614 research outputs found
Semiclassical theory of surface plasmons in spheroidal clusters
A microscopic theory of linear response based on the Vlasov equation is
extended to systems having spheroidal equilibrium shape. The solution of the
linearized Vlasov equation, which gives a semiclassical version of the random
phase approximation, is studied for electrons moving in a deformed equilibrium
mean field. The deformed field has been approximated by a cavity of spheroidal
shape, both prolate and oblate. Contrary to spherical systems, there is now a
coupling among excitations of different multipolarity induced by the
interaction among constituents. Explicit calculations are performed for the
dipole response of deformed clusters of different size. In all cases studied
here the photoabsorption strength for prolate clusters always displays a
typical double-peaked structure. For oblate clusters we find that the
high--frequency component of the plasmon doublet can get fragmented in the
medium size region (). This fragmentation is related to the
presence of two kinds of three-dimensional electron orbits in oblate cavities.
The possible scaling of our semiclassical equations with the valence electron
number and density is investigated.Comment: 23 pages, 8 figures, revised version, includes discussion of scalin
Beyond the Planar Limit in ABJM
In this article we consider gauge theories with a U(N)X U(N) gauge group. We
provide, for the first time, a complete set of operators built from scalar
fields that are in the bi fundamental of the two groups. Our operators
diagonalize the two point function of the free field theory at all orders in
1/N. We then use this basis to investigate non-planar anomalous dimensions in
the ABJM theory. We show that the dilatation operator reduces to a set of
decoupled harmonic oscillators, signaling integrability in a nonplanar large N
limit.Comment: v2: minor revisison
Light-cone gauge Hamiltonian for AdS_4 x CP^3 superstring
It is developed the phase-space formulation for the Type IIA superstring on
the AdS_4 x CP^3 background in the kappa-symmetry light-cone gauge for which
the light-like directions are taken from the D=3 Minkowski boundary of AdS_4.
After fixing bosonic light-cone gauge the superstring Hamiltonian is expressed
as a function of the transverse physical variables and in the quadratic
approximation corresponds to the light-cone gauge-fixed IIA superstring in flat
space.Comment: 12 pages, LaTeX; v2 minor improvements of the text, misprints
corrected, reference added; v3: missing terms in Eqs.(8),(53) and (56) adde
Large N Free Energy of 3d N=4 SCFTs and AdS/CFT
We provide a non-trivial check of the AdS_4/CFT_3 correspondence recently
proposed in arXiv:1106.4253 by verifying the GKPW relation in the large N
limit. The CFT free energy is obtained from the previous works
(arXiv:1105.2551, arXiv:1105.4390) on the S^3 partition function for
3-dimensional N=4 SCFT T[SU(N)]. This is matched with the computation of the
type IIB action on the corresponding gravity background. We unexpectedly find
that the leading behavior of the free energy at large N is 1/2 N^2 ln N. We
also extend our results to richer theories and argue that 1/2 N^2 ln N is the
maximal free energy at large N in this class of gauge theories.Comment: 20 pages, 3 figure
Calculation of atomic spontaneous emission rate in 1D finite photonic crystal with defects
We derive the expression for spontaneous emission rate in finite
one-dimensional photonic crystal with arbitrary defects using the effective
resonator model to describe electromagnetic field distributions in the
structure. We obtain explicit formulas for contributions of different types of
modes, i.e. radiation, substrate and guided modes. Formal calculations are
illustrated with a few numerical examples, which demonstrate that the
application of effective resonator model simplifies interpretation of results.Comment: Cent. Eur. J. Phys, in pres
Entanglement entropy of Wilson surfaces from bubbling geometries in M-theory
We consider solutions of eleven-dimensional supergravity constructed in [1,2]
that are half-BPS, locally asymptotic to and are the
holographic dual of heavy Wilson surfaces in the six-dimensional
theory. Using these bubbling solutions we calculate the holographic
entanglement entropy for a spherical entangling surface in the presence of a
planar Wilson surface. In addition, we calculate the holographic stress tensor
and, by evaluating the on-shell supergravity action, the expectation value of
the Wilson surface operator.Comment: 42 pages, 4 figures, v2: minor modification
Universal corrections to scaling for block entanglement in spin-1/2 XX chains
We consider the R\'enyi entropies in the one dimensional spin-1/2
Heisenberg XX chain in a magnetic field. The case n=1 corresponds to the von
Neumann ``entanglement'' entropy. Using a combination of methods based on the
generalized Fisher-Hartwig conjecture and a recurrence relation connected to
the Painlev\'e VI differential equation we obtain the asymptotic behaviour,
accurate to order , of the R\'enyi entropies
for large block lengths . For n=1,2,3,10 this constitutes the 3,6,10,48
leading terms respectively. The o(1) contributions are found to exhibit a rich
structure of oscillatory behaviour, which we analyze in some detail both for
finite and in the limit .Comment: 25 pages, 5 figure
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