13,171 research outputs found
Lattice calculations on the spectrum of Dirac and Dirac-K\"ahler operators
We present a matrix technique to obtain the spectrum and the analytical index
of some elliptic operators defined on compact Riemannian manifolds. The method
uses matrix representations of the derivative which yield exact values for the
derivative of a trigonometric polynomial. These matrices can be used to find
the exact spectrum of an elliptic operator in particular cases and in general,
to give insight into the properties of the solution of the spectral problem. As
examples, the analytical index and the eigenvalues of the Dirac operator on the
torus and on the sphere are obtained and as an application of this technique,
the spectrum of the Dirac-Kahler operator on the sphere is explored.Comment: 11 page
Large Scale Morphological Segregation in Optically Selected Galaxy Redshift Catalogs
We present the results of an exhaustive analysis of the morphological
segregation of galaxies in the CfA and SSRS catalogs through the scaling
formalism. Morphological segregation between ellipticals and spirals has been
detected at scales up to 15-20 h Mpc in the CfA catalog, and up to 20-30
h Mpc in the SSRS catalog. Moreover, it is present not only in the
densest areas of the galaxy distribution, but also in zones of moderate
density.Comment: 9 pages, (1 figure included), uuencode compressed Postscript,
(accepted for publication in ApJ Letters), FTUAM-93-2
The Volume Source Technique for flavor singlets: a second look
We reconsider the Volume Source Technique (VST) for the determination of
flavor singlet quantities on the lattice. We point out a difficulty arising in
the case of fermions in real representations of the gauge group and propose an
improved version of the method (IVST) based on random gauge transformations of
the background configuration. We compare the performance of IVST with the
method based on stochastic estimators (SET). We consider the case of the N=1
Supersymmetric Yang-Mills Theory (SYM), where just one fermionic flavor is
present, the gluino in the adjoint representation, and only flavor singlet
states are possible. The work is part of an inclusive analysis of the spectrum
of the lightest particles of the theory, based on the simulation of the model
on a lattice with dynamical gluinos in the Wilson scheme.Comment: 11 pages, 6 figures, some formulations change
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