25,570 research outputs found
The inverse problem for pulsating neutron stars: A ``fingerprint analysis'' for the supranuclear equation of state
We study the problem of detecting, and infering astrophysical information
from, gravitational waves from a pulsating neutron star. We show that the fluid
f and p-modes, as well as the gravitational-wave w-modes may be detectable from
sources in our own galaxy, and investigate how accurately the frequencies and
damping rates of these modes can be infered from a noisy gravitational-wave
data stream. Based on the conclusions of this discussion we propose a strategy
for revealing the supranuclear equation of state using the neutron star
fingerprints: the observed frequencies of an f and a p-mode. We also discuss
how well the source can be located in the sky using observations with several
detectors.Comment: 9 pages, 3 figure
String Effects on Fermi--Dirac Correlation Measurements
We investigate some recent measurements of Fermi--Dirac correlations by the
LEP collaborations indicating surprisingly small source radii for the
production of baryons in -annihilation at the peak. In the
hadronization models there are besides the Fermi--Dirac correlation effect also
a strong dynamical (anti-)correlation. We demonstrate that the extraction of
the pure FD effect is highly dependent on a realistic Monte Carlo event
generator, both for separation of those dynamical correlations which are not
related to Fermi--Dirac statistics, and for corrections of the data and
background subtractions. Although the model can be tuned to well reproduce
single particle distributions, there are large model-uncertainties when it
comes to correlations between identical baryons. We therefore, unfortunately,
have to conclude that it is at present not possible to make any firm conclusion
about the source radii relevant for baryon production at LEP
Manifold structures for sets of solutions of the general relativistic constraint equations
We construct manifold structures on various sets of solutions of the general
relativistic initial data sets.Comment: latex2e, 32 A4 pages, minor correction
Baryon Number Violation and String Topologies
In supersymmetric scenarios with broken R-parity, baryon number violating
sparticle decays become possible. In order to search for such decays, a good
understanding of expected event properties is essential. We here develop a
complete framework that allows detailed studies. Special attention is given to
the hadronization phase, wherein the baryon number violating vertex is
associated with the appearance of a junction in the colour confinement field.
This allows us to tell where to look for the extra (anti)baryon directly
associated with the baryon number violating decay.Comment: 1+55 pages, 30 figure
Event-by-event fluctuations of the charged particle ratio from non-equilibrium transport theory
The event by event fluctuations of the ratio of positively to negatively
charged hadrons are predicted within the UrQMD model. Corrections for finite
acceptance and finite net charge are derived. These corrections are relevant to
compare experimental data and transport model results to previous predictions.
The calculated fluctuations at RHIC and SPS energies are shown to be compatible
with a hadron gas. Thus, deviating by a factor of 3 from the predictions for a
thermalized quark-gluon plasma.Comment: This paper clarifies the previous predictions of Jeon and Koch
(hep-ph/0003168) and addresses issues raised in hep-ph/0006023. 2 Figures,
10pp, uses RevTe
Asymptotically simple solutions of the vacuum Einstein equations in even dimensions
We show that a set of conformally invariant equations derived from the
Fefferman-Graham tensor can be used to construct global solutions of the vacuum
Einstein equations, in all even dimensions. This gives, in particular, a new,
simple proof of Friedrich's result on the future hyperboloidal stability of
Minkowski space-time, and extends its validity to even dimensions.Comment: 25p
Space-Time Picture of Fragmentation in PYTHIA/JETSET for HERMES and RHIC
We examine the space-time evolution of (pre-)hadron production within the
Lund string fragmentation model. The complete four-dimensional information of
the string breaking vertices and the meeting points of the prehadron
constituents are extracted for each single event in Monte Carlo simulations
using the Jetset-part of Pythia. We discuss the implication on the deep
inelastic lepton scattering experiments at HERMES as well as on observables in
ultra-relativistic heavy ion collisions at RHIC, using Pythia also for modeling
the hard part of the interaction.Comment: 15 pages, 7 figures, final version as accepted by Phys Lett
Forward-Backward Correlations and Event Shapes as probes of Minimum-Bias Event Properties
Measurements of inclusive observables, such as particle multiplicities and
momentum spectra, have already delivered important information on
soft-inclusive ("minimum-bias") physics at the Large Hadron Collider. In order
to gain a more complete understanding, however, it is necessary to include also
observables that probe the structure of the studied events. We argue that
forward-backward (FB) correlations and event-shape observables may be
particulary useful first steps in this respect. We study the sensitivity of
several different types of FB correlations and two event shape variables -
transverse thrust and transverse thrust minor - to various sources of
theoretical uncertainty: multiple parton interactions, parton showers, colour
(re)connections, and hadronization. The power of each observable to furnish
constraints on Monte Carlo models is illustrated by including comparisons
between several recent, and qualitatively different, PYTHIA 6 tunes, for pp
collisions at sqrt(s) = 900 GeV.Comment: 13 page
Stochastic backgrounds of gravitational waves from extragalactic sources
Astrophysical sources emit gravitational waves in a large variety of
processes occurred since the beginning of star and galaxy formation. These
waves permeate our high redshift Universe, and form a background which is the
result of the superposition of different components, each associated to a
specific astrophysical process. Each component has different spectral
properties and features that it is important to investigate in view of a
possible, future detection. In this contribution, we will review recent
theoretical predictions for backgrounds produced by extragalactic sources and
discuss their detectability with current and future gravitational wave
observatories.Comment: 10 pages, 9 figures, proceedings of the GWDAW 10 Conference,
submitted to Class. & Quantum Gra
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