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1.
We show that for the regularized exponential interaction :e : ind space-time dimensions the Schwinger functions converge to the Schwinger functions for the free field ifd>2 for all or ifd=2 for all such that ||>0.Partially sponsored by the I.H.E.S. through the Stiftung Volkswagenwerk  相似文献   

2.
The2H(d, )4He differential cross section was measured at deuteron laboratory energies of 20, 24, and 28 MeV between cm=45° and cm=135°. AtE d =28 MeV a complete angular distribution was determined and fitted with Legendre polynomials. The ratioR=d/d (cm=90°)/d/d (cm=135°) was measured for each deuteron energy.  相似文献   

3.
We report analyses of series enumerations for the mean radius of gyration for isotropic and directed lattice animals and for percolation clusters, in two and three dimensions. We allow for the leading correction to the scaling behaviour and obtain estimates of the leading correction-to-scaling exponent . We find -0.640±0.004 and =0.87±0.07 for isotropic animals in 2d, and =0.64±0.06 in 3d. For directed lattice animals we argue that the leading correction has= or= ; we also estimate =0.82±0.01 and 0.69 ±0.01 ind=2, 3 respectively. For percolation clusters at and abovep c, we find (p c) =0.58±0.06 and (p>p c)=0.84±0.09 in 2d, and (p c)=0.42±0.11 and (p>p c)=0.41 ±0.09 in 3d.  相似文献   

4.
Letzf (z) be a complex holomorphic function depending holomorphically on the complex parameter . If, for =0, a critical point off 0 falls after a finite number of steps onto an unstable fixed point off 0, then, in the parameter space, near 0, an infinity of more and more accurate copies of the Mandelbrot set appears. We compute their scaling properties.On leave from the University of Geneva  相似文献   

5.
This paper concerns the properties of a symmetric barrier between two reservoirs. The barrier can passK conserved quantities. The current of theith quantity is assumed to satisfy the nonlinear relationJ i=A ijj+Bijkljkl where the i's are the affinity differences across the barrier andA ij andB ijkl are functions of the average affinities of the reserviors. It is shown thatB ijkl is symmetric in all indices.  相似文献   

6.
The surface resistance of a metal coated with amorphous superconducting films is investigated. With an improved microwave cryostat and a two layer model considering the influence of the substrate, much thinner films can be used than previously. As an example the surface resistance of amorphous Ga is determined. A set of parameters 0/k BTc=2,27; L=13,4 nm; 0=223 nm andl=1,0 nm describes the temperature dependence independent of thickness. As expected a model of free electrons is in agreement with the experimental results. For crystalline-Ga 0/k B T c =1,91; L=24 nm; 0=163 nm and a much larger mean free pathl=22 nm is found.  相似文献   

7.
Rates of particle-emitting decay of the resonant state of the muonic molecular ion (dHe) J=1 lying below the (d)1s-He threshold can decay to the d-He scattering state. The resonant state is estimated by scattering calculations with the non-adiabatic coupled-rearrangement-channel method. Strong isotope dependence of the decay rates of (d3He) J=1 and (d4He) J=1 is predicted, though the calculated radiative decay rates of the states are almost the same. In (d3He) J=1, the particle decay width is three times larger than the radiative decay width, while the two types of decay widths are almost the same in (d4He) J=1. This results in a strong hindrance of the branching ratio of the radiative decay of (d3He) J=1 compared with the case of (d4He) J=1. This is consistent with a recent observation of the radiative decay of the two molecular states.  相似文献   

8.
Letw = {w(x)xZd} be a positive random field with i.i.d. distribution. Given its realization, letX t be the position at timet of a particle starting at the origin and performing a simple random walk with jump rate w–1(Xt). The processX={X t:t0} combined withw on a common probability space is an example of random walk in random environment. We consider the quantities t =(d/dt) E (X t 2M –1 t and t(w) = (d/dt)Ew(X t 2 – M 1t). Here Ew. is expectation overX at fixedw and E = Ew (dw) is the expectation over bothX andw. We prove the following long-time tail results: (1) limt td/2t= V2Md/2–3(d/2)d/2 and (2) limt td/4 st(w)= Zs weakly in path space, with {Zs:s>0} the Gaussian process with EZs=0 and EZrZs= V2Md/2–4(d)d/2 (r + s)–d/2. HereM and V2 are the mean and variance of w(0) under . The main surprise is that fixingw changes the power of the long-time tail fromd/2 tod/4. Since , with 0 the stationary measure for the environment process, our result (1) exhibits a long-time tail in an equilibrium autocorrelation function.  相似文献   

9.
Let t be an analytic solution of the Schrödinger equation with the initial condition . Let t be the solution of the Schrödinger equation with the initial condition =, where is an analytic function. When 0, then t (x) t (x)1 ( t (x)), where t (x) trajectory starting from x. We relate this result to Feynman's sum over trajectories and complex stochastic differential equations.  相似文献   

10.
The possibility to obtain information on n scattering at intermediate energies from the reaction dnp is analyzed. To this aim, the differential cross sectiond 3 /d ,d n dE n and the scattering asymmetry with linearly polarized photons are calculated at photon energies 100 to 400 MeV in the diagrammatic approach. The pole diagrams of the impulse approximation are evaluated with realistic n and p scattering amplitudes. One-loop diagrams withnp rescattering in the final state and with meson-exchange and isobar currents are taken into account as well. The main contribution to the differential cross sectiond 3 /d ,d n dE n in the kinematics of quasi-free n scattering arises from the neutron pole diagram. The correction due to other diagrams is typically –30% to –10% and decreases with increasing photon energy and momentum transfer. The sensitivity of the cross sections to the magnitude of the neutron electric polarizability and to the sign of the 02 decay constant is demonstrated.  相似文献   

11.
This paper shows that a new class of axially symmetric static electrovacuum/magnetovacuum solutions is obtainable from Weyl's class of static vacuum solutions. The new class contains an infinite set of asymptotically flat solutions (in closed form) each of which involves an arbitrary set (d, i) of parameters. These parameters have to be interpreted as functions of massm, chargee, and higher electric/magnetic multipole moments i of the particle. The cased = 0, i =0 leads to the Darmois solution and the cased = 0, i 0 leads to the results of [1]. The case d=0, e=i=0 leads to the Schwarzschild solution, the cased 0, i =0,e 0 leads to the Reissner-Nordström solution. To get more general examples is a lengthy but straightforward exercise.  相似文献   

12.
The statistical mechanics is considered of any polymer network with a prescribed topology, in dimensiond, which was introduced previously. The basic direct renormalization theory of the associated continuum model is established. It has a very simple multiplicative structure in terms of the partition functions of the star polymers constituting the vertices of the network. A calculation is made toO(2), whered=4–, of the basic critical dimensions L associated with anyL-leg vertex (L1). From this infinite series of critical exponents, any topology-dependent critical exponent can be derived. This is applied to the configuration exponent G of any networkG toO(2), includingL-leg star polymers. The infinite sets of contact critical exponents between multiple points of polymers or between the cores of several star polymers are also deduced. As a particular case, the three exponents 0, 1, 2 calculated by des Cloizeaux by field-theoretic methods are recovered. The limiting exact logarithmic laws are derived at the upper critical dimensiond=4. The results are generalized to the series of topological exponents of polymer networks near a surface and of tricritical polymers at the-point. Intersection properties of networks of random walks can be studied similarly. The above factorization theory of the partition function of any polymer network over its constitutingL-vertices also applies to two dimensions, where it can be related to conformal invariance. The basic critical exponents L and thus any topological polymer exponents are then exactly known. Principal results published elsewhere are recalled.  相似文献   

13.
The exponent d for the probability of nonintersection of two random walks starting at the same point is considered. It is proved that 1/2<23/4. Monte Carlo simulations are done to suggest 2=0.61 and 30.29.  相似文献   

14.
The current and logarithm-of-the-current distributionsn(i) andn(ln i) on bond diluted two-dimensional random-resistor networks at the percolation threshold are studied by a modified transfer matrix method. Thek th moment (–9k8) of n(ln i) i.e., ln i&k, is found to scale with the linear sizeL as (InL)(k). The exponents (k) are not inconsistent with the recent theoretical prediction (k)=k, with deviations which may be attributed to severe finitesize effects. For small currents, ln n(y), yielding information on the threshold below which the multifractality of (i) breaks down. Our numerical results for the moments of the currents are consistent with other available results.  相似文献   

15.
A polymer chain with attractive and repulsive forces between the building blocks is modeled by attaching a weight e for every self-intersection and e /(2d) for every self-contact to the probability of an n-step simple random walk on d , where , >0 are parameters. It is known that for d=1 and > the chain collapses down to finitely many sites, while for d=1 and < it spreads out ballistically. Here we study for d=1 the critical case = corresponding to the collapse transition and show that the end-to-end distance runs on the scale n = (log n)–1/4. We describe the asymptotic shape of the accordingly scaled local times in terms of an explicit variational formula and prove that the scaled polymer chain occupies a region of size n times a constant. Moreover, we derive the asymptotics of the partition function.  相似文献   

16.
Refractive-index and optical-absorption spectra of Bi-substituted yttrium iron garnet films, epitaxially grown by liquid-phase epitaxy, have been measured in the spectral regime 0.26 m1.9 m by thin-film interference for 0.52 m and by ellipsometry for0.52 m. The Y3–x–y Bi x Pb y Fe5–z Pt z O12 films contain bismuth in the range Ox 1.42, lead in the range 0.01 y0.08 and platinum in the range 0.005<=z0.03. There is satisfactory coincidence between the results from ellipsometry and thin-film interference in the overlapping wavelength region. The materials investigated are the same as reported earlier from this laboratory in ter mof their magnetic and magnetooptic properties.  相似文献   

17.
The asymmetric contact process onZ has two distinct critical values 1 > 2 (at least with sufficient asymmetry). One can consider the process on {0,...,N} and analyze the time (which we call N ) till complete vacany starting from complete occupation. Its behavior has already been resolved for all regions of except for =2. For this value, Schinazi proved that lim N log N /logN=2 in probability and conjectured that N /N 2 converges in distribution. It is that result that we prove in this paper. We rely heavily on the Brownian motion behavior of the edge particle, which comes from Galves and Presutti and Kuczek.  相似文献   

18.
Three definitions of logical independence of two von Neumann latticesP1,P2 of two sub-von Neumann algebras 1, 2 of a von Neumann algebra are given and the relations of the definitions clarified. It is shown that under weak assumptions the following notion, called logical independence is the strongest:A B 0 for any 0 A P1, 0 B P2. Propositions relating logical independence ofP1,P2 toC *-independence,W * independence, and strict locality of 1, 2 are presented.  相似文献   

19.
From the eigenvalue equationH \ n () =E n ()\ n () withH H 0 +V one can derive an autonomous system of first order differential equations for the eigenvaluesE n () and the matrix elementsV mn () where is the independent variable. To solve the dynamical system we need the initial valuesE n ( = 0) and \ n ( = 0). Thus one finds the motion of the energy levelsE n (). We discuss the question of energy level crossing. Furthermore we describe the connection with the stationary state perturbation theory. The dependence of the survival probability as well as some thermodynamic quantities on is derived. This means we calculate the differential equations which these quantities obey. Finally we derive the equations of motion for the extended caseH =H 0 +V 1 + 2 V 2 and give an application to a supersymmetric Hamiltonian.  相似文献   

20.
The reaction p K0+ was measured in the photon energy range from threshold up to 2.6 GeV with the SAPHIR detector at the electron stretcher facility, ELSA, in Bonn. Results are presented on the reaction cross-section and the polarization of the + as a function of the kaon production angle in the centre-of-mass system, cosc.m.K, and the photon energy. The cross-section is lower and varies less with photon energy and kaon production angle than that of p K+0. The + is polarized predominantly at cosc.m.K 0. The data presented here are more precise than previous ones obtained with SAPHIR and extend the photon energy range to higher values. They are compared to isobar model calculations.  相似文献   

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