c=1 String as a Topological Model

The discrete states in the $c=1$ string are shown to be the physical states of a certain topological sigma model. We define a set of new fields directly from $c=1$ variables, in terms of which the BRST charge and energy-momentum tensor are rewritten as those of the topological sigma model. Remarkably, ground ring generator $x$ turns out to be a coordinate of the sigma model. All of the discrete states realize a graded ring which contains ground ring as a subset.Comment: 23 pages + 3 figures in PostScript, LaTeX, UT-Komaba/93-7. Description of the $c=1$ physical spectrum in terms of topological model is improved. Some references and new figures added. (figures are available upon request.

Four-quark final state in W-pair production: Case of signal and background

We discuss theoretical predictions for W-pair production and decay at LEP2 and higher energies in a form suitable for comparison with raw data. We present a practical framework for calculating uncertainties of predictions given by the KORALW and grc4f Monte Carlo programs. As an example we use observables in the $s\bar s c\bar c$ decay channel: the total four-quark (four-jet) cross section and two-quark/jet invariant-mass distribution and cross section, in the case when the other two may escape detection. Effects of QED bremsstrahlung, effective couplings, running W and Z widths, Coulomb interaction and the complete tree level set of diagrams are discussed. We also revisit the question of technical precision of the new version 1.21 of the KORALW Monte Carlo code as well as of version 1.2(26) of the grc4f one. Finally we find predictions of the two programs to have an overall physical uncertainty of 2%. As a side result we show, on the example of an $s\bar s$ invariant mass distribution, the strong interplay of spin correlations and detector cut-offs in the case of four-fermion final states.Comment: 26 pages, LaTe

How to construct a coordinate representation of a Hamiltonian operator on a torus

The dynamical system of a point particle constrained on a torus is quantized \`a la Dirac with two kinds of coordinate systems respectively; the Cartesian and toric coordinate systems. In the Cartesian coordinate system, it is difficult to express momentum operators in coordinate representation owing to the complication in structure of the commutation relations between canonical variables. In the toric coordinate system, the commutation relations have a simple form and their solutions in coordinate representation are easily obtained with, furthermore, two quantum Hamiltonians turning up. A problem comes out when the coordinate system is transformed, after quantization, from the Cartesian to the toric coordinate system.Comment: 17 pages, LaTeX, 1 Figure included as a compressed uuencoded postscript fil

Electromagnetic Form Factors of Nucleons with QCD Constraints Sytematic Study of the Space and Time-like Regions

Elastic electromagnetic form factors of nucleons are investigated both for the time-like and the space-like momentums under the condition that the QCD constraints are satisfied asymptotically. The unsubtracted dispersion relation with the superconvergence conditions are used as a realization of the QCD conditions. The experimental data are analyzed by using the dispersion formula and it is shown that the calculated form factors reproduce the experimental data reasonably well.Comment: 14 page

Diagnóstico de doenças de peixes no laboratório de piscicultura.

bitstream/item/50984/1/Diagnostico-de-doencas-de-p..pdfSIDE 021/10 - Portal Dia de Campo, 18 maio 2010; SIDE 021/10A - Douradosnews, 12 jun. 2010; SIDE 021/10B - Jornal Correio do Estado: Opinião, 17 maio 2010; SIDE 021/10C - Portal do Agronegócio, 13 maio 2010; SIDE 021/10D - Guia da Pesca, 12 maio 2010

Polarization observables in dp backward elastic scattering at high and intermediate energies

The tensor analyzing power $T_{20}$ and the polarization transfer coefficients $\kappa_0 (= 3/2 K_y^y)$ and $K_{xz}^y$ are investigated for dp backward elastic scattering by the invariant-amplitude method. Discrepancies between the conventional calculations and the experimental data on $T_{20}$ and $\kappa_0$ at high and intermediate energies are mostly dissolved by including imaginary parts in the amplitudes. The quantity $K_{xz}^y$ is shown to be useful in criticizing nuclear force assumptions.Comment: 10 pages, LaTeX, 3 Postscript figure

The square-lattice spiral magnet Ba_2CuGe_2O_7 in an in-plane magnetic field

The magnetic structure of Ba_2CuGe_2O_7 is investigated by neutron diffraction in magnetic fields applied along several directions in the $(a,b)$ plane of the crystal. In relatively weak fields, $H\lesssim 0.5$~T, the propagation vector of the spin-spiral rotates to form a finite angle with the field direction. This angle depends on the orientation of $H$ itself. The rotation of the propagation vector is accompanied by a re-orientation of the plane of spin rotation in the spiral. The observed behaviour is well described by a continuous-limit form of a free energy functional that includes exchange and Dzyaloshinskii-Moriya interactions, as well as the Zeeman energy and an empirical anisotropy term.Comment: 7 pages, 6 figure