共查询到20条相似文献,搜索用时 31 毫秒
1.
In numerical simulations of nonabelian plasma instabilities in the hard-loop approximation, a turbulent spectrum has been
observed that is characterized by a phase-space density of particles n(p)∼p
−ν
with exponent ν≃2, which is larger than expected from relativistic 2↔2 scatterings. Using the approach of Zakharov, L’vov and Falkovich,
we analyze possible Kolmogorov coefficients for relativistic (m≥4)-particle processes, which give at most ν=5/3 perturbatively for an energy cascade. We discuss non-perturbative scenarios which lead to larger values. As an extreme
limit we find the result ν=5 generically in an inherently non-perturbative effective field theory situation, which coincides with results obtained by
Berges et al. in large-N scalar field theory. If we instead assume that scaling behavior is determined by Schwinger–Dyson resummations such that the
different scaling of bare and dressed vertices matters, we find that intermediate values are possible. We present one simple
scenario, which would single out ν=2. 相似文献
2.
We considerN-particle systems whose probability distributions obey the master equation. For these systems, we derive the necessary and sufficient conditions under which the reducedn-particle (n) probabilities also obey master equations and under which the Ursell functions decay to their equilibrium values faster than the probability distributions. These conditions impose restrictions on the form of the transition rate matrix and thus on the form of its eigenfunctions. We first consider systems in which the eigenfunctions of theN-particle transition rate matrix are completely factorized and demonstrate that for such systems, the reduced probabilities obey master equations and the Ursell functions decay rapidly if certain additional conditions are imposed. As an example of such a system, we discuss a random walk ofN pairwise interacting walkers. We then demonstrate that for systems whoseN-particle transition matrix can be written as a sum of one-particle, two-particle, etc. contributions, and for which the reduced probabilities obey master equations, the reduced master equations become, in the thermodynamic limit, those for independent particles, which have been discussed by us previously. As an example of suchN-particle systems, we discuss the relaxation of a gas of interacting harmonic oscillators.Supported in part (grants to D.B. and K.E.S.) by the Advanced Research Projects Agency of the Department of Defense as monitored by the U.S. Office of Naval Research under Contract N00014-69-A-0200-6018, and in part (grant to I.O.) by the National Science Foundation. 相似文献
3.
O. V. Anisimov V. P. Germogenov L. S. Khludkova O. V. Yurkovskii 《Russian Physics Journal》1999,42(1):38-46
The effect of an invertedp-region along the free surface ofn-Al
x
Ga1−x
Sb on the reverse current ofp−n structures from the given solid solution is analyzed. Expressions which describe “collection” of the inverted layer current
on the cylindrical surface of ann-region are discussed. The contribution of the near-surface and bulk components to the reverse current ofp−n structures with a semi-infiniten-region is estimated. For structures with a two-layern-region of finite thickness we have calculated the dependence of the near-surface current on the voltage across thep−n structure, the thickness of then-region, and its composition and doping level. We have compared the calculated current-voltage characteristics with experiment
using a Al0.15Ga0.85Sbp−n structure as an example.
Tomsk State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 42, No. 1, pp. 34–40,
January, 1999. 相似文献
4.
T. Csörgö B. Lörstad J. Schmidt-Sørensen A. Ster 《The European Physical Journal C - Particles and Fields》1999,9(2):275-281
We study the influence of a possible coherent component in the boson source on the two-, three- and n-particle correlation functions in a generalized core–halo-type boson-emitting source. In particular, a simple formula is
presented for the strength of the n-particle correlation functions for such systems. Graph rules are obtained to evaluate the correlation functions of arbitrarily
high order. The importance of an experimental determination of the 4-th and 5-th order Bose–Einstein correlation function
is emphasized.
Received: 18 December 1998 / Published online: 20 May 1999 相似文献
5.
K. Kademova 《International Journal of Theoretical Physics》1970,3(2):109-114
Using the matrix realisations of para-Fermi operators we find isomorphic mappings with respect to the Green product of the
para-Fermi algebra into second-order polynomials of creation and annihilation para-Bose operators with arbitrary order of
parastatistics. In the Fock space ℋ
2
1
of two Bose operators all the irreducible representations of the para-Fermi algebra are realised. The spaces ofn-particle Bose statesn=1,2,..., from which ℋ
2
1
is constructed as a direct sum, can be interpreted as spaces of para-Fermi states of para-statisticsn. 相似文献
6.
We discuss diffractive production in the context of two-component models. After defining the class of models that we consider and discussing their general properties, we develop integral equations for the generating functions of diffractive processes. We consider single and double diffraction and two fireball production. We investigate the behavior of the partial cross sections for n-particle production in all three cases and obtain a successful fit to recent data. 相似文献
7.
E.O. Alt T. Csörgő B. Lörstad J. Schmidt-Sørensen 《The European Physical Journal C - Particles and Fields》2000,13(4):663-670
The effect of multi-particle Coulomb final state interactions on higher-order intensity correlations is determined in general,
based on a scattering wave function which is a solution of the n-body Coulomb Schr?dinger equation in (a large part of) the asymptotic region of n-body configuration space. In particular, we study Coulomb effects on the n-particle Bose–Einstein correlation functions of similarly charged particles and remove a systematic error as big as 100%
from higher-order multi-particle Bose–Einstein correlation functions.
Received: 24 November 1999 / Published online: 17 March 2000 相似文献
8.
K. Murayama H. Nagasawa S. Ozaki M. Morifuji C. Hamaguchi A. Di Carlo P. Vogl G. Böhm G. Weimann 《Superlattices and Microstructures》1996,20(4):493-498
We present DC transport measurements of the valence to conduction band (Zener) tunneling current in ap–i–ndiode with an ultrathin intrinsic layer containing a (GaAs)5/(AlAs)2multi-quantum well structure. According to recent theoretical predictions, the DC current should show maxima as a function of the reverse bias voltage that reflect the formation of Wannier–Stark resonances. So far, Wannier–Stark resonances have only been observed optically and never in a regime of strong Zener tunneling. Experimentally, we find the second derivative of the current-voltage characteristics to show a weak oscillatory structure indeed, indicating the existence of Wannier–Stark resonances in Zener tunneling. 相似文献
9.
T. M. H. Tran B. E. Pieters M. Schneemann T. C. M. Müller A. Gerber T. Kirchartz U. Rau 《固体物理学:研究快报》2013,7(9):627-630
This work presents a method for extracting the absolute local junction voltage of a‐Si:H thin‐film solar cells and modules from electroluminescence (EL) images. It is shown that the electroluminescent emission of a‐Si:H devices follows a diode law with a radiative ideality factor nr larger than one. We introduce an evaluation method that allows us to determine the absolute local junction voltage in cases of nr > 1, while existing approaches rely on the assumption of nr = 1. Furthermore, we find that the experimentally determined values of nr vary from sample to sample. It is also explained why the derived radiative ideality factor is influenced by the spectral sensitivity of the camera system used in the experiment. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
10.
We present an analysis of the geometric structure of nonstationary multisoliton vacuum metrics obtained from a general background using the inverse scattering method of Belinsky and Zakharov. In the case of real pole trajectories, in general the algorithm leads, for ann-soliton metric, ton+1 disjoint coordinate patches. We show, by an explicit construction, that each coordinate patch can be smoothly extended to a separate spacetime manifold. As a result we find that there are no shock fronts associated with the pole trajectories and that, contrasting with the situation for pairs of complex pole, there are no structures that can be easily identified with the region of interaction of a given number of solitons.CONICET research member. 相似文献
11.
G. M. Min’kov O. É. Rut A. V. Germanenko 《Journal of Experimental and Theoretical Physics》1997,85(2):292-299
We study tunneling conductivity oscillations in a magnetic field in narrow-gap p-HgCdTe-oxide-metal (Yb, Al) structures. In tunnel structures with Yb we detect two types of tunneling conductivity oscillations.
The first is related to the crossing of the Landau levels of two-dimensional (2D) states localized in the surface quantum well of the semiconductor, and has an energy E
F+eV, where E
F is the Fermi energy of the semiconductor and V is the bias voltage; the second has an energy E
F. We find that in such structures with an asymmetric quantum well there is strong spin-orbit splitting in the spectrum of
the 2D states. In p-HgCdTe-oxide-Al tunnel structures the surface potential is much weaker and only oscillations of the first type are observed.
We find that in such structures there is only one spin state of the 2D carriers, while the second is pushed into the continuous spectrum because of strong spin-orbit coupling. To analyze the experimental
results we calculate the spectrum of 2D states localized in the surface quantum well in a semiconductor with a Kane dispersion law. We find that all the experimental
results are in good agreement with the results of calculations. Finally, we discuss the features of “kinematically coupled”
states in an asymmetric quantum well.
Zh. éksp. Teor. Fiz. 112, 537–550 (August 1997) 相似文献
12.
We consider a general class of (intersecting) loop models in d dimensions, including those related to high-temperature expansions of well-known spin models. We find that the loop models exhibit some interesting features – often in the “unphysical” region of parameter space where all connection with the original spin Hamiltonian is apparently lost. For a particular n=2, d=2 model, we establish the existence of a phase transition, possibly associated with divergent loops. However, for n1 and arbitrary d there is no phase transition marked by the appearance of large loops. Furthermore, at least for d=2 (and n large) we find a phase transition characterised by broken translational symmetry. 相似文献
13.
提出一种任意两粒子纠缠态1→2普适远程克隆方案. 此方案仅需一个特殊的四粒子纠缠态作为量子信道, 就可使处于空间不同位置的两个接收者分别以5/6的保真度得到任意输入态的近似拷贝, 该保真度远高于已有方案中的保真度. 将方案推广到任意两粒子纠缠态1→N(N>2)普适远程克隆的情况, 可使处于不同地点的N个接收者分别以(2N+1)/(3N)的保真度得到输入态的近似拷贝. 另外, 提出一种以上述单个特殊四粒子纠缠态作为量子信道, 在多目标量子比特受控非门和
关键词:
量子纠缠态
普适远程克隆
保真度 相似文献
14.
I. S. Virt 《Technical Physics》1997,42(7):841-844
The pulse characteristics of Hg0.8Cd0.2Te n
+-p junctions are investigated. It is shown that the shape of the voltage pulse appearing in a junction on passage of a forward
(reverse) current is determined by the recombination (generation) of nonequilibrium electrons in the hole region. An increase
in the current pulse causes the appearance of an electric field, which draws electrons into the interior of the base region,
and leads to variation of their lifetime because of the complex structure of the n
+-p junction.
Zh. Tekh. Fiz. 67, 130–133 (July 1997 相似文献
15.
V.B. Kuznetsov F.W. Nijhoff E.K. Sklyanin 《Communications in Mathematical Physics》1997,189(3):855-877
We construct a separation of variables for the classical n-particle Ruijsenaars system (the relativistic analog of the elliptic Calogero-Moser system). The separated coordinates appear
as the poles of the properly normalised eigenvector (Baker-Akhiezer function) of the corresponding Lax matrix. Two different
normalisations of the BA functions are analysed. The canonicity of the separated variables is verified with the use of the
r-matrix technique. The explicit expressions for the generating function of the separating canonical transform are given in
the simplest cases n=2 and n=3. Taking the nonrelativistic limit we also construct a separation of variables for the elliptic Calogero-Moser system.
Received: 10 January 1997 / Accepted: 1 April 1997 相似文献
16.
B.M. Emerling M.E. Itkis J.W. Brill 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(2):295-301
The infrared transmission of the quasi-one dimensional charge-density-wave (CDW) conductor blue bronze (K0.3MoO3) is affected by polarization of the CDW, and therefore by application of a voltage near or above the threshold for CDW depinning.
In this paper, we compare the spectra associated with the relative change in transmission taken for different temperatures and oscillating voltages. We find that the phonon spectrum is affected by CDW polarization;
the linewidths or frequencies of most phonons change by cm-1. However, no new intragap states that can be associated with current injection are observed; i.e. the spectra associated with polarization of the CDW in the crystal bulk is identical to that associated with CDW current
injection near the contacts. Our results indicate that, for light polarized perpendicular to the conducting chains, the density
(n), cross-section , and bandwidth of intragap states are related by: n
(?cm-1)-1. For expected values of the cross-section and bandwidth, this implies that the intragap states can be optically excited for
a time less than s.
Received 21 February 2000 相似文献
17.
18.
A two-parameter family of asymmetric exclusion processes for particles on a one-dimensional lattice is defined. The two parameters of the model control the driving force and effect which we call pushing, due to the fact that particles can push each other in this model. We show that this model is exactly solvable via the coordinate Bethe Ansatz and show that its N-particle S-matrix is factorizable. We also study the interplay of the above effects in determining various steady state and dynamical characteristics of the system. 相似文献
19.
The
n
Baxter model is an exactly solvable lattice model in the special case of the Belavin parametrization. For this parametrization we calculate the partition function,, in an antiferromagnetic region and the order parameter in a ferromagnetic region. We find that the order parameter is expressible in terms of a modular function of leveln which forn = 2 is the Onsager-Yang-Baxter result. In addition we determine the symmetry group of the finite lattice partition function for the general
n
Baxter model. 相似文献
20.
E. Hantzsche 《等离子体物理论文集》1980,20(5):329-342
Unipolar arcs have achieved considerable importance as a plentiful source of contaminations in tokamak plasmas. A definition of unipolar and plasma induced discharges is given, and the main properties of the space charge sheath between plasma and wall as well as the existence conditions of unipolar arcs (necessary voltage drop, current balance) are considered. From a simple model that includes the superposition of two completely different plasmas — the tokamak plasma and the cathode spot plasma of the arc — the radial dependencies of the current densities and voltages between plasma and wall and of the plasma parameters are derived. It is shown, that — in typical cases — the anode region is a ring-shaped area situated at distances from the arc cathode spot r > b with 0.3 cm ? b ? 1 cm, and that the density decrease of the arc plasma n ~ r?μ necessitates an exponent 2 ? μ ? 3 because of the current balance condition (arc current = backflow current). Moreover some thermodynamic aspects (unipolar arcs as a kind of dissipative structures), the ignition problem, the effects of magnetic fields, the problems of diagnostics and the possibilities of simulations are shortly discussed. 相似文献