3,388 research outputs found
Supersymmetry of Tensionless Rotating Strings in AdS_5 x S^5, and Nearly-BPS Operators
It is shown that a class of rotating strings in AdS_5 x S^5 with SO(6)
angular momenta (J,J',J') preserve 1/8-supersymmetry for large J,J', in which
limit they are effectively tensionless; when J=0, supersymmetry is enhanced to
1/4. These results imply that recent checks of the AdS/CFT correspondence
actually test a nearly-BPS sector.Comment: 12 pages, no figures; v2: new section on CFT operators and new
references added, discussion section and acknowledgements modified, abstract
rephrashe
Vacuum polarization in a cosmic string spacetime induced by flat boundary
In this paper we analyze the vacuum expectation values of the field squared
and the energy-momentum tensor associated to a massive scalar field in a higher
dimensional cosmic string spacetime, obeying Dirichlet or Neumann boundary
conditions on the surface orthogonal to the string.Comment: 12 pages, 5 figures, talk presented at the 8th Alexander Friedmann
International Seminar on Gravitation and Cosmology, in Rio de Janeiro, Brazi
Asymptotic symmetries on Kerr--Newman horizon without anomaly of diffeomorphism invariance
We analyze asymptotic symmetries on the Killing horizon of the
four-dimensional Kerr--Newman black hole. We first derive the asymptotic
Killing vectors on the Killing horizon, which describe the asymptotic
symmetries, and find that the general form of these asymptotic Killing vectors
is the universal one possessed by arbitrary Killing horizons. We then construct
the phase space associated with the asymptotic symmetries. It is shown that the
phase space of an extreme black hole either has the size comparable with a
non-extreme black hole, or is small enough to exclude degeneracy, depending on
whether or not the global structure of a Killing horizon particular to an
extreme black hole is respected. We also show that the central charge in the
Poisson brackets algebra of these asymptotic symmetries vanishes, which implies
that there is not an anomaly of diffeomorphism invariance. By taking into
account other results in the literature, we argue that the vanishing central
charge on a black hole horizon, in an effective theory, looks consistent with
the thermal feature of a black hole. We furthermore argue that the vanishing
central charge implies that there are infinitely many classical configurations
that are associated with the same macroscopic state, while these configurations
are distinguished physically.Comment: 14 pages, v2: references added, minor corrections, v3: new pars and
refs. added and corresponding correction
Vacuum polarization of massive scalar fields in the spacetime of the electrically charged nonlinear black hole
The approximate renormalized stress-energy tensor of the quantized massive
conformally coupled scalar field in the spacetime of electrically charged
nonlinear black hole is constructed. It is achieved by functional
differentiation of the lowest order of the DeWitt-Schwinger effective action
involving coincidence limit of the Hadamard-Minakshisundaram-DeWitt-Seely
coefficient The result is compared with the analogous result derived
for the Reissner-Nordstr\"om black hole. It is shown that the most important
differences occur in the vicinity of the event horizon of the black hole near
the extremality limit. The structure of the nonlinear black hole is briefly
studied by means of the Lambert functions.Comment: 22 pages, 10 figure
Covalently Binding the Photosystem I to Carbon Nanotubes
We present a chemical route to covalently couple the photosystem I (PS I) to
carbon nanotubes (CNTs). Small linker molecules are used to connect the PS I to
the CNTs. Hybrid systems, consisting of CNTs and the PS I, promise new
photo-induced transport phenomena due to the outstanding optoelectronic
properties of the robust cyanobacteria membrane protein PS I
Orbifolded Konishi from the Mirror TBA
Starting with a discussion of the general applicability of the simplified
mirror TBA equations to simple deformations of the AdS_5 x S^5 superstring, we
proceed to study a specific type of orbifold to which the undeformed simplified
TBA equations directly apply. We then use this set of equations, as well as
Luscher's approach, to determine the NLO wrapping correction to the energy of
what we call the orbifolded Konishi state, and show that they perfectly agree.
In addition we discuss wrapping corrections to the ground state energy of the
orbifolded model under consideration.Comment: 26 pages, 5 figures, v2: corrected typos, added a short discussion on
the ground state of the model; as submitted to J. Phys.
Energy-Spin Trajectories in AdS_5 x S^5 from Semiclassical Vertex Operators
We study the relation between vertex operators in AdS_5 x S^5 and classical
spinning string solutions. In the limit of large quantum numbers the treatment
of vertex operators becomes semiclassical. In this regime, a given vertex
operator carrying a certain set of quantum numbers defines a singular solution.
We show in a number of examples that this solution coincides with the classical
string solution with the same quantum numbers but written in a different
two-dimensional coordinate system. The marginality condition imposed on an
operator yields a relation between the energy and the other quantum numbers
which is shown to coincide with that of the corresponding classical string
solution. We also argue that in some cases vertex operators in AdS_5 x S^5
cannot be given by expressions similar to the ones in flat space and a more
involved consideration is required.Comment: 23 pages, 1 Figur
On Determinants of Euro-Dollar Rates : An Empirical Study by DOLS
© 2015 Springer Science+Business Media New York. Characteristics of the wave disturbances of the ionospheric electron number density were measured using the Kharkov incoherent scatter radar. The disturbance generation accompanied the SURA heating of the near-Earth plasma by high-power periodic radiation. The distance between the heater and the radar was about 960 km. The possibility of generating ionospheric wave disturbances with a period of 20 to 30 min in the internal gravity wave range was confirmed. The disturbance propagation velocity was near 320–400 m/s, and the relative amplitude of the electron density variation was 1–10%. The wave disturbances appeared in the altitude range 145–235 km. Aperiodic bursts of the electron number density with a relative amplitude of up to 5–10% were detected after the first switch-ons of periodic radiation in the 30-min heating — 30-min pause regime at altitudes of 145 to 310 km. The observation results generally conform to the synchronous observation data obtained using the Kharkov vertical-sounding Doppler radar and a network of ionosondes
Numerical study of resonant spin relaxation in quasi-1D channels
Recent experiments demonstrate that a ballistic version of spin resonance,
mediated by spin-orbit interaction, can be induced in narrow channels of a
high-mobility GaAs two-dimensional electron gas by matching the spin precession
frequency with the frequency of bouncing trajectories in the channel. Contrary
to the typical suppression of Dyakonov-Perel' spin relaxation in confined
geometries, the spin relaxation rate increases by orders of magnitude on
resonance. Here, we present Monte Carlo simulations of this effect to explore
the roles of varying degrees of disorder and strength of spin-orbit
interaction. These simulations help to extract quantitative spin-orbit
parameters from experimental measurements of ballistic spin resonance, and may
guide the development of future spintronic devices
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