14,485 research outputs found
An analysis of the noise reduction of orthotropic cylindrical shells Final report
Statistical energy and classical methods for calculating noise reduction of orthotropic cylindrical shell
Non-perturbative calculations for the effective potential of the symmetric and non-Hermitian field theoretic model
We investigate the effective potential of the symmetric
field theory, perturbatively as well as non-perturbatively. For the
perturbative calculations, we first use normal ordering to obtain the first
order effective potential from which the predicted vacuum condensate vanishes
exponentially as in agreement with previous calculations. For the
higher orders, we employed the invariance of the bare parameters under the
change of the mass scale to fix the transformed form totally equivalent to
the original theory. The form so obtained up to is new and shows that all
the 1PI amplitudes are perurbative for both and regions. For
the intermediate region, we modified the fractal self-similar resummation
method to have a unique resummation formula for all values. This unique
formula is necessary because the effective potential is the generating
functional for all the 1PI amplitudes which can be obtained via and thus we can obtain an analytic calculation for the 1PI
amplitudes. Again, the resummed from of the effective potential is new and
interpolates the effective potential between the perturbative regions.
Moreover, the resummed effective potential agrees in spirit of previous
calculation concerning bound states.Comment: 20 page
Spatially resolved spectroscopy of Coma cluster early-type galaxies IV. Completing the dataset
The long-slit spectra obtained along the minor axis, offset major axis and
diagonal axis are presented for 12 E and S0 galaxies of the Coma cluster drawn
from a magnitude-limited sample studied before. The rotation curves, velocity
dispersion profiles and the H_3 and H_4 coefficients of the Hermite
decomposition of the line of sight velocity distribution are derived. The
radial profiles of the Hbeta, Mg, and Fe line strength indices are measured
too. In addition, the surface photometry of the central regions of a subsample
of 4 galaxies recently obtained with Hubble Space Telescope is presented. The
data will be used to construct dynamical models of the galaxies and study their
stellar populations.Comment: 40 pages, 7 figures, 6 tables. Accepted for publication in ApJ
Nonlinear Integral-Equation Formulation of Orthogonal Polynomials
The nonlinear integral equation P(x)=\int_alpha^beta dy w(y) P(y) P(x+y) is
investigated. It is shown that for a given function w(x) the equation admits an
infinite set of polynomial solutions P(x). For polynomial solutions, this
nonlinear integral equation reduces to a finite set of coupled linear algebraic
equations for the coefficients of the polynomials. Interestingly, the set of
polynomial solutions is orthogonal with respect to the measure x w(x). The
nonlinear integral equation can be used to specify all orthogonal polynomials
in a simple and compact way. This integral equation provides a natural vehicle
for extending the theory of orthogonal polynomials into the complex domain.
Generalizations of the integral equation are discussed.Comment: 7 pages, result generalized to include integration in the complex
domai
On the eigenproblems of PT-symmetric oscillators
We consider the non-Hermitian Hamiltonian H=
-\frac{d^2}{dx^2}+P(x^2)-(ix)^{2n+1} on the real line, where P(x) is a
polynomial of degree at most n \geq 1 with all nonnegative real coefficients
(possibly P\equiv 0). It is proved that the eigenvalues \lambda must be in the
sector | arg \lambda | \leq \frac{\pi}{2n+3}. Also for the case
H=-\frac{d^2}{dx^2}-(ix)^3, we establish a zero-free region of the
eigenfunction u and its derivative u^\prime and we find some other interesting
properties of eigenfunctions.Comment: 21pages, 9 figure
Asymptotic Analysis of the Boltzmann Equation for Dark Matter Relics in the presence of a Running Dilaton and Space-Time Defects
The interplay of dilatonic effects in dilaton cosmology and stochastic
quantum space-time defects within the framework of string/brane cosmologies is
examined. The Boltzmann equation describes the physics of thermal
dark-matter-relic abundances in the presence of rolling dilatons. These
dilatons affect the coupling of stringy matter to D-particle defects, which are
generic in string theory. This coupling leads to an additional source term in
the Boltzmann equation. The techniques of asymptotic matching and
boundary-layer theory, which were recently applied by two of the authors (CMB
and SS) to a Boltzmann equation, are used here to find the detailed asymptotic
relic abundances for all ranges of the expectation value of the dilaton field.
The phenomenological implications for the search of supersymmetric dark matter
in current colliders, such as the LHC, are discussed
Asymptotic Analysis of the Boltzmann Equation for Dark Matter Relics
This paper presents an asymptotic analysis of the Boltzmann equations
(Riccati differential equations) that describe the physics of thermal
dark-matter-relic abundances. Two different asymptotic techniques are used,
boundary-layer theory, which makes use of asymptotic matching, and the delta
expansion, which is a powerful technique for solving nonlinear differential
equations. Two different Boltzmann equations are considered. The first is
derived from general relativistic considerations and the second arises in
dilatonic string cosmology. The global asymptotic analysis presented here is
used to find the long-time behavior of the solutions to these equations. In the
first case the nature of the so-called freeze-out region and the
post-freeze-out behavior is explored. In the second case the effect of the
dilaton on cold dark-matter abundances is calculated and it is shown that there
is a large-time power-law fall off of the dark-matter abundance. Corrections to
the power-law behavior are also calculated.Comment: 15 pages, no figure
Bulgeless Giant Galaxies Challenge our Picture of Galaxy Formation by Hierarchical Clustering
We dissect giant Sc-Scd galaxies with Hubble Space Telescope photometry and
Hobby-Eberly Telescope spectroscopy. We use HET's High Resolution Spectrograph
(resolution = 15,000) to measure stellar velocity dispersions in the nuclear
star clusters and pseudobulges of the pure-disk galaxies M33, M101, NGC 3338,
NGC 3810, NGC 6503, and NGC 6946. We conclude: (1) Upper limits on the masses
of any supermassive black holes are MBH <= (2.6+-0.5) * 10**6 M_Sun in M101 and
MBH <= (2.0+-0.6) * 10**6 M_Sun in NGC 6503. (2) HST photometry shows that the
above galaxies contain tiny pseudobulges that make up <~ 3 % of the stellar
mass but no classical bulges. We inventory a sphere of radius 8 Mpc centered on
our Galaxy to see whether giant, pure-disk galaxies are common or rare. In this
volume, 11 of 19 galaxies with rotation velocity > 150 km/s show no evidence
for a classical bulge. Four may contain small classical bulges that contribute
5-12% of the galaxy light. Only 4 of the 19 giant galaxies are ellipticals or
have classical bulges that contribute 1/3 of the galaxy light. So pure-disk
galaxies are far from rare. It is hard to understand how they could form as the
quiescent tail of a distribution of merger histories. Recognition of
pseudobulges makes the biggest problem with cold dark matter galaxy formation
more acute: How can hierarchical clustering make so many giant, pure-disk
galaxies with no evidence for merger-built bulges? This problem depends
strongly on environment: the Virgo cluster is not a puzzle, because >2/3 of its
stellar mass is in merger remnants.Comment: 28 pages, 16 Postscript figures, 2 tables; requires emulateapj.sty
and apjfonts.sty; accepted for publication in ApJ; for a version with full
resolution figures, see http://chandra.as.utexas.edu/~kormendy/kdbc.pd
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