection of benzene vapor at atmospheric pressure. A benzene absorption feature centered at 1684.24 nm was accessed
by reducing the heat sink temperature of a VCSEL designed for room-temperature operation to −55°C. This allowed us to increase
the injection current and thus to extend a single-scan tuning interval up to 46.4 cm−1 or 13.2 nm around a central wavelength of 1687.4 nm. Five absorption lines of methane in the 5903–5950 cm−1 range could be acquired within single laser scans at a repetition rate of 500 Hz. A benzene absorption feature between 5926
and 5948 cm−1 was recorded for concentration measurements at atmospheric pressure using a single-pass 1.2 m absorption cell. A 50 ppmv
mixture of CH4 in N2 was introduced into the cell along with benzene vapor to calibrate benzene concentration measurements. Benzene mixing ratios
down to ∼90 ppmv were measured using a direct absorption technique. The minimum detectable absorbance and detection limit
of benzene were estimated to be ∼10−4 and 30 ppmv, respectively. Using the wavelength modulation technique, we measured a second harmonic sensor response to benzene
vapor absorption in air at atmospheric pressure as a function of modulation index. We conclude that a low-temperature monolithic
VCSEL operating near 1684 nm can be employed in compact benzene sensors with a detection limit in the sub-ppm range. 相似文献
17.
This paper investigates the entanglement dynamics of two-spin Ising model with the Dzialoshinskii-Moriya (DM) interaction
in an inhomogeneous magnetic field. The system is initially prepared in the Werner state.It is found that the phenomenon of
the entanglement sudden death (ESD) appears during the evolution process. We also analyze in detail the effects of the DM
interaction, the degree of inhomogeneous magnetic field and the purity of the initial state on the time of ESD. These effects
indicate that one can control the entanglement of the system. It is helpful for quantum information processing. 相似文献
18.
A magnetometer designed for permanent magnet manufacturing and operated around 25 mT with 10 ppm absolute accuracy is described. The magnetometer uses pulse electron paramagnetic resonance methodology. The use of a pulsed broadband acquisition allowed reliable measurements in the presence of the magnetic field gradient and in relatively inhomogeneous magnetic fields of un-shimmed magnets. 相似文献
19.
Lorenzo Sebastiani 《The European Physical Journal C - Particles and Fields》2010,65(3-4):547-553
Motivated by Kerner and Man’s fermions tunneling method of dimension 4 black holes, in this paper, we further improve the analysis to investigate Hawking radiation of charged Dirac particles with spin 1/2 from general non-extremal rotating charged black holes with two parameters and a non-zero cosmological constant in minimal five-dimensional gauged supergravity. For space-times with different horizon topology and different dimensions, constructing a set of appropriate γ μ matrices for general covariant Dirac equation is an important technique for the fermion tunneling method. By introducing a set of appropriate matrices γ μ and employing the ansatz for the spin-up spinor field, we successfully recovered the tunneling probability of charged Dirac particles and the expected Hawking temperature of the black hole, which is exactly consistent with that obtained by other methods. Moreover, the fermion tunneling method can be directly applied to the other five-dimensional charged black holes, which strengthens the validity and power of the fermion tunneling method. 相似文献
20.
An-Ling Wang Fu-Ping Liu Zhao-Xian Yu 《International Journal of Theoretical Physics》2010,49(3):531-535
By using of the invariant theory, we have studied the geometric phase in a time-dependent system with Laguerre polynomial
state, the dynamical and geometric phases are given, respectively. The Aharonov-Anandan phase is also obtained under the cyclical
evolution. 相似文献