40,139 research outputs found
Scattering of surface plasmons by one-dimensional periodic nanoindented surfaces
In this work, the scattering of surface plasmons by a finite periodic array
of one-dimensional grooves is theoretically analyzed by means of a modal
expansion technique. We have found that the geometrical parameters of the array
can be properly tuned to achieve optimal performance of the structure either as
a Bragg reflector or as a converter of surface plasmons into light. In this
last case, the emitted light is collimated within a few degrees cone.
Importantly, we also show that a small number of indentations in the array are
sufficient to fully achieve its functional capabilities.Comment: 5 pages, 5 figures; changed sign convention in some definition
Higgs boson production with one bottom quark including higher-order soft-gluon corrections
A Higgs boson produced in association with one or more bottom quarks is of
great theoretical and experimental interest to the high-energy community. A
precise prediction of its total and differential cross-section can have a great
impact on the discovery of a Higgs boson with large bottom-quark Yukawa
coupling, like the scalar (h^0 and H^0) and pseudoscalar (A^0) Higgs bosons of
the Minimal Supersymmetric Standard Model (MSSM) in the region of large
\tan\beta. In this paper we apply the threshold resummation formalism to
determine both differential and total cross-sections for b g \to b\Phi (where
\Phi = h^0, H^0), including up to next-to-next-to-next-to-leading order (NNNLO)
soft plus virtual QCD corrections at next-to-leading logarithmic (NLL)
accuracy. We present results for both the Fermilab Tevatron and the CERN Large
Hadron Collider (LHC).Comment: revtex4, 13 pages, 11 figures; new references and additional comment
Structural concepts and experimental considerations for a versatile high-speed research airplane
Future aircraft may be hydrogen fueled and fly at hypersonic speeds. The resulting environments will require new structural concepts to satisfy performance goals. Large representative structures will have to be flight tested prior to commitment to a costly vehicle fleet. To perform flight tests, a versatile, economical, high-speed research airplane is defined. Results of this study including experimental considerations for a hypersonic research airplane are reported
Real-Time Description of the Electronic Dynamics for a Molecule close to a Plasmonic Nanoparticle
The optical properties of molecules close to plasmonic nanostructures greatly
differ from their isolated molecule counterparts. To theoretically investigate
such systems in a Quantum Chemistry perspective, one has to take into account
that the plasmonic nanostructure (e.g., a metal nanoparticle - NP) is often too
large to be treated atomistically. Therefore, a multiscale description, where
the molecule is treated by an ab initio approach and the metal NP by a lower
level description, is needed. Here we present an extension of one such
multiscale model [Corni, S.; Tomasi, J. {\it J. Chem. Phys.} {\bf 2001}, {\it
114}, 3739] originally inspired by the Polarizable Continuum Model, to a
real-time description of the electronic dynamics of the molecule and of the NP.
In particular, we adopt a Time-Dependent Configuration Interaction (TD CI)
approach for the molecule, the metal NP is described as a continuous dielectric
of complex shape characterized by a Drude-Lorentz dielectric function and the
molecule- NP electromagnetic coupling is treated by an equation-of-motion (EOM)
extension of the quasi-static Boundary Element Method (BEM). The model includes
the effects of both the mutual molecule- NP time-dependent polarization and the
modification of the probing electromagnetic field due to the plasmonic
resonances of the NP. Finally, such an approach is applied to the investigation
of the light absorption of a model chromophore, LiCN, in the presence of a
metal NP of complex shape.Comment: This is the final peer-reviewed manuscript accepted for publication
of an open access article published under an ACS AuthorChoice License, which
permits copying and redistribution of the article or any adaptations for
non-commercial purposes. Link to the original article:
http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.6b1108
Multipole expansion at the level of the action
Sources of long wavelength radiation are naturally described by an effective
field theory (EFT) which takes the form of a multipole expansion. Its action is
given by a derivative expansion where higher order terms are suppressed by
powers of the ratio of the size of the source over the wavelength. In order to
determine the Wilson coefficients of the EFT, i.e. the multipole moments, one
needs the mapping between a linear source term action and the multipole
expansion form of the action of the EFT. In this paper we perform the multipole
expansion to all orders by Taylor expanding the field in the source term and
then decomposing the action into symmetric trace free tensors which form
irreducible representations of the rotation group. We work at the level of the
action, and we obtain the action to all orders in the multipole expansion and
the exact expressions for the multipole moments for a scalar field,
electromagnetism and linearized gravity. Our results for the latter two cases
are manifestly gauge invariant. We also give expressions for the energy flux
and the (gauge dependent) radiation field to all orders in the multipole
expansion. The results for linearized gravity are a component of the EFT
framework NRGR and will greatly simplify future calculations of gravitational
wave observables in the radiation sector of NRGR.Comment: 39 pages, some typos corrected, published versio
Local gauge invariance implies Siegert's hypothesis
The nonrelativistic Ward-Takahashi identity, a consequence of local gauge
invariance in quantum mechanics, shows the necessity of exchange current
contributions in case of nonlocal and/or isospin-dependent potentials. It also
implies Siegert's hypothesis: in the nonrelativistic limit, two-body charge
densities identically vanish. Neither current conservation, which follows from
global gauge invariance, nor the constraints of (lowest order) relativity are
sufficient to arrive at this result. Furthermore, a low-energy theorem for
exchange contributions is established.Comment: 5 pages, REVTE
Lax matrices for Yang-Baxter maps
It is shown that for a certain class of Yang-Baxter maps (or set-theoretical
solutions to the quantum Yang-Baxter equation) the Lax representation can be
derived straight from the map itself. A similar phenomenon for 3D consistent
equations on quad-graphs has been recently discovered by A. Bobenko and one of
the authors, and by F. Nijhoff
Consistency of a Causal Theory of Radiative Reaction with the Optical Theorem
The Abraham-Lorentz-Dirac equation for a point electron, while suffering from
runaway solutions and an acausal response to external forces, is compatible
with the optical theorem. We show that a theory of radiative reaction that
allows for a finite charge distribution is not only causal and free of runaway
solutions, but is also consistent with the optical theorem and the standard
formula for the Rayleigh scattering cross section.Comment: 4 pages, 2 figure
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