共查询到20条相似文献,搜索用时 46 毫秒
1.
V. Čápek 《Czechoslovak Journal of Physics》1990,40(8):857-863
The symmetric spin-boson model without external field is treated for any type of coupling to the boson bath and any initial bath density matrix. With initially fully aligned spin (z (0)= =1), the proof is given that a partial relaxation (z (+) t1<) implies that there is no asymptotic-time (up-and-down) symmetry breaking (i.e. that z (+)=0). For the problem of a particle (interacting with free bosons) in a symmetric double well without spatial symmetry breaking before the infinite time limit, this means that att + the particle distribution becomes symmetric (irrespective of the full initial asymmetry) unless the particle fully remains (att + ) in Ihe starting well. 相似文献
2.
V. Čápek 《Czechoslovak Journal of Physics》1979,29(5):545-556
The usual kinetic equations for the site occupation probabilities in an external field are solved exactly in a simple one-dimensional periodic model with two kinds of atoms using a) free boundary conditions and order of limitsN, 0 needed for a proper treatment of the dc conductivity here b) boundary conditions with metallic contacts and order of limitsN, 0 and c) the same boundary conditions but reversed order of limiting processes 0,N typical of e.g. numerical and percolation treatments. (N and are the number of sites and frequency.) It is demonstrated that though the bulk dc conductivity is the same in all three cases, local bulk properties of the material are strongly dependent on the régime used. The role of the order of all three limiting processes 0,N+ andn+ (N–n+) for local shifts of the chemical potential
n in the dc limit is examined (n is the number of the relevant site calculated from a boundary of the chain). It is shown especially that the rate equation treatment (régime a) on the one hand and numerical or percolation treatments (régime c) on the other hand never yield the same bulk values of
r. 相似文献
3.
LetH
p
=–1/2+V denote a Schrödinger operator, acting inL
p
v
, 1p. We show that (H
p
)=(H
2) for allp[1, ], for rather general potentialsV. 相似文献
4.
Anders Martin-Löf 《Communications in Mathematical Physics》1973,32(1):75-92
For the Ising model with nearest neighbour interaction it is shown that the spin correlations
A
B
-
A
B
decrease exponentially asd(A, B) in a pure phase when the temperature is well belowT
c. This is used to prove that the free energyF(,h) is infinitely differentiable in and has one sided derivatives inh of all orders forh=0. The bounds are also used to prove that the central limit theorem holds for several variables such as e.g. the total energy and the total magnetization of the system, the limit distribution being gaussian with variances determined by the second derivatives ofF(,h). 相似文献
5.
R. Lang 《Communications in Mathematical Physics》1979,65(2):129-149
We consider gradient systems of infinitely many particles in one-dimensional space interacting via a positive invariant pair potential with a hard core. The main assumption is that is strictly convex within the rangeR of (whereR is a fixed number ). Under some technical conditions we prove the following theorems: Let the initial distribution be given by a translation invariant point process onR
1. Then there exists only one extreme equilibrium state with a given intensityI() satisfyingI()R
–1, and all ergodic initial distributions with an intensityI()R
–1 converge weakly ast to the extreme equilibrium state with the same intensity. 相似文献
6.
A. M. Mariz F. van Wijland H. J. Hilhorst S. R. Gomes Júnior C. Tsallis 《Journal of statistical physics》2001,102(1-2):259-283
The Riemann walk is the lattice version of the Lévy flight. For the one-dimensional Riemann walk of Lévy exponent 0<<2 we study the statistics of the support, i.e., set of visited sites, after t steps. We consider a wide class of support related observables M(t), including the number S(t) of visited sites and the number I(t) of sequences of adjacent visited sites. For t we obtain the asymptotic power laws for the averages, variances, and correlations of these observables. Logarithmic correction factors appear for =2/3 and =1. Bulk and surface observables have different power laws for 1<2. Fluctuations are shown to be universal for 2/3 <2. This means that in the limit t the deviations from average M(t)M(t)–M-0304;(t-0304;) are fully described either by a single M independent stochastic process (when 2/3 <1) or by two such processes, one for the bulk and one for the surface observables (when 1<<2). 相似文献
7.
LetH
l
be the Hamiltonian in aP()2 theory with sharp space cutoff in the interval (–l/2,l/2). LetE
l
=inf(H
l
), (l)=–E
l
/l, and let l be the vacuum forH
l
. discuss properties of (l) and
l
. In particular, asl, there are finite constants <0 and such that (l), ((l)–)l, and hence (l)=+/l+o(l
–1). Moreover exp(–c
1
l)
l
1exp(–c
2
l) forc
1,c
2 positive constants, where
l
1 is theL
1(Q, d0) norm of 1 with respect to the Fock vacuum measure. We also present a new proof of recent estimates of Glimm and Jaffe on local perturbations ofH
l
in the infinite volume limit.Research sponsored by AFOSR under Contract No. F44620-71-C-0108.On leave from Istituto di Fisica Teorica, Universitá di Napoli and Istituto Nazionale di Fisica Nucleare, Sezione di Napoli.A. Sloan Foundation Fellow. 相似文献
8.
We show the existence of a constant (0, ) such that if
n is the extinction time for a supercritical contact process on [1, n]
d
starting from full occupancy, then {log(E[
n])}/n
d tend to as n tends to infinity. 相似文献
9.
We show that in the limitp ,N 0,=p/N 0 the limit free energy of the Hopfield model equals in probability the Curie-Weiss free energy. We prove also that the free energy of the Hopfield model is self-averaging for any finite . 相似文献
10.
We consider the Ginsburg-Landau equation for a complex scalar field in one dimension and consider initial data which have two different stationary solutions as their limits in space asx±. If these solutions are not very different, then we show that the initial data will evolve to a stationary solution by a phase melting process which avoids phase slips, i.e., which does not go through zero amplitude. 相似文献
11.
R. K. Dodd 《Letters in Mathematical Physics》1988,16(4):289-299
The algebras g(m) are interpreted as realisations of the infinite rank affine Lie algebras g. 相似文献
12.
F. Gesztesy D. Gurarie H. Holden M. Klaus L. Sadun B. Simon P. Vogl 《Communications in Mathematical Physics》1988,118(4):597-634
We consider eigenvaluesE
of the HamiltonianH
=–+V+W,W compactly supported, in the limit. ForW0 we find monotonic convergence ofE
to the eigenvalues of a limiting operatorH
(associated with an exterior Dirichlet problem), and we estimate the rate of convergence for 1-dimensional systems. In 1-dimensional systems withW0, or withW changing sign, we do not find convergence. Instead, we find a cascade phenomenon, in which, as , each eigenvalueE
stays near a Dirichlet eigenvalue for a long interval (of lengthO(
)) of the scaling range, quickly drops to the next lower Dirichlet eigenvalue, stays there for a long interval, drops again, and so on. As a result, for most large values of the discrete spectrum ofH
is close to that ofE
, but when reaches a transition region, the entire spectrum quickly shifts down by one. We also explore the behavior of several explicit models, as .Max Kade Foundation FellowPartially supported by USNSF under Grant DMS-8416049On leave of absence from Department of Mathematics and Statistics, Case Western Reserve University, Cleveland, OH 44106, USA. Partially supported by USNSF under Grant DMS-8620231 and the Case Institute of Technology, RIG 相似文献
13.
We investigate the limit of Brans-Dicke spacetimes applying a coordinate-free technique. We obtain the limits of some known exact solutions. It is shown that these limits may not correspond to similar solutions in the general relativity theory. 相似文献
14.
D. Eidus 《Letters in Mathematical Physics》1986,12(2):123-126
We define the positive resonance points of self-adjoint operators without using the analytical continuation of corresponding resolvents and show that the limiting amplitude principle for the abstract wave equation does not take place in general, if 2 = , where is the disturbing frequency and is the resonance point. The asymptotics of corresponding solutions as t are obtained, which imply the growth of the oscillation amplitude as t
, 0<<1, or as ln t, t . 相似文献
15.
Jan Philip Solovej 《Letters in Mathematical Physics》1990,20(2):165-172
It was proved by Benguria and Lieb that for an atom where the electrons do not satisfy the exclusion principle, the critical electron number N
c, i.e., the maximal number of electrons the atom can bind, satisfies lim infzNc/Z 1 + , where Z is the nuclear charge. Here is a positive constant derived from the Hartree model. We complete this result by proving that the correct asymptotics for N
c(Z) is indeed zNc/Z = 1 + .This work was done while the author was a graduate student at Princeton University supported by a Danish Research Academy fellowship and U.S. National Science Foundation grant PHY-85-15288-A03. 相似文献
16.
F. Janouch 《Czechoslovak Journal of Physics》1960,10(1):1-6
Double beta decay is discussed in relation to parity non-conservation. Two possible ways of neutrino-less double beta decay (allowed and forbidden) are investigated and the half-life of decay is calculated. For allowed transitions we obtain for Ca48 an estimatedT1/2=2×1019 years. The negative results of the experiments by Lukjanov et al., who give the valueT1/2=0.7×1019 years for the lower limit of the half-life of double beta decay of Ca48, cannot therefore be regarded as a definitive solution of the question, whether the neutrino is a Dirac or Majorana particle. Further study of double beta decay, aimed at finding higher values of the lower limit of half-life, are of considerable importance for theory.
In conclusion the author thanks Prof. I. S. apiro for suggesting this work and help in elaborating it. 相似文献
-
- . - ( ) . 48 T1/221019 . - . [1] ( - 48 T1/2 0,71019 ), , . - .
In conclusion the author thanks Prof. I. S. apiro for suggesting this work and help in elaborating it. 相似文献
17.
Yisong Yang 《Letters in Mathematical Physics》1990,19(1):25-33
It is shown that the chiral angle, (r), of the hedgehog (symmetric) Skyrmions with an arbitrary baryon number, is a strictly decreasing or increasing function. For large values of r>0, (r) is strictly convex or concave. As r, (r) and (r) approach their limit values at the rate Or
-
for any (0,2). 相似文献
18.
The paper contains an interpretation of the domain patterns found on iron whiskers. An explanation of the closure structure at the end of a whisker grown in the [111] direction is given on the basis of a quantitative analysis. Structures, which form on whiskers strained by axial pressure and bending, are also dealt with. The results are in good agreement with experiment.
, . [111]. , . .相似文献
19.
E. Hbivnák 《Czechoslovak Journal of Physics》1960,10(9):633-644
The Bardeen-Shockley formula for the mobility of an electron or hole in a homopolar semi-conductor is derived in a different way to that in which its authors obtained it. The interaction energy of the electron with the acoustic lattice oscillations is derived in an original way. A new possibility for determining the energy gap is given.
-
- , , , . . .相似文献
20.
S. L. Woronowicz 《Letters in Mathematical Physics》1991,23(2):143-145
Two solutionsT andT of the braid equation acting onA A (whereA is a Hopf algebra) are described. IfA is a cocommutative, thenT=. IfA is commutative, thenT= ( denotes the flip: (a b) =b a for anya,b A).Supported by a grant of the Ministry of Education of Poland. 相似文献