The dipole phase in the two-dimensional hierarchical Coulomb gas: Analyticity and correlations decay

We illustrate the mechanism producing the dipole phase in a two dimensional Coulomb system by a detailed analysis of a hierarchical model. We prove the analyticity of the pressure and of the correlations for ²e ²>8 (i.e. right above the usually conjectured value for the Kosterlitz-Thouless phase transition). We find also a power law decay for the correlations with exponent ²/2 as the hierarchical distance goes to infinity.Partially supported by Ministero della Pubblica Istruzione, Gruppo Nazionale per la Fisica Matematica del CNR and Grant A.F.O.S.R.-82-0016CPartially supported by Ministero della Pubblica Istruzione and Grant N.S.F. DMS 85-03333Partially supported by Ministera della Pubblica Istruzione     

Random fields on Riemannian manifolds: A constructive approach

We extend to Euclidean fields on a wide class of Riemannian manifolds two results which have proven to be crucial in the construction of interacting quantum fields in the flat case, namely local regularity properties of the free covariance in two dimensions and Osterwalder-Schrader positivity.Work supported in part by Ministero della Pubblica Istruzione     

A new procedure for thin-film deposition by solution spraying

The major reasons for the low photovoltaic efficiency of Cu₂S/CdS cells, in which the CdS film is deposited by spraying, are due to small film thicknesses which do not exceed 4 m and the small average grain size which ranges from 0.1 to 0.5 m.A new experimental solution spraying procedure is described that prevents both restrictions by controlling the substrate temperature. Average grain sizes of more than 1 m are obtained.Work supported by Ministere Pubblica Istruzione and Centro Regionale Ricerche Nucleari e di Struttura della Materia     

The evaluation map in field theory,sigma-models and strings I

The rôle of the evaluation map in anomaly calculations for field theory, sigma-models and strings is investigated. In this paper, anomalies in field theory (with and without a backgrounds connection), are obtained as pull-backs of suitable forms via evaluation maps. The cohomology of the group of gauge transformations is computed in terms of the cohomology of the base manifold and of the cohomology of the structure group. This allows us to clarify the different topological significance of gauge and gravitational anomalies. The relation between locality and universality is discussed and local cohomology is linked to the cohomology of classifying spaces. The problem of combining the locality requirement and the index theorem approach to anomalies is also examined. Anomaly cancellation in field theories derived from superstrings is analyzed and the relevant geometrical constraints are discussed.On leave of absence from Dipartimento di Fisica dell'Universitá di Padova and Istituto Nazionale di Fisica Nucleare, Sezione di PadovaWork supported in part by: Ministero Pubblica Istruzione (research project on Geometry and Physics)On leave of absence from Department of Mathematics, University of North Carolina, Chapel Hill, N.C. 27514. Work supported in part by N.S.F.     

The continuity equation and the Hamiltonian formalism in quantum mechanics

The relationship between the continuity equation and the HamiltonianH of a quantum system is investigated from a nonstandard point of view. In contrast to the usual approaches, the expression of the current densityJ is givenab initio by means of a transport-velocity operatorV _T, whose existence follows from a weak formulation of the correspondence principle. Once given a Hilbert-space metricM, it is shown that the equation of motion and the continuity equation actually represent a system in theunknown operatorsH andV _T, due to the arbitrariness on the initial condition of the quantum state. The general solution is given in some cases of special interest and a straightforward application to relativistic quantum mechanics is performed.This work was partially supported by the Ministero della Pubblica Istruzione.     

The mermin-wagner phenomenon and cluster properties of one- and two-dimensional systems

We give optimal conditions concerning the range of interactions for the absence of spontaneous breakdown of continuous symmetries for one- and two-dimensional quantum and classical lattice and continuum systems. For a class of models verifying infrared bounds our conditions are necessary and sufficient. Using the same techniques we obtain a priori bounds on clustering for systems with continuous symmetry, improving results of Jasnow and Fisher.Partially supported by CAPES-PICD.Partially supported by the CNP_q.Partially supported by N.S.F. under grant MCS 7801433.     

An iterated Mayer expansion for the Yukawa gas

We construct a convergent expansion for the Yukawa gas at small activity and inverse temperature < 4/e ².Research partially supported by Ministero della Pubblica Istruzione and CNR-GNFM.     

Some properties of topological geons

We investigate the Finkelstein-Misner geons for a non-simply-connected space-time manifold (M, g ₀). We use relations between different Lorentzian structures unequivalent tog ₀ and topological properties ofM given by the Morse theory. It implies that to some pieces of geons we have to associate Wheeler's worm-holes. Geons that correspond to time-orientable Lorentz structures are related tog ₀ by Morse functions that describe the attaching of a handle of index one. In the case of geons associated to time-nonorientable Lorentzian structures, appropriate handles are related to loops along which the notion of time reverses. If we assume electromagnetic properties of geons, then only four species, v, e, p, m, of different geons can exist and geon m has to decay according to mv+p+e.     

A novel preparation method and investigation of sprayed CdS films

The main reason for the low photovoltaic efficiency of Cu₂S/CdS cells, in which the CdS film is deposited by solution spraying, is the very small average dimensions of the crystalline grains. The difficulty in depositing films with transverse dimensions of crystalline grains larger than 1 m is due to the fast decrease of substrate temperature during the spraying deposition of the CdS film. We have since arranged an experimental set-up able to maintain the surface temperature of the substrate constant. In this way it is possible to control the parameters which affect the deposition and to obtain a high degree of reproducibility of morphological properties. Average grain sizes of more than 1 m are obtained. We have investigated the crystalline grain sizes and the film thickness as a function of the deposition temperature and the spraying rate.Work supported by Ministero Pubblica Istruzione and Centro Regionale Ricerche Nucleari e Struttura della materia     

Convergence of Chorin-Marsden product formula in the half-plane

Consider a viscous incompressible fluid in the half-plane and letu _t be a solution of the Navier-Stokes equation. In this paper we prove that the product formula (E _t/n G _t/n u) ⁿ u ₀, whereE _t is the Euler flow,G _t is the heat flow and is a suitable operator describing the vorticity production due to the boundary, converges uniformly tou _t in the limitn .Research supported by Ministero della Pubblica Istruzione, CNR contract No. 84.00016.02 and GNFM     

Attempt of an axiomatic foundation of quantum mechanics and more general theories VI

This contribution continues the series of papers [2, 4, 5, 12] treated by Ludwig and collaborators. It is based on the generalized frame given in [6]; there Ludwig has set up an infinite axiomatic scheme as extension of the finite system [4, 5]. The results of [12] are then proved for a locally finite case; they lead to an extended representation theorem.This paper was supported by the Deutsche Forschungsgemeinschaft.     

BRS cohomology and topological anomalies

The occurrence of non-abelian anomalies in gauge theories and gravitation, first discovered via perturbative techniques, is now completely explained from the mathematical point of view by means of the family index theorem of Atiyah and Singer. Here we make contact between this approach and BRS cohomology, by showing that they yield the same non-abelian anomalies, provided a certain restriction to local functionals is not introduced from the very beginning. In particular, this solves the unicity problem for this kind of anomalies. Local BRS cohomology is still relevant for the abelian case.Work partially supported by Gruppo Nazionale di Fisica Matematica del CNR and Progetto Nazionale Geometria e Fisica del MPI     

Evidence of Hg-chain formation in Hg x TiS2: a199mHg-TDPAC study

We determined the^199mHg nuclear quadrupole interaction in the misfit or superstoichiometric compound Hg _x TiS₂ by time differential perturbed angular correlation. A unique Hg-site withv _Q =511(1) MHz and =0.410(4) was observed, irrespective of the Hg-uptake (2/3x4/3). We propose a model of Hg-Hg zig-zag chains which accounts for these observations as well as for the X-ray diffraction data.     

Nuclear maps and modular structures II: Applications to quantum field theory

A correspondence between spectral properties of modular operators appearing in quantum field theory and the Hamiltonian is established. It allows to prove the distal split property for a wide class of models. Conversely, any model having this property is shown to satisfy the Haag-Swieca compactness criterion. The results lead to a new type of nuclearity condition which can be applied to quantum field theories on arbitrary space-time manifolds.Supported by the A. von Humboldt Stiftung, BonnSupported in part by Ministero della Pubblica Instruzione and CNR-GNAFA     

Generalized enveloping algebras and quantum kinematic coherent states of noncompact Lie groups

A new concept of generalized enveloping algebra is introduced by means of the generalized Heisenberg commutation relations of non-Abelian quantum kinematics. This concept is examined within the quantum-kinematic formalism of some noncompact Lie groups of a special kind. The well known Gel'fand theorem (which relates the center of the traditional enveloping algebra with the adjoint representation) is then extended to the generalized enveloping algebra of the group. In this way, the isomorphism of the generalized left-center and the traditional right-center of the corresponding enveloping algebras is proved within the left regular representation of noncompact Lie groups of the chosen kind. As an interesting application of generalized enveloping algebras, this paper contains a brief discussion of quantum-kinematic (boson) ladder operators for non-Abelian noncompact finite Lie groups and of their corresponding coherent states.     

Electromagnetic-gravitational energy systems

Two methods axe considered to tap the earths' rotational energy. This ancient collapsed gravitational energy exceeds the earth-lunar binding energy. One involves an orbiting electromagnetic-gravitational coupling system whereby the earth's rotation, with its nonuniform mass distribution, first uses gravity to add orbital energy to a satellite, similar to a planetary flyby.rd The second stage involves enhanced satellite drag as current-carrying coils withdraw the added orbital energy as they pass through the earth's nonuniform magnetic field. A second more direct method couples the earth's rotational motion using conducting wires moving through the noncorotating part (ionospheric current systems) of the geomagnetic field. These methods, although not immediately feasible, are considerably more efficient than using pure gravitational coupling to earth-moon tides.     

On a “structure intermediate between quasiperiodic and random”

This paper proves rigorously that the structure factor of the structure intermediate between quasiperiodic and random introduced by Aubry. Godréche, and Luck is purely singluar continuous apart from a delta function at zero for most choices of the parameters. The result is based on a proof that a flow under a steep function over an irrational circle rotation is weakly mixing for most parameters, and on the wonderland Theorem.     

Correlation functions for quasi-linear response theory

A quasi-linear regression formula is derived by an expansion around quasi-static equilibrium. It relates the relaxation of thermodynamic forces to the regression of correlations of thermodynamic coordinates in quasi-static equilibrium. Correlation functions and memory kernels can be introduced in almost complete analogy to linear response theory. A non-linear, non-Markovian kinetic equation is derived. The kinetic coefficients are given in terms of correlation functions of stochastic forces in quasi-static equilibrium similar to the linear theory.     

Stiff magnetic field lines. I. A geometrical foundation

It is shown that the foliation of a space-time manifold of codimension 2 provides a basis for the study of the deformation of magnetic field lines. It is found that the fluid flow vector and the curvature vector of a nongeodesic stiff magnetic field line are always orthogonal. Further, it is shown that the metric tensor of the 2-space orthogonal to the Maxwellian string is Lie-transported along the magnetic field lines when the magnetic field lines are stiff. If there exists a spacelike Killing vector field parallel to the magnetic field, then the magnetic field lines must be stiff.     

Reconstruction of abstract quantum theory

Understanding quantum theory as a general theory of prediction, we reconstruct abstract quantum theory. Abstract means the general frame of quantum theory, without reference to a three-dimensional position space, to concepts like particle or field, or to special laws of dynamics. Reconstruction is the attempt to do this by formulating simple and plausible postulates on prediction in order to derive the basic concepts of quantum theory from them. Thereby no law of classical physics is presupposed which would then have to be quantized. We briefly discuss the relationship of theory and interpretation in physics and the fundamental role of time as a basic concept for physics. Then a number ofassertions are given, formulated as succinctly as possible in order to make them easily quotable and comparable. The assertions are arranged in four groups: heuristic principles, verbal definitions of some terms, three basic postulates, and consequences. The three postulates of separable alternatives, indeterminism, and kinematics are the central points of this work. These brief assertions are commented upon, and their relationship with the interpretation of quantum theory is discussed. Also given are an outlook on the further development into concrete quantum theory and some philosophical reflections.