176 research outputs found
Multiplier Sequences for Simple Sets of Polynomials
In this paper we give a new characterization of simple sets of polynomials B
with the property that the set of B-multiplier sequences contains all
Q-multiplier sequence for every simple set Q. We characterize sequences of real
numbers which are multiplier sequences for every simple set Q, and obtain some
results toward the partitioning of the set of classical multiplier sequences
Comment on "Finite Size Corrections to the Radiation Reaction Force in Classical Electrodynamics" [arXiv:1005.2617]
In [1, arXiv:1005.2617] effective field theory methods have been employed to
compute the equations of motion of a spherically symmetric charged shell of
radius R, taking into account the radiation reaction force exerted by the
shell's own electromagnetic field up to O(R^2). The authors of Ref. [1] have
stated that the known result for the self force of the shell as can be found
from Eq. (16.28) of the textbook of Jackson [2] (see also Chap. 4 in the review
of Pearle [3]) is incorrect, in that the term linear in R should be absent. We
claim that this conclusion of Ref. [1] is incorrect, and that the textbook
result, Eq. (1) does hold.Comment: 1 pag
Gravitational waves from binaries on unbound orbits
A generalized true anomaly-type parametrization, convenient to describe both
bound and open orbits of a two-body system in general relativity is introduced.
A complete description of the time evolution of both the radial and of the
angular equations of a binary system taking into account the first order
post-newtonian (1PN) is given. The gravitational radiation field emitted by the
system is computed in the 1PN approximation including higher multipole moments
beyond the standard quadrupole term. The gravitational waveforms in the time
domain are explicitly given up to the 1PN order for unbound orbits, but the
results are also illustrated on binaries on elliptic orbits with special
attention given to the effects of eccentricity.Comment: 27 pages, 10 figures, to appear in Phys. Rev.
Negative radiation pressure exerted on kinks
The interaction of a kink and a monochromatic plane wave in one dimensional
scalar field theories is studied. It is shown that in a large class of models
the radiation pressure exerted on the kink is negative, i.e. the kink is {\sl
pulled} towards the source of the radiation. This effect has been observed by
numerical simulations in the model, and it is explained by a
perturbative calculation assuming that the amplitude of the incoming wave is
small. Quite importantly the effect is shown to be robust against small
perturbations of the model. In the sine-Gordon (sG) model the time
averaged radiation pressure acting on the kink turns out to be zero. The
results of the perturbative computations in the sG model are shown to be in
full agreement with an analytical solution corresponding to the superposition
of a sG kink with a cnoidal wave. It is also demonstrated that the acceleration
of the kink satisfies Newton's law.Comment: 23 pages, 8 figures, LaTeX/RevTe
Static spherically symmetric monopole solutions in the presence of a dilaton field
A numerical study of static spherically symmetric monople solutions of a
spontaneously broken SU(2) gauge theory coupled to a dilaton field is
presented. Regular solutions seem to exist only up to a maximal value of the
dilaton coupling. In addition to the generalization of the 't Hooft-Polyakov
monopole a discrete family of regular solutions is found, corresponding to
radial excitations, absent in the theory without dilaton.Comment: 9 pages (incl. 14 figures in eps format) Latex. Figures are to be
decompressed from figs.uu included here as an uuencoded file. Cause of
resubmission:problem with the previously uuencoded fil
Superconducting Electroweak Strings
Classical solutions describing strings endowed with an electric charge and
carrying a constant electromagnetic current are constructed within the bosonic
sector of the Electroweak Theory. For any given ratio of the Higgs boson mass
to W boson mass and for any Weinberg's angle, these strings comprise a family
that can be parameterized by values of the current through their cross section,
, by their electric charge per unit string length, , and by two
integers. These parameters determine the electromagnetic and Z fluxes, as well
as the angular momentum and momentum densities of the string. For
and the solutions reduce to Z strings, or, for solutions with
, to the W-dressed Z strings whose existence was discussed some
time ago.Comment: A figure showing profiles of the W-dressed Z strings is adde
Long-term variation in distribution of sunspot groups
We studied the relation between the distribution of sunspot groups and the
Gleissberg cycle. As the magnetic field is related to the area of the sunspot
groups, we used area-weighted sunspot group data. On the one hand, we confirm
the previously reported long-term cyclic behaviour of the sum of the northern
and southern sunspot group mean latitudes, although we found a somewhat longer
period (P~104 years). We introduced the difference between the ensemble average
area of sunspot groups for the two hemispheres, which turns out to show similar
behaviour. We also investigated a further aspect of the Gleissberg cycle where
while in the 19th century the consecutive Schwabe cycles are sharply separated
from each other, one century later the cycles overlap each other more and more.Comment: 4 page
On the Stability of Gravitating Nonabelian Monopoles
The behaviour of magnetic monopole solutions of the Einstein-Yang-Mills-Higgs
equations subject to linear spherically symmetric perturbations is studied.
Using Jacobi's criterion some of the monopoles are shown to be unstable.
Furthermore the numerical results and analytical considerations indicate the
existence of a set of stable solutions.Comment: 9 pages, 7 figures, minor change
Eclipse timing variation analysis of OGLE-IV eclipsing binaries towards the Galactic Bulge – I. Hierarchical triple system candidates
We report a study of the eclipse timing variation (ETV) of short period
() eclipsing binaries (EB) monitored during the photometric survey
OGLE-IV. From the 425\,193 EBs we selected approximately 80\,000 binaries that
we found suitable for further examination. Among them we identified 992
potential hierarchical triple (or multiple ) system candidates exhibiting
light-travel-time effect (LTTE). Besides, we obtained the orbital parameters of
these systems and carried out statistical analyses on the properties of these
candidates. We found that (i) there is a significant lack of triple systems
where the outer period is less than 500 days; (ii) the distribution of the
outer eccentricities has a maximum around ; (iii) the outer mass
ratio calculated from an estimated minimum mass of the third component is lower
than for the majority of the sample. We also present some systems
that deserve special attention. (i) There are four candidates that show double
periodic ETV, which we explain by the presence of a fourth companion. (ii) For
two systems the perturbations of the third component are also found to be
significant therefore we give a combined dynamical and LTTE ETV solution. (iii)
For one system the third component is found to be probably in the substellar
mass domain.Comment: Accepted for publication in MNRA
Computation of the radiation amplitude of oscillons
The radiation loss of small amplitude oscillons (very long-living, spatially
localized, time dependent solutions) in one dimensional scalar field theories
is computed in the small-amplitude expansion analytically using matched
asymptotic series expansions and Borel summation. The amplitude of the
radiation is beyond all orders in perturbation theory and the method used has
been developed by Segur and Kruskal in Phys. Rev. Lett. 58, 747 (1987). Our
results are in good agreement with those of long time numerical simulations of
oscillons.Comment: 22 pages, 9 figure
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