22,572 research outputs found
Electromagnetic surface states in structured perfect-conductor surfaces
Surface-bound modes in metamaterials forged by drilling periodic hole arrays
in perfect-conductor surfaces are investigated by means of both analytical
techniques and rigorous numerical solution of Maxwell's equations. It is shown
that these metamaterials cannot be described in general by local,
frequency-dependent permittivities and permeabilities for small periods
compared to the wavelength, except in certain limiting cases that are discussed
in detail. New related metamaterials are shown to exhibit exciting optical
properties that are elucidated in the light of our simple analytical approach.Comment: 5 figure
The radiation of a uniformly accelerated charge is beyond the horizon: a simple derivation
We show, by exploring some elementary consequences of the covariance of
Maxwell's equations under general coordinate transformations, that, despite
inertial observers can indeed detect electromagnetic radiation emitted from a
uniformly accelerated charge, comoving observers will see only a static
electric field. This simple analysis can help understanding one of the most
celebrated paradoxes of last century.Comment: Revtex, 6 pages, 2 figures. v2: Some small corrections. v3: Citation
of a earlier paper included. v4: Some stylistic changes. v5: Final version to
appear in AJ
Full transmission through perfect-conductor subwavelength hole arrays
Light transmission through 2D subwavelength hole arrays in perfect-conductor
films is shown to be complete (100%) at some resonant wavelengths even for
arbitrarily narrow holes. Conversely, the reflection on a 2D planar array of
non-absorbing scatterers is shown to be complete at some wavelengths regardless
how weak the scatterers are. These results are proven analytically and
corroborated by rigorous numerical solution of Maxwell's equations. This work
supports the central role played by dynamical diffraction during light
transmission through subwavelength hole arrays and it provides a systematics to
analyze more complex geometries and many of the features observed in connection
with transmission through hole arrays.Comment: 5 pages, 4 figure
On the origin dependence of multipole moments in electromagnetism
The standard description of material media in electromagnetism is based on
multipoles. It is well known that these moments depend on the point of
reference chosen, except for the lowest order. It is shown that this "origin
dependence" is not unphysical as has been claimed in the literature but forms
only part of the effect of moving the point of reference. When also the
complementary part is taken into account then different points of reference
lead to different but equivalent descriptions of the same physical reality.
This is shown at the microscopic as well as at the macroscopic level. A similar
interpretation is valid regarding the "origin dependence" of the reflection
coefficients for reflection on a semi infinite medium. We show that the
"transformation theory" which has been proposed to remedy this situation (and
which is thus not needed) is unphysical since the transformation considered
does not leave the boundary conditions invariant.Comment: 14 pages, 0 figure
A relativistic parton cascade with radiation
We consider the evolution of a parton system which is formed at the central
rapidity region just after an ultrarelativistic heavy ion collision. The
evolution of the system, which is composed of gluons, quarks and antiquarks, is
described by a relativistic Boltzmann equations with collision terms including
radiation and retardation effects. The equations are solved by the test
particle method using Monte-Carlo sampling. Our simulations do not show any
evidence of kinetic equilibration, unless the cross sections are artificially
increased to unrealistically large values.Comment: 14 pages, 4 figure
Three-dimensional numerical simulation of 1GeV/Nucleon U92+ impact against atomic hydrogen
The impact of 1GeV/Nucleon U92+ projectiles against atomic hydrogen is
studied by direct numerical resolution of the time-dependent wave equation for
the atomic electron on a three-dimensional Cartesian lattice. We employ the
fully relativistic expressions to describe the electromagnetic fields created
by the incident ion. The wave equation for the atom interacting with the
projectile is carefully derived from the time-dependent Dirac equation in order
to retain all the relevant terms.Comment: 12 pages and 7 figures included in the tex
Second order equation of motion for electromagnetic radiation back-reaction
We take the viewpoint that the physically acceptable solutions of the
Lorentz--Dirac equation for radiation back-reaction are actually determined by
a second order equation of motion, the self-force being given as a function of
spacetime location and velocity. We propose three different methods to obtain
this self-force function. For two example systems, we determine the second
order equation of motion exactly in the nonrelativistic regime via each of
these three methods, the three methods leading to the same result. We reveal
that, for both systems considered, back-reaction induces a damping proportional
to velocity and, in addition, it decreases the effect of the external force.Comment: 13 page
Testing spontaneous localization theories with matter-wave interferometry
We propose to test the theory of continuous spontaneous localization (CSL) in
an all-optical time-domain Talbot-Lau interferometer for clusters with masses
exceeding 1000000 amu. By assessing the relevant environmental decoherence
mechanisms, as well as the growing size of the particles relative to the
grating fringes, we argue that it will be feasible to test the quantum
superposition principle in a mass range excluded by recent estimates of the CSL
effect.Comment: 4 pages, 3 figures; corresponds to published versio
Fractal Weyl law for chaotic microcavities: Fresnel's laws imply multifractal scattering
We demonstrate that the harmonic inversion technique is a powerful tool to
analyze the spectral properties of optical microcavities. As an interesting
example we study the statistical properties of complex frequencies of the fully
chaotic microstadium. We show that the conjectured fractal Weyl law for open
chaotic systems [W. T. Lu, S. Sridhar, and M. Zworski, Phys. Rev. Lett. 91,
154101 (2003)] is valid for dielectric microcavities only if the concept of the
chaotic repeller is extended to a multifractal by incorporating Fresnel's laws.Comment: 8 pages, 12 figure
The Taurus Boundary of Stellar/Substellar (TBOSS) Survey II. Disk Masses from ALMA Continuum Observations
We report 885m ALMA continuum flux densities for 24 Taurus members
spanning the stellar/substellar boundary, with spectral types from M4 to M7.75.
Of the 24 systems, 22 are detected at levels ranging from 1.0-55.6 mJy. The two
non-detections are transition disks, though other transition disks in the
sample are detected. Converting ALMA continuum measurements to masses using
standard scaling laws and radiative transfer modeling yields dust mass
estimates ranging from 0.3-20M. The dust mass shows a
declining trend with central object mass when combined with results from
submillimeter surveys of more massive Taurus members. The substellar disks
appear as part of a continuous sequence and not a distinct population. Compared
to older Upper Sco members with similar masses across the substellar limit, the
Taurus disks are brighter and more massive. Both Taurus and Upper Sco
populations are consistent with an approximately linear relationship in
to , although derived power-law slopes depend strongly
upon choices of stellar evolutionary model and dust temperature relation. The
median disk around early M-stars in Taurus contains a comparable amount of mass
in small solids as the average amount of heavy elements in Kepler planetary
systems on short-period orbits around M-dwarf stars, with an order of magnitude
spread in disk dust mass about the median value. Assuming a gas:dust ratio of
100:1, only a small number of low-mass stars and brown dwarfs have a total disk
mass amenable to giant planet formation, consistent with the low frequency of
giant planets orbiting M-dwarfs.Comment: 41 pages and 32 figures, with all tables and appendices presented
here in their entirety. Accepted for publication in AJ (November 26, 2017
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