3,608 research outputs found
Comments on black holes I: The possibility of complementarity
We comment on a recent paper of Almheiri, Marolf, Polchinski and Sully who
argue against black hole complementarity based on the claim that an infalling
observer 'burns' as he approaches the horizon. We show that in fact
measurements made by an infalling observer outside the horizon are
statistically identical for the cases of vacuum at the horizon and radiation
emerging from a stretched horizon. This forces us to follow the dynamics all
the way to the horizon, where we need to know the details of Planck scale
physics. We note that in string theory the fuzzball structure of microstates
does not give any place to 'continue through' this Planck regime. AMPS argue
that interactions near the horizon preclude traditional complementarity. But
the conjecture of 'fuzzball complementarity' works in the opposite way: the
infalling quantum is absorbed by the fuzzball surface, and it is the resulting
dynamics that is conjectured to admit a complementary description.Comment: 34 pages, 6 figures, v3: clarifications & references adde
Black hole microstate geometries from string amplitudes
In this talk we review recent calculations of the asymptotic supergravity
fields sourced by bound states of D1 and D5-branes carrying travelling waves.
We compute disk one-point functions for the massless closed string fields. At
large distances from the branes, the effective open string coupling is small,
even in the regime of parameters where the classical D1-D5-P black hole may be
considered. The fields sourced by the branes differ from the black hole
solution by various multipole moments, and have led to the construction of a
new 1/8-BPS ansatz in type IIB supergravity.Comment: 14 pages, 3 figures, Contribution to the proceedings of the Black
Objects in Supergravity School, Frascati, 201
From Black Holes to Glueballs: The QCD_3 Tensor Glueball at Strong Coupling
A strong coupling calculation of glueball masses based on the duality between
supergravity and Yang-Mills theory is presented. Earlier work is extended to
non-zero spin. Fluctuations in the gravitational metric lead to the 2^{++}
state on the leading Pomeron trajectory with a mass relation: m(0^{++}) <
m(2^{++}) < m(1^{-+}). Contrary to expectation, the mass of our new 0^{++}
state (m^2=5.4573) associated with the graviton is smaller than the mass of the
state (m^2=11.588) from the dilaton, which in fact is exactly
degenerate with the tensor 2^{++}.Comment: 3 pages, 1 figure, Talk at Lattice 99 by R. Browe
The information paradox: A pedagogical introduction
The black hole information paradox is a very poorly understood problem. It is
often believed that Hawking's argument is not precisely formulated, and a more
careful accounting of naturally occurring quantum corrections will allow the
radiation process to become unitary. We show that such is not the case, by
proving that small corrections to the leading order Hawking computation cannot
remove the entanglement between the radiation and the hole. We formulate
Hawking's argument as a `theorem': assuming `traditional' physics at the
horizon and usual assumptions of locality we will be forced into mixed states
or remnants. We also argue that one cannot explain away the problem by invoking
AdS/CFT duality. We conclude with recent results on the quantum physics of
black holes which show the the interior of black holes have a `fuzzball'
structure. This nontrivial structure of microstates resolves the information
paradox, and gives a qualitative picture of how classical intuition can break
down in black hole physics.Comment: 38 pages, 7 figures, Latex (Expanded form of lectures given at CERN
for the RTN Winter School, Feb 09), typo correcte
Charmonium Spectrum from Quenched QCD with Overlap Fermions
We present preliminary results using overlap fermions for the charmonium
spectrum, in particular for hyperfine splitting. Simulations are performed on
lattices, with Wilson gauge action at .
Depending on how the scale is set, we obtain 104(5) MeV (using
) or 88(4) MeV (using =0.5 fm) for the hyperfine
splitting.Comment: 3 pages, 5 fiugres. Talk presented at Lattice 2004 (heavy
Radiation from the non-extremal fuzzball
The fuzzball proposal says that the information of the black hole state is
distributed throughout the interior of the horizon in a `quantum fuzz'. There
are special microstates where in the dual CFT we have `many excitations in the
same state'; these are described by regular classical geometries without
horizons. Jejjala et.al constructed non-extremal regular geometries of this
type. Cardoso et. al then found that these geometries had a classical
instability. In this paper we show that the energy radiated through the
unstable modes is exactly the Hawking radiation for these microstates. We do
this by (i) starting with the semiclassical Hawking radiation rate (ii) using
it to find the emission vertex in the CFT (iii) replacing the Boltzman
distributions of the generic CFT state with the ones describing the microstate
of interest (iv) observing that the emission now reproduces the classical
instability. Because the CFT has `many excitations in the same state' we get
the physics of a Bose-Einstein condensate rather than a thermal gas, and the
usually slow Hawking emission increases, by Bose enhancement, to a classically
radiated field. This system therefore provides a complete gravity description
of information-carrying radiation from a special microstate of the nonextremal
hole.Comment: corrected typo
A nano-biosensor for DNA sequence detection using absorption spectra of SWNT-DNA composite
biosensor based on Single Walled Carbon Nanotube (SWNT)-Poly (GT)n ssDNA hybrid has been developed for medical diagnostics. The absorption spectrum of this assay is determined with the help of a Shimadzu UV-VIS-NIR spectrophotometer. Two
distinct bands each containing three peaks corresponding to first and second van Hove singularities in the density of states of the nanotubes were observed in the absorption spectrum. When a single-stranded DNA (ssDNA) having a sequence
complementary to probic DNA is added to the ssDNA-SWNT conjugates, hybridization takes place, which causes the red shift of absorption spectrum of nanotubes. On the
other hand, when the DNA is noncomplementary, no shift in the absorption spectrum occurs since hybridization between the DNA and probe does not take place. The red shifting of the spectrum is considered to be due to change in the dielectric
environment around nanotubes.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2212
An X-ray view of Mrk 705: A borderline narrow-line Seyfert 1 galaxy
Mrk 705 exhibits optical properties of both narrow- and broad-line Seyfert 1
galaxies. We examine the X-ray properties of this borderline object utilising
proprietary and public data from Chandra, ASCA, ROSAT and RXTE, spanning more
than twelve years. Though long-term flux variability from the pointed
observations appears rather modest (about 3 times), we do find examples of rare
large amplitude outbursts in the RXTE monitoring data. There is very little
evidence of long-term spectral variability as the low- and high-energy spectra
appear constant with time. A 6.4 keV emission line is detected in the ASCA
spectra of Mrk 705, but not during the later, higher flux state Chandra
observation. However, the upper limit on the equivalent width of a line in the
Chandra spectrum is consistent with a constant-flux emission line and a
brighter continuum, suggesting that the line is emitted from distant material
such as the putative torus. Overall, the X-ray properties of Mrk 705 appear
typical of BLS1 activity.Comment: 7 pages, 7 figures. Accepted for publication in A&A (Research Note
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