604 research outputs found
Surface plasmon assisted magnetic anomalies on room temperature gold films in high-intensity laser fields
Supplementing our STM and electron emission studies investigations,
concluding in electron pairing in strong laser fields [1], further
time-of-flight electron emission studies were carried out, changing the angle
of polarization of the incident light, exciting surface plasmon oscillations.
It has been found, that those parts of the electron spectrum which have been
attributed to electron pairing have a significantly different angular
dependence around 80 GW/cm2 where the pairing effect has been found than
outside this region (e.g. 120 GW/cm2). These results have been interpreted as
the appearance of ideal or partly ideal diamagnetism on the one hand and as
anomaly in the magneto-optical effect (rotation) on the other, in the same
laser intensity region where the pairing effect has been found
On Further Generalization of the Rigidity Theorem for Spacetimes with a Stationary Event Horizon or a Compact Cauchy Horizon
A rigidity theorem that applies to smooth electrovac spacetimes which
represent either (A) an asymptotically flat stationary black hole or (B) a
cosmological spacetime with a compact Cauchy horizon ruled by closed null
geodesics was given in a recent work \cite{frw}. Here we enlarge the framework
of the corresponding investigations by allowing the presence of other type of
matter fields. In the first part the matter fields are involved merely
implicitly via the assumption that the dominant energy condition is satisfied.
In the second part Einstein-Klein-Gordon (EKG), Einstein-[non-Abelian] Higgs
(E[nA]H), Einstein-[Maxwell]-Yang-Mills-dilaton (E[M]YMd) and
Einstein-Yang-Mills-Higgs (EYMH) systems are studied. The black hole event
horizon or, respectively, the compact Cauchy horizon of the considered
spacetimes is assumed to be a smooth non-degenerate null hypersurface. It is
proven that there exists a Killing vector field in a one-sided neighborhood of
the horizon in EKG, E[nA]H, E[M]YMd and EYMH spacetimes. This Killing vector
field is normal to the horizon, moreover, the associated matter fields are also
shown to be invariant with respect to it. The presented results provide
generalizations of the rigidity theorems of Hawking (for case A) and of
Moncrief and Isenberg (for case B) and, in turn, they strengthen the validity
of both the black hole rigidity scenario and the strong cosmic censor
conjecture of classical general relativity.Comment: 25 pages, LaTex, a shortened version, including a new proof for lemma
5.1, the additional case of Einstein-Yang-Mills-Higgs systems is also
covered, to appear in Class. Quant. Gra
Trajectories of the S-matrix poles in Salamon-Vertse potential
The trajectories of S-matrix poles are calculated in the finite-range
phenomenological potential introduced recently by P. Salamon and T. Vertse
(SV). The trajectories of the resonance poles in this SV potential are compared
to the corresponding trajectories in a cut-off Woods-Saxon (WS) potential for
l>0. The dependence on the cut-off radius is demonstrated. The starting points
of the trajectories turn out to be related to the average ranges of the two
terms in the SV potential
Space-time extensions II
The global extendibility of smooth causal geodesically incomplete spacetimes
is investigated. Denote by one of the incomplete non-extendible causal
geodesics of a causal geodesically incomplete spacetime . First, it
is shown that it is always possible to select a synchronised family of causal
geodesics and an open neighbourhood of a final segment
of in such that is comprised by members of ,
and suitable local coordinates can be defined everywhere on
provided that does not terminate either on a tidal force tensor
singularity or on a topological singularity. It is also shown that if, in
addition, the spacetime, , is globally hyperbolic, and the
components of the curvature tensor, and its covariant derivatives up to order
are bounded on , and also the line integrals of the
components of the -order covariant derivatives are finite along the
members of ---where all the components are meant to be registered with
respect to a synchronised frame field on ---then there exists a
extension so that for each , which
is inextendible in , the image, , is
extendible in . Finally, it is also proved that
whenever does terminate on a topological singularity
cannot be generic.Comment: 42 pages, no figures, small changes to match the published versio
Noble Gas Clusters and Nanoplasmas in High Harmonic Generation
We report a study of high harmonic generation from noble gas clusters of
xenon atoms in a gas jet. Harmonic spectra were investigated as a function of
backing pressure, showing spectral shifts due to the nanoplasma electrons in
the clusters. At certain value of laser intensity this process may oppose the
effect of the well-known ionization-induced blueshift. In addition, these
cluster-induced harmonic redshifts may give the possibility to estimate cluster
density and cluster size in the laser-gas jet interaction range.Comment: 5 pages, 4 figure
Space-Times Admitting Isolated Horizons
We characterize a general solution to the vacuum Einstein equations which
admits isolated horizons. We show it is a non-linear superposition -- in
precise sense -- of the Schwarzschild metric with a certain free data set
propagating tangentially to the horizon. This proves Ashtekar's conjecture
about the structure of spacetime near the isolated horizon. The same
superposition method applied to the Kerr metric gives another class of vacuum
solutions admitting isolated horizons. More generally, a vacuum spacetime
admitting any null, non expanding, shear free surface is characterized. The
results are applied to show that, generically, the non-rotating isolated
horizon does not admit a Killing vector field and a spacetime is not
spherically symmetric near a symmetric horizon.Comment: 11 pages, no figure
On Killing vectors in initial value problems for asymptotically flat space-times
The existence of symmetries in asymptotically flat space-times are studied
from the point of view of initial value problems. General necessary and
sufficient (implicit) conditions are given for the existence of Killing vector
fields in the asymptotic characteristic and in the hyperboloidal initial value
problem (both of them are formulated on the conformally compactified space-time
manifold)
Dynamic Scaling of Width Distribution in Edwards--Wilkinson Type Models of Interface Dynamics
Edwards--Wilkinson type models are studied in 1+1 dimensions and the
time-dependent distribution, P_L(w^2,t), of the square of the width of an
interface, w^2, is calculated for systems of size L. We find that, using a flat
interface as an initial condition, P_L(w^2,t) can be calculated exactly and it
obeys scaling in the form _\infty P_L(w^2,t) = Phi(w^2 / _\infty,
t/L^2) where _\infty is the stationary value of w^2. For more complicated
initial states, scaling is observed only in the large- time limit and the
scaling function depends on the initial amplitude of the longest wavelength
mode. The short-time limit is also interesting since P_L(w^2,t) is found to
closely approximate the log-normal distribution. These results are confirmed by
Monte Carlo simulations on a `roof-top' model of surface evolution.Comment: 5 pages, latex, 3 ps figures in a separate files, submitted to
Phys.Rev.
Fluctuations in subsystems of the zero temperature XX chain: Emergence of an effective temperature
The zero-temperature XX chain is studied with emphasis on the properties of a
block of spins inside the chain. We investigate the quantum fluctuations
resulting from the entanglement of the block with the rest of the chain using
analytical as well as numerical (density matrix renormalization group) methods.
It is found that the rest of the chain acts as a thermal environment and an
effective temperature can be introduced to describe the fluctuations. We show
that the effective temperature description is robust in the sense that several
independent definitions (through fluctuation dissipation theorem, comparing
with a finite temperature system) yield the same functional form in the limit
of large block size (). The effective temperature can also be shown
to satisfy the basic requirements on how it changes when two bodies of equal or
unequal temperatures are brought into contact.Comment: 19 pages, 7 figure
- …