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1.
We analyze the long time behavior of an infinitely extended system of particles in one dimension, evolving according to the Newton laws and interacting via a non-negative superstable Kac potential (x)=(x), (0, 1]. We first prove that the velocity of a particle grows at most linearly in time, with rate of order . We next study the motion of a fast particle interacting with a background of slow particles, and we prove that its velocity remains almost unchanged for a very long time (at least proportional to –1 times the velocity itself). Finally we shortly discuss the so called Vlasov limit, when time and space are scaled by a factor .  相似文献   

2.
Metrics induced by a conformally invariant scalar field in both the absence and presence of electric charge are obtained and investigated. It is shown that the structure of the considered space-time is significantly different in three cases: 1)qa2+ G2/3g 2 /4; 2)q2+G2/3=r g 2 /4 and 3)q2+G2/3>r g 2 /4. In the first case the space has a throat; in the second case there is a black hole, and in the third the space — time has the properties of the Reissner — Nordström space forq2>r g 2 /4.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 80–85, December, 1978.  相似文献   

3.
We propose a Veneziano-like model for VV reactions near threshold involving exchanges of 0 trajectories int- andu-channels. The model is applied to , , , and processes. The model in its simplest form cannot account for the disparities in the cross sections for andK *+ K *– and for 00 and +. Further refinements of the model are suggested.  相似文献   

4.
The cross section for the radiative photoproduction of + mesons on hydrogenp + n in dependence on the momentum transfer squared has been measured at the 1·2 GeV electron synchrotron PACHRA. Using extrapolation of the data to pion pole the differential cross section for the pion Compton scattering + + has been obtained, and the electric polarizability of the + meson has been estimated to be =(20±12) x 10-43cm3.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.The authors thank P. A. Cherenkov for his constant attention to this work and helpful discussions at all stages of the work.  相似文献   

5.
The nuclear magnetic moment of103Ru has been determined using the technique of low-temperature nuclear orientation on103Ru as a dilute impurity in Fe. The Fe lattice was cooled to 1.7 mK using a PrNi5 enhanced nuclear demagnetisation stage precooled with a3He–4He dilution refrigerator. The103RuFe system was observed to have a long nuclear spin-lattice relaxation time, but analysis of the relaxation indicates that the103Ru nuclei are close to thermal equilibrium with the Fe lattice at times>200 min after demagnetising. From the near thermal equilibrium anisotropy of the 497 keV -ray in103Rh we have deduced the nuclear magnetic moment as |(103Ru)|=0.18(2)N. This value is almost independent of the choice of spinI=3/2 or 5/2 for the nucleus, but is only consistent with systematics ifI(103Ru)=3/2 and <0. UsingI=3/2 we obtain the E2/M1 mixing ratio of the 497 keV -ray as =–0.42(4). The sign of the anisotropy of the 610 keV -ray from the 650 keV level in103Rh is only consistent with an allowed -decay to the state ifI(650 keV,103Rh)=5/2. The E2/M1 mixing ratio of the 610 keV -ray is then =+0.15(3) or +60( –40 + ), <–80. From the initial rise in -ray anisotropy following demagnetisation we determine the Korringa constant for103RuFe to beC=5.7(5) K·s.  相似文献   

6.
The relativistic momentum approximation has been used to calculate the tensor analyzing capacity F20 of the d p reaction. At high proton moments (p50 MeV/sec), the dependence of F20 of the parameters of the n vertex becomes substantial, which shows that experiments on F20 can provide information on the electromagnetic form factor of the n transition.Research performed with financial support from the Russian Fundamental Research Fund (project code 93-02-3514).Nuclear Physics Research Institute, Tomsk Polytechnical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 35–38, October, 1994.  相似文献   

7.
The beam asymmetryB has been measured for the reactiond pn in the energy rangeE = 0·4 ÷ 0·8 GeV and angles p cm = 45 ÷ 95° and ford 0d at energiesE =0·5, 0·6, 0·7 GeV and angle cm = 130°. The results obtained are compared to existing theoretical predictions which take into account the possible contribution of dibaryon resonances.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.  相似文献   

8.
It is shown that in discontinuous decomposition in Ni36Cr12TiAl steel, rodlike lamellae of the -phase are precipitated, which are coherently (possibly quasi-coherently) bonded to the matrix. It is concluded from data on the continuous precipitation of the -phase that continuous decomposition in this steel takes place in two stages: in the first, partially ordered zones are formed and, in the second, particles of the -phase.  相似文献   

9.
The investigation of microstructure and chemical composition of the and phases were performed in a Ni-base superalloy by means of analytical electron microscopy. The distribution of particular elements in the alloy was revealed using X-ray mapping in a transmission electron microscope. The detected concentration profiles of alloying elements at the / interface were relatively sharp in the case of cuboidal shape of the phase while they resembled the classical diffusion profile for the oval phase. The quantitative analysis of the phase revealed much higher content of Al and lower of Ti, W, Co and Mo in the oval precipitates compared to cuboidal ones. This result is attributed to the different solidification paths, which is eutectic for the cuboidal precipitates and peritectic for the oval precipitates.  相似文献   

10.
This article presents a Pauli-Dirac matrix approach to Clifford Algebras. It is shown that the algebra C2 is generated by two Pauli matrices i2 and i3; C3 is generated by the three Pauli matrices 1, 2, 3; C4 is generated by four Dirac matrices 0, 1, 2, 3 and C5 is generated by five Dirac matrices i0, i1, i2, i3, i5. The higher dimensional anticommuting matrices which generate arbitrarily high order Clifford algebras are given in closed form. The results obtained with this Clifford algebra approach are compared with the vector product method which was described in a recent article [Found. Phys. 10, 531–553 (1980) by Poole, Farach and Aharonov] and with the Dirac, Rashevskii and Ramakrishnan methods of matrix generation.Supported by the National Science Foundation under Grant ISP-80-11451.  相似文献   

11.
We investigate the time evolution of a model system of interacting particles moving in a d-dimensional torus. The microscopic dynamics is first order in time with velocities set equal to the negative gradient of a potential energy term plus independent Brownian motions: is the sum of pair potentials, V(r)+ d J(r); the second term has the form of a Kac potential with inverse range . Using diffusive hydrodynamic scaling (spatial scale –1, temporal scale –2) we obtain, in the limit 0, a diffusive-type integrodifferential equation describing the time evolution of the macroscopic density profile.  相似文献   

12.
For a -dimensional system of particles with the two-body potentialq(r)+ v K(r) and density , it is proved under fairly weak conditions onq andK that the canonical pressure (, ) and chemical potential (, ) tend to definite limits when 0. The limiting functions are absolutely continuous and are given in terms of the derivative of the limiting free energy density which was found in Part I.  相似文献   

13.
We present some asymptotic results for the family of pausing time densities having the asymptotic (t) property(t) [t ln1+(t/T)]–1. In particular, we show that for this class of pausing time densities the mean-squared displacement r 2(t) is asymptotically proportional to ln(t/T), and the asymptotic distribution of the displacement has a negative exponential form.  相似文献   

14.
The results of NMR/ON measurements on56'57'60Co isotopes in iron are presented. To avoid the uncertainties caused by local demagnetizing field inhomogenities the measurements on two cobalt isotopes in one sample have been carried out. The values of nuclear-factor ratios 57/ 60 = 1.805 (20), 60/ 56 = 0.761 (20), 56/ 57 = 0.726 (20) and hyperfine anomalies5660 = -0.036 (10),60 57 = 0.017 (10) and5756 = 0.018 (10) have been calculated from the experimental results.  相似文献   

15.
We employ QCD sum rules to calculate the coupling constant g by studying the three point -correlation function. Our result complements the analysis of this coupling constant utilizing the experimental value of the 00 decay rate studied within the framework of chiral perturbation theory including vector meson and meson intermediate states.  相似文献   

16.
We consider the relaxation of an order-parameter fluctuation of wave numberk in a system undergoing a second-order phase transition. In general, close to the critical point, wherek –1 –1 (the correlation length) the relaxation rate has a linear dependence on/k of the form (k, ) = (k, 0)x(1–a/k). In analogy with the use of Ward's identity in elementary particle physics, we show that the numerical coefficienta is readily calculated by means of a mass insertion. We demonstrate, furthermore, that this initial linear drop is the main feature of the full/k dependence of the scaling functionR –x (k,), wherex is the dynamic critical exponent andR=(k2+ 2)1/2 is the distance variable.  相似文献   

17.
The spinor strong interaction theory recentlydeveloped is applied to the radiative decay of atwo-quark vector meson into pseudoscalar meson V P. Expression of the decay rate isderived in this first-principle theory without assumptionand free parameter. The ratio (D*0 D0)/(D*+ D+) is correctly predicted. Theorders of magnitude of the radiative decay rates of B*,D*, K*, and estimated from this expression areconsistent with data. Very fast mesons have a smallersize then do mesons at rest, similar to Lorentzcontraction in laboratory space.  相似文献   

18.
Killing vectors give the linear first integrals of the geodesic equations on Riemannian manifolds and spacetimes, while Killing tensors give the quadratic, cubic, and higher-order first integrals. Here it is shown that the Lie algebra of Killing vectors,, is extended by Killing tensors into a graded algebra,. This sheds some light on the comment by Xanthopoulos [1] on the apparent scarcity of irreducible Killing tensors. Examples are presented of the graded algebras when is abelian and when is nonabelian.  相似文献   

19.
The phase transition for a spin in a magnetic fieldB coupled to acoustic phonons by a coupling constant is studied. The caseB1 with an upper cutoff of unity for the phonons is studied systematically by using an adiabatic canonical transformation. In leading order the transition line is at =2/B=1. In the normal phase (<1) the ground-state energy is –B/2 plus a function of that is given explicitly as the solution of a pair theory. In the broken symmetry phase (>1) the energy is the classical energy plus the same function of =1/2. It is found that the first derivatives of the energy with respect to and with respect toB have finite jumps across the transition line. Quantum fluctuations in both phases are treated. Higher-order terms are a series of powers of 1/B times functions of . The case of a small transverse fieldB is also studied. The sharp transition disappears and is replaced by rapid variation in a region of order (B1/B)2/3 about =1.  相似文献   

20.
It is shown that an unstable crystal structure in a stress field can be treated as a quantum system of pseudospins. A stimulating strain field gives rise to quantum tunneling of atoms. The latter effect is a physical cause for a coherent behavior of the crystal in a stress-concentrator zone wherein the material undergoes the nonequilibrium structural transformation a highly-excited state under load.  相似文献   

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