1,950,587 research outputs found
The Anisotropic Two-Point Correlation Functions of the Nonlinear Traceless Tidal Field in the Principal-Axis Frame
Galaxies on the largest scales of the Universe are observed to be embedded in
the filamentary cosmic web which is shaped by the nonlinear tidal field. As an
efficient tool to quantitatively describe the statistics of this cosmic web, we
present the anisotropic two-point correlation functions of the nonlinear
traceless tidal field in the principal-axis frame, which are measured using
numerical data from an N-body simulation. We show that both of the nonlinear
density and traceless tidal fields are more strongly correlated along the
directions perpendicular to the eigenvectors associated with the largest
eigenvalues of the local tidal field. The correlation length scale of the
traceless tidal field is found to be ~20 Mpc/h, which is much larger than that
of the density field ~5 Mpc/h. We also provide analytic fitting formulae for
the anisotropic correlation functions of the traceless tidal field, which turn
out to be in excellent agreement with the numerical results. We expect that our
numerical results and analytic formula are useful to disentangle cosmological
information from the filamentary network of the large-scale structures.Comment: ApJ in press, accepted version, minor changes, discussion improve
Massless Monopoles and Multipronged Strings
We investigate the role of massless magnetic monopoles in the N=4
supersymmetric Yang-Mills Higgs theories. They can appear naturally in the
1/4-BPS dyonic configurations associated with multi-pronged string
configurations. Massless magnetic monopoles can carry nonabelian electric
charge when their associated gauge symmetry is unbroken. Surprisingly, massless
monopoles can also appear even when the gauge symmetry is broken to abelian
subgroups.Comment: 10 pages, LaTex file, more comments added. (To appear in Phys. Lett.
B
Regge Closed String Scattering and its Implication on Fixed angle Closed String Scattering
We calculate the complete closed string high energy scattering amplitudes
(HSA) in the Regge regime for arbitrary mass levels. As an application, we
deduce the complete ratios among closed string HSA in the fixed angle regime by
using Stirling number identities. These results are in contrast with the
incomplete set of closed string HSA in the fixed angle regime calculated
previously. The complete forms of the fixed angle amplitudes, and hence the
ratios, were not calculable previously without the input of zero-norm state
calculation. This is mainly due to the lack of saddle point in the fixed angle
closed string calculation.Comment: 10 pages. v2: typos correcte
Chart-driven Connectionist Categorial Parsing of Spoken Korean
While most of the speech and natural language systems which were developed
for English and other Indo-European languages neglect the morphological
processing and integrate speech and natural language at the word level, for the
agglutinative languages such as Korean and Japanese, the morphological
processing plays a major role in the language processing since these languages
have very complex morphological phenomena and relatively simple syntactic
functionality. Obviously degenerated morphological processing limits the usable
vocabulary size for the system and word-level dictionary results in exponential
explosion in the number of dictionary entries. For the agglutinative languages,
we need sub-word level integration which leaves rooms for general morphological
processing. In this paper, we developed a phoneme-level integration model of
speech and linguistic processings through general morphological analysis for
agglutinative languages and a efficient parsing scheme for that integration.
Korean is modeled lexically based on the categorial grammar formalism with
unordered argument and suppressed category extensions, and chart-driven
connectionist parsing method is introduced.Comment: 6 pages, Postscript file, Proceedings of ICCPOL'9
On the Intrinsic Alignments of the Late-Type Spiral Galaxies from the Sloan Digital Sky Survey Data Release 7
A robust detection of the tidally induced intrinsic alignments of the
late-type spiral galaxies with high statistical significance is reported. From
the spectroscopic galaxy sample of SDSS DR7 compiled by Huertas-Company et al.
which lists each galaxy's probabilities of being in five Hubble types,
P(E),P(Ell), P(S0),P(Sab), P(Scd), we select the nearby large late-type spiral
galaxies which have redshifts of 0=0.5 and
angular sizes of D>=7.92 arcsec. The spin axes of the selected nearby large
late-type spiral galaxies are determined up to the two-fold ambiguity with the
help of the circular thin-disk approximation and their spatial correlations are
measured as a function of the separation distance r. A clear signal of the
intrinsic correlation as high as 3.4 sigma and 2.4 sigma is found at the
separation distance of r~1Mpc/h and r~2Mpc/h, respectively. The comparison of
this observational results with the analytic model based on the tidal torque
theory reveals that the spin correlation function for the late-type spiral
galaxies follow the quadratic scaling of the linear density correlation and
that the intrinsic correlations of the galaxy spin axes are stronger than that
of the underlying dark halos. We investigate a local density dependence of the
galaxy spin correlations and found that the correlations are stronger for the
galaxies located in dense regions having more than 10 neighbors within 2Mpc/h.
We also attempt to measure a luminosity dependence of the galaxy spin
correlations, but find that it is impossible with our magnitude-split samples
to disentangle a luminosity from a redshift dependence. We provide the physical
explanations for these observational results and also discuss the effects of
possible residual systematics on the results.Comment: Accepted for publication in ApJ, revised version, The angular size
cut on the late-type spiral galaxies is additionally applied, the quadractic
scaling with the linear density field is found to work better when the
angular size cut is applied. Those galaxies located in denser regions are
found to be strongly correlate
Stringy Symmetries and Their High-energy Limits
We derive stringy symmetries with conserved charges of arbitrarily high spins
from the decoupling of two types of zero-norm states in the old covariant first
quantized (OCFQ) spectrum of open bosonic string. These symmetries are valid to
all energy and all loop orders in string perturbation theory. The high-energy
limit of these stringy symmetries can then be used to fix the proportionality
constants between scattering amplitudes of different string states
algebraically without referring to Gross and Mende's saddle point calculation
of high-energy string-loop amplitudes. These proportionality constants are, as
conjectured by Gross, independent of the scattering angle and the order of
string perturbation theory. However, we also discover some new nonzero
components of high-energy amplitudes not found previously by Gross and Manes.
These components are essential to preserve massive gauge invariances or
decouple massive zero-norm states of string theory. A set of massive scattering
amplitudes and their high energy limit are calculated explicitly to justify our
results.Comment: 10 pages. A corrected version of hep-th/0303012. Final version to
appear in Phys. Lett.
Surface r Modes and Burst Oscillations of Neutron Stars
We study the -modes propagating in steadily mass accreting, nuclear
burning, and geometrically thin envelopes on the surface of rotating neutron
stars. For the modal analysis, we construct the envelope models which are fully
radiaitive or have a convective region. As the angular rotation frequency
is increased, the oscillation frequency of the -modes in
the thin envelopes deviates appreciably from the asymptotic frequency
defined in the limit of ,
where is the frequency observed in the corotating frame of the star,
and and are the indices of the spherical harmonic function
representing the angular dependence of the modes. We find that
the fundamental -modes in the convective models are destabilized by strong
nuclear burning in the convective region. Because of excessive heating by
nuclear buring, the corotating-frame oscillation frequency of the
-modes in the convective models becomes larger, and hence the inertial-frame
oscillation frequency becomes smaller, than those of the
corresopnding -modes in the radiative models, where
is negative for the -modes of positive . We find that the relative
frequency change is always
positive and becomes less than 0.01 for the fundamental -modes of
at 300Hz for or at
600Hz for , where and
denote the oscillation frequencies for the convective and the
radiative envelope models, respectively.Comment: 20 pages, 12 figure
Spherical gauge fields
We introduce the spherical field formalism for free gauge fields. We discuss
the structure of the spherical Hamiltonian for both general covariant gauge and
radial gauge and point out several new features not present in the scalar field
case. We then use the evolution equations to compute gauge-field and
field-strength correlators
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