Electrically and Magnetically Charged States and Particles in the 2+1-Dimensional Z_N-Higgs Gauge Model

Electrically as well as magnetically charged states are constructed in the 2+1-dimensional Euclidean Z_N-Higgs lattice gauge model, the former following ideas of Fredenhagen and Marcu and the latter using duality transformations on the algebra of observables. The existence of electrically and of magnetically charged particles is also established. With this work we prepare the ground for the constructive study of anyonic statistics of multiparticle scattering states of electrically and magnetically charged particles in this model (work in progress).Comment: 57 pages, Sfb 288 Preprint No. 109. To appear in Commun. Math. Phys. About the file: This is a uuencoded, "gzip-ed" postscript file. It is about 300kB large. The original ps file is about 700kB large. All figures are included. The LaTeX sources ou even hard copies can be required to the authors at [email protected] or Freie Universitaet Berlin. Institut fuer Theoretische Physik. Arnimallee 14. Berlin 14195 German

Localizability in de Sitter space

An analogue of the Newton-Wigner position operator is defined for a massive neutral scalar field in de Sitter space. The one-particle subspace of the theory, consisting of positive-energy solutions of the Klein-Gordon equation selected by the Hadamard condition, is identified with an irreducible representation of de Sitter group. Postulates of localizability analogous to those written by Wightman for fields in Minkowski space are formulated on it, and a unique solution is shown to exist. A simple expression for the time-evolution of the operator is presented.Comment: Presentation improved; references adde

Radical Fluoroalkylation Reactions

Recent protocols and reactions for catalytic radical perfluoroalkylations will be described. The production of perfluoroalkyl radicals (RF = CnF2n+1, n ≥ 2), which effect both addition and substitution reactions on organic substrates, can be realized through a range of diverse methods such as the well-established visible-light transition-metal-mediated photocatalysis, organic-dye-photocatalyzed reactions, electron donor-acceptor complexes, and more recently frustrated Lewis pairs. Thus, perfluoroalkylation reactions of carbon-carbon multiple bonds, isocyanides, nitrones, hydrazones, β-keto esters, α-cyano arylacetates, sulfides, and (hetero)arenes will be described. Special emphasis will be placed on examples published after 2015, where higher fluorinated series of fluoroalkylating reagents are studied.Fil: Barata Vallejo, Sebastian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cooke, María Victoria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Postigo, A.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentin

The Two-Point Function and the Effective Magnetic Field in Diluted Ising Models on the Cayley Tree

Some results on the two-point function and on the analytic structure of the momenta of the effective fugacity at the origin for a class of diluted ferromagnetic Ising models on the Cayley tree are presented.Comment: 22 page

Aspects of Two-Level Systems under External Time Dependent Fields

The dynamics of two-level systems in time-dependent backgrounds is under consideration. We present some new exact solutions in special backgrounds decaying in time. On the other hand, following ideas of Feynman, Vernon and Hellwarth, we discuss in detail the possibility to reduce the quantum dynamics to a classical Hamiltonian system. This, in particular, opens the possibility to directly apply powerful methods of classical mechanics (e.g. KAM methods) to study the quantum system. Following such an approach, we draw conclusions of relevance for ``quantum chaos'' when the external background is periodic or quasi-periodic in time.Comment: To appear in J. Phys. A. Mathematical and Genera

Multiple classical limits in relativistic and nonrelativistic quantum mechanics

The existence of a classical limit describing interacting particles in a second-quantized theory of identical particles with bosonic symmetry is proved. This limit exists in addition to a previously established classical limit with a classical field behavior, showing that the limit $\hbar \to 0$ of the theory is not unique. An analogous result is valid for a free massive scalar field: two distinct classical limits are proved to exist, describing a system of particles or a classical field. The introduction of local operators in order to represent kinematical properties of interest is shown to break the permutation symmetry under some localizability conditions, allowing the study of individual particle properties.Comment: 13 page