2,069 research outputs found
Intersecting non-SUSY -brane with chargeless 0-brane as black -brane
Unlike BPS -brane, non-supersymmetric (non-susy) -brane could be either
charged or chargeless. As envisaged in [hep-th/0503007], we construct an
intersecting non-susy -brane with chargeless non-susy -brane by taking
T-dualities along the delocalized directions of the non-susy -brane solution
delocalized in transverse directions (where ). In general
these solutions are characterized by four independent parameters. We show that
when the intersecting charged as well as chargeless non-susy -brane
with chargeless 0-brane can be mapped by a coordinate transformation to black
-brane when two of the four parameters characterizing the solution take some
special values. For definiteness we restrict our discussion to space-time
dimensions . We observe that parameters characterizing the black brane
and the related dynamics are in general in a different branch of the parameter
space from those describing the brane-antibrane annihilation process. We
demonstrate this in the two examples, namely, the non-susy D0-brane and the
intersecting non-susy D4 and D0-branes, where the solutions with the explicit
microscopic descriptions are known.Comment: 25 page
Non-SUSY -branes, bubbles and tubular branes
We consider non-supersymmetric -brane solutions of type II string theories
characterized by three parameters. When the charge parameter vanishes and one
of the other two takes a specific value, the corresponding chargeless solutions
can be regular and describe ``bubbles'' in static (unstable) equilibrium when
lifted to . In appropriate coordinates, they represent D6 branes with a
tubular topology R S when reduced to , called
the tubular D6 branes, held in static equilibrium by a fixed magnetic flux
(fluxbrane). Moreover, a `rotation parameter' can be introduced to either of
the above two eleven dimensional configurations, giving rise to a generalized
configuration labelling by the parameter. As such, it brings out the relations
among non-supersymmetric -branes, bubbles and tubular D6 branes. Given our
understanding on tubular D6 branes, we are able to reinforce the interpretation
of the chargeless non-supersymmetric -branes as representing
-brane-anti-brane (or non-BPS -brane) systems, and understand the
static nature and various singularities of these systems in a classical
supergravity approximation.Comment: 18 pages, footnote 7 removed due to some erro
Steganography integration into a low-bit rate speech codec
Low bit-rate speech codecs have been widely used in audio communications like VoIP and mobile communications, so that steganography in low bit-rate audio streams would have broad applications in practice. In this paper, the authors propose a new algorithm for steganography in low bit-rate VoIP audio streams by integrating information hiding into the process of speech encoding. The proposed algorithm performs data embedding while pitch period prediction is conducted during low bit-rate speech encoding, thus maintaining synchronization between information hiding and speech encoding. The steganography algorithm can achieve high quality of speech and prevent detection of steganalysis, but also has great compatibility with a standard low bit-rate speech codec without causing further delay by data embedding and extraction. Testing shows, with the proposed algorithm, the data embedding rate of the secret message can attain 4 bits / frame (133.3 bits / second)
All Multiparty Quantum States Can Be Made Monogamous
Monogamy of quantum correlation measures puts restrictions on the sharability
of quantum correlations in multiparty quantum states. Multiparty quantum states
can satisfy or violate monogamy relations with respect to given quantum
correlations. We show that all multiparty quantum states can be made monogamous
with respect to all measures. More precisely, given any quantum correlation
measure that is non-monogamic for a multiparty quantum state, it is always
possible to find a monotonically increasing function of the measure that is
monogamous for the same state. The statement holds for all quantum states,
whether pure or mixed, in all finite dimensions and for an arbitrary number of
parties. The monotonically increasing function of the quantum correlation
measure satisfies all the properties that is expected for quantum correlations
to follow. We illustrate the concepts by considering a thermodynamic measure of
quantum correlation, called the quantum work deficit.Comment: 6.5 pages, 2 figures, RevTeX 4-1, Title in the published version is
"Monotonically increasing functions of any quantum correlation can make all
multiparty states monogamous
The Tachyon Potential in the Sliver Frame
We evaluate the tachyon potential in the Schnabl gauge through off-shell
computations in the sliver frame. As an application of the results of our
computations, we provide a strong evidence that Schnabl's analytic solution for
tachyon condensation in open string field theory represents a saddle point
configuration of the full tachyon potential. Additionally we verify that
Schnabl's analytic solution lies on the minimum of the effective tachyon
potential.Comment: v1: 19 pages, 1 figure, 1 table; v2: 20 pages, 1 figure, 2 tables, 1
reference added, comments added; v3: 21 pages, 1 figure, 2 tables, 4
references added, comments adde
Conservation laws and tachyon potentials in the sliver frame
Conservation laws have provided an elegant and efficient tool to evaluate the
open string field theory interaction vertex, they have been originally
implemented in the case where the string field is expanded in the Virasoro
basis. In this work we derive conservation laws in the case where the string
field is expanded in the so-called sliver -basis. As an
application of these conservation laws derived in the sliver frame, we compute
the open string field action relevant to the tachyon condensation and in order
to present not only an illustration but also an additional information, we
evaluate the action without imposing a gauge choice.Comment: 26 pages, some typos fixed, comments added, references adde
Relating Schwarzschild Black Holes to Branes-Antibranes
We construct in the supergravity framework a relation between thermal
chargeless non-extremal black three-branes and thermal Dirichlet
branes-antibranes systems. We propose this relation as a possible explanation
for the intriguing similarity between the black branes Bekenstein-Hawking
entropy and the field theory entropy of thermal branes-antibranes. We comment
on various relations between branes, antibranes and non-BPS branes in type II
string theories.Comment: 40 pages, 1 figure. Subsections 4.5 (BH degrees of freedom) and 4.6
(charged BH) added; Added a note on bubble geometry; References adde
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