2,078 research outputs found

    Intersecting non-SUSY pp-brane with chargeless 0-brane as black pp-brane

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    Unlike BPS pp-brane, non-supersymmetric (non-susy) pp-brane could be either charged or chargeless. As envisaged in [hep-th/0503007], we construct an intersecting non-susy pp-brane with chargeless non-susy qq-brane by taking T-dualities along the delocalized directions of the non-susy qq-brane solution delocalized in (p−q)(p-q) transverse directions (where p≥qp\geq q). In general these solutions are characterized by four independent parameters. We show that when q=0q=0 the intersecting charged as well as chargeless non-susy pp-brane with chargeless 0-brane can be mapped by a coordinate transformation to black pp-brane when two of the four parameters characterizing the solution take some special values. For definiteness we restrict our discussion to space-time dimensions d=10d=10. 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 pp-branes, bubbles and tubular branes

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    We consider non-supersymmetric pp-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 d=11d = 11. In appropriate coordinates, they represent D6 branes with a tubular topology R1,p^{1,p} ×\times S6−p^{6-p} when reduced to d=10d=10, 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 pp-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 pp-branes as representing pp-brane-antipp-brane (or non-BPS pp-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

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    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

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    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

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    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

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    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 L0\mathcal{L}_0-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

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    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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