9,185 research outputs found

### Structure and diffusion time scales of disordered clusters

The eigenvalue spectra of the transition probability matrix for random walks
traversing critically disordered clusters in three different types of
percolation problems show that the random walker sees a developing Euclidean
signature for short time scales as the local, full-coordination constraint is
iteratively applied.Comment: 5 pages, 4 figures, submitted to Physics Letters

### Exact Solutions to the Two-dimensional BF and Yang-Mills Theories in the Light-cone Gauge

It is shown that the BRS-formulated two-dimensional BF theory in the
light-cone gauge (coupled with chiral Dirac fields) is solved very easily in
the Heisenberg picture. The structure of the exact solution is very similar to
that of the BRS-formulated two-dimensional quantum gravity in the conformal
gauge. In particular, the BRS Noether charge has anomaly. Based on this fact, a
criticism is made on the reasoning of Kato and Ogawa, who derived the critical
dimension D=26 of string theory on the basis of the anomaly of the BRS Noether
charge. By adding the $\widetilde{B}^2$ term to the BF-theory Lagrangian
density, the exact solution to the two-dimensional Yang-Mills theory is also
obtained.Comment: 11 pages, LaTe

### Diffusion and spectral dimension on Eden tree

We calculate the eigenspectrum of random walks on the Eden tree in two and
three dimensions. From this, we calculate the spectral dimension $d_s$ and the
walk dimension $d_w$ and test the scaling relation $d_s = 2d_f/d_w$ ($=2d/d_w$
for an Eden tree). Finite-size induced crossovers are observed, whereby the
system crosses over from a short-time regime where this relation is violated
(particularly in two dimensions) to a long-time regime where the behavior
appears to be complicated and dependent on dimension even qualitatively.Comment: 11 pages, Plain TeX with J-Phys.sty style, HLRZ 93/9

### The Dog on the Ship: The "Canis Major Dwarf Galaxy" as an Outlying Part of the Argo Star System

Overdensities in the distribution of low latitude, 2MASS giant stars are
revealed by systematically peeling away from sky maps the bulk of the giant
stars conforming to ``isotropic'' density laws generally accounting for known
Milky Way components. This procedure, combined with a higher resolution
treatment of the sky density of both giants and dust allows us to probe to
lower Galactic latitudes than previous 2MASS giant star studies. While the
results show the swath of excess giants previously associated with the
Monoceros ring system in the second and third Galactic quadrants at distances
of 6-20 kpc, we also find a several times larger overdensity of giants in the
same distance range concentrated in the direction of the ancient constellation
Argo. Isodensity contours of the large structure suggest that it is highly
elongated and inclined by about 3 deg to the disk, although details of the
structure -- including the actual location of highest density, overall extent,
true shape -- and its origin, remain unknown because only a fraction of it lies
outside highly dust-obscured, low latitude regions. Nevertheless, our results
suggest that the 2MASS M giant overdensity previously claimed to represent the
core of a dwarf galaxy in Canis Major (l ~ 240 deg) is an artifact of a dust
extinction window opening to the overall density rise to the more significant
Argo structure centered at larger longitude (l ~ 290 +- 10 deg, b ~ -4 +- 2
deg).Comment: 4 pages, 4 figure

### Geometry of fully coordinated, two-dimensional percolation

We study the geometry of the critical clusters in fully coordinated
percolation on the square lattice. By Monte Carlo simulations (static
exponents) and normal mode analysis (dynamic exponents), we find that this
problem is in the same universality class with ordinary percolation statically
but not so dynamically. We show that there are large differences in the number
and distribution of the interior sites between the two problems which may
account for the different dynamic nature.Comment: ReVTeX, 5 pages, 6 figure

### The Virgo High-Resolution CO Survey. II. Rotation Curves and Dynamical Mass Distributions

Based on a high-resolution CO survey of Virgo spirals with the Nobeyama
Millimeter-wave Array, we determined the dynamical centers using velocity
fields, and derived position-velocity diagrams (PVDs) along the major axes of
the galaxies across their dynamical centers. We applied a new iteration method
to derive rotation curves (RCs), which reproduce the observed PVDs. The
obtained high-accuracy RCs generally show steep rise in the central 100 to 200
pc regions, followed by flat rotation in the disk. We applied a deconvolution
method to calculate the surface-mass density (SMD) using the RCs based on two
extreme assumptions that the mass distribution is either spherical or thin-disk
shaped. Both assumptions give nearly identical results, agreeing with each
other within a factor of two at any radii. The SMD distributions revealed
central massive cores with peak SMD of 10^4 - 10^5 Msun pc^-2 and total mass
within 200 pc radius of the order of about 10^9 Msun Correlation analysis among
the derived parameters show that the central CO-line intensity is positively
correlated with the central SMD, which suggests that the deeper is the
gravitational potential, the higher is the molecular gas concentration in the
nuclei regardless morphological types.Comment: PASJ 2003 in press, Latex 12 pages, 6 figures (Bigger gif/ps figures
available at http://www.ioa.s.u-tokyo.ac.jp/radio/virgo2

### There are no abnormal solutions of the Bethe$-$Salpeter equation in the static model

The four-point Green's function of static QED, where a fermion and an
antifermion are located at fixed space positions, is calculated in covariant
gauges. The bound state spectrum does not display any abnormal state
corresponding to excitations of the relative time. The equation that was
established by Mugibayashi in this model and which has abnormal solutions does
not coincide with the Bethe$-$Salpeter equation. Gauge transformation from the
Coulomb gauge also confirms the absence of abnormal solutions in the
Bethe$-$Salpeter equation.Comment: 11 pages, late

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