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1.
It is demonstrated that a closed symmetric derivation δ of aC?-algebra \(\mathfrak{A}\) generates a strongly continuous one-parameter group of automorphisms of aC?-algebra \(\mathfrak{A}\) if and only if, it satisfies one of the following three conditions
- (αδ+1)(D(δ))= \(\mathfrak{A}\) , α∈?\{0}.
- δ possesses a dense set of analytic elements.
- δ possesses a dense set of geometric elements.
- ∥(αδ+1)(A)∥≧∥A∥, α∈IR,A∈D(δ).
- If α∈IR andA∈D(δ) then (αδ+1)(A)≧0 impliesA≧0.
2.
J. Ginibre 《Communications in Mathematical Physics》1969,14(3):205-234
We prove that the following lattice systems:
- anisotropic Heisenberg model,
- Ising model with transverse magnetic field,
- quantum lattice gas with hard cores extending over nearest neighbours,
3.
J. Halbritter 《Applied Physics A: Materials Science & Processing》1986,39(1):49-57
Broad-area electrodes show electron emission already at electric field strengthsF≈107 V/m. This enhanced field emission (EFE) occurs only for contaminated surfaces. EFE is accompanied by photon emission and gas desorption yielding finally discharges. EFE is caused by dust and contaminants initiating the following effects: an electron is stochastically emitted in a trigger zone the electron gains energyΔE?eΔxF * which excites electronic states which relax by the emission of electrons, photons, and atoms where the positive charges left behind enhanceF *=βF (β?1) initiating so an electron avalanche, i.e., a high conductivity channel. Because of charge migration and neutralization, this avalanche has a life time. This pulsating EFE is accompanied by light emission and gas desorption yielding finally a gas cloud and a discharge. The pulsating, self-sustained EFE has the same root as: the enhanced secondary emission found first by Malter the conductivity switching exhibited by thin (≈ 1 μm) layers of semiconductors or insulators the normal cathode fall and the firing-wave instability in neurodynamics. 相似文献
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.
Massimo Campanino Abel Klein J. Fernando Perez 《Communications in Mathematical Physics》1991,135(3):499-515
We study the zero-temperature behavior of the Ising model in the presence of a random transverse field. The Hamiltonian is given by $$H = - J\sum\limits_{\left\langle {x,y} \right\rangle } {\sigma _3 (x)\sigma _3 (y) - \sum\limits_x {h(x)\sigma _1 (x)} } $$ whereJ>0,x,y∈Z d, σ1, σ3 are the usual Pauli spin 1/2 matrices, andh={h(x),x∈Z d} are independent identically distributed random variables. We consider the ground state correlation function 〈σ3(x)σ3(y)〉 and prove:
- Letd be arbitrary. For anym>0 andJ sufficiently small we have, for almost every choice of the random transverse fieldh and everyx∈Z d, that $$\left\langle {\sigma _3 (x)\sigma _3 (y)} \right\rangle \leqq C_{x,h} e^{ - m\left| {x - y} \right|} $$ for ally∈Z d withC x h <∞.
- Letd≧2. IfJ is sufficiently large, then, for almost every choice of the random transverse fieldh, the model exhibits long range order, i.e., $$\mathop {\overline {\lim } }\limits_{\left| y \right| \to \infty } \left\langle {\sigma _3 (x)\sigma _3 (y)} \right\rangle > 0$$ for anyx∈Z d.
6.
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.
7.
Inequalities on eigenvalues of the Schrödinger operator are re-examined in the case of spherically symmetric potentials. In particular, we obtain:
- A connection between the moments of order (n ? 1)/2 of the eigenvalues of a one-dimensional problem and the total number of bound statesN n, inn space dimensions;
- optimal bounds on the total number of bound states below a given energy in one dimension;
- alower bound onN 2;
- a self-contained proof of the inequality for α ≧ 0,n ≧ 3, leading to the optimalC 04,C 3;
- solutions of non-linear variation equations which lead, forn ≧ 7, to counter examples to the conjecture thatC 0n is given either by the one-bound state case or by the classic limit; at the same time a conjecture on the nodal structure of the wave functions is disproved.
8.
We consider a two-dimensional Ising ferromagnet with (+) boundary conditions and negative external field, where a Markovian time evolution is assumed. We construct, suitably restricting the allowed configurations att=0, a non equilibrium state with positive magnetization such that:
- only one phase is present,
- the relaxation time for unit volume is finite and can be made very large.
9.
E. Mourre 《Communications in Mathematical Physics》1981,78(3):391-408
We give a sufficient condition for a self-adjoint operator to have the following properties in a neighborhood of a pointE of its spectrum:
- its point spectrum is finite;
- its singular continuous spectrum is empty;
- its resolvent satisfies a class of a priori estimates.
10.
P. Steiner V. Kinsinger I. Sander B. Siegwart S. Hüfner C. Politis 《Zeitschrift für Physik B Condensed Matter》1987,67(1):19-23
XPS and UPS photoemission experiments on the highT c superconductors (T c ≈90 K) with nominal composition YBa2Cu3O9-y (y≈2) show the following:
- The density of electronic states at the Fermi energy is very small, much smaller than in pure Cu.
- The Cu 2p spectra show only a Cu2+ contribution.
- The Ba core levels show a structure with two components of nearly equal magnitude, which leads to the suggestion that these compounds have large O2? vacancies coordinated to Ba2+ sites.
- Annealing at 400°C under UHV conditions leads possibly to a partial reduction of Cu2+ to lower Cu valence states and to a small increase of the O2? vacancy component of the Ba2+ line.
11.
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.
12.
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.
13.
Stefano Moretti 《Zeitschrift fur Physik C Particles and Fields》1997,73(4):653-667
The complete matrix element for e + e? → bb?W+ W? is computed at tree-level within the Minimal Supersymmetric Standard Model. Rates of interest to phenomenological analyses at the Next Linear Collider are given. In particular, we study:
- ? tt? production and decay tt? →(bW +)(b?W ?)
- ? ZH production followed by Z → bb? and H → W + W?
- ? AH production followed by A→ bb? and H → W + W?
- ? hW + W? production followed by h→ bb?.
14.
J. C. M. Henning J. H. den Boef 《Applied Physics A: Materials Science & Processing》1978,16(4):353-357
A novel method for measuring magnetostriction constants is presented. A strain, periodic in time, applied to the sample, causes a modulation of the ferromagnetic resonance line position. The height of the signal obtained after phase-sensitive detection is proportional to the strain modulation depth. The appropriate magnetostriction constant λ is obtained by comparing the height of the SMFMR signal with that of the FMR line, as recorded by means of magnetic field modulation. Features of the new technique are:
- high sensitivity: λmin? 10?9 forM=100 Oe and linewidth ΔH d=1 Oe;
- λ's belonging to distinct precession modes are separately determined;
- applicable to thin layers for which strain gauge techniques cannot be used;
- wide temperature range: 1.2 K<T<300 K;
- uniform stress.
15.
Theq states Potts model exhibits a first order phase transition at some inverse temperature β t between “ordered” and “disordered” phases forq large as proved in [1]. In space dimension 2 we use theduality transformation as aninternal symmetry of the partition function at β t to derive an estimate on the probability of a contour. This enables us to prove the preceding result and the following new results:
- The discontinuity of the mass gap at β t .
- The existence of astrictly positive surface tension between two ordered phases up to β t .
- The existence of a non-zero surface tension between an “ordered” and the “disordered” phase at β t .
16.
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
17.
Noboru Nakanishi 《Letters in Mathematical Physics》1977,1(5):361-366
The following new findings are briefly reported:
- A consistent quantum theory can be formulated for a free massless scalar field in two-dimensional spacetime.
- Satisfactory operator solutions in terms of asymptotic fields can be constructed in the Thirring and Schwinger models.
- Gauge invariance is spontaneously broken in the Thirring model as well as in the Schwinger model.
18.
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.
19.
Francesco Pegoraro 《Communications in Mathematical Physics》1975,42(1):41-63
We consider a theorem due to Michel [1] which relates the invariance properties in peculiar directions in a linear space on which we represent a Lie groupG to the extremal points of an arbitrary smoothG-invariant function. The group we are interested in isSO(4) and we apply the mathematical results to the following problems:
- mixed linear Stark Zeeman effect in a hydrogen atom,
- perturbation of a finite Robertson-Walker metric,
- gas evolutions preserving angular momentum and vorticity.
20.
It is shown that
- an appreciable change of magnetic moment of a neutron star cannot occur via ohmic dissipation
- pulsars provide evidence for large internal magnetic fields in main sequence stars. If pulsars are born from stars with masses exceeding 3 ?⊙ the internal field must be of the order of 103-104 Gauss while if they derived from less massive urstars 102 Gauss are sufficient to give rise to a magnetic moment ofM~1030 Gauss cm3.