共查询到20条相似文献,搜索用时 31 毫秒
1.
J. Kupsch 《Communications in Mathematical Physics》1977,57(3):219-233
We give a complete proof of the existence of scattering amplitudesA(s,t,u) with the following properties
- the amplitudes are total symmetric ins,t, andu.
- they satisfy elastic unitarity for 4≦s≦16, and
- they develop resonances forl≧2 on a bounded Regge trajectory which dominates the asymptotics for large energies.
2.
A. Jánosi 《Zeitschrift für Physik B Condensed Matter》1990,80(3):393-400
We study the effects of some of the most important and typical structural changes in two-phase systems on selected structural parameters obtained from small-angle x-ray scattering (SAXS) measurements. To limit the present study, it was assumed that the Phase, 1, embedded in the matrix
- is monodispersed and homogeneous,
- possesses one of the three most extreme shapes (spherical, fibrillar or lamellar) and
- changes its behaviour
- through type change (spinodal or nucleotic or coarsening), without changing the shape,
- through a change of the shape only, or
- through a) (type change) and b) (shape change) simultaneously.
- chord lengthl 1 (and/or radius of gyrationR),
- volume partw 1 of the Phase 1, and
- relative inner surfaceS v of the system.
- spinodal change, all three SAXRS parameters are increasing or decreasing simultaneously and proportional to a power of the intensity of the change,
- nucleotic change,l 1 (and/orR) is unchanged, the other two (w 1 andS v ) are increasing or decreasing simultaneously and directly proportional to the intensity,
- coarsening change,w 1 is unchanged and anincreasing ofl 1 is always accompanied by adecreasing ofS v and vice versa.
3.
In a previous paper, “strong” decrease properties of the truncated correlation functions, taking into account the separation of all particles with respect to each other, have been presented and discussed. In this paper, we prove these properties for finite range interactions in various situations, in particular
- at low activity for lattice and continuous systems,
- at arbitrary activity and high temperature for lattice systems,
- at ReH≠0, β arbitrary and atH=0 for appropriate temperatures in the case of ferromagnets.
4.
We study the consequences of the KMS-condition on the properties of quasi-particles, assuming their existence. We establish
- If the correlation functions decay sufficiently, we can create them by quasi-free field operators.
- The outgoing and incoming quasi-free fields coincide, there is no scattering.
- There are may age-operatorsT conjugate toH. For special forms of the dispersion law ε(k) of the quasi-particles there is aT commuting with the number of quasi-particles and its time-monotonicity describes how the quasi-particles travel to infinity.
5.
6.
Masato Tsujii 《Communications in Mathematical Physics》1996,177(1):1-11
Let us consider a family of mapsQ a (x)=ax(1?x) from the unit interval [0,1] to itself, wherea∈[0,4] is the parameter. We show that, for any β<2, there exists a subsetE?4 in [0,4] with the properties
- Leb([4??,4]?E) < ?β for sufficiently small ?>0,
- Q a admits an absolutely continuous BRS measure µa whena∈E, and
- µa converges to the measure µ4 asa tends to 4 on the setE. Also we give some generalization of this results.
7.
Bernard S. Kay 《Communications in Mathematical Physics》1978,62(1):55-70
We give mathematically rigorous results on the quantization of the covariant Klein Gordon field with an external stationary scalar interaction in a stationary curved space-time. We show how, following Segal, Weinless etc., the problem reduces to finding a “one particle structure” for the corresponding classical system. Our main result is an existence theorem for such a one-particle structure for a precisely specified class of stationary space-times. Byproducts of our approach are:
- A discussion of when a given “equal-time” surface in a given stationary space-time is Cauchy.
- A modification and extension of the methods of Chernoff [3] for proving the essential self-adjointness of certain partial differential operators.
8.
The positive sign of theη-nucleon scattering lengthb ηN was predicted in [1] assuming the resonance mechanism for theπ ?p → ηn reaction. We demonstrate that
- the assumption about thet-channel mechanism of the reaction leads tob ηN < 0 and
- the experimental data on theη production cross section are equally compatible with both resonance andt-channel mechanisms.
9.
R. Oppermann 《Zeitschrift für Physik B Condensed Matter》1983,49(4):273-287
The interplay of Coulomb interactions and disorder is formulated on the basis of local gauge invariant models withn orbitals per site. Universality classes of correlation-influenced metal insulator transitions are examined from the conducting region of an approximately semi-elliptical band. The microscopic 1/n expansion is brought into direct correspondence with the 1/(k F ?) expansion of Altshuler et al. Based on1. the assumption that theO(1/n)-expansion can be exponentiated and2. on the renormalization group β-function for finite length scaling, critical exponents are derived in leading order ofd-2 (d is dimensionality). The density of states-at-E F as the order parameter vanishes at the critical pointE c like \(\left| {E_F - E_c } \right|^{\beta _{MA} } \) with \(\beta _{MA} = \frac{1}{{4(d - 2)}}\) for the interacting real matrix (orthogonal) ensemble and \(\beta _{MA} = \frac{1}{{2(d - 2)}}\) for the unitary ensemble. If the bare Coulomb interactionU b (q)∝q 1-d is replaced by a general long range interactionV b (q)∝q ?x withx>0 ford=2, βMA depends on the “interaction range exponent”x like βMA(x) = xβMA(1). Also in leading order ofd?2, the conductivity exponent ist=1 for both models with or without time reversal invariance respectively. This implies a correlation-induced crossover fromt=1/2 for unitary Anderson localization (broken time reversal invariance) tot=1 at the Mott Anderson transition. 相似文献
10.
Stewart D. Johnson 《Communications in Mathematical Physics》1989,122(2):293-320
Families of unimodal maps satisfying
- T λ: [?1,1]?[?1,1] withT(±1)=?1 and |T λ ′ (1)|>1.
- T λ(x) isC 2 inx 2 and λ, and symmetric inx.
- T 0(0)=0,T 1(0)=1 with \(\frac{d}{{d\lambda }}\) T λ(0)>0
11.
The critical behaviour of the electromagnetically coupled superconductor magnet system is investigated by means of a generalized mean field theory and a renormalization group analysis. We show that in the presence of a genuine anisotropy in systems with an additional pressure-like parameter (like concentration in pseudo-ternary ferromagnetic superconductors (FMS), e.g. Er1?x Ho x Rh4B4) the indirect coupling between superconducting and magnetic order parameters (i.e. gauge coupling) can lead to a peculiar kind of critical behaviour characterized by Lifshitz points (LP). These points (quite generally) occur as merging points of three phases: a (magnetically) disordered phase, a homogeneously ordered phase and a modulated phase. In FMS the latter phase may result from exchange screening by supercurrents. This unusual critical behaviour is found in two varieties:
- a regular LP which may occur on the lower transition line of a reentrant FMS
- a similar but slightly different critical point which we term modified Lifshitz point (MLP), and which is to be expected at the merging point of the upper and lower superconducting transition lines with the magnetic order disorder transition lines in the (x, T) phase diagrams of FMS's.
12.
E. Boos I. Ginzburg K. Melnikov T. Sack S. Shichanin 《Zeitschrift fur Physik C Particles and Fields》1992,56(3):487-491
Three possibilities to observe the Higgs-top interation at future γγ-colliders are discussed:
- associated Higgs production via the \(\gamma \gamma \to t\bar tH\) reaction,
- Higgs obliged radiative correction to the \(\gamma \gamma \to t\bar t\) channel,
- Higgs resonance production via γγ→H→ZZ.
13.
A consistent theory describing the initial stage of spinodal decomposition of a two-component system is proposed. It is shown that the structure factor S(q, t) has two maxima as a function of wavenumber at this stage. The main maximum point q+ varies with time, first moving from qsaddle to qm (given by expressions (22) and (12), respectively) and then back after the turning point in time given by (26) is passed. The other maximum point is localized at q ≈ 0, and the corresponding peak amplitude is virtually independent of time. The characteristics of the main maximum are sensitive to the existence of the “zero” peak. Available experimental observations support the predictions of the theory. 相似文献
14.
《Solid State Communications》1987,63(4):303-305
We have shown by X-ray analysis and magnetic measurements, that the easy growth axis of Nd2Fe14B crystals corresponds to the “a” axis of the tetragonal structure while the easy magnetization axis is the “c” axis at temperatures above 135K. This correlation allows to understand some interesting features in NdFeB magnets:
- •-anisotropic contraction during sintering in magnets obtained by classical powder metallurgy,
- •-orientation mechanism during hot pressing (“die upset”) of magnets based on melt spun ribons.
15.
V. Yu. Klepikov 《Radiophysics and Quantum Electronics》1996,39(10):857-861
Analyzing statistically the magnetic and Doppler velocity data for 85 quiescent prominences observed in 1983–1987 by Nikolsky's magnetograph, we came to the following preliminary conclusions: The average longitudinal magnetic field of the prominence determines the dynamic velocity of the latter: the stronger magnetic fields correspond to the higher Doppler velocities. A longitudinal magnetic field less than 25 G allows the material to move with arbitrary velocity within the limits of several kilometers per second. A magnetic field higher than 25 G suppresses such movements. The horizontal length of the flux tube exceeds its vertical part by 1.5 orders of magnitude (the upper limit). There is an angle of 10°between the horizontal component of the velocity vector in quiescent prominences and the long axis of the filament. The maximum velocity in quiescent prominences is about 7 km/s. 相似文献
16.
G. Müller 《Zeitschrift für Physik B Condensed Matter》1987,68(2-3):149-159
The present study highlights some of the complexities observed in the dynamical properties of one-dimensional quantum spin systems. Exact results for zero-temperature dynamic correlation functions are presented for two contrasting situations:
- a system with a fully ordered ferromagnetic ground state;
- a system at aT c=0 critical point.
17.
Michael Henle 《Communications in Mathematical Physics》1970,19(4):273-275
Theorem. Let a topological groupG be represented (a→φ a ) by *-automorphisms of a von Neumann algebraR acting on a separable Hilbert spaceH. Suppose that
- G is locally compact and separable,
- R′ is properly infinite,
- for anyT∈R,x,y∈H the function
18.
The creation and propagation of jump discontinuities in the solutions of semilinear strictly hyperbolic systems is studied in the case where the initial data has a discrete set, {x i } i =1n , of jump discontinuities. LetS be the smallest closed set which satisfies:
- S is a union of forward characteristics.
- S contains all the forward characteristics from the points {x i } i =1n .
- if two forward characteristics inS intersect, then all forward characteristics from the point of intersection lie inS.
19.
We derive new inequalities for the plane rotator ferromagnetic model and use them to obtain the following results:
- If the model is isotropic, the derivability of the free energy as function of the magnetic fieldh implies the existence of a unique translation invariant Gibbs state and if furthermoreh=0 all Gibbs states are invariant by rotation of the spins.
- If the model is anisotropic the above assertion holds forh non-zero.
- If the model is anisotropic then there are at most two extremal translation invariant Gibbs states for almost all values of the anisotropy parameter.
20.
Notker Rösch 《Zeitschrift für Physik A Hadrons and Nuclei》1968,215(4):368-376
We use the molecular model of low energy fission, which describes the nucleus by two interacting fragments, to calculate the moment of inertia for U236 in the cranking approximation including BCS theory. We show that the moment of inertia at the saddle point:
- depends almost linearly on the fragment distance.
- is influenced only very weakly by the pairing constant and by the fragment deformations.
- shows, as a function of the distribution of mass between the two fragments (A 1 ,A 2 ), a minimum near the magic configurationA 1=132,Z 1=50 and depends in this mass region strongly on the term structure near the Fermi energy.
- is approximately that of a rigid body.