5,851 research outputs found
Thick Domain Walls in AdS Black Hole Spacetimes
Equations of motion for a real self-gravitating scalar field in the
background of a black hole with negative cosmological constant were solved
numerically. We obtain a sequence of static axisymmetric solutions representing
thick domain wall cosmological black hole systems, depending on the mass of
black hole, cosmological parameter and the parameter binding black hole mass
with the width of the domain wall. For the case of extremal cosmological black
hole the expulsion of scalar field from the black hole strongly depends on it.Comment: 20 pages, 19 figures, accepted for publication in Phys. Rev.
Concurrence of mixed bipartite quantum states in arbitrary dimensions
We derive a lower bound for the concurrence of mixed bipartite quantum
states, valid in arbitrary dimensions. As a corollary, a weaker, purely
algebraic estimate is found, which detects mixed entangled states with positive
partial transpose.Comment: accepted py PR
Application of Single-Station Sigma and Site-Response Characterization in a Probabilistic Seismic-Hazard Analysis for a New Nuclear Site
Aleatory variability in ground-motion prediction, represented by the standard deviation (sigma) of a ground-motion prediction equation, exerts a very strong influence on the results of probabilistic seismic-hazard analysis (PSHA). This is especially so at the low annual exceedance frequencies considered for nuclear facilities; in these cases, even small reductions in sigma can have a marked effect on the hazard estimates. Proper separation and quantification of aleatory variability and epistemic uncertainty can lead to defensible reductions in sigma. One such approach is the single-station sigma concept, which removes that part of sigma corresponding to repeatable site-specific effects. However, the site-to-site component must then be constrained by site-specific measurements or else modeled as epistemic uncertainty and incorporated into the modeling of site effects. The practical application of the single-station sigma concept, including the characterization of the dynamic properties of the site and the incorporation of site-response effects into the hazard calculations, is illustrated for a PSHA conducted at a rock site under consideration for the potential construction of a nuclear power plant.Civil, Architectural, and Environmental Engineerin
Energy dependence of transverse mass spectra of kaons produced in p+p and p+pbar interactions.A compilation
The data on m_T spectra of K0S K+ and K- mesons produced in all inelastic p+p
and p+pbar interactions in the energy range sqrt(s)NN=4.7-1800GeV are compiled
and analyzed. The spectra are parameterized by a single exponential function,
dN/(m_T*dm_T)=C exp(-m_T/T), and the inverse slope parameter T is the main
object of study. The T parameter is found to be similar for K0S, K+ and K-
mesons. It increases monotonically with collision energy from T~30MeV at
sqrt(s)NN=4.7GeV to T~220MeV at sqrt(s)NN=1800GeV. The T parameter measured in
p+p and p+pbar interactions is significantly lower than the corresponding
parameter obtained for central Pb+Pb collisions at all studied energies. Also
the shape of the energy dependence of is different for central Pb+Pb
collisions and p+p(pbar) interactions.Comment: more differential analysis adde
Properties of the solvation force of a two-dimensional Ising strip in scaling regimes
We consider d=2 Ising strip with surface fields acting on boundary spins.
Using the properties of the transfer matrix spectrum we identify two
pseudotransition temperatures and show that they satisfy similar scaling
relations as expected for real transition temperatures in strips with d>2. The
solvation force between the boundaries of the strip is analysed as a function
of temperature, surface fields and the width of the strip. For large widths the
solvation force can be described by scaling functions in three different
regimes: in the vicinity of the critical wetting temperature of 2D
semi-infinite system, in the vicinity of the bulk critical temperature, and in
the regime of weak surface fields where the critical wetting temperature tends
towards the bulk critical temperature. The properties of the relevant scaling
functions are discussed
Ultrafast Molecular Transport on Carbon Surfaces: The Diffusion of Ammonia on Graphite
We present a combined experimental and theoretical study of the
self-diffusion of ammonia on exfoliated graphite. Using neutron time-of-flight
spectroscopy we are able to resolve the ultrafast diffusion process of adsorbed
ammonia, NH, on graphite. Together with van der Waals corrected density
functional theory calculations we show that the diffusion of NH follows a
hopping motion on a weakly corrugated potential energy surface with an
activation energy of about 4 meV which is particularly low for this type of
diffusive motion. The hopping motion includes further a significant number of
long jumps and the diffusion constant of ammonia adsorbed on graphite is
determined with D=3.9 \cdot 10^{-8}~\mbox{m}^2 /\mbox{s} at 94 K
The Formation and Gravitational-Wave Detection of Massive Stellar Black-Hole Binaries
If binaries consisting of two 100 Msun black holes exist they would serve as
extraordinarily powerful gravitational-wave sources, detectable to redshifts of
z=2 with the advanced LIGO/Virgo ground-based detectors. Large uncertainties
about the evolution of massive stars preclude definitive rate predictions for
mergers of these massive black holes. We show that rates as high as hundreds of
detections per year, or as low as no detections whatsoever, are both possible.
It was thought that the only way to produce these massive binaries was via
dynamical interactions in dense stellar systems. This view has been challenged
by the recent discovery of several stars with mass above 150 Msun in the R136
region of the Large Magellanic Cloud. Current models predict that when stars of
this mass leave the main sequence, their expansion is insufficient to allow
common envelope evolution to efficiently reduce the orbital separation. The
resulting black-hole--black-hole binary remains too wide to be able to coalesce
within a Hubble time. If this assessment is correct, isolated very massive
binaries do not evolve to be gravitational-wave sources. However, other
formation channels exist. For example, the high multiplicity of massive stars,
and their common formation in relatively dense stellar associations, opens up
dynamical channels for massive black hole mergers (e.g., via Kozai cycles or
repeated binary-single interactions). We identify key physical factors that
shape the population of very massive black-hole--black-hole binaries. Advanced
gravitational-wave detectors will provide important constraints on the
formation and evolution of very massive stars.Comment: ApJ accepted, extended description of modelin
Violation of Bell's inequality: criterion for quantum communication complexity advantage
We prove that for every Bell's inequality and for a broad class of protocols,
there always exists a multi-party communication complexity problem, for which
the protocol assisted by states which violate the inequality is more efficient
than any classical protocol. Moreover, for that advantage Bell's inequality
violation is a necessary and sufficient criterion. Thus, violation of Bell's
inequalities has a significance beyond that of a non-optimal-witness of
non-separability.Comment: 4 pages, 1 figur
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