767 research outputs found
Microscopic Black Hole Production in TeV-Scale Gravity
Models with extra spatial dimensions and TeV-scale gravity offer the first
opportunity to test the conjecture of black hole formation in trans-Planckian
energy scattering with small impact parameters. After a brief review of
gravitational scattering at ultrahigh energies and scenarios of TeV-scale
gravity, search strategies at the LHC, at the Pierre Auger (cosmic ray)
Observatory and at the neutrino telescopes AMANDA/IceCube are illustrated with
the simplest but nevertheless representative example: production of
Schwarzschild black holes and their observation via Hawking radiation in the
large extra dimension scenario. Some more general features of the production of
higher-dimensional black holes and/or uncertainties in the estimates are also
outlined.Comment: 18 pages, 5 figures; Talk presented at XXX ITEP Winter School of
Physics, Moscow, Russia, February 2002, references adde
Coherent control of population transfer between communicating defects
Population transfer between two identical, communicating defects in a
one-dimensional tight-binding lattice can be systematically controlled by
external time-periodic forcing. Employing a force with slowly changing
amplitude, the time it takes to transfer a particle from one defect to the
other can be altered over several orders of magnitude. An analytical expression
is derived which shows how the forcing effectively changes the energy splitting
between the defect states, and numerical model calculations illustrate the
possibility of coherent control of the transfer.Comment: 7 pages, 6 figures, to appear in Phys. Rev.
"Exotic" quantum effects in the laboratory?
This Article provides a brief (non-exhaustive) review of some recent
developments regarding the theoretical and possibly experimental study of
"exotic" quantum effects in the laboratory with special emphasis on
cosmological particle creation, Hawking radiation, and the Unruh effect.Comment: 5 page
Selfgravitating Gas Spheres in a Box and Relativistic Clusters: Relation between Dynamical and Thermodynamical Stability
We derive a variational principle for the dynamical stability of a cluster as
a gas sphere in a box. Newtonian clusters are always dynamically stable and,
for relativistic clusters, the relation between dynamical and thermodynamical
instabilities is analyzed. The boundaries between dynamically and
thermodynamically stable and unstable models are found numerically for
relativistic stellar systems with different cut off parameters. A criterion
based on binding energy curve is used for determination of the boundary of
dynamical stability.Comment: 10 figure
Molecular Dynamics Simulations of Weak Detonations
Detonation of a three-dimensional reactive non-isotropic molecular crystal is
modeled using molecular dynamics simulations. The detonation process is
initiated by an impulse, followed by the creation of a stable fast reactive
shock wave. The terminal shock velocity is independent of the initiation
conditions. Further analysis shows supersonic propagation decoupled from the
dynamics of the decomposed material left behind the shock front. The dependence
of the shock velocity on crystal nonlinear compressibility resembles solitary
behavior. These properties categorize the phenomena as a weak detonation. The
dependence of the detonation wave on microscopic potential parameters was
investigated. An increase in detonation velocity with the reaction
exothermicity reaching a saturation value is observed. In all other respects
the model crystal exhibits typical properties of a molecular crystal.Comment: 38 pages, 20 figures. Submitted to Physical Review
The Cosmological Mean Density and its Local Variations Probed by Peculiar Velocities
Peculiar velocities thoughout the region of the local supercluster are
reconstructed by two different orbit-retracing methods. The requirement of the
optimal correlation between the radial components of reconstructed velocities
and the observed peculiar velocities derived from our extensive new catalog of
distances puts stringent constraints on the values of the cosmological
parameters. Our constraints intersect those from studies of microwave
background fluctuations and statistical properties of galaxy clustering: the
ensemble of constraints are consistent with Omega_m=0.22\pm 0.02. While motions
throughout the Local Supercluster provide a measure of the mean ratio of mass
to light, there can be large local fluctuations. Our reconstruction of the
infall velocities in the immediate vicinity of the Virgo Cluster shows that
there is a mass-to-light anomaly of a factor of 3 to 6 between groups in the
general field environment and the heavily populated Virgo Cluster.Comment: 4 pages, 2 figures, version to appear in Astrophysical Journal
Letter
The anapole moments in disk-form MS-wave ferrite particle
The anapole moments describe the parity-violating parity-odd,
time-reversal-even couplings between elementary particles and the
electromagnetic (EM) field. Surprisingly, the anapole-like moment properties
can be found in certain artificially engineered physical systems. In
microwaves, ferrite resonators with multi-resonance magnetostatic-wave
(MS-wave) oscillations may have sizes two-four orders less than the free-space
EM wavelength at the same frequency. MS-wave oscillations in a ferrite sample
occupy a special place between the pure electromagnetic and spin-wave
(exchange) processes. The energy density of MS-wave oscillations is not the
electromagnetic-wave density of energy and not the exchange energy density as
well. These microscopic oscillating objects -- the particles -- may interact
with the external EM fields by a very specific way, forbidden for the classical
description. To describe such interactions, the quantum mechanical analysis
should be used. The presence of surface magnetic currents is one of the
features of MS oscillations in a normally magnetized ferrite disk resonator.
Because of such magnetic currents, MS oscillations in ferrite disk resonators
become parity violating. The parity-violating couplings between disk-form
ferrite particles and the external EM field should be analyzed based on the
notion of an anapole moment.Comment: 20 pages, 2 figures, PDF (created from MS-Word
On the Environmental Dependence of Galaxy Properties Established by the Initial Cosmological Conditions
We study theoretically how the initial cosmological conditions establish the
dependence of galaxy properties on the environment. First, we adopt the linear
tidal torque theory according to which the angular momentum of a proto-galaxy
is generated at first order by the misalignment between the proto-galaxy
inertia tensor and the local tidal tensor. Then, we quantify analytically the
degree of the misalignment between the two tensors, and show quantitatively
that it increases as the density of the environment decreases. It implies that
the proto-galaxies forming in the lower density regions should end up with
having higher angular momentum than those in the higher density regions, which
is consistent with recent numerical finding that the void and field galaxies
have higher spin parameters than the cluster galaxies. Since the galaxy angular
momentum plays a role of developing a disk-like structure and hindering the
star-formation, our theoretical insight provides an answer to such fundamental
observational question as why the large void galaxies have young stellar
populations and high specific star formation rate, which was not explained by
the previous morphology-density relation.Comment: accepted version, ApJL in press, all typos correcte
Origin of Correlations between Central Black Holes Masses and Galactic Bulge Velocity Dispersions
We argue that the observed correlations between central black holes masses
M_{BH} and galactic bulge velocity dispersions \sigma_e in the form
M_{BH}\propto\sigma_e^4 may witness on the pregalactic origin of massive black
holes. Primordial black holes would be the centers for growing protogalaxies
which experienced multiple mergers with ordinary galaxies. This process is
accompanied by the merging of black holes in the galactic nuclei.Comment: 6 pages, 1 figure, submitted to Astron. and Astrophys. Transaction
A numerical investigation of the stability of steady states and critical phenomena for the spherically symmetric Einstein-Vlasov system
The stability features of steady states of the spherically symmetric
Einstein-Vlasov system are investigated numerically. We find support for the
conjecture by Zeldovich and Novikov that the binding energy maximum along a
steady state sequence signals the onset of instability, a conjecture which we
extend to and confirm for non-isotropic states. The sign of the binding energy
of a solution turns out to be relevant for its time evolution in general. We
relate the stability properties to the question of universality in critical
collapse and find that for Vlasov matter universality does not seem to hold.Comment: 29 pages, 10 figure
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