Moduli effective action in warped brane-world compactifications
Energy Technology Data Exchange (ETDEWEB)
Garriga, Jaume E-mail: garriga@ifae.es; Pujolas, Oriol; Tanaka, Takahiro
2003-04-07
We consider a class of 5D brane-world solutions with a power-law warp factor a(y){proportional_to}y{sup q}, and bulk dilaton with profile phi{proportional_to}lny, where y is the proper distance in the extra dimension. This class includes the heterotic M-theory brane-world of [Phys. Rev. D 59 (1999) 086001, and] and the Randall-Sundrum (RS) model as a limiting case. In general, there are two moduli fields y{sub {+-}}, corresponding to the 'positions' of two branes (which live at the fixed points of an orbifold compactification). Classically, the moduli are massless, due to a scaling symmetry of the action. However, in the absence of supersymmetry, they develop an effective potential at one loop. Local terms proportional to K{sub {+-}}{sup 4}, where K{sub {+-}}=q/y{sub {+-}} is the local curvature scale at the location of the corresponding brane, are needed in order to remove the divergences in the effective potential. Such terms break the scaling symmetry and hence they may act as stabilizers for the moduli. When the branes are very close to each other, the effective potential induced by massless bulk fields behaves like V{approx}d{sup -4}, where d is the separation between branes. When the branes are widely separated, the potentials for each one of the moduli generically develop a 'Coleman-Weinberg'-type behaviour of the form a{sup 4}(y{sub {+-}})K{sub {+-}}{sup 4}ln(K{sub {+-}}/{mu}{sub {+-}}), where {mu}{sub {+-}} are renormalization scales. In the RS case, the bulk geometry is AdS and K{sub {+-}} are equal to a constant, independent of the position of the branes, so these terms do not contribute to the mass of the moduli. However, for generic warp factor, they provide a simple stabilization mechanism. For q > or approx. 10, the observed hierarchy can be naturally generated by this potential, giving the lightest modulus a mass of order m{sub -} < or approx. TeV.
Moduli effective action in warped brane-world compactifications
International Nuclear Information System (INIS)
Garriga, Jaume; Pujolas, Oriol; Tanaka, Takahiro
2003-01-01
We consider a class of 5D brane-world solutions with a power-law warp factor a(y)∝y q , and bulk dilaton with profile phi∝lny, where y is the proper distance in the extra dimension. This class includes the heterotic M-theory brane-world of [Phys. Rev. D 59 (1999) 086001, and] and the Randall-Sundrum (RS) model as a limiting case. In general, there are two moduli fields y ± , corresponding to the 'positions' of two branes (which live at the fixed points of an orbifold compactification). Classically, the moduli are massless, due to a scaling symmetry of the action. However, in the absence of supersymmetry, they develop an effective potential at one loop. Local terms proportional to K ± 4 , where K ± =q/y ± is the local curvature scale at the location of the corresponding brane, are needed in order to remove the divergences in the effective potential. Such terms break the scaling symmetry and hence they may act as stabilizers for the moduli. When the branes are very close to each other, the effective potential induced by massless bulk fields behaves like V∼d -4 , where d is the separation between branes. When the branes are widely separated, the potentials for each one of the moduli generically develop a 'Coleman-Weinberg'-type behaviour of the form a 4 (y ± )K ± 4 ln(K ± /μ ± ), where μ ± are renormalization scales. In the RS case, the bulk geometry is AdS and K ± are equal to a constant, independent of the position of the branes, so these terms do not contribute to the mass of the moduli. However, for generic warp factor, they provide a simple stabilization mechanism. For q > or approx. 10, the observed hierarchy can be naturally generated by this potential, giving the lightest modulus a mass of order m - < or approx. TeV
Gravitational quantum corrections in warped supersymmetric brane worlds
International Nuclear Information System (INIS)
Gregoire, T.; Rattazzi, R.; Scrucca, C.A.; Strumia, A.; Trincherini, E.
2005-01-01
We study gravitational quantum corrections in supersymmetric theories with warped extra dimensions. We develop for this a superfield formalism for linearized gauged supergravity. We show that the 1-loop effective Kahler potential is a simple functional of the KK spectrum in the presence of generic localized kinetic terms at the two branes. We also present a simple understanding of our results by showing that the leading matter effects are equivalent to suitable displacements of the branes. We then apply this general result to compute the gravity-mediated universal soft mass m 0 2 in models where the visible and the hidden sectors are sequestered at the two branes. We find that the contributions coming from radion mediation and brane-to-brane mediation are both negative in the minimal set-up, but the former can become positive if the gravitational kinetic term localized at the hidden brane has a sizable coefficient. We then compare the features of the two extreme cases of flat and very warped geometry, and give an outlook on the building of viable models
Scales and hierarchies in warped compactifications and brane worlds
International Nuclear Information System (INIS)
DeWolfe, Oliver; Giddings, Steven B.
2003-01-01
Warped compactifications with branes provide a new approach to the hierarchy problem and generate a diversity of four-dimensional thresholds. We investigate the relationships between these scales, which fall into two classes. Geometrical scales, such as thresholds for Kaluza-Klein, excited string, and black hole production, are generically determined solely by the spacetime geometry. Dynamical scales, notably the scale of supersymmetry breaking and moduli masses, depend on other details of the model. We illustrate these relationships in a class of solutions of type IIB string theory with imaginary self-dual fluxes. After identifying the geometrical scales and the resulting hierarchy, we determine the gravitino and moduli masses through explicit dimensional reduction, and estimate their value to be near the four-dimensional Planck scale. In the process we obtain expressions for the superpotential and Kaehler potential, including the effects of warping. We identify matter living on certain branes to be effectively sequestered from the supersymmetry breaking fluxes: specifically, such 'visible sector' fields receive no tree-level masses from the supersymmetry breaking. However, loop corrections are expected to generate masses, at the phenomenologically viable TeV scale
Closed timelike curves in asymmetrically warped brane universes
Päs, Heinrich; Pakvasa, Sandip; Dent, James; Weiler, Thomas J.
2009-08-01
In asymmetrically-warped spacetimes different warp factors are assigned to space and to time. We discuss causality properties of these warped brane universes and argue that scenarios with two extra dimensions may allow for timelike curves which can be closed via paths in the extra-dimensional bulk. In particular, necessary and sufficient conditions on the metric for the existence of closed timelike curves are presented. We find a six-dimensional warped metric which satisfies the CTC conditions, and where the null, weak and dominant energy conditions are satisfied on the brane (although only the former remains satisfied in the bulk). Such scenarios are interesting, since they open the possibility of experimentally testing the chronology protection conjecture by manipulating on our brane initial conditions of gravitons or hypothetical gauge-singlet fermions (“sterile neutrinos”) which then propagate in the extra dimensions.
Self-accelerated brane Universe with warped extra dimension
Gorbunov, D S
2008-01-01
We propose a cosmological model which exhibits the phenomenon of self-acceleration: the Universe is attracted to the phase of accelerated expansion at late times even in the absence of the cosmological constant. The self-acceleration is inevitable in the sense that it cannot be neutralized by any negative explicit cosmological constant. The model is formulated in the framework of brane-world theories with a warped extra dimension. The key ingredient of the model is the brane-bulk energy transfer which is carried by bulk vector fields with a sigma-model-like boundary condition on the brane. We explicitly find the 5-dimensional metric corresponding to the late-time de Sitter expansion on the brane; this metric describes an AdS_5 black hole with growing mass. The present value of the Hubble parameter implies the scale of new physics of order 1 TeV, where the proposed model has to be replaced by putative UV-completion. The mechanism leading to the self-acceleration has AdS/CFT interpretation as occurring due to s...
On Closed Timelike Curves and Warped Brane World Models
Directory of Open Access Journals (Sweden)
Slagter Reinoud Jan
2013-09-01
Full Text Available At first glance, it seems possible to construct in general relativity theory causality violating solutions. The most striking one is the Gott spacetime. Two cosmic strings, approaching each other with high velocity, could produce closed timelike curves. It was quickly recognized that this solution violates physical boundary conditions. The effective one particle generator becomes hyperbolic, so the center of mass is tachyonic. On a 5-dimensional warped spacetime, it seems possible to get an elliptic generator, so no obstruction is encountered and the velocity of the center of mass of the effective particle has an overlap with the Gott region. So a CTC could, in principle, be constructed. However, from the effective 4D field equations on the brane, which are influenced by the projection of the bulk Weyl tensor on the brane, it follows that no asymptotic conical space time is found, so no angle deficit as in the 4D counterpart model. This could also explain why we do not observe cosmic strings.
Indian Academy of Sciences (India)
with gravity at TeV scale by confining the gauge theory to a three-brane embedded in higher dimen .... In ADD model, KK modes are uniformly distributed in the internal dimensions. ... Warp factor exp( 2πkr y ) falls exponentially from the Planck.
Regular Bulk Solutions in Brane-Worlds with Inhomogeneous Dust and Generalized Dark Radiation
International Nuclear Information System (INIS)
Rocha, Roldão da; Kuerten, A. M.; Herrera-Aguilar, A.
2015-01-01
From the dynamics of a brane-world with matter fields present in the bulk, the bulk metric and the black string solution near the brane are generalized, when both the dynamics of inhomogeneous dust/generalized dark radiation on the brane-world and inhomogeneous dark radiation in the bulk as well are considered as exact dynamical collapse solutions. Based on the analysis on the inhomogeneous static exterior of a collapsing sphere of homogeneous dark radiation on the brane, the associated black string warped horizon is studied, as well as the 5D bulk metric near the brane. Moreover, the black string and the bulk are shown to be more regular upon time evolution, for suitable values for the dark radiation parameter in the model, by analyzing the soft physical singularities
Scalar fields and higher-derivative gravity in brane worlds
International Nuclear Information System (INIS)
Pichler, S.
2004-01-01
We consider the brane world picture in the context of higher-derivative theories of gravity and tackle the problematic issues fine-tuning and brane-embedding. First, we give an overview of extra-dimensional physics, from the Kaluza-Klein picture up to modern brane worlds with large extra dimensions. We describe the different models and their physical impact on future experiments. We work within the framework of Randall-Sundrum models in which the brane is a gravitating object, which warps the background metric. We add scalar fields to the original model and find new and self-consistent solutions for quadratic potentials of the fields. This gives us the tools to investigate higher-derivative gravity theories in brane world models. Specifically, we take gravitational Lagrangians that depend on an arbitrary function of the Ricci scalar only, so-called f(R)-gravity. We make use of the conformal equivalence between f(R)-gravity and Einstein-Hilbert gravity with an auxiliary scalar field. We find that the solutions in the higher-derivative gravity framework behave very differently from the original Randall-Sundrum model: the metric functions do not have the typical kink across the brane. Furthermore, we present solutions that do not rely on a cosmological constant in the bulk and so avoid the fine-tuning problem. We address the issue of brane-embedding, which is important in perturbative analyses. We consider the embedding of codimension one hypersurfaces in general and derive a new equation of motion with which the choice for the embedding has to comply. In particular, this allows for a consistent consideration of brane world perturbations in the case of higher-derivative gravity. We use the newly found background solutions for quadratic potentials and find that gravity is still effectively localized on the brane, i.e that the Newtonian limit holds
International Nuclear Information System (INIS)
Barrow, John D; Hervik, Sigbjorn
2002-01-01
We investigate brane-worlds with a pure magnetic field and a perfect fluid. We extend earlier work to brane-worlds and find new properties of the Bianchi type I brane-world. We find new asymptotic behaviours on approach to singularity and classify the critical points of the dynamical phase space. It is known that the Einstein equations for the magnetic Bianchi type I models are in general oscillatory and are believed to be chaotic, but in the brane-world model this chaotic behaviour does not seem to be possible
On the localization of four-dimensional brane-world black holes
International Nuclear Information System (INIS)
Kanti, P; Pappas, N; Zuleta, K
2013-01-01
In the context of brane-world models, we pursue the question of the existence of five-dimensional solutions describing regular black holes localized close to the brane. Employing a perturbed Vaidya-type line-element embedded in a warped fifth dimension, we attempt to localize the extended black-string singularity, and to restore the regularity of the AdS spacetime at a finite distance from the brane by introducing an appropriate bulk energy–momentum tensor. As a source for this bulk matter, we are considering a variety of non-ordinary field-theory models of scalar fields either minimally coupled to gravity, but including non-canonical kinetic terms, mixing terms, derivative interactions and ghosts, or non-minimally coupled to gravity through a general coupling to the Ricci scalar. In all models considered, even in those characterized by a high degree of flexibility, a negative result was reached. Our analysis demonstrates how difficult the analytic construction of a localized brane-world black hole may be in the context of a well-defined field-theory model. Finally, with regard to the question of the existence or not of a static classical black-hole solution on the brane, our analysis suggests that such solutions could in principle exist; however, the associated field configuration itself has to be dynamic. (paper)
Modulus stabilization in a non-flat warped braneworld scenario
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Indrani [S.N. Bose National Centre for Basic Sciences, Department of Astrophysics and Cosmology, Kolkata (India); SenGupta, Soumitra [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)
2017-05-15
The stability of the modular field in a warped brane world scenario has been a subject of interest for a long time. Goldberger and Wise (GW) proposed a mechanism to achieve this by invoking a massive scalar field in the bulk space-time neglecting the back-reaction. In this work, we examine the possibility of stabilizing the modulus without bringing about any external scalar field. We show that instead of flat 3-branes as considered in Randall-Sundrum (RS) warped braneworld model, if one considers a more generalized version of warped geometry with de Sitter 3-brane, then the brane vacuum energy automatically leads to a modulus potential with a metastable minimum. Our result further reveals that in this scenario the gauge hierarchy problem can also be resolved for an appropriate choice of the brane's cosmological constant. (orig.)
Classical dynamics of brane-world extended objects
International Nuclear Information System (INIS)
Vasilic, Milovan
2010-01-01
We make use of the universally valid stress-energy conservation law to study the motion of various branelike extended objects in a generic brane-world. Without specifying any particular action, we are able to derive the world-sheet equations that govern the dynamics of brane-world test branes. In particular, the brane-world test particles are shown to follow geodesics with respect to the brane-world induced metric. At the same time, the presence of extended objects is shown to influence the brane-world geometry. It is demonstrated that codimension-1 branes necessarily violate the brane-world smooth structure, while lower-dimensional branes violate the very continuity. In particular, the truly zero-size massive particles are shown not to exist in a continuous brane-world. As an example, static, axially symmetric membrane-world in 4d Minkowski background is analyzed.
Cosmological evolution in a two-brane warped geometry model
Directory of Open Access Journals (Sweden)
Sumit Kumar
2015-07-01
Full Text Available We study an effective 4-dimensional scalar–tensor field theory, originated from an underlying brane–bulk warped geometry, to explore the scenario of inflation. It is shown that the inflaton potential naturally emerges from the radion energy–momentum tensor which in turn results in an inflationary model of the Universe on the visible brane that is consistent with the recent results from the Planck's experiment. The dynamics of modulus stabilization from the inflaton rolling condition is demonstrated. The implications of our results in the context of recent BICEP2 results are also discussed.
Enveloping branes and brane-world singularities
Energy Technology Data Exchange (ETDEWEB)
Antoniadis, Ignatios; Cotsakis, Spiros [CERN-Theory Division, Department of Physics, Geneva 23 (Switzerland); Klaoudatou, Ifigeneia [University of the Aegean, Research Group of Geometry, Dynamical Systems and Cosmology, Department of Information and Communication Systems Engineering, Samos (Greece)
2014-12-01
The existence of envelopes is studied for systems of differential equations in connection with the method of asymptotic splittings which allows one to determine the singularity structure of the solutions. The result is applied to brane-worlds consisting of a 3-brane in a five-dimensional bulk, in the presence of an analog of a bulk perfect fluid parameterizing a generic class of bulk matter. We find that all flat brane solutions suffer from a finite-distance singularity contrary to previous claims. We then study the possibility of avoiding finite-distance singularities by cutting the bulk and gluing regular solutions at the position of the brane. Further imposing physical conditions such as finite Planck mass on the brane and positive energy conditions on the bulk fluid, excludes, however, this possibility as well. (orig.)
International Nuclear Information System (INIS)
Bernardini, A.E.; Bertolami, O.
2013-01-01
An equivalence between Born–Infeld and effective real scalar field theories for brane structures is built in some specific warped space–time scenarios. Once the equations of motion for tachyon fields related to the Born–Infeld action are written as first-order equations, a simple analytical connection with a particular class of real scalar field superpotentials can be found. This equivalence leads to the conclusion that, for a certain class of superpotentials, both systems can support identical thick brane solutions as well as brane structures described through localized energy densities, T 00 (y), in the 5th dimension, y. Our results indicate that thick brane solutions realized by the Born–Infeld cosmology can be connected to real scalar field brane scenarios which can be used to effectively map the tachyon condensation mechanism
A non-minimally coupled quintom dark energy model on the warped DGP brane
International Nuclear Information System (INIS)
Nozari, K; Azizi, T; Setare, M R; Behrouz, N
2009-01-01
We construct a quintom dark energy model with two non-minimally coupled scalar fields, one quintessence and the other phantom field, confined to the warped Dvali-Gabadadze-Porrati (DGP) brane. We show that this model accounts for crossing of the phantom divide line in appropriate subspaces of the model parameter space. This crossing occurs for both normal and self-accelerating branches of this DGP-inspired setup.
Configurational entropy in brane-world models
Energy Technology Data Exchange (ETDEWEB)
Correa, R.A.C. [CCNH, Universidade Federal do ABC, Santo Andre, SP (Brazil); Rocha, Roldao da [CMCC, Universidade Federal do ABC, Santo Andre, SP (Brazil); International School for Advanced Studies (SISSA), Trieste (Italy)
2015-11-15
In this work we investigate the entropic information on thick brane-world scenarios and its consequences. The brane-world entropic information is studied for the sine-Gordon model and hence the brane-world entropic information measure is shown to be an accurate way for providing the most suitable range for the bulk AdS curvature, in particular from the informational content of physical solutions. Besides, the brane-world configurational entropy is employed to demonstrate a high organisational degree in the structure of the configuration of the system, for large values of a parameter of the sine-Gordon model but the one related to the AdS curvature. The Gleiser and Stamatopoulos procedure is finally applied in order to achieve a precise correlation between the energy of the system and the brane-world configurational entropy. (orig.)
Configurational entropy in brane-world models
Energy Technology Data Exchange (ETDEWEB)
Correa, R. A. C., E-mail: fis04132@gmail.com [CCNH, Universidade Federal do ABC, 09210-580, Santo André, SP (Brazil); Rocha, Roldão da, E-mail: roldao.rocha@ufabc.edu.br [CMCC, Universidade Federal do ABC, 09210-580, Santo André, SP (Brazil); International School for Advanced Studies (SISSA), Via Bonomea 265, 34136, Trieste (Italy)
2015-11-02
In this work we investigate the entropic information on thick brane-world scenarios and its consequences. The brane-world entropic information is studied for the sine-Gordon model and hence the brane-world entropic information measure is shown to be an accurate way for providing the most suitable range for the bulk AdS curvature, in particular from the informational content of physical solutions. Besides, the brane-world configurational entropy is employed to demonstrate a high organisational degree in the structure of the configuration of the system, for large values of a parameter of the sine-Gordon model but the one related to the AdS curvature. The Gleiser and Stamatopoulos procedure is finally applied in order to achieve a precise correlation between the energy of the system and the brane-world configurational entropy.
Configurational entropy in brane-world models
International Nuclear Information System (INIS)
Correa, R. A. C.; Rocha, Roldão da
2015-01-01
In this work we investigate the entropic information on thick brane-world scenarios and its consequences. The brane-world entropic information is studied for the sine-Gordon model and hence the brane-world entropic information measure is shown to be an accurate way for providing the most suitable range for the bulk AdS curvature, in particular from the informational content of physical solutions. Besides, the brane-world configurational entropy is employed to demonstrate a high organisational degree in the structure of the configuration of the system, for large values of a parameter of the sine-Gordon model but the one related to the AdS curvature. The Gleiser and Stamatopoulos procedure is finally applied in order to achieve a precise correlation between the energy of the system and the brane-world configurational entropy
Radion effective potential in the brane-world
International Nuclear Information System (INIS)
Garriga, Jaume; Pujolas, Oriol; Tanaka, Takahiro
2001-01-01
We show that in brane-world scenarios with warped extra dimensions, the Casimir force due to bulk matter fields may be sufficient to stabilize the radion field phi. In particular, we calculate one loop effective potential for phi induced by bulk gravitons and other possible massless bulk fields in the Randall-Sundrum background. This potential has a local extremum, which can be a maximum or a minimum depending on the detailed bulk matter content. If the parameters of the background are chosen so that the hierarchy problem is solved geometrically, then the radion mass induced by Casimir corrections is hierarchically smaller than the TeV. Hence, in this important case, we must invoke an alternative mechanism (classical or nonperturbative) which gives the radion a sizable mass, to make it compatible with observations
Radion effective potential in the brane-world
Energy Technology Data Exchange (ETDEWEB)
Garriga, Jaume E-mail: garriga@ifae.es; Pujolas, Oriol; Tanaka, Takahiro
2001-07-02
We show that in brane-world scenarios with warped extra dimensions, the Casimir force due to bulk matter fields may be sufficient to stabilize the radion field phi. In particular, we calculate one loop effective potential for phi induced by bulk gravitons and other possible massless bulk fields in the Randall-Sundrum background. This potential has a local extremum, which can be a maximum or a minimum depending on the detailed bulk matter content. If the parameters of the background are chosen so that the hierarchy problem is solved geometrically, then the radion mass induced by Casimir corrections is hierarchically smaller than the TeV. Hence, in this important case, we must invoke an alternative mechanism (classical or nonperturbative) which gives the radion a sizable mass, to make it compatible with observations.
Systematics of multi-field effects at the end of warped brane inflation
Chen, Heng-Yu; Shiu, Gary
2008-01-01
We investigate in the context of brane inflation the possibility of additional light scalar fields generating significant power spectrum and non-Gaussianities at the end of inflation affecting the CMB scale observations. We consider the specific mechanism outlined by Lyth and describe the necessary criteria for it to be potentially important in a warped throat. We also discuss different mechanisms for uplifting the vacuum energy which can lead to different dominant contributions of the inflaton potential near the end of inflation. We then apply such criteria to one of the most detailed brane inflation models to date, and show that inflation can persist towards the tip of the throat, however for the specific stable inflationary trajectory, the light residual isometry direction becomes degenerate. We also estimate the effects for other inflationary trajectories with non-degenerate residual isometries.
Bianchi type II brane-world cosmologies (U≥0)
International Nuclear Information System (INIS)
Hoogen, R.J. van den; Ibanez, J.
2003-01-01
The asymptotic properties of the Bianchi type II cosmological model in the brane-world scenario are investigated. The matter content is assumed to be a combination of a perfect fluid and a minimally coupled scalar field that is restricted to the brane. The isotropic brane-world solution is determined to represent the initial singularity in all brane-world cosmologies. Additionally, it is shown that it is the kinetic energy of the scalar field which dominates the initial dynamics in these brane-world cosmologies. It is important to note that the dynamics of these brane-world cosmologies is not necessarily asymptotic to general relativistic cosmologies to the future in the case of a zero four-dimensional cosmological constant
Brane-world cosmology and inflation
Indian Academy of Sciences (India)
This brane-world scenario is quite attractive because of the non-trivial geometry in the bulk and because it successfully gives four-dimensional general relativity in the low energy limit. After reviewing basic features of the RS2 scenario, we consider a brane-world inflation model driven by the dynamics of a scalar field living ...
Bouncing cosmology from warped extra dimensional scenario
Das, Ashmita; Maity, Debaprasad; Paul, Tanmoy; SenGupta, Soumitra
2017-12-01
From the perspective of four dimensional effective theory on a two brane warped geometry model, we examine the possibility of "bouncing phenomena"on our visible brane. Our results reveal that the presence of a warped extra dimension lead to a non-singular bounce on the brane scale factor and hence can remove the "big-bang singularity". We also examine the possible parametric regions for which this bouncing is possible.
Fermions in five-dimensional brane world models
Energy Technology Data Exchange (ETDEWEB)
Smolyakov, Mikhail N. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University,119991, Moscow (Russian Federation)
2016-06-28
In the present paper the fermion fields, living in the background of five-dimensional warped brane world models with compact extra dimension, are thoroughly examined. The Kaluza-Klein decomposition and isolation of the physical degrees of freedom is performed for those five-dimensional fermion field Lagrangians, which admit such a decomposition to be performed in a mathematically consistent way and provide a physically reasonable four-dimensional effective theory. It is also shown that for the majority of five-dimensional fermion field Lagrangians there are no (at least rather obvious) ways to perform the Kaluza-Klein decomposition consistently. Moreover, in these cases one may expect the appearance of various pathologies in the four-dimensional effective theory. Among the cases, for which the Kaluza-Klein decomposition can be performed in a mathematically consistent way, the case, which reproduces the Standard Model by the zero Kaluza-Klein modes most closely regardless of the size of the extra dimension, is examined in detail in the background of the Randall-Sundrum model.
Bouncing cosmology from warped extra dimensional scenario
Energy Technology Data Exchange (ETDEWEB)
Das, Ashmita; Maity, Debaprasad [Indian Institute of Technology, Department of Physics, Guwahati, Assam (India); Paul, Tanmoy; SenGupta, Soumitra [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)
2017-12-15
From the perspective of four dimensional effective theory on a two brane warped geometry model, we examine the possibility of ''bouncing phenomena''on our visible brane. Our results reveal that the presence of a warped extra dimension lead to a non-singular bounce on the brane scale factor and hence can remove the ''big-bang singularity''. We also examine the possible parametric regions for which this bouncing is possible. (orig.)
Indian Academy of Sciences (India)
Abstract. A Kerr metric describing a rotating black hole is obtained on the three brane in a five-dimensional Randall-Sundrum brane world by considering a rotating five-dimensional black string in the bulk. We examine the causal structure of this space-time through the geodesic equations.
Supergravity, Non-Conformal Field Theories and Brane-Worlds
Gherghetta, Tony; Gherghetta, Tony; Oz, Yaron
2002-01-01
We consider the supergravity dual descriptions of non-conformal super Yang-Mills theories realized on the world-volume of Dp-branes. We use the dual description to compute stress-energy tensor and current correlators. We apply the results to the study of dilatonic brane-worlds described by non-conformal field theories coupled to gravity. We find that brane-worlds based on D4 and D5 branes exhibit a localization of gauge and gravitational fields. We calculate the corrections to the Newton and Coulomb laws in these theories.
Cosmological and black hole brane-world universes in higher derivative gravity
International Nuclear Information System (INIS)
Nojiri, Shin'ichi; Odintsov, Sergei D.; Ogushi, Sachiko
2002-01-01
A general model of multidimensional R 2 gravity including a Riemann tensor square term (nonzero c case) is considered. The number of brane-worlds in such a model is constructed (mainly in five dimensions) and their properties are discussed. The thermodynamics of a Schwarzschild-anti-deSitter (S-AdS) BH (with boundary) is presented when perturbation on c is used. The entropy, free energy, and energy are calculated. For a nonzero c the entropy (energy) is not proportional to the area (mass). The equation of motion of the brane in a BH background is presented as a FRW equation. Using a dual CFT description it is shown that the dual field theory is not a conformal one when c is not zero. In this case the holographic entropy does not coincide with the BH entropy (they coincide for Einstein gravity or c=0 HD gravity where the AdS/CFT description is well applied). An asymmetrically warped background (an analogue of a charged AdS BH) where Lorentz invariance violation occurs is found. The cosmological 4D dS brane connecting two dS bulk spaces is formulated in terms of the parameters of R 2 gravity. Within the proposed dS/CFT correspondence the holographic conformal anomaly from five-dimensional higher derivative gravity in a de Sitter background is evaluated
Simple inflationary models in Gauss–Bonnet brane-world cosmology
International Nuclear Information System (INIS)
Okada, Nobuchika; Okada, Satomi
2016-01-01
In light of the recent Planck 2015 results for the measurement of the cosmic microwave background (CMB) anisotropy, we study simple inflationary models in the context of the Gauss–Bonnet (GB) brane-world cosmology. The brane-world cosmological effect modifies the power spectra of scalar and tensor perturbations generated by inflation and causes a dramatic change for the inflationary predictions of the spectral index ( n s ) and the tensor-to-scalar ratio ( r ) from those obtained in the standard cosmology. In particular, the predicted r values in the inflationary models favored by the Planck 2015 results are suppressed due to the GB brane-world cosmological effect, which is in sharp contrast with inflationary scenario in the Randall–Sundrum brane-world cosmology, where the r values are enhanced. Hence, these two brane-world cosmological scenarios are distinguishable. With the dramatic change of the inflationary predictions, the inflationary scenario in the GB brane-world cosmology can be tested by more precise measurements of n s and future observations of the CMB B -mode polarization. (paper)
From Soft Walls to Infrared Branes
von Gersdorff, Gero
2010-01-01
Five dimensional warped spaces with soft walls are generalizations of the standard Randall-Sundrum compactifications, where instead of an infrared brane one has a curvature singularity (with vanishing warp factor) at finite proper distance in the bulk. We project the physics near the singularity onto a hypersurface located a small distance away from it in the bulk. This results in a completely equivalent description of the soft wall in terms of an effective infrared brane, hiding any singular point. We perform explicitly this calculation for two classes of soft wall backgrounds used in the literature. The procedure has several advantages. It separates in a clean way the physics of the soft wall from the physics of the five dimensional bulk, facilitating a more direct comparison with standard two-brane warped compactifications. Moreover, consistent soft walls show a sort of universal behavior near the singularity which is reflected in the effective brane Lagrangian. Thirdly, for many purposes, a good approxima...
Heun equation in a 5D sine-Gordon brane-world model with dilaton
International Nuclear Information System (INIS)
Cunha, M.S.; Christiansen, H.
2011-01-01
Full text: In a brane-world scenario we find the propagation modes of the gauge field in a five-dimensional space-time. We adopt warping factors of the Randall-Sundrum type which are appropriate to regularize the hierarchy problem without imposing finite compactified extra dimensions. The existence and localization of gauge particles in the ordinary four-dimensional world is studied in detail on a thick brane derived out from the equations of motion of an action with a sine-Gordon potential contribution. Maxwell zero modes together with torsion effective fields are then obtained in a gravity-dilaton background inspired in close string theories. The dilaton plays a crucial role in order that the gauge field gets localized in a conformally invariant context. Kaluza-Klein massive states are also computed and, depending on certain parameters like dilaton coupling constant and asymptotic curvature, we are able to do it fully analytically. In a general approach we find that the solutions are of the Heun type. In some specific cases we can show that the Heun general solutions can be transformed into hypergeometric functions. In others, confluent Heun solutions can be transformed into simpler functions like Mathieu functions. Exact mass spectra are found in several cases. In others, we performed numerical calculations that show a well behaved phenomenology as well. In all the cases, Kaluza-Klein modes are strongly suppressed on the brane in the effective four-dimensional theory. (author)
Energy Technology Data Exchange (ETDEWEB)
Bazeia, D.; Lima, Elisama E.M.; Losano, L. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil)
2017-02-15
This work reports on models described by two real scalar fields coupled with gravity in the five-dimensional spacetime, with a warped geometry involving one infinite extra dimension. Through a mechanism that smoothly changes a thick brane into a hybrid brane, one investigates the appearance of hybrid branes hosting internal structure, characterized by the splitting on the energy density and the volcano potential, induced by the parameter which controls interactions between the two scalar fields. In particular, we investigate distinct symmetric and asymmetric hybrid brane scenarios. (orig.)
PRAMANA Black holes in brane worlds M s MODGIL, s PANDA and ...
Indian Academy of Sciences (India)
However the hierarchy between the Planck and the electroweak scale has been an outstanding issue. ... pactification where the hierarchy is driven by the warp factor and allows both small as well as large compact .... In higher dimensions also GTR on an appropriate co-dimension brane needs to be reproduced for ...
Geodesic congruences in warped spacetimes
International Nuclear Information System (INIS)
Ghosh, Suman; Dasgupta, Anirvan; Kar, Sayan
2011-01-01
In this article, we explore the kinematics of timelike geodesic congruences in warped five-dimensional bulk spacetimes, with and without thick or thin branes. Beginning with geodesic flows in the Randall-Sundrum anti-de Sitter geometry without and with branes, we find analytical expressions for the expansion scalar and comment on the effects of including thin branes on its evolution. Later, we move on to congruences in more general warped bulk geometries with a cosmological thick brane and a time-dependent extra dimensional scale. Using analytical expressions for the velocity field, we interpret the expansion, shear and rotation (ESR) along the flows, as functions of the extra dimensional coordinate. The evolution of a cross-sectional area orthogonal to the congruence, as seen from a local observer's point of view, is also shown graphically. Finally, the Raychaudhuri and geodesic equations in backgrounds with a thick brane are solved numerically in order to figure out the role of initial conditions (prescribed on the ESR) and spacetime curvature on the evolution of the ESR.
Unexorcized ghost in DGP brane world
International Nuclear Information System (INIS)
Izum, Keisuke; Tanaka, Takahiro; Koyama, Kazuya
2007-01-01
The brane world model proposed by Dvali-Gabadadze-Porrati realizes self-acceleration of the universe. However, it is known that this cosmological solution contains a spin-2 ghost. We study the possibility of avoiding the appearance of the ghost by slightly modifying the model via the introduction of a second brane. First, we consider a simple model without stabilization of the brane separation. By changing the separation between the branes, we find that we can erase the spin-2 ghost. However, this can be done only at the expense of the appearance of a spin-0 ghost instead. We discuss why these two different types of ghosts are correlated. Then, we examine a model with stabilization of the brane separation. Even in this case, we find that the correlation between spin-0 and spin-2 ghosts remains. As a result we find that we cannot avoid the appearance of a ghost by introducing a second brane in the model
Brane worlds theories with one or two extra dimensions
Salvio, Alberto
2013-01-01
This book is roughly divided in three parts. The first one is a general introduction to theories with extra dimensions and, more specifically, to brane worlds. Both old-fashioned topics (such as Kaluza-Klein theories) and more modern aspects (e.g. Large Extra Dimensions and Randall-Sundrum models) are discussed. The second and third parts (which we refer to as Part I and II respectively) are essentially two monographs. There, the reader is guided through the construction of the 4D effective field theory derived from higher dimensional (in particular five-dimensional and six-dimensional) models. Part I is devoted to the study of how the heavy Kaluza-Klein modes contribute to the low energy dynamics of the light modes. Part II concerns instead the analysis of the spectrum arising from non-standard compactifications of six-dimensional (supersymmetric) theories, involving a warp factor and conical defects in the internal manifold. Several applications of the above mentioned topics are discussed, providing an up t...
Gravity localization on hybrid branes
Directory of Open Access Journals (Sweden)
D.F.S. Veras
2016-03-01
Full Text Available This work deals with gravity localization on codimension-1 brane worlds engendered by compacton-like kinks, the so-called hybrid branes. In such scenarios, the thin brane behavior is manifested when the extra dimension is outside the compact domain, where the energy density is non-trivial, instead of asymptotically as in the usual thick brane models. The zero mode is trapped in the brane, as required. The massive modes, although not localized in the brane, have important phenomenological implications such as corrections to the Newton's law. We study such corrections in the usual thick domain wall and in the hybrid brane scenarios. By means of suitable numerical methods, we attain the mass spectrum for the graviton and the corresponding wavefunctions. The spectra possess the usual linearly increasing behavior from the Kaluza–Klein theories. Further, we show that the 4D gravitational force is slightly increased at short distances. The first eigenstate contributes highly for the correction to the Newton's law. The subsequent normalized solutions have diminishing contributions. Moreover, we find out that the phenomenology of the hybrid brane is not different from the usual thick domain wall. The use of numerical techniques for solving the equations of the massive modes is useful for matching possible phenomenological measurements in the gravitational law as a probe to warped extra dimensions.
World-volume effective action of exotic five-brane in M-theory
International Nuclear Information System (INIS)
Kimura, Tetsuji; Sasaki, Shin; Yata, Masaya
2016-01-01
We study the world-volume effective action of an exotic five-brane, known as the M-theory 5"3-brane (M5"3-brane) in eleven dimensions. The supermultiplet of the world-volume theory is the N=(2,0) tensor multiplet in six dimensions. The world-volume action contains three Killing vectors k̂_I_̂"M (Î=1,2,3) associated with the U(1)"3 isometry. We find the effective T-duality rule for the eleven-dimensional backgrounds that transforms the M5-brane effective action to that of the M5"3-brane. We also show that our action provides the source term for the M5"3-brane geometry in eleven-dimensional supergravity.
Chasing brane inflation in string theory
International Nuclear Information System (INIS)
Krause, Axel; Pajer, Enrico
2008-01-01
We investigate the embedding of brane–antibrane inflation into a concrete type IIB string theory compactification with all moduli fixed. Specifically, we are considering a D3-brane, whose position represents the inflaton φ, in a warped conifold throat in the presence of supersymmetrically embedded D7-branes and an anti-D3-brane localized at the tip of the warped conifold cone. After presenting the moduli stabilization analysis for a general D7-brane embedding, we concentrate on two explicit models, the Ouyang and the Kuperstein embeddings. We analyze whether the forces induced by moduli stabilization and acting on the D3-brane might be canceled by fine-tuning so as to leave us with the original Coulomb attraction of the anti-D3-brane as the driving force for inflation. For a large class of D7-brane embeddings we obtain a negative result. Cancelations are possible only for very small intervals of φ around an inflection point and not globally. For the most part of its motion the inflaton then feels a steep, non-slow-roll potential. We study the inflationary dynamics induced by this potential
Dimensional reduction for D3-brane moduli
International Nuclear Information System (INIS)
Cownden, Brad; Frey, Andrew R.; Marsh, M.C. David; Underwood, Bret
2016-01-01
Warped string compactifications are central to many attempts to stabilize moduli and connect string theory with cosmology and particle phenomenology. We present a first-principles derivation of the low-energy 4D effective theory from dimensional reduction of a D3-brane in a warped Calabi-Yau compactification of type IIB string theory with imaginary self-dual 3-form flux, including effects of D3-brane motion beyond the probe approximation, and find the metric on the moduli space of brane positions, the universal volume modulus, and axions descending from the 4-form potential. As D3-branes may be considered as carrying either electric or magnetic charges for the self-dual 5-form field strength, we present calculations in both duality frames. Our results are consistent with, but extend significantly, earlier results on the low-energy effective theory arising from D3-branes in string compactifications.
World-volume effective action of exotic five-brane in M-theory
Energy Technology Data Exchange (ETDEWEB)
Kimura, Tetsuji [Research and Education Center for Natural Sciences, Keio University, Hiyoshi 4-1-1, Yokohama, Kanagawa 223-8521 (Japan); Department of Physics, Tokyo Institute of Technology,Tokyo 152-8551 (Japan); Sasaki, Shin [Department of Physics, Kitasato University,Sagamihara 252-0373 (Japan); Yata, Masaya [Department of Physics, National University of Singapore,2, Science Drive 3, Singapore 117542 (Singapore)
2016-02-25
We study the world-volume effective action of an exotic five-brane, known as the M-theory 5{sup 3}-brane (M5{sup 3}-brane) in eleven dimensions. The supermultiplet of the world-volume theory is the N=(2,0) tensor multiplet in six dimensions. The world-volume action contains three Killing vectors k̂{sub Î}{sup M} (Î=1,2,3) associated with the U(1){sup 3} isometry. We find the effective T-duality rule for the eleven-dimensional backgrounds that transforms the M5-brane effective action to that of the M5{sup 3}-brane. We also show that our action provides the source term for the M5{sup 3}-brane geometry in eleven-dimensional supergravity.
A Delicate Universe: Compactification Obstacles to D-brane Inflation
International Nuclear Information System (INIS)
Baumann, Daniel; Dymarsky, Anatoly; McAllister, Liam; Klebanov, Igor R.; Steinhardt, Paul J.
2007-01-01
We investigate whether explicit models of warped D-brane inflation are possible in string compactifications. To this end, we study the potential for D3-brane motion in a warped conifold that includes holomorphically embedded D7-branes involved in moduli stabilization. The presence of the D7-branes significantly modifies the inflaton potential. We construct an example based on a very simple and symmetric embedding due to Kuperstein, z 1 =const, in which it is possible to fine-tune the potential so that slow-roll inflation can occur. The resulting model is rather delicate: inflation occurs in the vicinity of an inflection point, and the cosmological predictions are extremely sensitive to the precise shape of the potential
Bare and effective fluid description in brane world cosmology
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Cruz, Norman [Universidad de Santiago, Departamento de Fisica, Facultad de Ciencia, Casilla 307, Santiago (Chile); Lepe, Samuel; Saavedra, Joel [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Casilla 4950, Valparaiso (Chile); Pena, Francisco [Universidad de La Frontera, Departamento de Ciencias Fisicas, Facultad de Ingenieria, Ciencias y Administracion, Avda. Francisco Salazar 01145, Casilla 54-D, Temuco (Chile)
2010-03-15
An effective fluid description, for a brane world model in five dimensions, is discussed for both signs of the brane tension. We found several cosmological scenarios where the effective equation differs widely from the bare equation of state. For universes with negative brane tension, with a bare fluid satisfying the strong energy condition, the effective fluid can cross the barrier {omega} {sub eff}=-1. (orig.)
Gauge and moduli hierarchy in a multiply warped braneworld scenario
International Nuclear Information System (INIS)
Das, Ashmita; SenGupta, Soumitra
2013-01-01
Discovery of Higgs-like boson near the mass scale ∼126 Gev generates renewed interest to the gauge hierarchy problem in the standard model related to the stabilisation of the Higgs mass within Tev scale without any unnatural fine tuning. One of the successful attempts to resolve this problem has been the Randall–Sundrum warped geometry model. Subsequently this 5-dimensional model was extended to a doubly warped 6-dimensional (or higher) model which can offer a geometric explanation of the fermion mass hierarchy in the standard model of elementary particles (D. Choudhury and S. SenGupta, 2007 [1]). In an attempt to address the dark energy issue, we in this work extend such 6-dimensional warped braneworld model to include non-flat 3-branes at the orbifold fixed points such that a small but non-vanishing brane cosmological constant is induced in our observable brane. We show that the requirements of a Planck to Tev scale warping along with a vanishingly small but non-zero cosmological constant on the visible brane with non-hierarchical moduli, each with scale close to Planck length, lead to a scenario where the 3-branes can have energy scales either close to Tev or close to Planck scale. Such a scenario can address both the gauge hierarchy as well as fermion mass hierarchy problem in standard model without introducing hierarchical scales between the two moduli. Thus simultaneous resolutions to the gauge hierarchy problem, fermion mass hierarchy problem and non-hierarchical moduli problem are closely linked with the near flatness condition of our universe.
Gravity mediation in 6d brane-world supergravity
International Nuclear Information System (INIS)
Lee, H.M.
2005-09-01
We consider the gravity-mediated SUSY breaking within the effective theory of six-dimensional brane-world supergravity. We construct the supersymmetric bulk-brane action by Noether method and find the nontrivial moduli coupling of the brane F- and D-terms. We find that the low energy Kaehler potential is not of sequestered form, so gravity mediation may occur at tree level. In moduli stabilization with anomaly effects included, the scalar soft mass squared can be positive at tree level and it can be comparable to the anomaly mediation. (orig.)
Brane Bremsstrahlung in DBI Inflation
Brax, Philippe
2010-01-01
We consider the effect of trapped branes on the evolution of a test brane whose motion generates DBI inflation along a warped throat. The coupling between the inflationary brane and a trapped brane leads to the radiation of non-thermal particles on the trapped brane. We calculate the Gaussian spectrum of the radiated particles and their backreaction on the DBI motion of the inflationary brane. Radiation occurs for momenta lower than the speed of the test brane when crossing the trapped brane. The slowing down effect is either due to a parametric resonance when the interaction time is small compared to the Hubble time or a tachyonic resonance when the interaction time is large. In both cases the motion of the inflationary brane after the interaction is governed by a chameleonic potential,which tends to slow it down. We find that a single trapped brane can hardly slow down a DBI inflaton whose fluctuations lead to the Cosmic Microwave Background spectrum. A more drastic effect is obtained when the DBI brane enc...
Vacuum thin shells in Einstein–Gauss–Bonnet brane-world cosmology
Ramirez, Marcos A.
2018-04-01
In this paper we construct new solutions of the Einstein–Gauss–Bonnet field equations in an isotropic Shiromizu–Maeda–Sasaki brane-world setting which represent a couple of Z 2-symmetric vacuum thin shells splitting from the central brane, and explore the main properties of the dynamics of the system. The matching of the separating vacuum shells with the brane-world is as smooth as possible and all matter fields are restricted to the brane. We prove the existence of these solutions, derive the criteria for their existence, analyse some fundamental aspects or their evolution and demonstrate the possibility of constructing cosmological examples that exhibit this feature at early times. We also comment on the possible implications for cosmology and the relation of this system with the thermodynamic instability of highly symmetric vacuum solutions of Lovelock theory.
Global black p-brane world: a new approach to stable mass hierarchy
International Nuclear Information System (INIS)
Moon, Sei-Hoon; Rey, Soo-Jong; Kim, Yoonbai
2001-01-01
We find a class of extremal black hole-like global p-brane in higher-dimensional gravity with a negative cosmological constant. The region inside the p-brane horizon possesses all essential features required for the Randall-Sundrum type brane world scenario. The set-up allows to interpret the horizon size as the compactification size in that the Planck scale M Pl is determined by the fundamental scale M * and the horizon size r H via the familiar relation M Pl 2 ∼M * 2+n r H n , and the gravity behaves as expected in a world with n-extra dimensions compactified with size r H . Most importantly, a stable mass hierarchy between M Pl and M * can be generated from topological charge of the p-brane and the horizon size r H therein. We also offer a new perspective on various issues associated to the brane world scenarios including the cosmological constant problem
Bianchi-type II spacetime and anisotropic brane-world cosmology
International Nuclear Information System (INIS)
Sevinc, O.
2010-01-01
Anisotropic generalization of Randall and Sundrum brane-world model is considered. I studied a bulk with an anisotropic space of motion of the brane, depending on both time and extra coordinate. Then I discussed possibility of obtaining the fine-tuning condition of Randall and Sundrum following the method of Andrei V. Frolov (Phys. Lett. B, 514,213).
International Nuclear Information System (INIS)
Davis, Stephen C.; Brechet, Sylvain
2005-01-01
The bubble nucleation rate for a first order phase transition occurring on a brane world is calculated. Both the Coleman-de Luccia thin wall instanton and the Hawking-Moss instanton are considered. The results are compared with the corresponding nucleation rates for standard four-dimensional gravity
Path integral formulation of the Hodge duality on the brane
International Nuclear Information System (INIS)
Hahn, Sang-Ok; Kiem, Youngjai; Kim, Yoonbai; Oh, Phillial
2001-01-01
In the warped compactification with a single Randall-Sundrum brane, a puzzling claim has been made that scalar fields can be bound to the brane but their Hodge dual higher-rank antisymmetric tensors cannot. By explicitly requiring the Hodge duality, a prescription to resolve this puzzle was recently proposed by Duff and Liu. In this Brief Report, we implement the Hodge duality via the path integral formulation in the presence of the background gravity fields of warped compactifications. It is shown that the prescription of Duff and Liu can be naturally understood within this framework
An aniso tropic brane world cosmological model with the bulk-based approach
International Nuclear Information System (INIS)
Uluyazi, G.
2010-01-01
To investigate brane world models there are two approaches; brane-based or bulk based. In the brane-based approach, the brane is chosen to be fixed on a coordinate system, where as in the bulk-based approach it is no longer static as it moves along the extra dimension. At first attempt, it is aimed to solve five dimensional field equations in the bulk, then limitation of Weyl Curvature describing geometrical anisotropy is analyzed.
Thick brane in f(R) gravity with Palatini dynamics
International Nuclear Information System (INIS)
Bazeia, D.; Losano, L.; Menezes, R.; Olmo, Gonzalo J.; Rubiera-Garcia, D.
2015-01-01
This work deals with modified gravity in five-dimensional space-time. We study a thick Palatini f(R) brane, that is, a braneworld scenario described by an anti-de Sitter warped geometry with a single extra dimension of infinite extent, sourced by a real scalar field under the Palatini approach, where the metric and the connection are regarded as independent degrees of freedom. We consider a first-order framework which we use to provide exact solutions for the scalar field and warp factor. We also investigate a perturbative scenario such that the Palatini approach is implemented through a Lagrangian f(R)=R+ϵR n , where the small parameter ϵ controls the deviation from the standard thick brane case. In both cases it is found that the warp factor tends to localize the extra dimension due to the nonlinear corrections
Thick brane in f(R) gravity with Palatini dynamics
Energy Technology Data Exchange (ETDEWEB)
Bazeia, D.; Losano, L. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Menezes, R. [Universidade Federal da Paraiba, Departamento de Ciencias Exatas, Rio Tinto, PB (Brazil); Universidade Federal de Campina Grande, Departamento de Fisica, Campina Grande, PB (Brazil); Olmo, Gonzalo J. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Universidad de Valencia, Departamento de Fisica Teorica, IFIC, Centro Mixto Universidad de Valencia-CSIC, Burjassot, Valencia (Spain); Rubiera-Garcia, D. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Universidade de Lisboa, Faculdade de Ciencias, Instituto de Astrofisica e Ciencias do Espaco, Lisbon (Portugal); Fudan University, Department of Physics, Center for Field Theory and Particle Physics, Shanghai (China)
2015-12-15
This work deals with modified gravity in five-dimensional space-time. We study a thick Palatini f(R) brane, that is, a braneworld scenario described by an anti-de Sitter warped geometry with a single extra dimension of infinite extent, sourced by a real scalar field under the Palatini approach, where the metric and the connection are regarded as independent degrees of freedom. We consider a first-order framework which we use to provide exact solutions for the scalar field and warp factor. We also investigate a perturbative scenario such that the Palatini approach is implemented through a Lagrangian f(R) = R + εR{sup n}, where the small parameter ε controls the deviation from the standard thick brane case. In both cases it is found that the warp factor tends to localize the extra dimension due to the nonlinear corrections. (orig.)
Thick brane in f(R) gravity with Palatini dynamics
Energy Technology Data Exchange (ETDEWEB)
Bazeia, D., E-mail: bazeia@fisica.ufpb.br; Losano, L., E-mail: losano@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, 58051-900, João Pessoa, PB (Brazil); Menezes, R., E-mail: rmenezes@dce.ufpb.br [Departamento de Ciências Exatas, Universidade Federal da Paraíba, 58297-000, Rio Tinto, PB (Brazil); Departamento de Física, Universidade Federal de Campina Grande, 58109-970, Campina Grande, PB (Brazil); Olmo, Gonzalo J., E-mail: gonzalo.olmo@csic.es [Departamento de Física, Universidade Federal da Paraíba, 58051-900, João Pessoa, PB (Brazil); Departamento de Física Teórica, IFIC, Centro Mixto Universidad de Valencia-CSIC, Universidad de Valencia, 46100, Burjassot, Valencia (Spain); Rubiera-Garcia, D., E-mail: drgarcia@fc.ul.pt [Departamento de Física, Universidade Federal da Paraíba, 58051-900, João Pessoa, PB (Brazil); Faculdade de Ciências, Instituto de Astrofísica e Ciências do Espaço, Universidade de Lisboa, Campo Grande, 1749-016, Lisbon (Portugal); Department of Physics, Center for Field Theory and Particle Physics, Fudan University, 220 Handan Road, 200433, Shanghai (China)
2015-11-30
This work deals with modified gravity in five-dimensional space-time. We study a thick Palatini f(R) brane, that is, a braneworld scenario described by an anti-de Sitter warped geometry with a single extra dimension of infinite extent, sourced by a real scalar field under the Palatini approach, where the metric and the connection are regarded as independent degrees of freedom. We consider a first-order framework which we use to provide exact solutions for the scalar field and warp factor. We also investigate a perturbative scenario such that the Palatini approach is implemented through a Lagrangian f(R)=R+ϵR{sup n}, where the small parameter ϵ controls the deviation from the standard thick brane case. In both cases it is found that the warp factor tends to localize the extra dimension due to the nonlinear corrections.
The hoop conjecture and cosmic censorship in the brane-world
Energy Technology Data Exchange (ETDEWEB)
Nakao, Ken-ichi; Nakamura, Kouji; Mishima, Takashi
2003-07-03
The initial data of gravity for a cylindrical matter distribution confined on the brane is studied in the framework of the single brane Randall-Sundrum scenario. We numerically found that the sufficiently thin configuration of matter leads to the formation of the marginal surface on the brane in the Randall-Sundrum model, even if the configuration is infinitely long. This means that the hoop conjecture proposed by Thorne does not hold in the Randall-Sundrum scenario; Even if a mass M does not get compacted into a region whose circumference (C) in every direction is C{approx}<4{pi}GM, black holes with horizons can form on the brane-world of the Randall-Sundrum scenario.
A closer look at two AdS4 branes in an AdS5 bulk
International Nuclear Information System (INIS)
Thambyahpillai, Shiyamala
2005-01-01
We investigate a scenario with two AdS 4 branes in an AdS 5 bulk. In this scenario there are two gravitons and we investigate the role played by each of them for different positions of the second brane. We show that both gravitons play a significant role only when the turn-around point in the warp factor is approximately equidistant from both branes. We find that the ultralight mode becomes heavy as the second brane approaches the turn-around point, and the physics begins to resemble that of the RS model. Thus we demonstrate the crucial role played by the turn-around in the warp factor in enabling the presence of both gravitons. (author)
Classical and quantum aspects of brane-world cosmology
International Nuclear Information System (INIS)
Cordero, Ruben; Rojas, Efrain
2011-01-01
We give a brief overview of several models in brane-world cosmology. In particular, we focus on the asymmetric DGP and Regge-Teiltelboim models. We present the associated equations of motion governing the dynamics of the brane and their corresponding Friedmann-like equations. In order to develop the quantum Regge-Teiltelboim type cosmology we construct its Ostrogradski Hamiltonian formalism which naturally leads to the corresponding Wheeler-DeWitt equation. In addition, we comment on possible generalizations for these models including second order derivative geometrical terms.
Realistic D-brane models on warped throats: Fluxes, hierarchies and moduli stabilization
International Nuclear Information System (INIS)
Cascales, J.F.G.; Garcia del Moral, M.P.; Quevedo, F.; Uranga, A.
2004-01-01
We describe the construction of string theory models with semirealistic spectrum in a sector of (anti) D3-branes located at an orbifold singularity at the bottom of a highly warped throat geometry, which is a generalisation of the Klebanov-Strassler deformed conifold. These models realise the Randall-Sundrum proposal to naturally generate the Planck/electroweak hierarchy in a concrete string theory embedding, and yielding interesting chiral open string spectra. We describe examples with Standard Model gauge group (or left-right symmetric extensions) and three families of SM fermions, with correct quantum numbers including hypercharge. The dilaton and complex structure moduli of the geometry are stabilised by the 3-form fluxes required to build the throat. We describe diverse issues concerning the stabilisation of geometric Kahler moduli, like blow-up modes of the orbifold singularities, via D term potentials and gauge theory non-perturbative effects, like gaugino condensation. This local geometry, once embedded in a full compactification, could give rise to models with all moduli stabilised, and with the potential to lead to de Sitter vacua. Issues of gauge unification, proton stability, supersymmetry breaking and Yukawa couplings are also discussed. (author)
Mannheim, Philip D
2005-01-01
This timely and valuable book provides a detailed pedagogical introduction and treatment of the brane-localized gravity program of Randall and Sundrum, in which gravitational signals are able to localize around our four-dimensional world in the event that it is a brane embedded in an infinitely-sized, higher dimensional anti-de Sitter bulk space. A completely self-contained development of the material needed for brane-world studies is provided for both students and workers in the field, with a significant amount of the material being previously unpublished. Particular attention is given to issues not ordinarily treated in the brane-world literature, such as the completeness of tensor gravitational fluctuation modes, the causality of brane-world propagators, and the status of the massless graviton fluctuation mode in brane worlds in which it is not normalizable.
A varying-α brane world cosmology
International Nuclear Information System (INIS)
Youm, Donam
2001-08-01
We study the brane world cosmology in the RS2 model where the electric charge varies with time in the manner described by the varying fine-structure constant theory of Bekenstein. We map such varying electric charge cosmology to the dual variable-speed-of-light cosmology by changing system of units. We comment on cosmological implications for such cosmological models. (author)
International Nuclear Information System (INIS)
Bergshoeff, E.; Ortin, T.
1998-01-01
We investigate the effective world-volume theories of branes in a background given by (the bosonic sector of) 10-dimensional massive IIA supergravity (''''massive branes'''') and their M-theoretic origin. In the case of the solitonic 5-brane of type IIA superstring theory the construction of the Wess-Zumino term in the world-volume action requires a dualization of the massive Neveu-Schwarz/Neveu-Schwarz target space 2-form field. We find that, in general, the effective world-volume theory of massive branes contains new world-volume fields that are absent in the massless case, i.e. when the mass parameter m of massive IIA supergravity is set to zero. We show how these new world-volume fields can be introduced in a systematic way. (orig.)
Effective theories and black hole production in warped compactifications
International Nuclear Information System (INIS)
Giddings, Steven B.; Katz, Emanuel
2001-01-01
We investigate aspects of the four-dimensional (4D) effective description of brane world scenarios based on warped compactification on anti-de Sitter space. The low-energy dynamics is described by visible matter gravitationally coupled to a ''dark'' conformal field theory. We give the linearized description of the 4D stress tensor corresponding to an arbitrary 5D matter distribution. In particular a 5D falling particle corresponds to a 4D expanding shell, giving a 4D interpretation of a trajectory that misses a black hole only by moving in the fifth dimension. Breakdown of the effective description occurs when either five-dimensional physics or strong gravity becomes important. In scenarios with a TeV brane, the latter can happen through the production of black holes near the TeV scale. This could provide an interesting experimental window on quantum black hole dynamics
International Nuclear Information System (INIS)
Dzhunushaliev, Vladimir; Minamitsuji, Masato; Folomeev, Vladimir
2010-01-01
This paper gives a comprehensive review on thick brane solutions and related topics. Such models have attracted much attention from many aspects since the birth of the brane world scenario. In many works, it has been usually assumed that a brane is an infinitely thin object; however, in more general situations, one can no longer assume this. It is also widely considered that more fundamental theories such as string theory would have a minimal length scale. Many multidimensional field theories coupled to gravitation have exact solutions of gravitating topological defects, which can represent our brane world. The inclusion of brane thickness can realize a variety of possible brane world models. Given our understanding, the known solutions can be classified into topologically non-trivial solutions and trivial ones. The former class contains solutions of a single scalar (domain walls), multi-scalar, gauge-Higgs (vortices), Weyl gravity and so on. As an example of the latter class, we consider solutions of two interacting scalar fields. Approaches to obtain cosmological equations in the thick brane world are reviewed. Solutions with spatially extended branes (S-branes) and those with an extra time-like direction are also discussed.
Origin of a small cosmological constant in a brane world
International Nuclear Information System (INIS)
Ghoroku, Kazuo; Yahiro, Masanobu
2002-01-01
We address the relation between the parameters of an accelerating brane universe embedded in five-dimensional bulk space. It is pointed out that the tiny cosmological constant of our world can be obtained as quantum corrections around a given brane solution in the bulk theory or in the field theory on the boundary from a holographic viewpoint. Some implications to the cosmology and constraints on the parameters are also given
Modified holographic dark energy in DGP brane world
International Nuclear Information System (INIS)
Liu, Dao-Jun; Wang, Hua; Yang, Bin
2010-01-01
In this Letter, the cosmological dynamics of a modified holographic dark energy which is derived from the UV/IR duality by considering the black hole mass in higher dimensions as UV cutoff, is investigated in Dvali-Gabadadze-Porrati (DGP) brane world model. We choose Hubble horizon and future event horizon as IR cutoff respectively. And the two branches of the DGP model are both taken into account. When Hubble horizon is considered as IR cutoff, the modified holographic dark energy (HDE) behaves like an effect dark energy that modification of gravity in pure DGP brane world model acts and it can drive the expansion of the universe speed up at late time in ε=-1 branch which in pure DGP model cannot undergo an accelerating phase. When future event horizon acts as IR cutoff, the equation of state parameter of the modified HDE can cross the phantom divide.
Moduli stabilization in higher dimensional brane models
International Nuclear Information System (INIS)
Flachi, Antonino; Pujolas, Oriol; Garriga, Jaume; Tanaka, Takahiro
2003-01-01
We consider a class of warped higher dimensional brane models with topology M x Σ x S 1 /Z 2 , where Σ is a D2 dimensional manifold. Two branes of co-dimension one are embedded in such a bulk space-time and sit at the orbifold fixed points. We concentrate on the case where an exponential warp factor (depending on the distance along the orbifold) accompanies the Minkowski M and the internal space Σ line elements. We evaluate the moduli effective potential induced by bulk scalar fields in these models, and we show that generically this can stabilize the size of the extra dimensions. As an application, we consider a scenario where supersymmetry is broken not far below the cutoff scale, and the hierarchy between the electroweak and the effective Planck scales is generated by a combination of redshift and large volume effects. The latter is efficient due to the shrinking of Σ at the negative tension brane, where matter is placed. In this case, we find that the effective potential can stabilize the size of the extra dimensions (and the hierarchy) without fine tuning, provided that the internal space Σ is flat. (author)
Moduli stabilization in higher dimensional brane models
Energy Technology Data Exchange (ETDEWEB)
Flachi, Antonino; Pujolas, Oriol [IFAE, Campus UAB, 08193 Bellaterra, Barcelona (Spain)]. E-mail: pujolas@ifae.es; Garriga, Jaume [IFAE, Campus UAB, 08193 Bellaterra, Barcelona (Spain); Departament de Fisica Fonamental and C.E.R. en Astrofisica, Fisica de Particules i Cosmologia Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); Tanaka, Takahiro [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford MA 02155 (United States); Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)
2003-08-01
We consider a class of warped higher dimensional brane models with topology M x {sigma} x S{sup 1}/Z{sub 2}, where {sigma} is a D2 dimensional manifold. Two branes of co-dimension one are embedded in such a bulk space-time and sit at the orbifold fixed points. We concentrate on the case where an exponential warp factor (depending on the distance along the orbifold) accompanies the Minkowski M and the internal space {sigma} line elements. We evaluate the moduli effective potential induced by bulk scalar fields in these models, and we show that generically this can stabilize the size of the extra dimensions. As an application, we consider a scenario where supersymmetry is broken not far below the cutoff scale, and the hierarchy between the electroweak and the effective Planck scales is generated by a combination of redshift and large volume effects. The latter is efficient due to the shrinking of {sigma} at the negative tension brane, where matter is placed. In this case, we find that the effective potential can stabilize the size of the extra dimensions (and the hierarchy) without fine tuning, provided that the internal space {sigma} is flat. (author)
Brane world perspective on the cosmological constant and the hierarchy problems
International Nuclear Information System (INIS)
Flanagan, Eanna; Jones, Nicholas; Stoica, Horace; Tye, S.-H. Henry; Wasserman, Ira
2001-01-01
We elaborate on the recently proposed static brane world scenario, where the effective 4D cosmological constant is exponentially small when parallel 3-branes are far apart. We extend this result to a compactified model with two positive tension branes. In addition to an exponentially small effective 4D cosmological constant, this model incorporates a Randall-Sundrum-like solution to the hierarchy problem. Furthermore, the exponential factors for the hierarchy problem and the cosmological constant problem obey an inequality that is satisfied in nature. This inequality implies that the cosmological constant problem can be explained if the hierarchy problem is understood. The basic idea generalizes to the multibrane world scenario. We discuss models with piecewise adjustable bulk cosmological constants (to be determined by the 5-dimensional Einstein equation), a key element of the scenario. We also discuss the global structure of this scenario and clarify the physical properties of the particle (Rindler) horizons that are present. Finally, we derive a 4D effective theory in which all observers on all branes not separated by particle horizons measure the same Newton's constant and 4D cosmological constant
Supersymmetric 3-branes on smooth ALE manifolds with flux
International Nuclear Information System (INIS)
Bertolini, M.; Campos, V.L.; Ferretti, G.; Fre, P.; Salomonson, P.; Trigiante, M.
2001-01-01
We construct a new family of classical BPS solutions of type IIB supergravity describing 3-branes transverse to a 6-dimensional space with topology R 2 xALE. They are characterized by a non-trivial flux of the supergravity 2-forms through the homology 2-cycles of a generic smooth ALE manifold. Our solutions have two Killing spinors and thus preserve N=2 supersymmetry. They are expressed in terms of a quasi harmonic function H (the 'warp factor'), whose properties we study in the case of the simplest ALE, namely the Eguchi-Hanson manifold. The equation for H is identified as an instance of the confluent Heun equation. We write explicit power series solutions and solve the recurrence relation for the coefficients, discussing also the relevant asymptotic expansions. While, as in all such N=2 solutions, supergravity breaks down near the brane, the smoothing out of the vacuum geometry has the effect that the warp factor is regular in a region near the cycle. We interpret the behavior of the warp factor as describing a three-brane charge 'smeared' over the cycle and consider the asymptotic form of the geometry in that region, showing that conformal invariance is broken even when the complex type IIB 3-form field strength is assumed to vanish. We conclude with a discussion of the basic features of the gauge theory dual
Bulk renormalization and particle spectrum in codimension-two brane worlds
International Nuclear Information System (INIS)
Salvio, Alberto
2013-01-01
We study the Casimir energy due to bulk loops of matter fields in codimension-two brane worlds and discuss how effective field theory methods allow us to use this result to renormalize the bulk and brane operators. In the calculation we explicitly sum over the Kaluza-Klein (KK) states with a new convenient method, which is based on a combined use of zeta function and dimensional regularization. Among the general class of models we consider we include a supersymmetric example, 6D gauged chiral supergravity. Although much of our discussion is more general, we treat in some detail a class of compactifications, where the extra dimensions parametrize a rugby ball shaped space with size stabilized by a bulk magnetic flux. The rugby ball geometry requires two branes, which can host the Standard Model fields and carry both tension and magnetic flux (of the bulk gauge field), the leading terms in a derivative expansion. The brane properties have an impact on the KK spectrum and therefore on the Casimir energy as well as on the renormalization of the brane operators. A very interesting feature is that when the two branes carry exactly the same amount of flux, one half of the bulk supersymmetries survives after the compactification, even if the brane tensions are large. We also discuss the implications of these calculations for the natural value of the cosmological constant when the bulk has two large extra dimensions and the bulk supersymmetry is partially preserved (or completely broken).
Little Randall-Sundrum model and a multiply warped spacetime
International Nuclear Information System (INIS)
McDonald, Kristian L.
2008-01-01
A recent work has investigated the possibility that the mass scale for the ultraviolet (UV) brane in the Randall-Sundrum (RS) model is of the order 10 3 TeV. In this so called 'little Randall-Sundrum' (LRS) model the bounds on the gauge sector are less severe, permitting a lower Kaluza-Klein scale and cleaner discovery channels. However employing a low UV scale nullifies one major appeal of the RS model, namely, the elegant explanation of the hierarchy between the Planck and weak scales. In this work we show that by localizing the gauge, fermion, and scalar sector of the LRS model on a five dimensional slice of a doubly warped spacetime one may obtain the low UV brane scale employed in the LRS model and motivate the weak-Planck hierarchy. We also consider the generalization to an n-warped spacetime
D-brane. Superstrings and new perspective of our world
Energy Technology Data Exchange (ETDEWEB)
Hashimoto, Koji [RIKEN, Saitama, Wako (Japan). Mathematical Physics Lab.
2012-07-01
Superstring theory is a promising theory which can potentially unify all the forces and the matters in particle physics. A new multi-dimensional object which is called ''D-brane'' was found. It drastically changed our perspective of a unified world. We may live on membrane-like hypersurfaces in higher dimensions (''braneworld scenario''), or we can create blackholes at particle accelerators, or the dynamics of quarks is shown to be equivalent to the higher dimensional gravity theory. All these scenarios are explained in this book with plain words but with little use of equations and with many figures. The book starts with a summary of long-standing problems in elementary particle physics and explains the D-branes and many applications of them. It ends with future roads for a unified ultimate theory of our world. (orig.)
Gravitational field equations on and off a 3-brane world
International Nuclear Information System (INIS)
Aliev, A N; Guemruekcueoglu, A E
2004-01-01
The effective gravitational field equations on and off a 3-brane world possessing a Z 2 mirror symmetry and embedded in a five-dimensional bulk spacetime with cosmological constant were derived by Shiromizu, Maeda and Sasaki (SMS) in the framework of the Gauss-Codazzi projective approach with the subsequent specialization to the Gaussian normal coordinates in the neighbourhood of the brane. However, the Gaussian normal coordinates imply a very special slicing of spacetime and clearly, the consistent analysis of the brane dynamics would benefit from complete freedom in the slicing of spacetime, pushing the layer surfaces in the fifth dimension at any rates of evolution and in arbitrary positions. We rederive the SMS effective gravitational field equations on a 3-brane and generalize the off-brane equations to the case where there is an arbitrary energy-momentum tensor in the bulk. We use a more general setting to allow for acceleration of the normals to the brane surface through the lapse function and the shift vector in the spirit of Arnowitt, Deser and Misner. We show that the gravitational influence of the bulk spacetime on the brane may be described by a traceless second-rank tensor W ij , constructed from the 'electric' part of the bulk Riemann tensor. We also present the evolution equations for the tensor W ij , as well as for the corresponding 'magnetic' part of the bulk curvature. These equations involve terms determined by both the nonvanishing acceleration of normals in the nongeodesic slicing of spacetime and the presence of other fields in the bulk
International Nuclear Information System (INIS)
Moura, C.
2009-06-01
This thesis is devoted to the analysis of phenomena based on the presence of extra dimensions and branes, within the framework of supersymmetric theories. We propose an extension of the MSSM (Minimal Supersymmetric Standard Model) motivated by theories containing extra dimensions, in which the gauge sector is extended to form a N = 2 representation of the supersymmetry algebra. We describe how Dirac masses appear naturally for the gauginos in this model, and calculate the interactions and mass matrices of the new the neutralinos and charginos. Then we study, within the framework of 5-dimensional supergravity theories, the coupling of the bulk gravitational fields to the chiral multiplets localized on the branes. This study leads to the introduction of a new off-shell extension of supergravity in 5 dimensions, which is well suited for coupling chiral fields on the branes to the bulk supergravity multiplet in the presence of a general superpotential and non vanishing F-terms vacuum expectation values. The generalized Scherk-Schwarz mechanism and the super-Higgs mechanism are also studied in detail in this class of theories. In particular we describe how the pseudo-Goldstinos appear when the supersymmetry is broken by F-terms on the branes and by a Scherk-Schwarz mechanism in the bulk. We also study possibilities for the identification of the pseudo-Goldstinos with the sterile neutrinos. Finally properties of the gravitino in theories with six dimensions are studied. (author)
A scalar-tensor bimetric brane world cosmology
International Nuclear Information System (INIS)
Youm, Donam
2001-08-01
We study a scalar-tensor bimetric cosmology in the Randall-Sundrum model with one positive tension brane, where the biscalar field is assumed to be confined on the brane. The effective Friedmann equations on the brane are obtained and analyzed. We comment on resolution of cosmological problems in this bimetric model. (author)
Brane-worlds pseudo-Goldstinos
International Nuclear Information System (INIS)
Benakli, Karim; Moura, Cesar
2008-01-01
We consider a space-time with extra dimensions containing sectors, branes and bulk, that communicate only through gravitational interactions. In each sector, if considered separately, supersymmetry could be spontaneously broken, leading to the appearance of Goldstinos. However, when taken all together, only certain combinations of the latter states turn out to be true 'would-be-Goldstinos', eaten by the gravitinos. The other (orthogonal) combinations, we call pseudo-Goldstinos, remain in the low energy spectrum. We discuss explicitly how this happen in the simplest set-up of five-dimensional space compactified on S 1 /Z 2 . Our results divide into two parts that can be considered separately. First, we build an extension of the bulk five-dimensional supergravity, by a set of new auxiliary fields, that allows coupling it to branes where supersymmetry is spontaneously broken. Second, we discuss in details the super-Higgs mechanism in the R ξ and unitary gauges, in the presence of both of a bulk Scherk-Schwarz mechanism and brane localized F-terms. This leads us to compute the gravitino mass and provide explicit formulae for the pseudo-Goldstinos spectrum
Induced cosmological constant in braneworlds with warped internal spaces
International Nuclear Information System (INIS)
Saharian, Aram A.
2006-01-01
We investigate the vacuum energy density induced by quantum fluctuations of a bulk scalar field with general curvature coupling parameter on two codimension one parallel branes in a (D + 1)-dimensional background spacetime AdS D1+1 x Σ with a warped internal space Σ. It is assumed that on the branes the field obeys Robin boundary conditions. Using the generalized zeta function technique in combination with contour integral representations, the surface energies on the branes are presented in the form of the sums of single brane and second brane induced parts. For the geometry of a single brane both regions, on the left (L-region) and on the right (R-region), of the brane are considered. The surface densities for separate L- and R-regions contain pole and finite contributions. For an infinitely thin brane taking these regions together, in odd spatial dimensions the pole parts cancel and the total surface energy is finite. The parts in the surface densities generated by the presence of the second brane are finite for all nonzero values of the interbrane separation. The contribution of the Kaluza-Klein modes along Σ is investigated in various limiting cases. It is shown that for large distances between the branes the induced surface densities give rise to an exponentially suppressed cosmological constant on the brane. In the higher dimensional generalization of the Randall-Sundrum braneworld model, for the interbrane distances solving the hierarchy problem, the cosmological constant generated on the visible brane is of the right order of magnitude with the value suggested by the cosmological observations. (author)
Effective theory of brane world with small tension
Hisano, Junji; Okada, Nobuchika
2000-05-01
The five dimensional theory compactified on S1 with two ``branes'' (two domain walls) embedded in it is constructed, based on the field-theoretic mechanism to generate the ``brane.'' Some light states localized in the ``brane'' appear in the theory. One is the Nambu-Goldstone boson, which corresponds to the breaking of the translational invariance in the transverse direction of the ``brane.'' In addition, if the tension of the ``brane'' is smaller than the fundamental scale of the original theory, it is found that there may exist not only massless states but also some massive states lighter than the fundamental scale in the ``brane.'' We analyze the four dimensional effective theory by integrating out the freedom of the fifth dimension. We show that some effective couplings can be explicitly calculated. As one of our results, some effective couplings of the state localized in the ``brane'' to the higher Kaluza-Klein modes in the bulk are found to be suppressed by the width of the ``brane.'' The resultant suppression factor can be quantitatively different from the one analyzed by Bando et al. using the Nambu-Goto action, while they are qualitatively the same.
Brane-world motion in compact dimensions
Greene, Brian; Levin, Janna; Parikh, Maulik
2011-08-01
The topology of extra dimensions can break global Lorentz invariance, singling out a globally preferred frame even in flat spacetime. Through experiments that probe global topology, an observer can determine her state of motion with respect to the preferred frame. This scenario is realized if we live on a brane universe moving through a flat space with compact extra dimensions. We identify three experimental effects due to the motion of our universe that one could potentially detect using gravitational probes. One of these relates to the peculiar properties of the twin paradox in multiply-connected spacetimes. Another relies on the fact that the Kaluza-Klein modes of any bulk field are sensitive to boundary conditions. A third concerns the modification to the Newtonian potential on a moving brane. Remarkably, we find that even small extra dimensions are detectable by brane observers if the brane is moving sufficiently fast. Communicated by P R L V Moniz
Fractional Branes and Dynamical Supersymmetry Breaking
Franco, S; Saad, F; Uranga, Angel M; Franco, Sebastian; Hanany, Amihay; Saad, Fouad; Uranga, Angel M.
2006-01-01
We study the dynamics of fractional branes at toric singularities, including cones over del Pezzo surfaces and the recently constructed Y^{p,q} theories. We find that generically the field theories on such fractional branes show dynamical supersymmetry breaking, due to the appearance of non-perturbative superpotentials. In special cases, one recovers the known cases of supersymmetric infrared behaviors, associated to SYM confinement (mapped to complex deformations of the dual geometries, in the gauge/string correspondence sense) or N=2 fractional branes. In the supersymmetry breaking cases, when the dynamics of closed string moduli at the singularity is included, the theories show a runaway behavior (involving moduli such as FI terms or equivalently dibaryonic operators), rather than stable non-supersymmetric minima. We comment on the implications of this gauge theory behavior for the infrared smoothing of the dual warped throat solutions with 3-form fluxes, describing duality cascades ending in such field th...
Gravity on a little warped space
International Nuclear Information System (INIS)
George, Damien P.; McDonald, Kristian L.
2011-01-01
We investigate the consistent inclusion of 4D Einstein gravity on a truncated slice of AdS 5 whose bulk-gravity and UV scales are much less than the 4D Planck scale, M * Pl . Such 'Little Warped Spaces' have found phenomenological utility and can be motivated by string realizations of the Randall-Sundrum framework. Using the interval approach to brane-world gravity, we show that the inclusion of a large UV-localized Einstein-Hilbert term allows one to consistently incorporate 4D Einstein gravity into the low-energy theory. We detail the spectrum of Kaluza-Klein metric fluctuations and, in particular, examine the coupling of the little radion to matter. Furthermore, we show that Goldberger-Wise stabilization can be successfully implemented on such spaces. Our results demonstrate that realistic low-energy effective theories can be constructed on these spaces, and have relevance for existing models in the literature.
Warped Extra-Dimensional Opportunities and Signatures (1/3)
CERN. Geneva
2008-01-01
I plan to discuss ways of searching for warped geometry and other extra-dimensional scenarios, with emphasis on the general lessons for search strategies. We will consider RS geometry on the brane and in the bulk, as well as possible black hole or quantum gravity signatures. If time permits, we will also consider fermion masses and/or precision Higgs measurements.
Warped Extra-Dimensional Opportunities and Signatures (3/3)
CERN. Geneva
2008-01-01
I plan to discuss ways of searching for warped geometry and other extra-dimensional scenarios, with emphasis on the general lessons for search strategies. We will consider RS geometry on the brane and in the bulk, as well as possible black hole or quantum gravity signatures. If time permits, we will also consider fermion masses and/or precision Higgs measurements.
Warped Extra-Dimensional Opportunities and Signatures (2/3)
CERN. Geneva
2008-01-01
I plan to discuss ways of searching for warped geometry and other extra-dimensional scenarios, with emphasis on the general lessons for search strategies. We will consider RS geometry on the brane and in the bulk, as well as possible black hole or quantum gravity signatures. If time permits, we will also consider fermion masses and/or precision Higgs measurements.
International Nuclear Information System (INIS)
Okuda, Takuya; Takayanagi, Tadashi
2006-01-01
We define a ghost D-brane in superstring theories as an object that cancels the effects of an ordinary D-brane. The supergroups U(N|M) and OSp(N/M) arise as gauge symmetries in the supersymmetric world-volume theory of D-branes and ghost D-branes. A system with a pair of D-brane and ghost D-brane located at the same location is physically equivalent to the closed string vacuum. When they are separated, the system becomes a new brane configuration. We generalize the type I/heterotic duality by including n ghost D9-branes on the type I side and by considering the heterotic string whose gauge group is OSp(32+2n/2n). Motivated by the type IIB S-duality applied to D9- and ghost D9-branes, we also find type II-like closed superstrings with U(n/n) gauge symmetry
k-essence in the DGP brane-world cosmology
International Nuclear Information System (INIS)
Bouhmadi-Lopez, Mariam; Chimento, Luis P.
2010-01-01
We analyze a Dvali-Gabadadze-Porrati (DGP) brane filled with a k-essence field and assume the k field evolving linearly with the cosmic time of the brane. We then solve analytically the Friedmann equation and deduce the different behavior of the brane at the low- and the high-energy regimes. The asymptotic behavior can be quite different involving accelerating branes, big bangs, big crunches, big rips, or quiescent singularities. The latter correspond to a type of sudden singularity.
Transport coefficients of black MQGP -branes
Dhuria, Mansi; Misra, Aalok
2015-01-01
The Strominger-Yau-Zaslow (SYZ) mirror, in the `delocalised limit' of Becker et al. (Nucl Phys B 702:207, 2004), of -branes, fractional -branes and flavour -branes wrapping a non-compact four-cycle in the presence of a black hole (BH) resulting in a non-Kähler resolved warped deformed conifold (NKRWDC) in Mia et al. (Nucl Phys B 839:187, 2010), was carried out in Dhuria and Misra (JHEP 1311:001, 2013) and resulted in black -branes. There are two parts in our paper. In the first we show that in the `MQGP' limit discussed in Dhuria and Misra (JHEP 1311:001, 2013) a finite (and hence expected to be more relevant to QGP), finite and very large , and very small , we have the following. (i) The uplift, if valid globally (like Dasgupta et al., Nucl Phys B 755:21, 2006) for fractional branes in conifolds), asymptotically goes to -branes wrapping a two-cycle (homologously a (large) integer sum of two-spheres) in . (ii) Assuming the deformation parameter to be larger than the resolution parameter, by estimating the five structure torsion () classes we verify that in the large- limit, implying the NKRWDC reduces to a warped Kähler deformed conifold. (iii) The local of Dhuria and Misra (JHEP 1311:001, 2013) in the large- limit satisfies the same conditions as the maximal -invariant special Lagrangian three-cycle of of Ionel and Min-OO (J Math 52(3), 2008), partly justifying use of SYZ-mirror symmetry in the `delocalised limit' of Becker et al. (Nucl Phys B 702:207, 2004) in Dhuria and Misra (JHEP 1311:001, 2013). In the second part of the paper, by either integrating out the angular coordinates of the non-compact four-cycle which a -brane wraps around, using the Ouyang embedding, in the DBI action of a -brane evaluated at infinite radial boundary, or by dimensionally reducing the 11-dimensional EH action to five () dimensions and at the infinite radial boundary, we then calculate in particular the (part of the 'MQGP') limit, a variety of gauge and metric
Dynamical study of DBI-essence in loop quantum cosmology and brane world
International Nuclear Information System (INIS)
Bhadra, Jhumpa; Debnath, Ujjal
2012-01-01
We have studied homogeneous isotropic FRW model having dynamical dark energy DBI-essence with scalar field. Existence of cosmological scaling solutions restricts the Lagrangian of the scalar field φ. Choosing p=Xg(Xe λφ ), where X=-g μν ∂ μ φ∂ ν φ/2 with g any function of Xe λφ and defining some suitable transformations, we have constructed the dynamical system in different models of gravity: (i) Loop Quantum Cosmology (LQC), (ii) DGP brane world and (iii) RS II brane world. We have investigated stability of this dynamical system around the critical point for three gravity models and investigated the scalar-field dominated attractor solution in support of accelerated universe. The roles of the physical parameters have also been shown graphically during the accelerating phase of the universe. (orig.)
The cosmological constant in the brane world of string theory on S{sup 1}/Z{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Wang Anzhong [GCAP-CASPER, Department of Physics, Baylor University, Waco, TX 76798-7316 (United States); Department of Theoretical Physics, State University of Rio de Janeiro, RJ (Brazil); LERMA/CNRS-FRE 2460, Universite Pierre et Marie Curie, ERGA, Boite 142, 4 Place Jussieu, 75005 Paris cedex 05 (France)], E-mail: anzhong_wang@baylor.edu; Santos, N.O. [LERMA/CNRS-FRE 2460, Universite Pierre et Marie Curie, ERGA, Boite 142, 4 Place Jussieu, 75005 Paris cedex 05 (France); School of Mathematical Sciences, Queen Mary, University of London, London E1 4NS (United Kingdom); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil)
2008-11-06
Orbifold branes in string theory are investigated, and the general field equations both outside and on the branes are given explicitly for type II and heterotic string. The radion stability is studied using the Goldberger-Wise mechanism, and shown explicitly that it is stable. It is also found that the effective cosmological constant on each of the two branes can be easily lowered to its current observational value, using large extra dimensions. This is also true for type I string. Therefore, brane world of string theory provides a viable and built-in mechanism for solving the long-standing cosmological constant problem. Applying the formulas to cosmology, we obtain the generalized Friedmann equations on the branes.
D-brane anti-D-brane system in string theory
Hyakutake, Y
2003-01-01
In this paper, we review a system of D-brane and anti-D-brane in type II superstring theories. [A. Sen, hep-th/9904207 and references there in; Y.Hyakutake, Master-Th., Doctor-Th. (in Japanese)] This system is unstable an tachyonic modes, which have negative mass squared, appear from open strings between D-brane and anti-D-brane. The effective field theory on the world-volume is described by U(1) x U(1) gauge theory with a complex tachyon field. Since the mass squared of the techyon field is negative, a tachyon potential would be like a wine bottle. In order to make the system stable, the tachyon rolls down the potential and gets some vacuum expectation value. This is called the tachyon condensation mechanism. During this mechanism, Dp-brane and anti-Dp-brane annihilate completely, if we admit Sen's conjecture. The suspicions between tachyon condensation and Hawking radiation are also discussed. (author)
Dynamical study of DBI-essence in loop quantum cosmology and brane world
Energy Technology Data Exchange (ETDEWEB)
Bhadra, Jhumpa; Debnath, Ujjal [Bengal Engineering and Science University, Department of Mathematics, Howrah (India)
2012-08-15
We have studied homogeneous isotropic FRW model having dynamical dark energy DBI-essence with scalar field. Existence of cosmological scaling solutions restricts the Lagrangian of the scalar field {phi}. Choosing p=Xg(Xe{sup {lambda}{phi}}), where X=-g {sup {mu}{nu}}{partial_derivative}{sub {mu}}{phi}{partial_derivative}{sub {nu}}{phi}/2 with g any function of Xe{sup {lambda}{phi}} and defining some suitable transformations, we have constructed the dynamical system in different models of gravity: (i) Loop Quantum Cosmology (LQC), (ii) DGP brane world and (iii) RS II brane world. We have investigated stability of this dynamical system around the critical point for three gravity models and investigated the scalar-field dominated attractor solution in support of accelerated universe. The roles of the physical parameters have also been shown graphically during the accelerating phase of the universe. (orig.)
International Nuclear Information System (INIS)
Cai, R.
1997-01-01
By investigating the critical behavior appearing at the extremal limit of the nondilatonic, black p-branes in (d+p) dimensions, we find that some critical exponents related to the critical point obey the scaling laws. From the scaling laws we obtain that the effective spatial dimension of the nondilatonic black holes and black strings is one, and is p for the nondilatonic black p-branes. For the dilatonic black holes and black p-branes, the effective dimension will depend on the parameters in theories. Thus, we give an interpretation why the Bekenstein-Hawking entropy may be given a simple world volume interpretation only for the nondilatonic black p-branes. copyright 1997 The American Physical Society
Inflationary scenario from higher curvature warped spacetime
International Nuclear Information System (INIS)
Banerjee, Narayan; Paul, Tanmoy
2017-01-01
We consider a five dimensional warped spacetime, in presence of the higher curvature term like F(R) = R + αR 2 in the bulk, in the context of the two-brane model. Our universe is identified with the TeV scale brane and emerges as a four dimensional effective theory. From the perspective of this effective theory, we examine the possibility of ''inflationary scenario'' by considering the on-brane metric ansatz as an FRW one. Our results reveal that the higher curvature term in the five dimensional bulk spacetime generates a potential term for the radion field. Due to the presence of radion potential, the very early universe undergoes a stage of accelerated expansion and, moreover, the accelerating period of the universe terminates in a finite time. We also find the spectral index of curvature perturbation (n s ) and the tensor to scalar ratio (r) in the present context, which match with the observational results based on the observations of Planck (Astron. Astrophys. 594, A20, 2016). (orig.)
Inflationary scenario from higher curvature warped spacetime
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Narayan [Indian Institute of Science Education and Research Kolkata, Department of Physical Sciences, Nadia, West Bengal (India); Paul, Tanmoy [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)
2017-10-15
We consider a five dimensional warped spacetime, in presence of the higher curvature term like F(R) = R + αR{sup 2} in the bulk, in the context of the two-brane model. Our universe is identified with the TeV scale brane and emerges as a four dimensional effective theory. From the perspective of this effective theory, we examine the possibility of ''inflationary scenario'' by considering the on-brane metric ansatz as an FRW one. Our results reveal that the higher curvature term in the five dimensional bulk spacetime generates a potential term for the radion field. Due to the presence of radion potential, the very early universe undergoes a stage of accelerated expansion and, moreover, the accelerating period of the universe terminates in a finite time. We also find the spectral index of curvature perturbation (n{sub s}) and the tensor to scalar ratio (r) in the present context, which match with the observational results based on the observations of Planck (Astron. Astrophys. 594, A20, 2016). (orig.)
Brane-world extra dimensions in light of GW170817
Visinelli, Luca; Bolis, Nadia; Vagnozzi, Sunny
2018-03-01
The search for extra dimensions is a challenging endeavor to probe physics beyond the Standard Model. The joint detection of gravitational waves (GW) and electromagnetic (EM) signals from the merging of a binary system of compact objects like neutron stars can help constrain the geometry of extra dimensions beyond our 3 +1 spacetime ones. A theoretically well-motivated possibility is that our observable Universe is a 3 +1 -dimensional hypersurface, or brane, embedded in a higher 4 +1 -dimensional anti-de Sitter (AdS5 ) spacetime, in which gravity is the only force which propagates through the infinite bulk space, while other forces are confined to the brane. In these types of brane-world models, GW and EM signals between two points on the brane would, in general, travel different paths. This would result in a time lag between the detection of GW and EM signals emitted simultaneously from the same source. We consider the recent near-simultaneous detection of the GW event GW170817 from the LIGO/Virgo collaboration, and its EM counterpart, the short gamma-ray burst GRB170817A detected by the Fermi Gamma-ray Burst Monitor and the International Gamma-Ray Astrophysics Laboratory Anti-Coincidence Shield spectrometer. Assuming the standard Λ -cold dark matter scenario and performing a likelihood analysis which takes into account astrophysical uncertainties associated to the measured time lag, we set an upper limit of ℓ≲0.535 Mpc at 68% confidence level on the AdS5 radius of curvature ℓ. Although the bound is not competitive with current Solar System constraints, it is the first time that data from a multimessenger GW-EM measurement is used to constrain extra-dimensional models. Thus, our work provides a proof of principle for the possibility of using multimessenger astronomy for probing the geometry of our space-time.
International Nuclear Information System (INIS)
Brecher, D.; Perry, M.J.
2000-01-01
Up to overall harmonic factors, the D8-brane solution of the massive type IIA supergravity theory is the product of nine-dimensional Minkowski space (the world-volume) with the real line (the transverse space). We show that the equations of motion allow for the world-volume metric to be generalised to an arbitrary Ricci-flat one. If this nine-dimensional Ricci-flat manifold admits Killing spinors, then the resulting solutions are supersymmetric and satisfy the usual Bogomol'nyi bound, although they preserve fewer than the usual one half of the supersymmetries. We describe the possible choices of such manifolds, elaborating on the connection between the existence of Killing spinors and the self-duality condition on the curvature two-form. Since the D8-brane is a domain wall in ten dimensions, we are led to consider the general case: domain walls in any supergravity theory. Similar considerations hold here also. Moreover, it is shown that the world-volume of any magnetic brane - of which the domain walls are a specific example - can be generalised in precisely the same way. The general class of supersymmetric solutions have gravitational instantons as their spatial sections. Some mention is made of the world-volume solitons of such branes
Gravitons in multiply warped scenarios: At 750 GeV and beyond
Indian Academy of Sciences (India)
Mathew Thomas Arun
2017-06-05
Jun 5, 2017 ... the parameter space that can be probed at the 14 TeV run of the LHC. We also ... attempted a RS-graviton interpretation (in a later update, ... The remainder of this paper is organized as follows: ... Six dimensions, four branes and nested warping ..... problem at hand, the construction presented below is.
Nonlinear Gravitational Waves as Dark Energy in Warped Spacetimes
Directory of Open Access Journals (Sweden)
Reinoud Jan Slagter
2017-02-01
Full Text Available We find an azimuthal-angle dependent approximate wave like solution to second order on a warped five-dimensional manifold with a self-gravitating U(1 scalar gauge field (cosmic string on the brane using the multiple-scale method. The spectrum of the several orders of approximation show maxima of the energy distribution dependent on the azimuthal-angle and the winding numbers of the subsequent orders of the scalar field. This breakup of the quantized flux quanta does not lead to instability of the asymptotic wavelike solution due to the suppression of the n-dependency in the energy momentum tensor components by the warp factor. This effect is triggered by the contribution of the five dimensional Weyl tensor on the brane. This contribution can be understood as dark energy and can trigger the self-acceleration of the universe without the need of a cosmological constant. There is a striking relation between the symmetry breaking of the Higgs field described by the winding number and the SO(2 breaking of the axially symmetric configuration into a discrete subgroup of rotations of about 180 ∘ . The discrete sequence of non-axially symmetric deviations, cancelled by the emission of gravitational waves in order to restore the SO(2 symmetry, triggers the pressure T z z for discrete values of the azimuthal-angle. There could be a possible relation between the recently discovered angle-preferences of polarization axes of quasars on large scales and our theoretical predicted angle-dependency and this could be evidence for the existence of cosmic strings. Careful comparison of this spectrum of extremal values of the first and second order φ-dependency and the distribution of the alignment of the quasar polarizations is necessary. This can be accomplished when more observational data become available. It turns out that, for late time, the vacuum 5D spacetime is conformally invariant if the warp factor fulfils the equation of a vibrating
Higher-dimensional bulk wormholes and their manifestations in brane worlds
International Nuclear Information System (INIS)
Rodrigo, Enrico
2006-01-01
There is nothing to prevent a higher-dimensional anti-de Sitter bulk spacetime from containing various other branes in addition to hosting our universe, presumed to be a positive-tension 3-brane. In particular, it could contain closed, microscopic branes that form the boundary surfaces of void bubbles and thus violate the null energy condition in the bulk. The possible existence of such micro branes can be investigated by considering the properties of the ground state of a pseudo-Wheeler-DeWitt equation describing brane quantum dynamics in minisuperspace. If they exist, a concentration of these micro branes could act as a fluid of exotic matter able to support macroscopic wormholes connecting otherwise-distant regions of the bulk. Were the brane constituting our universe to expand into a region of the bulk containing such higher-dimensional macroscopic wormholes, they would likely manifest themselves in our brane as wormholes of normal dimensionality, whose spontaneous appearance and general dynamics would seem inexplicably peculiar. This encounter could also result in the formation of baby universes of a particular type
The goldstino brane, the constrained superfields and matter in N=1 supergravity
International Nuclear Information System (INIS)
Bandos, Igor; Heller, Markus; Kuzenko, Sergei M.; Martucci, Luca; Sorokin, Dmitri
2016-01-01
We show that different (brane and constrained superfield) descriptions for the Volkov-Akulov goldstino coupled to N=1, D=4 supergravity with matter produce similar wide classes of models with spontaneously broken local supersymmetry and discuss the relation between the different formulations. As with the formulations with irreducible constrained superfields, the geometric goldstino brane approach has the advantage of being manifestly off-shell supersymmetric without the need to introduce auxiliary fields. It provides an explicit solution of the nilpotent superfield constraints and avoids issues with non-Gaussian integration of auxiliary fields. We describe general couplings of the supersymmetry breaking sector, including the goldstino and other non-supersymmetric matter, to supergravity and matter supermultiplets. Among various examples, we discuss a goldstino brane contribution to the gravitino mass term and the supersymmetrization of the anti-D3-brane contribution to the effective theory of type IIB warped flux compactifications.
The goldstino brane, the constrained superfields and matter in N=1 supergravity
Energy Technology Data Exchange (ETDEWEB)
Bandos, Igor [Department of Theoretical Physics, University of the Basque Country UPV/EHU,P.O. Box 644, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science,48011, Bilbao (Spain); Heller, Markus [Dipartimento di Fisica e Astronomia “Galileo Galilei' , Università degli Studi di Padova,Via Marzolo 8, 35131 Padova (Italy); Institut für Theoretische Physik, Ruprecht-Karls-Universität,Philosophenweg 19, 69120 Heidelberg (Germany); Kuzenko, Sergei M. [School of Physics M013, The University of Western Australia35 Stirling Highway, Crawley W.A. 6009 (Australia); Martucci, Luca [Dipartimento di Fisica e Astronomia “Galileo Galilei' , Università degli Studi di Padova,Via Marzolo 8, 35131 Padova (Italy); INFN - Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy); Sorokin, Dmitri [INFN - Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy); Dipartimento di Fisica e Astronomia “Galileo Galilei' , Università degli Studi di Padova,Via Marzolo 8, 35131 Padova (Italy)
2016-11-21
We show that different (brane and constrained superfield) descriptions for the Volkov-Akulov goldstino coupled to N=1, D=4 supergravity with matter produce similar wide classes of models with spontaneously broken local supersymmetry and discuss the relation between the different formulations. As with the formulations with irreducible constrained superfields, the geometric goldstino brane approach has the advantage of being manifestly off-shell supersymmetric without the need to introduce auxiliary fields. It provides an explicit solution of the nilpotent superfield constraints and avoids issues with non-Gaussian integration of auxiliary fields. We describe general couplings of the supersymmetry breaking sector, including the goldstino and other non-supersymmetric matter, to supergravity and matter supermultiplets. Among various examples, we discuss a goldstino brane contribution to the gravitino mass term and the supersymmetrization of the anti-D3-brane contribution to the effective theory of type IIB warped flux compactifications.
International Nuclear Information System (INIS)
Csaki, Csaba; Erlich, Joshua; Grojean, Christophe
2001-01-01
Brane worlds are theories with extra spatial dimensions in which ordinary matter is localized on a (3+1) dimensional submanifold. Such theories could have interesting consequences for particle physics and gravitational physics. In this essay we concentrate on the cosmological constant (CC) problem in the context of brane worlds. We show how extra-dimensional scenarios may violate Lorentz invariance in the gravity sector of the effective 4D theory, while particle physics remains unaffected. In such theories the usual no-go theorems for adjustment of the CC do not apply, and we indicate a possible explanation of the smallness of the CC. Lorentz violating effects would manifest themselves in gravitational waves travelling with a speed different from light, which can be searched for in gravitational wave experiments
Electromagnetic force on a brane
International Nuclear Information System (INIS)
Li, Li-Xin
2016-01-01
A fundamental assumption in the theory of brane world is that all matter and radiation are confined on the four-dimensional brane and only gravitons can propagate in the five-dimensional bulk spacetime. The brane world theory did not provide an explanation for the existence of electromagnetic fields and the origin of the electromagnetic field equation. In this paper, we propose a model for explaining the existence of electromagnetic fields on a brane and deriving the electromagnetic field equation. Similar to the case in Kaluza–Klein theory, we find that electromagnetic fields and the electromagnetic field equation can be derived from the five-dimensional Einstein field equation. However, the derived electromagnetic field equation differs from the Maxwell equation by containing a term with the electromagnetic potential vector coupled to the spacetime curvature tensor. So it can be considered as generalization of the Maxwell equation in a curved spacetime. The gravitational field equation on the brane is also derived with the stress–energy tensor for electromagnetic fields explicitly included and the Weyl tensor term explicitly expressed with matter fields and their derivatives in the direction of the extra-dimension. The model proposed in the paper can be regarded as unification of electromagnetic and gravitational interactions in the framework of brane world theory. (paper)
Quantum fluctuations in brane-world inflation without an inflaton on the brane
International Nuclear Information System (INIS)
Sago, Norichika; Himemoto, Yoshiaki; Sasaki, Misao
2002-01-01
A Randall-Sundrum-type brane-cosmological model in which slow-roll inflation on the brane is driven solely by a bulk scalar field was recently proposed by Himemoto and Sasaki. We analyze their model in detail and calculate the quantum fluctuations of the bulk scalar field φ with m 2 =V '' (φ). We decompose the bulk scalar field into the infinite mass spectrum of four-dimensional fields; the field with the smallest mass square, called the zero mode, and the Kaluza-Klein modes above it with a mass gap. We find the zero-mode dominance of the classical solution holds if vertical bar m 2 vertical bar l-bar 2 2 vertical bar l-bar2>>1, though the violation is very small. Then we evaluate the vacuum expectation value 2 > on the brane. We find the zero-mode contribution completely dominates if vertical bar m 2 vertical barl-bar 2 2 vertical barl-bar 2 is large
Effective action and brane running
International Nuclear Information System (INIS)
Brevik, Iver; Ghoroku, Kazuo; Yahiro, Masanobu
2004-01-01
We address the renormalized effective action for a Randall-Sundrum brane running in 5D bulk space. The running behavior of the brane action is obtained by shifting the brane position without changing the background and fluctuations. After an appropriate renormalization, we obtain an effective, low energy brane world action, in which the effective 4D Planck mass is independent of the running position. We address some implications for this effective action
Generalized Israel junction conditions for a Gauss-Bonnet brane world
International Nuclear Information System (INIS)
Davis, Stephen C.
2003-01-01
In spacetimes of dimension greater than four it is natural to consider higher order (in R) corrections to the Einstein equations. In this paper generalized Israel junction conditions for a membrane in such a theory are derived. This is achieved by generalizing the Gibbons-Hawking boundary term. The junction conditions are applied to simple brane world models, and are compared to the many contradictory results in the literature
Warped AdS{sub 6}×S{sup 2} in Type IIB supergravity II: global solutions and five-brane webs
Energy Technology Data Exchange (ETDEWEB)
D’Hoker, Eric; Gutperle, Michael; Uhlemann, Christoph F. [Mani L. Bhaumik Institute for Theoretical Physics,Department of Physics and Astronomy, University of California Los Angeles,475 Portola Plaza, Los Angeles, CA 90095 (United States)
2017-05-23
Motivated by the construction of holographic duals to five-dimensional superconformal quantum field theories, we obtain global solutions to Type IIB supergravity invariant under the superalgebra F(4) on a space-time of the form AdS{sub 6}×S{sup 2} warped over a two-dimensional Riemann surface Σ. In earlier work, the general local solutions were expressed in terms of two locally holomorphic functions A{sub ±} on Σ and global solutions were sketched when Σ is a disk. In the present paper, the physical regularity conditions on the supergravity fields required for global solutions are implemented on A{sub ±} for arbitrary Σ. Global solutions exist only when Σ has a non-empty boundary ∂Σ. The differentials ∂A{sub ±} are allowed to have poles only on ∂Σ and each pole corresponds to a semi-infinite (p,q) five-brane. The construction for the disk is carried out in detail and the conditions for the existence of global solutions are articulated for surfaces with more than one boundary and higher genus.
Corrections to Newton’s law of gravitation - application to hybrid Bloch brane
Almeida, C. A. S.; Veras, D. F. S.; Dantas, D. M.
2018-02-01
We present in this work, the calculations of corrections in the Newton’s law of gravitation due to Kaluza-Klein gravitons in five-dimensional warped thick braneworld scenarios. We consider here a recently proposed model, namely, the hybrid Bloch brane. This model couples two scalar fields to gravity and is engendered from a domain wall-like defect. Also, two other models the so-called asymmetric hybrid brane and compact brane are considered. Such models are deformations of the ϕ 4 and sine-Gordon topological defects, respectively. Therefore we consider the branes engendered by such defects and we also compute the corrections in their cases. In order to attain the mass spectrum and its corresponding eigenfunctions which are the essential quantities for computing the correction to the Newtonian potential, we develop a suitable numerical technique. The calculation of slight deviations in the gravitational potential may be used as a selection tool for braneworld scenarios matching with future experimental measurements in high energy collisions
Quantum self-consistency of AdSxΣ brane models
International Nuclear Information System (INIS)
Flachi, Antonino; Pujolas, Oriol
2003-01-01
Continuing our previous work, we consider a class of higher dimensional brane models with the topology of AdS D 1 +1 xΣ, where Σ is a one-parameter compact manifold and two branes of codimension one are located at the orbifold fixed points. We consider a setup where such a solution arises from Einstein-Yang-Mills theory and evaluate the one-loop effective potential induced by gauge fields and by a generic bulk scalar field. We show that this type of brane model resolves the gauge hierarchy between the Planck and electroweak scales through redshift effects due to the warp factor a=e -πkr . The value of a is then fixed by minimizing the effective potential. We find that, as in the Randall-Sundrum case, the gauge field contribution to the effective potential stabilizes the hierarchy without fine-tuning as long as the Laplacian Δ Σ on Σ has a zero eigenvalue. Scalar fields can stabilize the hierarchy depending on the mass and the nonminimal coupling. We also address the quantum self-consistency of the solution, showing that the classical brane solution is not spoiled by quantum effects
Nonlinear viscosity in brane-world cosmology with a Gauss–Bonnet term
Debnath, P. S.; Beesham, A.; Paul, B. C.
2018-06-01
Cosmological solutions are obtained with nonlinear bulk viscous cosmological fluid in the Randall–Sundrum type II (RS) brane-world model with or without Gauss–Bonnet (GB) terms. To describe such a viscous fluid, we consider the nonlinear transport equation which may be used far from equilibrium during inflation or reheating. Cosmological models are explored for both (i) power law and (ii) exponential evolution of the early universe in the presence of an imperfect fluid described by the non-linear Israel and Stewart theory (nIS). We obtain analytic solutions and the complex field equations are also analyzed numerically to study the evolution of the universe. The stability analysis of the equilibrium points of the dynamical system associated with the evolution of the nonlinear bulk viscous fluid in the RS Brane in the presence (or absence) of a GB term are also studied.
Seesaw mechanism in warped geometry
International Nuclear Information System (INIS)
Huber, Stephan J.; Shafi, Qaisar
2004-01-01
We show how the seesaw mechanism for neutrino masses can be realized within a five-dimensional (5D) warped geometry framework. Intermediate scale standard model (SM) singlet neutrino masses, needed to explain the atmospheric and solar neutrino oscillations, are shown to be proportional to M Pl exp((2c-1)πkR), where c denotes the coefficient of the 5D Dirac mass term for the singlet neutrino which also has a Planck scale Majorana mass localized on the Planck-brane, and kR∼11 in order to resolve the gauge hierarchy problem. The case with a bulk 5D Majorana mass term for the singlet neutrino is briefly discussed
International Nuclear Information System (INIS)
Schwarz, J. H.
1998-01-01
BPS saturated p-branes play an important role in recent progress in understanding superstring theory and M theory. One approach to understanding the dynamics of p-branes is to formulate an effective (p+1) dimensional world-volume theory. The construction of such brane actions involves a number of interesting issues. One such issue is how to formulate the action for theories that contain chiral bosons. The two main examples, which are the M theory five-brane and the heterotic string, are described in this lecture. Also, double dimensional reduction of the M theory five-brane on K3 is shown to give the heterotic string. (Author). 32 refs
Radion and holographic brane gravity
International Nuclear Information System (INIS)
Kanno, Sugumi; Soda, Jiro
2002-01-01
The low energy effective theory for the Randall-Sundrum two-brane system is investigated with an emphasis on the role of the nonlinear radion in the brane world. The equations of motion in the bulk are solved using a low energy expansion method. This allows us, through the junction conditions, to deduce the effective equations of motion for gravity on the brane. It is shown that the gravity on the brane world is described by a quasi-scalar-tensor theory with a specific coupling function ω(Ψ)=3Ψ/2(1-Ψ) on the positive tension brane and ω(Φ)=-3Φ/2(1+Φ) on the negative tension brane, where Ψ and Φ are nonlinear realizations of the radion on the positive and negative tension branes, respectively. In contrast with the usual scalar-tensor gravity, the quasi-scalar-tensor gravity couples with two kinds of matter; namely, the matter on both positive and negative tension branes, with different effective gravitational coupling constants. In particular, the radion disguised as the scalar fields Ψ and Φ couples with the sum of the traces of the energy-momentum tensor on both branes. In the course of the derivation, it is revealed that the radion plays an essential role in converting the nonlocal Einstein gravity with generalized dark radiation to local quasi-scalar-tensor gravity. For completeness, we also derive the effective action for our theory by substituting the bulk solution into the original action. It is also shown that quasi-scalar-tensor gravity works as a hologram at low energy in the sense that the bulk geometry can be reconstructed from the solution of quasi-scalar-tensor gravity
Reheating the D-brane universe via instant preheating
International Nuclear Information System (INIS)
Panda, Sudhakar; Sami, M.; Thongkool, I.
2010-01-01
We investigate a possibility of reheating in a scenario of D-brane inflation in a warped deformed conifold background which includes perturbative corrections to throat geometry sourced by a chiral operator of dimension 3/2 in the conformal field theory. The effective D-brane potential, in this case, belongs to the class of nonoscillatory models of inflation for which the conventional reheating mechanism does not work. We find that gravitational particle production is inefficient and leads to reheating temperature of the order of 10 8 GeV. We show that instant preheating is quite suitable to the present scenario and can easily reheat the universe to a temperature which is higher by about 3 orders of magnitude than its counterpart associated with gravitational particle production. The reheating temperature is shown to be insensitive to a particular choice of inflationary parameters suitable to observations.
Rotating D0-branes and consistent truncations of supergravity
International Nuclear Information System (INIS)
Anabalón, Andrés; Ortiz, Thomas; Samtleben, Henning
2013-01-01
The fluctuations around the D0-brane near-horizon geometry are described by two-dimensional SO(9) gauged maximal supergravity. We work out the U(1) 4 truncation of this theory whose scalar sector consists of five dilaton and four axion fields. We construct the full non-linear Kaluza–Klein ansatz for the embedding of the dilaton sector into type IIA supergravity. This yields a consistent truncation around a geometry which is the warped product of a two-dimensional domain wall and the sphere S 8 . As an application, we consider the solutions corresponding to rotating D0-branes which in the near-horizon limit approach AdS 2 ×M 8 geometries, and discuss their thermodynamical properties. More generally, we study the appearance of such solutions in the presence of non-vanishing axion fields
Vacuum Expectation Value Profiles of the Bulk Scalar Field in the Generalized Randall-Sundrum Model
International Nuclear Information System (INIS)
Moazzen, M.; Tofighi, A.; Farokhtabar, A.
2015-01-01
In the generalized Randall-Sundrum warped brane-world model the cosmological constant induced on the visible brane can be positive or negative. In this paper we investigate profiles of vacuum expectation value of the bulk scalar field under general Dirichlet and Neumann boundary conditions in the generalized warped brane-world model. We show that the VEV profiles generally depend on the value of the brane cosmological constant. We find that the VEV profiles of the bulk scalar field for a visible brane with negative cosmological constant and positive tension are quite distinct from those of Randall-Sundrum model. In addition we show that the VEV profiles for a visible brane with large positive cosmological constant are also different from those of the Randall-Sundrum model. We also verify that Goldberger and Wise mechanism can work under nonzero Dirichlet boundary conditions in the generalized Randall-Sundrum model.
Seesaw mechanism in warped geometry
International Nuclear Information System (INIS)
Huber, S.J.; Shafi, Q.
2003-09-01
We show how the seesaw mechanism for neutrino masses can be realized within a five dimensional (5D) warped geometry framework. Intermediate scale standard model (SM) singlet neutrino masses, needed to explain the atmospheric and solar neutrino oscillations, are shown to be proportional to M P1 .exp((2c-1)πkR), where c denotes the coefficient of the 5D Dirac mass term for the singlet neutrino which also has a Planck scale Majorana mass localized on the Planck-brane, and kR∼11 in order to resolve the gauge hierarchy problem. The case with a bulk 5D Majorana mass term for the singlet neutrino is briefly discussed. (orig.)
Adding a brane to the brane-anti-brane action in BSFT
International Nuclear Information System (INIS)
Jones, Nicholas T.; Henry Tye, S.-H.; Leblond, Louis
2003-01-01
We attempt to generalize the effective action for the D-brane-anti-D-brane system obtained from boundary superstring field theory (BSFT) by adding an extra D-brane to it to obtain a co-variantized action for 2 D-branes and 1 anti-D-brane. We discuss the approximations made to obtain the effective action in closed form. Among other properties, this effective action admits solitonic solutions of co-dimension 2 (vortices) when one of the D-brane is far separated from the brane-anti-brane pair. (author)
Transport coefficients of black MQGP M3-branes
International Nuclear Information System (INIS)
Dhuria, Mansi; Misra, Aalok
2015-01-01
The Strominger-Yau-Zaslow (SYZ) mirror, in the 'delocalised limit' of Becker et al. (Nucl Phys B 702:207, 2004), of N D3-branes, M fractional D3-branes and N f flavour D7-branes wrapping a non-compact four-cycle in the presence of a black hole (BH) resulting in a non-Kahler resolved warped deformed conifold (NKRWDC) in Mia et al. (Nucl Phys B 839:187, 2010), was carried out in Dhuria and Misra (JHEP 1311:001, 2013) and resulted in black M3- branes. There are two parts in our paper. In the first we show that in the 'MQGP' limit discussed in Dhuria and Misra (JHEP 1311:001, 2013) a finite g s (and hence expected to be more relevant to QGP), finite g s M, N f , g s 2 MN f and very large g s N, and very small (g,M 2 )/(N), we have the following. (i) The uplift, if valid globally (like Dasgupta et al., Nucl Phys B 755:21, 2006) for fractional D3 branes in conifolds, asymptotically goes to M5-branes wrapping a two-cycle (homologously a (large) integer sum of two-spheres) in AdS 5 x M 6 . (ii) Assuming the deformation parameter to be larger than the resolution parameter, by estimating the five SU(3) structure torsion (τ) classes W 1,2,3,4,5 we verify that τ element of W 5 in the large-r limit, implying the NKRWDC reduces to a warped Kahler deformed conifold. (iii) The local T 3 of Dhuria and Misra (JHEP 1311:001, 2013) in the large-r limit satisfies the same conditions as the maximal T 2 -invariant special Lagrangian three-cycle of T*S 3 of Ionel and Min-OO (J Math 52(3), 2008), partly justifying use of SYZ-mirror symmetry in the ''delocalised limit'' of Becker et al. (Nucl Phys B 702:207, 2004) in Dhuria and Misra (JHEP 1311:001, 2013). In the second part of the paper, by either integrating out the angular coordinates of the non-compact four-cycle which a D7-brane wraps around, using the Ouyang embedding, in the DBI action of a D7-brane evaluated at infinite radial boundary, or by dimensionally reducing the 11-dimensional EH action to five (R 1,3 , r) dimensions and at
Gravitational field of static p -branes in linearized ghost-free gravity
Boos, Jens; Frolov, Valeri P.; Zelnikov, Andrei
2018-04-01
We study the gravitational field of static p -branes in D -dimensional Minkowski space in the framework of linearized ghost-free (GF) gravity. The concrete models of GF gravity we consider are parametrized by the nonlocal form factors exp (-□/μ2) and exp (□2/μ4) , where μ-1 is the scale of nonlocality. We show that the singular behavior of the gravitational field of p -branes in general relativity is cured by short-range modifications introduced by the nonlocalities, and we derive exact expressions of the regularized gravitational fields, whose geometry can be written as a warped metric. For large distances compared to the scale of nonlocality, μ r →∞ , our solutions approach those found in linearized general relativity.
Rotating D0-branes and consistent truncations of supergravity
Energy Technology Data Exchange (ETDEWEB)
Anabalón, Andrés [Departamento de Ciencias, Facultad de Artes Liberales, Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Av. Padre Hurtado 750, Viña del Mar (Chile); Université de Lyon, Laboratoire de Physique, UMR 5672, CNRS École Normale Supérieure de Lyon 46, allée d' Italie, F-69364 Lyon cedex 07 (France); Ortiz, Thomas; Samtleben, Henning [Université de Lyon, Laboratoire de Physique, UMR 5672, CNRS École Normale Supérieure de Lyon 46, allée d' Italie, F-69364 Lyon cedex 07 (France)
2013-12-18
The fluctuations around the D0-brane near-horizon geometry are described by two-dimensional SO(9) gauged maximal supergravity. We work out the U(1){sup 4} truncation of this theory whose scalar sector consists of five dilaton and four axion fields. We construct the full non-linear Kaluza–Klein ansatz for the embedding of the dilaton sector into type IIA supergravity. This yields a consistent truncation around a geometry which is the warped product of a two-dimensional domain wall and the sphere S{sup 8}. As an application, we consider the solutions corresponding to rotating D0-branes which in the near-horizon limit approach AdS{sub 2}×M{sub 8} geometries, and discuss their thermodynamical properties. More generally, we study the appearance of such solutions in the presence of non-vanishing axion fields.
Dark radiation dynamics on the brane
International Nuclear Information System (INIS)
Neves, Rui; Vaz, Cenalo
2002-01-01
We investigate the dynamics of a spherically symmetric vacuum on a Randall and Sundrum 3-brane world. Under certain natural conditions, the effective Einstein equations on the brane form a closed system for spherically symmetric dark radiation. We determine exact dynamical and inhomogeneous solutions, which are shown to depend on the brane cosmological constant, on the dark radiation tidal charge and on its initial energy configuration. We identify the conditions defining these solutions as singular or as globally regular. Finally, we discuss the confinement of gravity to the vicinity of the brane and show that a phase transition to a regime where gravity is not bound to the brane may occur at short distances during the collapse of positive dark energy density on a realistic de Sitter brane
Lorentz Violation in Warped Extra Dimensions
International Nuclear Information System (INIS)
Rizzo, Thomas G.
2011-01-01
Higher dimensional theories which address some of the problematic issues of the Standard Model(SM) naturally involve some form of D = 4 + n-dimensional Lorentz invariance violation (LIV). In such models the fundamental physics which leads to, e.g., field localization, orbifolding, the existence of brane terms and the compactification process all can introduce LIV in the higher dimensional theory while still preserving 4-d Lorentz invariance. In this paper, attempting to capture some of this physics, we extend our previous analysis of LIV in 5-d UED-type models to those with 5- d warped extra dimensions. To be specific, we employ the 5-d analog of the SM Extension of Kostelecky et al. which incorporates a complete set of operators arising from spontaneous LIV. We show that while the response of the bulk scalar, fermion and gauge fields to the addition of LIV operators in warped models is qualitatively similar to what happens in the flat 5-d UED case, the gravity sector of these models reacts very differently than in flat space. Specifically, we show that LIV in this warped case leads to a non-zero bulk mass for the 5-d graviton and so the would-be zero mode, which we identify as the usual 4-d graviton, must necessarily become massive. The origin of this mass term is the simultaneous existence of the constant non-zero AdS 5 curvature and the loss of general co-ordinate invariance via LIV in the 5-d theory. Thus warped 5-d models with LIV in the gravity sector are not phenomenologically viable.
Non-perturbative transitions among intersecting-brane vacua
Angelantonj, Carlo; Dudas, Emilian; Pradisi, Gianfranco; 10.1007/JHEP07(2011)123
2011-01-01
We investigate the transmutation of D-branes into Abelian magnetic backgrounds on the world-volume of higher-dimensional branes, within the framework of global models with compact internal dimensions. The phenomenon, T-dual to brane recombination in the intersecting-brane picture, shares some similarities to inverse small-instanton transitions in non-compact spaces, though in this case the Abelian magnetic background is a consequence of the compactness of the internal manifold, and is not ascribed to a zero-size non-Abelian instanton growing to maximal size. We provide details of the transition in various supersymmetric orientifolds and non-supersymmetric tachyon-free vacua with Brane Supersymmetry Breaking, both from brane recombination and from a field theory Higgs mechanism viewpoints.
Energy Technology Data Exchange (ETDEWEB)
McGreevy, John Austen; /Stanford U., Phys. Dept.
2005-07-06
This thesis is a study of D-branes in string compactifications. In this context, D-branes are relevant as an important component of the nonperturbative spectrum, as an incisive probe of these backgrounds, and as a natural stringy tool for localizing gauge interactions. In the first part of the thesis, we discuss half-BPS D-branes in compactifications of type II string theory on Calabi-Yau threefolds. The results we describe for these objects are pertinent both in their role as stringy brane-worlds, and in their role as solitonic objects. In particular, we determine couplings of these branes to the moduli determining the closed-string geometry, both perturbatively and non-perturbatively in the worldsheet expansion. We provide a local model for transitions in moduli space where the BPS spectrum jumps, and discuss the extension of mirror symmetry between Calabi-Yau manifolds to the case when D-branes are present. The next section is an interlude which provides some applications of D-branes to other curved backgrounds of string theory. In particular, we discuss a surprising phenomenon in which fundamental strings moving through background Ramond-Ramond fields dissolve into large spherical D3-branes. This mechanism is used to explain a previously-mysterious fact discovered via the AdS-CFT correspondence. Next, we make a connection between type IIA string vacua of the type discussed in the first section and M-theory compactifications on manifolds of G{sub 2} holonomy. Finally we discuss constructions of string vacua which do not have large radius limits. In the final part of the thesis, we develop techniques for studying the worldsheets of open strings ending on the curved D-branes studied in the first section. More precisely, we formulate a large class of massive two-dimensional gauge theories coupled to boundary matter, which flow in the infrared to the relevant boundary conformal field theories. Along with many other applications, these techniques are used to describe
Brane cosmology in teleparallel and f (T ) gravity
International Nuclear Information System (INIS)
Atazadeh, K; Eghbali, A
2015-01-01
We consider the cosmology of a brane-world scenario in the framework of teleparallel and f(T) gravity in a way that matter is localized on the brane. We show that the cosmology of such branes is different from the standard cosmology in teleparallelism. In particular, we obtain a class of new solutions with a constant five-dimensional radius and cosmologically evolving brane in the context of constant torsion f(T) gravity. (paper)
Phantomlike behavior in a brane-world model with curvature effects
International Nuclear Information System (INIS)
Bouhmadi-Lopez, Mariam; Moniz, Paulo Vargas
2008-01-01
Recent observational evidence seems to allow the possibility that our Universe may currently be under a dark energy effect of a phantom nature. A suitable effective phantom fluid behavior can emerge in brane cosmology; in particular, within the normal non-self-accelerating Dvali-Gabadadze-Porrati branch, without any exotic matter and due to curvature effects from induced gravity. The phantomlike behavior is based in defining an effective energy density that grows as the brane expands. This effective description breaks down at some point in the past when the effective energy density becomes negative and the effective equation of state parameter blows up. In this paper we investigate if the phantomlike regime can be enlarged by the inclusion of a Gauss-Bonnet (GB) term into the bulk. The motivation is that such a GB component would model additional curvature effects on the brane setting. More precisely, our aim is to determine if the GB term, dominating and modifying the early behavior of the brane universe, may eventually extend the regime of validity of the phantom mimicry on the brane. However, we show that the opposite occurs: the GB effect seems instead to induce a breakdown of the phantomlike behavior at an even smaller redshift.
Randall-Sundrum model with λ<0 and bulk brane viscosity
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Lepe, Samuel; Pena, Francisco; Saavedra, Joel
2008-01-01
We study the effect of the inclusion of bulk brane viscosity on brane world (BW) cosmology in the framework of the Eckart's theory, we focus in the Randall-Sundrum model with negative tension on the brane
Einstein-Rosen 'bridge' needs lightlike brane source
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Guendelman, Eduardo; Kaganovich, Alexander; Nissimov, Emil; Pacheva, Svetlana
2009-01-01
The Einstein-Rosen 'bridge' wormhole solution proposed in the classic paper (Einstein and Rosen (1935) ) does not satisfy the vacuum Einstein equations at the wormhole throat. We show that the fully consistent formulation of the original Einstein-Rosen 'bridge' requires solving Einstein equations of bulk D=4 gravity coupled to a lightlike brane with a well-defined world-volume action. The non-vanishing contribution of Einstein-Rosen 'bridge' solution to the right-hand side of Einstein equations at the throat matches precisely the surface stress-energy tensor of the lightlike brane which automatically occupies the throat ('horizon straddling') - a feature triggered by the world-volume lightlike brane dynamics.
Lightlike branes as natural candidates for wormhole throats
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Guendelman, E.I.; Kaganovich, A.; Pacheva, S.; Nissimov, E.
2009-01-01
We first briefly present a consistent world-volume Lagrangian description of lightlike p-branes (LL-branes) in two equivalent forms - a Polyakov-type and a dual to it Nambu-Goto-type formulations. The most important characteristic features of LL-brane dynamics are: (i) the brane tension appears as a non-trivial additional dynamical degree of freedom; (ii) consistency of LL-brane dynamics in a spherically or axially symmetric gravitational background of codimension one requires the presence of an event horizon which is automatically occupied by the LL-brane (''horizon straddling''). Next we consider a bulk Einstein-Maxwell system interacting self-consistently with a codimension one LL-brane. We find spherically symmetric traversable wormhole solutions of Misner-Wheeler type produced by the LL-brane sitting at the wormhole throat with wormhole parameters being functions of the dynamical LL-brane tension. (Abstract Copyright [2009], Wiley Periodicals, Inc.)
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Itoh, Hideo; Okada, Nobuchika; Yamashita, Toshifumi
2006-01-01
We propose a scenario of gravity mediated supersymmetry breaking (gravity mediation) in a supersymmetric Randall-Sundrum model. In our setup, both the visible sector and the hidden sector coexist on the infrared (IR) brane. We introduce the Polonyi model as a simple hidden sector. Because of the warped metric, the effective cutoff scale on the IR brane is 'warped down', so that the gravity mediation occurs at a low scale. As a result, the gravitino is naturally the lightest superpartner (LSP) and contact interactions between the hidden and the visible sector fields become stronger. We address phenomenologies for various IR cutoff scales. In particular, we investigate collider phenomenology involving a scalar field (Polonyi field) in the hidden sector for the case with the IR cutoff around 10 TeV. We find a possibility that the hidden sector scalar can be produced at the LHC and the international linear collider (ILC). Interestingly, the scalar behaves like the Higgs boson of the standard model in the production process, while its decay process is quite different and, once produced, it will provide us with a very clean signature. The hidden sector may be no longer hidden
Randall-Sundrum model with {lambda}<0 and bulk brane viscosity
Energy Technology Data Exchange (ETDEWEB)
Lepe, Samuel [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4950, Valparaiso (Chile); Pena, Francisco [Departamento de Ciencias Fisicas, Facultad de Ingenieria, Ciencias y Administracion, Universidad de la Frontera, Avda. Francisco Salazar 01145, Casilla 54-D, Temuco (Chile); Saavedra, Joel [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4950, Valparaiso (Chile)], E-mail: joel.saavedra@ucv.cl
2008-04-17
We study the effect of the inclusion of bulk brane viscosity on brane world (BW) cosmology in the framework of the Eckart's theory, we focus in the Randall-Sundrum model with negative tension on the brane.
Non-geometric five-branes in heterotic supergravity
Energy Technology Data Exchange (ETDEWEB)
Sasaki, Shin; Yata, Masaya [Department of Physics, Kitasato University,Sagamihara 252-0373 (Japan); Department of Physics, National University of Singapore,2, Science Drive 3, Singapore 117542 (Singapore)
2016-11-10
We study T-duality chains of five-branes in heterotic supergravity where the first order α{sup ′}-corrections are present. By performing the α{sup ′}-corrected T-duality transformations of the heterotic NS5-brane solutions, we obtain the KK5-brane and the exotic 5{sub 2}{sup 2}-brane solutions associated with the symmetric, the neutral and the gauge NS5-branes. We find that the Yang-Mills gauge field in these solutions satisfies the self-duality condition in the three- and two-dimensional transverse spaces to the brane world-volumes. The O(2,2) monodromy structures of the 5{sub 2}{sup 2}-brane solutions are investigated by the α{sup ′}-corrected generalized metric. Our analysis shows that the symmetric 5{sub 2}{sup 2}-brane solution, which satisfies the standard embedding condition, is a T-fold and it exhibits the non-geometric nature. We also find that the neutral 5{sub 2}{sup 2}-brane solution is a T-fold at least at O(α{sup ′}). On the other hand, the gauge 5{sub 2}{sup 2}-brane solution is not a T-fold but show unusual structures of space-time.
Notes on branes in matrix theory
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Keski-Vakkuri, E.; Kraus, P.
1998-01-01
We study the effective actions of various brane configurations in matrix theory. Starting from the 0+1-dimensional quantum mechanics, we replace coordinate matrices by covariant derivatives in the large N limit, thereby obtaining effective field theories on the brane world-volumes. Even for non-compact branes, these effective theories are of Yang-Mills type, with constant background magnetic fields. In the case of a D2-brane, we show explicitly how the effective action equals the large magnetic field limit of the Born-Infeld action, and thus derive from matrix theory the action used by Polchinski and Pouliot to compute M-momentum transfer between membranes. We also consider the effect of compactifying transverse directions. Finally, we analyze a scattering process involving a recently proposed background representing a classically stable D6+D0 brane configuration. We compute the potential between this configuration and a D0-brane, and show that the result agrees with supergravity. (orig.)
More on Probing Branes with Branes
Brandhuber, A.; Itzhaki, N.; Sonnenschein, J.; Yankielowicz, S.
1997-01-01
We generalize the Gibbons-Wiltshire solution of four dimensional Kaluza-Klein black holes in order to describe Type IIA solutions of bound states of D6 and D0-branes. We probe the solutions with a D6-brane and a D0-brane. We also probe a system of D2+D0-branes and of a D2-brane bound to a F1-string with a D2-brane. A precise agreement between the SYM and the SUGRA calculations is found for the static force as well as for the $v^2$ force in all cases.
6D supergravity. Warped solution and gravity mediated supersymmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Luedeling, C
2006-07-15
We consider compactified six-dimensional gauged supergravity and find the general warped solution with four-dimensional maximal symmetry. Important features of the solution such as the number and position of singularities are determined by a free holomorphic function. Furthermore, in a particular torus compactification we derive the supergravity coupling of brane fields by the Noether procedure and investigate gravity-mediated supersymmetry breaking. The effective Kaehler potential is not sequestered, yet tree level gravity mediation is absent as long as the superpotential is independent of the radius modulus. (orig.)
6D supergravity. Warped solution and gravity mediated supersymmetry breaking
International Nuclear Information System (INIS)
Luedeling, C.
2006-07-01
We consider compactified six-dimensional gauged supergravity and find the general warped solution with four-dimensional maximal symmetry. Important features of the solution such as the number and position of singularities are determined by a free holomorphic function. Furthermore, in a particular torus compactification we derive the supergravity coupling of brane fields by the Noether procedure and investigate gravity-mediated supersymmetry breaking. The effective Kaehler potential is not sequestered, yet tree level gravity mediation is absent as long as the superpotential is independent of the radius modulus. (orig.)
Pre-big-bang model on the brane
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Foffa, Stefano
2002-01-01
The equations of motion and junction conditions for a gravidilaton brane world scenario are studied in the string frame. It is shown that they allow Kasner-like solutions on the brane, which makes the dynamics of the brane very similar to the low curvature phase of pre-big-bang cosmology. Analogies and differences of this scenario with the Randall-Sundrum one and with the standard bulk pre-big-bang dynamics are also discussed
Kink-induced symmetry breaking patterns in brane-world SU(3)3 trinification models
International Nuclear Information System (INIS)
Demaria, Alison; Volkas, Raymond R.
2005-01-01
The trinification grand unified theory (GUT) has gauge group SU(3) 3 and a discrete symmetry permuting the SU(3) factors. In common with other GUTs, the attractive nature of the fermionic multiplet assignments is obviated by the complicated multiparameter Higgs potential apparently needed for phenomenological reasons, and also by vacuum expectation value (VEV) hierarchies within a given multiplet. This motivates the rigorous consideration of Higgs potentials, symmetry breaking patterns, and alternative symmetry breaking mechanisms in models with this gauge group. Specifically, we study the recently proposed 'clash of symmetries' brane-world mechanism to see if it can help with the symmetry breaking conundrum. This requires a detailed analysis of Higgs potential global minima and kink or domain wall solutions interpolating between the disconnected global minima created through spontaneous discrete symmetry breaking. Sufficiently long-lived metastable kinks can also be considered. We develop what we think is an interesting, albeit speculative, brane-world scheme whereby the hierarchical symmetry breaking cascade, trinification to left-right symmetry to the standard model to color cross electromagnetism, may be induced without an initial hierarchy in vacuum expectation values. Another motivation for this paper is simply to continue the exploration of the rich class of kinks arising in models that are invariant under both discrete and continuous symmetries
Brane-Higgs-boson phenomenology in five-dimensional warped supersymmetry
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Bouchart, Charles; Moreau, Gregory; Knochel, Alexander
2011-01-01
Constructing supersymmetric extensions of higher-dimensional models can have several motivations; it is, for instance, necessary in the context of string theories. Studying the supersymmetric version of the well-motivated model proposed by Randall and Sundrum, with the Higgs boson localized on the so-called TeV-brane, is not trivial since singularities appear in the Higgs couplings. Those are regularized by the contribution from the exchange of infinite towers of Kaluza-Klein (KK) scalar modes with Dirichlet-Dirichlet boundary conditions. Here we first derive the regularized four-dimensional (4D) effective Higgs couplings and induced sfermion mass matrices. A general method is provided for this regularization, based on the completeness relation. The sfermion masses must be obtained either from integrating out the mentioned KK towers or by treating their mixing effects, depending on the cases. We then use the obtained Higgs couplings and sfermion masses for some phenomenological applications. On one side, we show at the one-loop level how all quadratic divergences in the Higgs mass cancel out for any cutoff, due to 5D supersymmetry (SUSY) and to 5D anomaly cancellation; the analytical way followed here also allows a justification of the infinite KK summation required for the so-called KK regularization in 5D SUSY, which has motivated a rich literature. On the other side, we show that a certain pattern of SUSY breaking in the bulk would allow one to distinguish experimentally the minimal SUSY model a la Randall and Sundrum with bulk matter from the minimal 4D SUSY model, in the scenario where only superpartners were produced at the Large Hadron Collider. In this SUSY-breaking context, two of the discriminating tests developed make use of some different features arising in the squark or slepton mass spectrum. The other distinctive supersymmetric Randall-Sundrum feature is the possibly larger (even dominant) Higgs boson decay branching ratios into sleptons, compared to
Cosmic microwave background radiation anisotropies in brane worlds.
Koyama, Kazuya
2003-11-28
We propose a new formulation to calculate the cosmic microwave background (CMB) spectrum in the Randall-Sundrum two-brane model based on recent progress in solving the bulk geometry using a low energy approximation. The evolution of the anisotropic stress imprinted on the brane by the 5D Weyl tensor is calculated. An impact of the dark radiation perturbation on the CMB spectrum is investigated in a simple model assuming an initially scale-invariant adiabatic perturbation. The dark radiation perturbation induces isocurvature perturbations, but the resultant spectrum can be quite different from the prediction of simple mixtures of adiabatic and isocurvature perturbations due to Weyl anisotropic stress.
Brane cosmology with curvature corrections
International Nuclear Information System (INIS)
Kofinas, Georgios; Maartens, Roy; Papantonopoulos, Eleftherios
2003-01-01
We study the cosmology of the Randall-Sundrum brane-world where the Einstein-Hilbert action is modified by curvature correction terms: a four-dimensional scalar curvature from induced gravity on the brane, and a five-dimensional Gauss-Bonnet curvature term. The combined effect of these curvature corrections to the action removes the infinite-density big bang singularity, although the curvature can still diverge for some parameter values. A radiation brane undergoes accelerated expansion near the minimal scale factor, for a range of parameters. This acceleration is driven by the geometric effects, without an inflation field or negative pressures. At late times, conventional cosmology is recovered. (author)
Newton's law in de Sitter brane
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Ghoroku, Kazuo; Nakamura, Akihiro; Yahiro, Masanobu
2003-01-01
Newton potential has been evaluated for the case of dS brane embedded in Minkowski, dS 5 and AdS 5 bulks. We point out that only the AdS 5 bulk might be consistent with the Newton's law from the brane-world viewpoint when we respect a small cosmological constant observed at present universe
Noncommutative D-branes from covariant AdS superstring
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Sakaguchi, Makoto; Yoshida, Kentaroh
2008-01-01
We study noncommutative (NC) D-branes on AdS 5 xS 5 from κ-invariance of covariant Green-Schwarz action of an open string with a non-trivial world-volume flux. Finding boundary conditions to ensure the κ-invariance, we can see possible configurations of the NC D-branes. With this method 1/4 BPS NC D-branes are discussed. The resulting NC Dp-branes are 1/4 BPS at arbitrary position other than the p=1 case. The exceptional D-string is 1/2 BPS at the origin and 1/4 BPS outside the origin. Those are reduced to possible 1/4 BPS or 1/2 BPS AdS D-branes in the commutative limit. The same analysis is applied to an open superstring in a pp-wave and leads to 1/4 BPS configurations of NC D-branes. These D-branes are consistently obtained from AdS D-branes via the Penrose limit
Entropy of the Randall-Sundrum black brane world to all orders in the Planck length
Energy Technology Data Exchange (ETDEWEB)
Nouicer, Khireddine [Frankfurt Institute of Advanced Studies, Johann Wolfgang Goethe Universitaet, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany)], E-mail: nouicer@fias.uni-frankfurt.de
2008-04-07
We study the effects, to all orders in the Planck length from a generalized uncertainty principle (GUP), on the statistical entropy of massive scalar bulk fields in the Randall-Sundrum black brane world. We show that the Bekenstein-Hawking area law is not preserved, and contains a correction term proportional to the black hole inverse area.
A Study of Universal Thermodynamics in Brane World Scenario
International Nuclear Information System (INIS)
Mitra, Saugata; Saha, Subhajit; Chakraborty, Subenoy
2015-01-01
A study of Universal thermodynamics is done in the framework of RSII brane model and DGP brane scenario. The Universe is chosen as FRW model bounded by apparent or event horizon. Assuming extended Hawking temperature on the horizon, the unified first law is examined for perfect fluid (with constant equation of state) and Modified Chaplygin Gas model. As a result there is a modification of Bekenstein entropy on the horizons. Further the validity of the generalized second law of thermodynamics and thermodynamical equilibrium are also investigated
Phantom-like behaviour in dilatonic brane-world scenario with induced gravity
International Nuclear Information System (INIS)
Bouhmadi-Lopez, Mariam
2008-01-01
The Dvali, Gabadadze and Porrati (DGP) model has a self-accelerating solution, the positive branch, where the brane is asymptotically de Sitter. A de Sitter space-time can be seen as a boundary between quintessence-like behaviour and phantom-like behaviour. We show that in a 5D dilatonic bulk, where the dilaton has an exponential potential, with an induced gravity term on the brane, whose matter content corresponds only to vacuum energy, the positive branch solution undergoes a phantom-like stage where it faces a curvature singularity in its infinite future. The singularity can be interpreted as the 'big rip' singularity pushed towards an infinite future cosmic time. The phantom-like behaviour on the brane occurs without violating the null energy condition. There is another solution, the negative branch, where the brane can undergo an early-epoch (transient) inflationary phase induced by the dilaton field
Stability of the graviton Bose–Einstein condensate in the brane-world
Energy Technology Data Exchange (ETDEWEB)
Casadio, Roberto, E-mail: casadio@bo.infn.it [Dipartimento di Fisica e Astronomia, Università di Bologna, via Irnerio 46, 40126 Bologna (Italy); INFN, Sezione di Bologna, viale B. Pichat 6, 40127 Bologna (Italy); Rocha, Roldão da, E-mail: roldao.rocha@ufabc.edu.br [CMCC, Universidade Federal do ABC, 09210-580, Santo André, SP (Brazil)
2016-12-10
We consider a solution of the effective four-dimensional Einstein equations, obtained from the general relativistic Schwarzschild metric through the principle of Minimal Geometric Deformation (MGD). Since the brane tension can, in general, introduce new singularities on a relativistic Eötvös brane model in the MGD framework, we require the absence of observed singularities, in order to constrain the brane tension. We then study the corresponding Bose–Einstein condensate (BEC) gravitational system and determine the critical stability region of BEC MGD stellar configurations. Finally, the critical stellar densities are shown to be related with critical points of the information entropy.
Thermodynamics of intersecting black branes from interacting elementary branes
Energy Technology Data Exchange (ETDEWEB)
Morita, Takeshi [Department of Physics, Shizuoka University,836 Ohya, Suruga-ku, Shizuoka 422-8529 (Japan); Shiba, Shotaro [Maskawa Institute for Science and Culture, Kyoto Sangyo University,Kamigamo-Motoyama, Kita-ku, Kyoto 603-8555 (Japan)
2015-09-14
If an Einstein-Maxwell-Dilaton system admits the extreme brane solution in which no force works between the parallel branes, the collective motion of nearly parallel branes exhibits the thermodynamical properties which are coincident with those of the corresponding black branes at low energy regime (up to unfixed numerical factors). Hence it may provide the microscopic description of the black branes (p-soup proposal). This fact motivates us to test this proposal in the intersecting black branes which have multiple brane charges and/or momentum along the brane direction. We consider the case that the multiple branes satisfy the intersection rule and feel no force when they are static, and find the agreement to the black hole thermodynamics.
D-brane anti-brane annihilation in an expanding universe
International Nuclear Information System (INIS)
Majumdar, Mahbub; Davis, Anne-Christine
2003-01-01
The time-varying density of D-branes and anti-D-branes in an expanding universe is calculated. The D-brane anti-brane annihilation rate is shown to be too small to compete with the expansion rate of a FRW type universe and the branes over-close the universe. This brane problem is analogous to the old monopole problem. Interestingly however, it is shown that small dimension D-branes annihilate more slowly than high dimension branes. Hence, an initially brany universe may be filled with only low dimension branes at late times. When combined with an appropriate late inflationary theory this leads to an attractive dynamical way to create a realistic braneworld scenario. (author)
Warped Dipole Completed, with a Tower of Higgs Bosons
Agashe, Kaustubh; Cui, Yanou; Randall, Lisa; Son, Minho
2015-01-01
In the context of warped extra-dimensional models which address both the Planck-weak- and flavor-hierarchies of the Standard Model (SM), it has been argued that certain observables can be calculated within the 5D effective field theory only with the Higgs field propagating in the bulk of the extra dimension, just like other SM fields. The related studies also suggested an interesting form of decoupling of the heavy Kaluza-Klein (KK) fermion states in the warped 5D SM in the limit where the profile of the SM Higgs approaches the IR brane. We demonstrate that a similar phenomenon occurs when we include the mandatory KK excitations of the SM Higgs in loop diagrams giving dipole operators for SM fermions, where the earlier work only considered the SM Higgs (zero mode). In particular, in the limit of a quasi IR-localized SM Higgs, the effect from summing over KK Higgs modes is unsuppressed (yet finite), in contrast to the naive expectation that KK Higgs modes decouple as their masses become large. In this case, a ...
Nonthreshold D-brane bound states and black holes with nonzero entropy
International Nuclear Information System (INIS)
Costa, M.S.; Cvetic, M.
1997-01-01
We start with Bogomol close-quote nyi-Prasad-Sommerfield- (BPS) saturated configurations of two (orthogonally) intersecting M-branes and use the electromagnetic duality or dimensional reduction along a boost, in order to obtain new p-brane bound states. In the first case the resulting configurations are interpreted as BPS-saturated nonthreshold bound states of intersecting p-branes, and in the second case as p-branes intersecting at angles and their duals. As a by-product we deduce the enhancement of supersymmetry as the angle approaches zero. We also comment on the D-brane theory describing these new bound states, and a connection between the angle and the world-volume gauge fields of the D-brane system. We use these configurations to find new embeddings of the four- and five-dimensional black holes with nonzero entropy, whose entropy now also depends on the angle and world-volume gauge fields. The corresponding D-brane configuration sheds light on the microscopic entropy of such black holes. copyright 1997 The American Physical Society
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Frolov, Valeri P.; Mukohyama, Shinji
2011-01-01
The aim of this paper is to demonstrate that in models with large extra dimensions under special conditions one can extract information from the interior of 4D black holes. For this purpose we study an induced geometry on a test brane in the background of a higher-dimensional static black string or a black brane. We show that, at the intersection surface of the test brane and the bulk black string or brane, the induced metric has an event horizon, so that the test brane contains a black hole. We call it a brane hole. When the test brane moves with a constant velocity V with respect to the bulk black object, it also has a brane hole, but its gravitational radius r e is greater than the size of the bulk black string or brane r 0 by the factor (1-V 2 ) -1 . We show that bulk ''photon'' emitted in the region between r 0 and r e can meet the test brane again at a point outside r e . From the point of view of observers on the test brane, the events of emission and capture of the bulk photon are connected by a spacelike curve in the induced geometry. This shows an example in which extra dimensions can be used to extract information from the interior of a lower-dimensional black object. Instead of the bulk black string or brane, one can also consider a bulk geometry without a horizon. We show that nevertheless the induced geometry on the moving test brane can include a brane hole. In such a case the extra dimensions can be used to extract information from the complete region of the brane-hole interior. We discuss thermodynamic properties of brane holes and interesting questions which arise when such an extra-dimensional channel for the information mining exists.
D-Brane Recoil Mislays Information
Ellis, Jonathan Richard; Nanopoulos, Dimitri V
1998-01-01
We discuss the scattering of a light closed-string state off a $D$ brane, taking into account quantum recoil effects on the latter, which are described by a pair of logarithmic operators. The light-particle and $D$-brane subsystems may each be described by a world-sheet with an external source due to the interaction between them. This perturbs each subsystem away from criticality, which is compensated by dressing with a Liouville field whose zero mode we interpret as time. The resulting evolution equations for the $D$ brane and the closed string are of Fokker-Planck and modified quantum Liouville type, respectively. The apparent entropy of each subsystem increases as a result of the interaction between them, which we interpret as the loss of information resulting from non-observation of the other entangled subsystem. We speculate on the possible implications of these results for the propagation of closed strings through a dilute gas of virtual $D$ branes.
Disappearing dark matter in brane world cosmology: New limits on noncompact extra dimensions
International Nuclear Information System (INIS)
Ichiki, K.; Garnavich, P.M.; Mathews, G.J.; Kajino, T.; Yahiro, M.
2003-01-01
We explore cosmological implications of dark matter as massive particles trapped on a brane embedded in a Randall-Sundrum noncompact higher dimension AdS 5 space. It is an unavoidable consequence of this cosmology that massive particles are metastable and can disappear into the bulk dimension. Here, we show that a massive dark matter particle (e.g. the lightest supersymmetric particle) is likely to have the shortest lifetime for disappearing into the bulk. We examine cosmological constraints on this new paradigm and show that disappearing dark matter is consistent (at the 95% confidence level) with all cosmological constraints, i.e., present observations of type Ia supernovae at the highest redshift, trends in the mass-to-light ratios of galaxy clusters with redshift, the fraction of x-ray emitting gas in rich clusters, and the spectrum of power fluctuations in the cosmic microwave background. A best 2σ concordance region is identified corresponding to a mean lifetime for dark matter disappearance of 15≤Γ -1 ≤80 Gyr. The implication of these results for brane-world physics is discussed
Black hole radiation in the brane world and the recoil effect
International Nuclear Information System (INIS)
Frolov, Valeri; Stojkovic, Dejan
2002-01-01
A black hole attached to a brane in a higher-dimensional space emitting quanta into the bulk may leave the brane as a result of a recoil. We study this effect. We consider black holes which have a size much smaller than the characteristic size of extra dimensions. Such a black hole can be effectively described as a massive particle with internal degrees of freedom. We consider an interaction of such particles with a scalar massless field and prove that for a special choice of the coupling constant describing the transition of the particle to a state with smaller mass the probability of massless quanta emission takes the form identical to the probability of the black hole emission. Using this model we calculate the probability for a black hole to leave the brane and study its properties. The discussed recoil effect implies that, for black holes which might be created in the interaction of high energy particles in colliders, the thermal emission of the formed black hole could be terminated and the energy nonconservation can be observed in brane experiments
Inflation from D3-brane motion in the background of D5-branes
International Nuclear Information System (INIS)
Panda, Sudhakar; Sami, M.; Tsujikawa, Shinji; Ward, John
2006-01-01
We study inflation arising from the motion of a Bogomol'nyi-Prasad-Sommerfield D3-brane in the background of a stack of k parallel D5-branes. There are two scalar fields in this setup: (i) the radion field R, a real scalar field, and (ii) a complex tachyonic scalar field χ living on the world volume of the open string stretched between the D3 and D5 branes. We find that inflation is realized by the potential of the radion field, which satisfies observational constraints coming from the cosmic microwave background. After the radion becomes of the order of the string length scale l s , the dynamics is governed by the potential of the complex scalar field. Since this field has a standard kinematic term, reheating can be successfully realized by the mechanism of tachyonic preheating with spontaneous symmetry breaking
Starobinsky-Like Inflation in Dilaton-Brane Cosmology
Ellis, John; Nanopoulos, Dimitri V
2014-01-01
We discuss how Starobinsky-like inflation may emerge from dilaton dynamics in brane cosmology scenarios based on string theory, in which our universe is represented as a three-brane. The effective potential may acquire a constant term from a density of effectively point-like non-pertubative defects on the brane. Higher-genus corrections generate corrections to the effective potential that are exponentially damped at large field values, as in the Starobinsky model, but at a faster rate, leading to a smaller prediction for the tensor-to scalar perturbation ratio r. This may be compensated partially by logarithmic deformations on the world-sheet due to recoil of the defects due to scattering by string matter on the brane, which tend to enhance the tensor-to-scalar ratio.
Grand unification in the heterotic brane world
International Nuclear Information System (INIS)
Vaudrevange, Patrick Karl Simon
2008-08-01
String theory is known to be one of the most promising candidates for a uni ed description of all elementary particles and their interactions. Starting from the ten-dimensional heterotic string, we study its compactification on six-dimensional orbifolds. We clarify some important technical aspects of their construction and introduce new parameters, called generalized discrete torsion. We identify intrinsic new relations between orbifolds with and without (generalized) discrete torsion. Furthermore, we perform a systematic search for MSSM-like models in the context of Z 6 -II orbifolds. Using local GUTs, which naturally appear in the heterotic brane world, we construct about 200 MSSM candidates. We find that intermediate SUSY breaking through hidden sector gaugino condensation is preferred in this set of models. A specific model, the so-called benchmark model, is analyzed in detail addressing questions like the identification of a supersymmetric vacuum with a naturally small μ-term and proton decay. Furthermore, as vevs of twisted fields correspond to a resolution of orbifold singularities, we analyze the resolution of Z 3 singularities in the local and in the compact case. Finally, we exemplify this procedure with the resolution of a Z 3 MSSM candidate. (orig.)
Grand unification in the heterotic brane world
Energy Technology Data Exchange (ETDEWEB)
Vaudrevange, Patrick Karl Simon
2008-08-15
String theory is known to be one of the most promising candidates for a uni ed description of all elementary particles and their interactions. Starting from the ten-dimensional heterotic string, we study its compactification on six-dimensional orbifolds. We clarify some important technical aspects of their construction and introduce new parameters, called generalized discrete torsion. We identify intrinsic new relations between orbifolds with and without (generalized) discrete torsion. Furthermore, we perform a systematic search for MSSM-like models in the context of Z{sub 6}-II orbifolds. Using local GUTs, which naturally appear in the heterotic brane world, we construct about 200 MSSM candidates. We find that intermediate SUSY breaking through hidden sector gaugino condensation is preferred in this set of models. A specific model, the so-called benchmark model, is analyzed in detail addressing questions like the identification of a supersymmetric vacuum with a naturally small {mu}-term and proton decay. Furthermore, as vevs of twisted fields correspond to a resolution of orbifold singularities, we analyze the resolution of Z{sub 3} singularities in the local and in the compact case. Finally, we exemplify this procedure with the resolution of a Z{sub 3} MSSM candidate. (orig.)
General class of brane-world black holes
International Nuclear Information System (INIS)
Bronnikov, K.A.; Melnikov, V.N.; Dehnen, Heinz
2003-01-01
We use the general solution to the trace of the 4-dimensional Einstein equations for static, spherically symmetric configurations as a basis for finding a general class of black hole (BH) metrics, containing one arbitrary function g tt =A(r) which vanishes at some r=r h >0, the horizon radius. Under certain reasonable restrictions, BH metrics are found with or without matter and, depending on the boundary conditions, can be asymptotically flat or have any other prescribed asymptotic. It is shown that our procedure generically leads to families of globally regular BHs with a Kerr-like global structure as well as symmetric wormholes. Horizons in space-times with zero scalar curvature are shown to be either simple or double. The same is generically true for horizons inside a matter distribution, but in special cases there can be horizons of any order. A few simple examples are discussed. A natural application of the above results is the brane world concept, in which the trace of the 4D gravity equations is the only unambiguous equation for the 4D metric, and its solutions can be continued into the 5D bulk according to the embedding theorems
LittleQuickWarp: an ultrafast image warping tool.
Qu, Lei; Peng, Hanchuan
2015-02-01
Warping images into a standard coordinate space is critical for many image computing related tasks. However, for multi-dimensional and high-resolution images, an accurate warping operation itself is often very expensive in terms of computer memory and computational time. For high-throughput image analysis studies such as brain mapping projects, it is desirable to have high performance image warping tools that are compatible with common image analysis pipelines. In this article, we present LittleQuickWarp, a swift and memory efficient tool that boosts 3D image warping performance dramatically and at the same time has high warping quality similar to the widely used thin plate spline (TPS) warping. Compared to the TPS, LittleQuickWarp can improve the warping speed 2-5 times and reduce the memory consumption 6-20 times. We have implemented LittleQuickWarp as an Open Source plug-in program on top of the Vaa3D system (http://vaa3d.org). The source code and a brief tutorial can be found in the Vaa3D plugin source code repository. Copyright © 2014 Elsevier Inc. All rights reserved.
Prospects of inflation in delicate D-brane cosmology
International Nuclear Information System (INIS)
Panda, Sudhakar; Sami, M.; Tsujikawa, Shinji
2007-01-01
We study D-brane inflation in a warped conifold background that includes brane-position dependent corrections for the nonperturbative superpotential. Instead of stabilizing the volume modulus χ at instantaneous minima of the potential and studying the inflation dynamics with an effective single field (radial distance between a brane and an antibrane) φ, we investigate the multifield inflation scenario involving these two fields. The two-field dynamics with the potential V(φ,χ) in this model is significantly different from the effective single-field description in terms of the field φ when the field χ is integrated out. The latter picture underestimates the total number of e-foldings even by 1 order of magnitude. We show that a correct single-field description is provided by a field ψ obtained from a rotation in the two-field space along the background trajectory. This model can give a large number of e-foldings required to solve flatness and horizon problems at the expense of fine-tunings of model parameters. We also estimate the spectra of density perturbations and show that the slow-roll parameter η ψψ =M pl 2 V ,ψψ /V in terms of the rotated field ψ determines the spectral index of scalar metric perturbations. We find that it is generally difficult to satisfy, simultaneously, both constraints of the spectral index and the cosmic background explorer normalization, while the tensor to scalar ratio is sufficiently small to match with observations
Bergshoeff, Eric A; Riccioni, Fabio
2012-01-01
We complete the classification of half-supersymmetric branes in toroidally compactified IIA/IIB string theory in terms of representations of the T-duality group. As a by-product we derive a last wrapping rule for the space-filling branes. We find examples of T-duality representations of branes in lower dimensions, suggested by supergravity, of which none of the component branes follow from the reduction of any brane in ten-dimensional IIA/IIB string theory. We discuss the constraints on the charges of half-supersymmetric branes, determining the corresponding T-duality and U-duality orbits.
Newton law in DGP brane-world with semi-infinite extra dimension
International Nuclear Information System (INIS)
Park, D.K.; Tamaryan, S.; Miao Yangang
2004-01-01
Newton potential for DGP brane-world scenario is examined when the extra dimension is semi-infinite. The final form of the potential involves a self-adjoint extension parameter α, which plays a role of an additional mass (or distance) scale. The striking feature of Newton potential in this setup is that the potential behaves as seven-dimensional in long range when α is non-zero. For small α there is an intermediate range where the potential is five-dimensional. Five-dimensional Newton constant decreases with increase of α from zero. In the short range the four-dimensional behavior is recovered. The physical implication of this result is discussed in the context of the accelerating behavior of universe
Gravity and antigravity in a brane world with metastable gravitons
Gregory, R.; Rubakov, V. A.; Sibiryakov, S. M.
2000-09-01
In the framework of a five-dimensional three-brane model with quasi-localized gravitons we evaluate metric perturbations induced on the positive tension brane by matter residing thereon. We find that at intermediate distances, the effective four-dimensional theory coincides, up to small corrections, with General Relativity. This is in accord with Csaki, Erlich and Hollowood and in contrast to Dvali, Gabadadze and Porrati. We show, however, that at ultra-large distances this effective four-dimensional theory becomes dramatically different: conventional tensor gravity changes into scalar anti-gravity.
On the equivalence of N=1 brane worlds and geometric singularities with flux
International Nuclear Information System (INIS)
Kaste, Peter; Partouche, Herve
2004-01-01
We consider Kaluza Klein reductions of M-theory on the Z N orbifold of the spin bundle over S 3 along two different U(1) isometries. The first one gives rise to the familiar 'large-N duality' of the N=1 SU(N) gauge theory in which the UV is realized as the world-volume theory of N D6-branes wrapped on S 3 , whereas the IR involves N units of RR flux through an S 2 . The second reduction gives an equivalent version of this duality in which the UV is realized geometrically in terms of a P 1 of A N-1 singularities, with one unit of RR flux through the P 1 . The IR is reached via a geometric transition and involves a single D6 brane on a lens space S 3 /Z N or, alternatively, a singular background (S 2 xR 4 )/Z N , with one unit of RR flux through S 2 and, localized at the singularities, an action of their stabilizer group in the U(1) RR gauge bundle, so that no massless twisted states occur. We also consider linear s-model descriptions of these backgrounds. (author)
Inflating baby-Skyrme branes in six dimensions
International Nuclear Information System (INIS)
Brihaye, Yves; Delsate, Terence; Kodama, Yuta; Sawado, Nobuyuki
2010-01-01
We consider a six-dimensional brane world model, where the brane is described by a localized solution to the baby-Skyrme model extending in the extra dimensions. The branes have a cosmological constant modeled by inflating four-dimensional slices, and we further consider a bulk cosmological constant. We construct solutions numerically and present evidence that the solutions cease to exist for large values of the brane cosmological constant in some particular case. Then we study the stability of the model by considering perturbation of the gravitational part (resp. baby Skyrmion) with fixed matter fields (resp. gravitational background). Our results indicate that the perturbation equations do not admit localized solutions for certain type of perturbation. The stability analysis can be alternatively seen as leading to a particle spectrum; we give mass estimations for the baby-Skyrme perturbation and for the graviton.
Pavšič, Matej
2002-01-01
This a book is for those who would like to learn something about special and general relativity beyond the usual textbooks, about quantum field theory, the elegant Fock-Schwinger-Stueckelberg proper time formalism, the elegant description of geometry by means of Clifford algebra, about the fascinating possibilities the latter algebra offers in reformulating the existing physical theories, and quantizing them in a natural way. It is shown how Clifford algebra provides much more: it provides room for new physics, with the prospects of resolving certain long standing puzzles. The theory of branes and the idea of how a 3-brane might represent our world is discussed in detail. Much attention is paid to the elegant geometric theory of branes which employs the infinite dimensional space of functions describing branes. Clifford algebra is generalized to the infinite dimensional spaces. In short, this is a book for anybody who would like to explore how the ``theory of everything'' might possibly be formulated. The the...
Interaction of a brane with a moving bulk black hole
International Nuclear Information System (INIS)
Frolov, Valeri; Snajdr, Martin; Stojkovic, Dejan
2003-01-01
We study the interaction of an n-dimensional topological defect (n-brane) described by the Nambu-Goto action with a higher-dimensional Schwarzschild black hole moving in the bulk spacetime. We derive the general form of the perturbation equations for an n-brane in the weak field approximation and solve them analytically in the most interesting cases. We especially analyze applications to brane world models. We calculate the induced geometry on the brane generated by a moving black hole. From the point of view of a brane observer, this geometry can be obtained by solving (n+1)-dimensional Einstein's equations with a nonvanishing right-hand side. We calculate the effective stress-energy tensor corresponding to this 'shadow matter'. We explicitly show that there exist regions on the brane where a brane observer sees an apparent violation of energy conditions. We also study the deflection of light propagating in the region of influence of this shadow matter
International Nuclear Information System (INIS)
Mitra, Indranil; Roy, Shibaji
2002-01-01
We generalize the nonthreshold bound state in type IIB supergravity of the form (NS5-brane, D5-brane, D3-brane) constructed by the present authors [J. High Energy Phys. 02, 026 (2001)] to a nonzero asymptotic value of the axion (χ 0 ). We identify the decoupling limits corresponding to both the open D3-brane theory and open D5-brane theory for this supergravity solution as expected. However, we do not find any noncommutative Yang-Mills theory (NCYM) limit for this solution in the presence of NS5-branes. We then study the SL(2,Z) duality symmetry of type IIB theory for both open D3-brane (OD3) limit and open D5-brane (OD5) limit. We find that for OD3 theory, a generic SL(2,Z) duality always gives another OD3 theory irrespective of the value of χ 0 being rational or not. This indicates that OD3 theory is self-dual. But, under a special set of SL(2,Z) transformations for which χ 0 is rational, OD3 theory goes over to a (5+1)-dimensional NCYM theory and these two theories in this case are related to each other by strong-weak duality symmetry. On the other hand, for OD5 theory, a generic SL(2,Z) duality gives another OD5 theory if χ 0 is irrational, but when χ 0 is rational it gives the little string theory limit indicating that OD5 theory is S dual to the type IIB little string theory
A proposal for M2-brane-anti-M2-brane action
International Nuclear Information System (INIS)
Garousi, Mohammad R.
2010-01-01
We propose a manifestly SO(8) invariant BF type Lagrangian for describing the dynamics of M2-brane-anti-M2-brane system in flat spacetime. When one of the scalars which satisfies a free-scalar equation takes a large expectation value, the M2-brane-anti-M2-brane action reduces to the tachyon DBI action of D2-brane-anti-D2-brane system in flat spacetime.
Unstoppable brane-flux decay of (D6)-bar branes
Energy Technology Data Exchange (ETDEWEB)
Danielsson, UniversityH. [Institutionen för Fysik och Astronomi, Uppsala Universitet, Uppsala (Sweden); Gautason, F.F. [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Riet, T. Van [Instituut voor Theoretische Fysica, K.University Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)
2017-03-27
We investigate p (D6)-bar branes inside a flux throat that carries K×M D6 charges with K the 3-form flux quantum and M the Romans mass. In such a setup brane-flux annihilation can proceed through the nucleation of KK5 branes. We find that within the calculable supergravity regime where g{sub s}p is large, the (D6)-bar branes annihilate immediately against the fluxes despite the existence of a metastable state at small p/M in the probe approximation. The crucial property that causes this naive conflict with effective field theory is a singularity in the 3-form flux, which we cut off at string scale. Our result explains the absence of regular solutions at finite temperature and suggests there should be a smooth time-dependent solution. We also discuss the qualitative differences between (D6)-bar branes and (D3)-bar branes, which makes it a priori not obvious to conclude the same instability for (D3)-bar branes.
International Nuclear Information System (INIS)
Clark, T.E.; Love, S.T.; Nitta, Muneto; Veldhuis, T. ter; Xiong, C.
2009-01-01
Local oscillations of the brane world are manifested as massive vector fields. Their coupling to the Standard Model can be obtained using the method of nonlinear realizations of the spontaneously broken higher-dimensional space-time symmetries, and to an extent, are model independent. Phenomenological limits on these vector field parameters are obtained using LEP collider data and dark matter constraints
On D-brane anti D-brane effective actions and their corrections to all orders in alpha-prime
International Nuclear Information System (INIS)
Hatefi, Ehsan
2013-01-01
Based on a four point function, the S-matrix elements at disk level of the scattering amplitude of one closed string Ramond-Ramond field (C) and two tachyons and one scalar field, we find out new couplings in brane anti brane effective actions for p = n, p+2 = n cases. Using the infinite corrections of the vertex of one RR, one gauge and one scalar field and applying the correct expansion, it is investigated in detail how we produce the infinite gauge poles of the amplitude for p = n case. By discovering new higher derivative corrections of two tachyon-two scalar couplings in brane anti brane systems to all orders in α', we also obtain the infinite scalar poles in (t'+s'+u)-channel in field theory. Working with the complete form of the amplitude with the closed form of the expansion and comparing all the infinite contact terms of this amplitude, we derive several new Wess-Zumino couplings with all their infinite higher derivative corrections in the world volume of brane anti brane systems. In particular, in producing all the infinite scalar poles of C V φ V T V T > , one has to consider the fact that scalar's vertex operator in (-1)-picture must carry the internal σ 3 Chan-Paton matrix. The symmetric trace effective action has a non-zero coupling between Dφ (1)i and Dφ (2) i while this coupling does not exist in ordinary trace effective action
Scalar brane backgrounds in higher order curvature gravity
International Nuclear Information System (INIS)
Charmousis, Christos; Davis, Stephen C.; Dufaux, Jean-Francois
2003-01-01
We investigate maximally symmetric brane world solutions with a scalar field. Five-dimensional bulk gravity is described by a general lagrangian which yields field equations containing no higher than second order derivatives. This includes the Gauss-Bonnet combination for the graviton. Stability and gravitational properties of such solutions are considered, and we particularly emphasise the modifications induced by the higher order terms. In particular it is shown that higher curvature corrections to Einstein theory can give rise to instabilities in brane world solutions. A method for analytically obtaining the general solution for such actions is outlined. Generically, the requirement of a finite volume element together with the absence of a naked singularity in the bulk imposes fine-tuning of the brane tension. A model with a moduli scalar field is analysed in detail and we address questions of instability and non-singular self-tuning solutions. In particular, we discuss a case with a normalisable zero mode but infinite volume element. (author)
Interaction of D0-brane bound states and Ramond-Ramond photons
International Nuclear Information System (INIS)
Fatollahi, Amir H.
2002-01-01
We consider the problem of the interaction between a D0-brane bound state and one-form Ramond-Ramond (RR) photons using the world-line theory. Based on the fact that in the world-line theory the RR gauge fields depend on the matrix coordinates of D0-branes, the gauge fields also appear as matrices in the formulation. At the classical level, we derive the Lorentz-like equations of motion for D0-branes, and it is observed that the center of mass is colorless with respect to the SU(N) sector of the background. Using the path integral method, the perturbation theory for the interaction between the bound state and the RR background is developed. Qualitative considerations show that the possibility of the existence of a map between the world-line theory and the non-Abelian gauge theory is very considerable
International Nuclear Information System (INIS)
Creutzig, Thomas
2009-06-01
In this thesis we initiate a systematic study of branes in Wess-Zumino-Novikov-Witten models with Lie supergroup target space. We start by showing that a branes' worldvolume is a twisted superconjugacy class and construct the action of the boundary WZNW model. Then we consider symplectic fermions and give a complete description of boundary states including twisted sectors. Further we show that the GL(1 vertical stroke 1) WZNW model is equivalent to symplectic fermions plus two scalars. We then consider the GL(1 vertical stroke 1) boundary theory. Twisted and untwisted Cardy boundary states are constructed explicitly and their amplitudes are computed. In the twisted case we find a perturbative formulation of the model. For this purpose the introduction of an additional fermionic boundary degree of freedom is necessary. We compute all bulk one-point functions, bulk-boundary two-point functions and boundary three-point functions. Logarithmic singularities appear in bulk-boundary as well as pure boundary correlation functions. Finally we turn to world-sheet and target space supersymmetric models. There is N=2 superconformal symmetry in many supercosets and also in certain supergroups. In the supergroup case we find some branes that preserve the topological A-twist and some that preserve the B-twist. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Creutzig, Thomas
2009-06-15
In this thesis we initiate a systematic study of branes in Wess-Zumino-Novikov-Witten models with Lie supergroup target space. We start by showing that a branes' worldvolume is a twisted superconjugacy class and construct the action of the boundary WZNW model. Then we consider symplectic fermions and give a complete description of boundary states including twisted sectors. Further we show that the GL(1 vertical stroke 1) WZNW model is equivalent to symplectic fermions plus two scalars. We then consider the GL(1 vertical stroke 1) boundary theory. Twisted and untwisted Cardy boundary states are constructed explicitly and their amplitudes are computed. In the twisted case we find a perturbative formulation of the model. For this purpose the introduction of an additional fermionic boundary degree of freedom is necessary. We compute all bulk one-point functions, bulk-boundary two-point functions and boundary three-point functions. Logarithmic singularities appear in bulk-boundary as well as pure boundary correlation functions. Finally we turn to world-sheet and target space supersymmetric models. There is N=2 superconformal symmetry in many supercosets and also in certain supergroups. In the supergroup case we find some branes that preserve the topological A-twist and some that preserve the B-twist. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Creutzig, Thomas
2009-06-15
In this thesis we initiate a systematic study of branes in Wess-Zumino-Novikov-Witten models with Lie supergroup target space. We start by showing that a branes' worldvolume is a twisted superconjugacy class and construct the action of the boundary WZNW model. Then we consider symplectic fermions and give a complete description of boundary states including twisted sectors. Further we show that the GL(1 vertical stroke 1) WZNW model is equivalent to symplectic fermions plus two scalars. We then consider the GL(1 vertical stroke 1) boundary theory. Twisted and untwisted Cardy boundary states are constructed explicitly and their amplitudes are computed. In the twisted case we find a perturbative formulation of the model. For this purpose the introduction of an additional fermionic boundary degree of freedom is necessary. We compute all bulk one-point functions, bulk-boundary two-point functions and boundary three-point functions. Logarithmic singularities appear in bulk-boundary as well as pure boundary correlation functions. Finally we turn to world-sheet and target space supersymmetric models. There is N=2 superconformal symmetry in many supercosets and also in certain supergroups. In the supergroup case we find some branes that preserve the topological A-twist and some that preserve the B-twist. (orig.)
Deformation of N = 4 SYM with varying couplings via fluxes and intersecting branes
Choi, Jaewang; Fernández-Melgarejo, José J.; Sugimoto, Shigeki
2018-03-01
We study deformations of N = 4 supersymmetric Yang-Mills theory with space-time dependent couplings by embedding probe D3-branes in supergravity backgrounds with non-trivial fluxes. The effective action on the world-volume of the D3-branes is analyzed and a map between the deformation parameters and the fluxes is obtained. As an explicit example, we consider D3-branes in a background corresponding to ( p, q) 5-branes intersecting them and show that the effective theory on the D3-branes precisely agrees with the supersymmetric Janus configuration found by Gaiotto and Witten in [1]. D3-branes in an intersecting D3-brane background is also analyzed and the D3-brane effective action reproduces one of the supersymmetric configurations with ISO(1 , 1) × SO(2) × SO(4) symmetry found in our previous paper [2].
Brane-world and loop cosmology from a gravity–matter coupling perspective
Energy Technology Data Exchange (ETDEWEB)
Olmo, Gonzalo J., E-mail: gonzalo.olmo@csic.es [Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia – CSIC, Universidad de Valencia, Burjassot-46100, Valencia (Spain); Departamento de Física, Universidade Federal da Paraíba, 58051-900 João Pessoa, Paraíba (Brazil); Rubiera-Garcia, D., E-mail: drubiera@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, 58051-900 João Pessoa, Paraíba (Brazil)
2015-01-05
We show that the effective brane-world and the loop quantum cosmology background expansion histories can be reproduced from a modified gravity perspective in terms of an f(R) gravity action plus a g(R) term non-minimally coupled with the matter Lagrangian. The reconstruction algorithm that we provide depends on a free function of the matter density that must be specified in each case and allows to obtain analytical solutions always. In the simplest cases, the function f(R) is quadratic in the Ricci scalar, R, whereas g(R) is linear. Our approach is compared with recent results in the literature. We show that working in the Palatini formalism there is no need to impose any constraint that keeps the equations second-order, which is a key requirement for the successful implementation of the reconstruction algorithm.
BPS quantization of the five-brane
Dijkgraaf, R; Verlinde, Herman L
1997-01-01
We give a unified description of all BPS states of M-theory compactified on T^5 in terms of the five-brane. We compute the mass spectrum and degeneracies and find that the SO(5,5,Z) U-duality symmetry naturally arises as a T-duality by assuming that the world-volume theory of the five-brane itself is described by a string theory. We also consider the compactification on S^1/Z_2 \\times T^4, and give a new explanation for its correspondence with heterotic string theory by exhibiting its dual equivalence to M-theory on K3\\times S^1.
Branes, anti-branes and Brauer algebras in gauge-gravity duality
International Nuclear Information System (INIS)
Kimura, Yusuke; Ramgoolam, Sanjaye
2007-01-01
We propose gauge theory operators built using a complex Matrix scalar which are dual to brane-anti-brane systems in AdS 5 x S 5 , in the zero coupling limit of the dual Yang-Mills. The branes involved are half-BPS giant gravitons. The proposed operators dual to giant-anti-giant configurations satisfy the appropriate orthogonality properties. Projection operators in Brauer algebras are used to construct the relevant multi-trace Matrix operators. These are related to the 'coupled representations' which appear in 2D Yang-Mills theory. We discuss the implications of these results for the quantum mechanics of a complex matrix model, the counting of non-supersymmetric operators and the physics of brane-anti-brane systems. The stringy exclusion principle known from the properties of half-BPS giant gravitons, has a new incarnation in this context. It involves a qualitative change in the map between brane-anti-brane states to gauge theory operators. In the case of a pair of sphere giant and anti-giant this change occurs when the sum of the magnitudes of their angular momenta reaches N
Topological extensions of Noether charge algebras carried by Dp-branes
International Nuclear Information System (INIS)
Hammer, H.
1998-01-01
We derive an extension of the supersymmetry algebra carried by D-branes in a massless type IIA superspace vacuum. We find that the extended algebra contains not only topological charges that probe the presence of compact space-time dimensions but also pieces that measure non-trivial configurations of the gauge field on the world-volume of the brane. Furthermore there are terms that measure the coupling of the non-triviality of the world-volume regarded as a U(1) bundle of the gauge field to possible compact space-time dimensions. In particular, the extended algebra carried by the D2-brane can contain the charge of a Dirac monopole of the gauge field. In the course of this work we derive a set of generalized Gamma-matrix identities that include the ones presently known for the IIA case. In the first part of the paper we give an introduction to the basic notions of Noether current algebras and charge algebras; furthermore we find a theorem that describes in a general context how the presence of a gauge field on the world-volume of an embedded object transforming under the symmetry group on the target space alters the algebra of the Noether charges, which otherwise would be the same as the algebra of the symmetry group. This is a phenomenon recently found by Sorokin and Townsend in the case of the M5-brane, but here we show that it holds quite generally, and in particular also in the case of D-branes. (orig.)
Nonuniversal soft parameters in the brane world and the flavor problem in supergravity
International Nuclear Information System (INIS)
Kyae, Bumseok; Shafi, Qaisar
2002-01-01
We consider gravity mediated supersymmetry (SUSY) breaking in 5D spacetime with two 4D branes B1 and B2 separated in the extra dimension. Using an off-shell 5D supergravity (SUGRA) formalism, we argue that the SUSY breaking scales could be nonuniversal even at the fundamental scale in a brane world setting, since SUSY breaking effects could be effectively localized. As an application, we suggest a model in which the two light chiral minimal supersymmetric standard model generations reside on B1, while the third generation is located on B2, and the Higgs multiplets as well as gravity and gauge multiplets reside in the bulk. For SUSY breaking of the order of 10-20 TeV caused by a hidden sector localized at B1, the scalars belonging to the first two generations can become sufficiently heavy to overcome the SUSY flavor problem. SUSY breaking on B2 from a different localized hidden sector gives rise to the third generation soft scalar masses of the order of 1 TeV. Gaugino masses are also of the order of 1 TeV if the size of the extra dimension is ∼10 -16 GeV -1 . As in 4D effective supersymmetric theory, an adjustment of TeV scale parameters is needed to realize the 100 GeV electroweak symmetry breaking scale
Comparing D-branes and black holes with 0- and 6-brane charges
International Nuclear Information System (INIS)
Pierre, J.M.
1997-01-01
We consider configurations of D6-branes with a D0-brane charge given by recent work of Taylor and compute interaction potentials with various D-brane probes using a 1-loop open string calculation. These results are compared to a supergravity calculation using the solution given by Sheinblatt of an extremal black hole carrying 0-brane and 6-brane charges. copyright 1997 The American Physical Society
D-brane solutions under market panic
Pincak, Richard
The relativistic quantum mechanic approach is used to develop stock market dynamics. The relativistic is conceptional here as the meaning of big external volatility or volatility shock on a financial market. We used a differential geometry approach with the parallel transport of prices to obtain a direct shift of the stock price movement. The prices are represented here as electrons with different spin orientation. Up and down orientations of the spin particle are likened here to an increase or a decrease of stock prices. The parallel transport of stock prices is enriched by Riemann curvature, which describes some arbitrage opportunities in the market. To solve the stock-price dynamics, we used the Dirac equation for bispinors on the spherical brane-world. We found out that when a spherical brane is abbreviated to the disk on the equator, we converge to the ideal behavior of financial market where Black-Scholes as well as semi-classical equations are sufficient. Full spherical brane-world scenarios can describe non-equilibrium market behavior where all arbitrage opportunities as well as transaction costs are taken into account. Real application of the model to the option pricing was done. The model developed in this paper brings quantitative different results of option pricing dynamics in the case of nonzero Riemann curvature.
International Nuclear Information System (INIS)
Medved, A J M
2002-01-01
The so-called 'brick-wall model' is a semiclassical approach that has been used to explain black hole entropy in terms of thermal matter fields. Here, we apply the brick-wall formalism to thermal bulk fields in a Randall-Sundrum brane world scenario. In this case, the black hole entity is really a string-like object in the anti-de Sitter bulk, while appearing as a Schwarzchild black hole to observers living on the brane. In spite of these exotic circumstances, we establish that the Bekenstein-Hawking entropy law is preserved. Although a similar calculation was recently considered in the literature, this prior study invoked a simplifying assumption (which we avoid) that cannot be adequately justified
String and brane models with spontaneously or dynamically induced tension
International Nuclear Information System (INIS)
Guendelman, E.I.; Kaganovich, A.; Nissimov, E.; Pacheva, S.
2002-01-01
We study in some detail the properties of a previously proposed new class of string and brane models whose world-sheet (world-volume) actions are built with a modified reparametrization-invariant measure of integration and which do not contain any ad hoc dimensionful parameters. The ratio of the new and the standard Riemannian integration measure densities plays the role of a dynamically generated string or brane tension. The latter is identified as (the magnitude of) an effective (non-Abelian) electric field strength on the world-sheet or world-volume obeying the standard Gauss-law constraint. As a result a simple classical mechanism for confinement via modified-measure 'color' strings is proposed where the colorlessness of the 'hadrons' is an automatic consequence of the new string dynamics
AdS Branes from Partial Breaking of Superconformal Symmetries
International Nuclear Information System (INIS)
Ivanov, E.A.
2005-01-01
It is shown how the static-gauge world-volume superfield actions of diverse superbranes on the AdS d+1 superbackgrounds can be systematically derived from nonlinear realizations of the appropriate AdS supersymmetries. The latter are treated as superconformal symmetries of flat Minkowski superspaces of the bosonic dimension d. Examples include the N = 1 AdS 4 supermembrane, which is associated with the 1/2 partial breaking of the OSp(1|4) supersymmetry down to the N = 1, d = 3 Poincare supersymmetry, and the T-duality related L3-brane on AdS 5 and scalar 3-brane on AdS 5 x S 1 , which are associated with two different patterns of 1/2 breaking of the SU(2, 2|1) supersymmetry. Another (closely related) topic is the AdS/CFT equivalence transformation. It maps the world-volume actions of the codimension-one AdS d+1 (super)branes onto the actions of the appropriate Minkowski (super)conformal field theories in the dimension d
AdS5 solutions from M5-branes on Riemann surface and D6-branes sources
Energy Technology Data Exchange (ETDEWEB)
Bah, Ibrahima [Department of Physics and Astronomy, University of Southern California,Los Angeles, CA 90089 (United States); Institut de Physique Théorique, CEA/Saclay,91191 Gif-sur-Yvette (France)
2015-09-24
We describe the gravity duals of four-dimensional N=1 superconformal field theories obtained by wrapping M5-branes on a punctured Riemann surface. The internal geometry, normal to the AdS{sub 5} factor, generically preserves two U(1)s, with generators (J{sup +},J{sup −}), that are fibered over the Riemann surface. The metric is governed by a single potential that satisfies a version of the Monge-Ampère equation. The spectrum of N=1 punctures is given by the set of supersymmetric sources of the potential that are localized on the Riemann surface and lead to regular metrics near a puncture. We use this system to study a class of punctures where the geometry near the sources corresponds to M-theory description of D6-branes. These carry a natural (p,q) label associated to the circle dual to the killing vector pJ{sup +}+qJ{sup −} which shrinks near the source. In the generic case the world volume of the D6-branes is AdS{sub 5}×S{sup 2} and they locally preserve N=2 supersymmetry. When p=−q, the shrinking circle is dual to a flavor U(1). The metric in this case is non-degenerate only when there are co-dimension one sources obtained by smearing M5-branes that wrap the AdS{sub 5} factor and the circle dual the superconformal R-symmetry. The D6-branes are extended along the AdS{sub 5} and on cups that end on the co-dimension one branes. In the special case when the shrinking circle is dual to the R-symmetry, the D6-branes are extended along the AdS{sub 5} and wrap an auxiliary Riemann surface with an arbitrary genus. When the Riemann surface is compact with constant curvature, the system is governed by a Monge-Ampère equation.
International Nuclear Information System (INIS)
Nakamura, Shin
2005-01-01
We propose a new method to describe a recoiling D-brane that is elastically scattered by closed strings in the nonrelativistic region. We utilize the low-energy effective field theory on the worldvolume of the D-brane, and the velocity of the D-brane is described by the time derivative of the expectation values of the massless scalar fields on the worldvolume. The effects of the closed strings are represented by a source term for the massless fields in this method. The momentum conservation condition between the closed strings and the D-brane is derived up to the relative sign of the momentum of the D-brane
A supersymmetric flipped SU(5) intersecting brane world
Energy Technology Data Exchange (ETDEWEB)
Chen, C.-M. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States)]. E-mail: cchen@physics.tamu.edu; Kraniotis, G.V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States)]. E-mail: kraniotis@physics.tamu.edu; Mayes, V.E. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States)]. E-mail: eric@physics.tamu.edu (and others)
2005-03-31
We construct an N=1 supersymmetric three-family flipped SU(5) model from type IIA orientifolds on T{sup 6}/(Z{sub 2}xZ{sub 2}) with D6-branes intersecting at general angles. The spectrum contains a complete grand unified and electroweak Higgs sector. In addition, it contains extra exotic matter both in bi-fundamental and vector-like representations as well as two copies of matter in the symmetric representation of SU(5)
Modified Friedmann equation and inflation in a warped codimension-two braneworld
International Nuclear Information System (INIS)
Chen Fang; Cline, James M.; Kanno, Sugumi
2008-01-01
We study the Friedmann equation for the warped codimension-two braneworld background which most closely resembles the Randall-Sundrum model. Extra matter on the (Planck) 4-brane, with equation of state p θ =(α-1)ρ for the azimuthal pressure, is required to satisfy the junction conditions. For 1 5 the model is intrinsically stable, without the need for a GW field, and in this case we show that inflationary predictions can be modified by the nonstandard Friedmann equation; in particular, it is possible to get an upper limit on the spectral index, large deviations from the consistency condition between the tensor spectrum and ratio r, and large running of the spectral index even though the slow-roll parameters remain small.
Fluid/gravity correspondence and the CFM black brane solutions
Energy Technology Data Exchange (ETDEWEB)
Casadio, R. [Universita di Bologna, Dipartimento di Fisica e Astronomia, Bologna (Italy); I.N.F.N., Sezione di Bologna, Bologna (Italy); Cavalcanti, R.T. [Universita di Bologna, Dipartimento di Fisica e Astronomia, Bologna (Italy); Universidade Federal do ABC-UFABC, Centro de Ciencias Naturais e Humanas, Santo Andre (Brazil); Rocha, Roldao da [Universidade Federal do ABC-UFABC, Centro de Matematica, Computacao e Cognicao, Santo Andre (Brazil)
2016-10-15
We consider the lower bound for the shear viscosity-to-entropy density ratio, obtained from the fluid/gravity correspondence, in order to constrain the post-Newtonian parameter of brane-world metrics. In particular, we analyse the Casadio-Fabbri-Mazzacurati (CFM) effective solutions for the gravity side of the correspondence and argue that including higher-order terms in the hydrodynamic expansion can lead to a full agreement with the experimental bounds, for the Eddington-Robertson-Schiff post-Newtonian parameter in the CFM metrics. This lends further support to the physical relevance of the viscosity-to-entropy ratio lower bound and fluid/gravity correspondence. Hence we show that CFM black branes are, effectively, Schwarzschild black branes. (orig.)
Generalized complex geometry, generalized branes and the Hitchin sigma model
International Nuclear Information System (INIS)
Zucchini, Roberto
2005-01-01
Hitchin's generalized complex geometry has been shown to be relevant in compactifications of superstring theory with fluxes and is expected to lead to a deeper understanding of mirror symmetry. Gualtieri's notion of generalized complex submanifold seems to be a natural candidate for the description of branes in this context. Recently, we introduced a Batalin-Vilkovisky field theoretic realization of generalized complex geometry, the Hitchin sigma model, extending the well known Poisson sigma model. In this paper, exploiting Gualtieri's formalism, we incorporate branes into the model. A detailed study of the boundary conditions obeyed by the world sheet fields is provided. Finally, it is found that, when branes are present, the classical Batalin-Vilkovisky cohomology contains an extra sector that is related non trivially to a novel cohomology associated with the branes as generalized complex submanifolds. (author)
String creation, D-branes and effective field theory
International Nuclear Information System (INIS)
Hung Lingyan
2008-01-01
This paper addresses several unsettled issues associated with string creation in systems of orthogonal Dp-D(8-p) branes. The interaction between the branes can be understood either from the closed string or open string picture. In the closed string picture it has been noted that the DBI action fails to capture an extra RR exchange between the branes. We demonstrate how this problem persists upon lifting to M-theory. These D-brane systems are analysed in the closed string picture by using gauge-fixed boundary states in a non-standard lightcone gauge, in which RR exchange can be analysed precisely. The missing piece in the DBI action also manifests itself in the open string picture as a mismatch between the Coleman-Weinberg potential obtained from the effective field theory and the corresponding open string calculation. We show that this difference can be reconciled by taking into account the superghosts in the (0+1) effective theory of the chiral fermion, that arises from gauge fixing the spontaneously broken world-line local supersymmetries
World-volumes and string target spaces
International Nuclear Information System (INIS)
Green, M.B.
1996-01-01
String duality suggests a fascinating juxtoposition of world-volume and target-space dynamics. This is particularly apparent in the D-brane description of stringy solitons that forms a major focus of this article (which is not intended to be a comprehensive review of this extensive and sophisticated subject). The article is divided into four sections: the oligarchy of string world-sheets; p-branes and world-volumes; world-sheets for world-volumes; boundary states. D-branes and space-time supersymmetry (orig.)
Energy Technology Data Exchange (ETDEWEB)
Dick, Rainer [University of Saskatchewan, Department of Physics and Engineering Physics, Saskatoon, SK (Canada); Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada)
2015-03-01
If two DGP branes carry U(1) gauge theories and overlap, particles of one brane can interact with the photons from the other brane. This coupling modifies in particular the Coulomb potentials between charges from the same brane in the overlapping regions. The coupling also introduces Coulomb interactions between charges from the different branes which can generate exotic bound states. The effective modification of the fine structure constant in the overlap region generates a trough in signals at the redshift of the overlap region and an increase at smaller or larger redshift, depending on the value of the crosstalk parameter g{sub e}g{sub p}. This implies potentially observable perturbations in the Lyman α forest if our 3-brane overlapped with another 3-brane in a region with redshift z
YM on the dielectric brane: a D0-brane tale
International Nuclear Information System (INIS)
Martucci, Luca; Silva, Pedro J.
2003-01-01
In this letter we present a derivation, from the D0-brane picture, of the background monopole field and in general of the full dynamics of the Yang-Mills theory on the dielectric D2-brane of Myers. To do this we study the large N limit of the fuzzy sphere relevant to the dielectric solution. In contrast to the usual interpretation where the commutative D2-brane picture arises directly from the large N limit of the D0-brane picture, we find that a residual non-commutativity must be preserved in order to make the connection by means of the Seiberg-Witten map
Supersymmetric non-singular fractional D2-branes and NS-NS 2-branes
International Nuclear Information System (INIS)
Cvetic, M.; Gibbons, G.W.; Lue, H.; Pope, C.N.
2001-01-01
We obtain regular deformed D2-brane solutions with fractional D2-branes arising as wrapped D4-branes. The space transverse to the D2-brane is a complete Ricci-flat 7-manifold of G 2 holonomy, which is asymptotically conical with principal orbits that are topologically CP 3 or the flag manifold SU(3)/(U(1)xU(1)). We obtain the solution by first constructing an L 2 normalisable harmonic 3-form. We also review a previously-obtained regular deformed D2-brane whose transverse space is a different 7-manifold of G 2 holonomy, with principal orbits that are topologically S 3 xS 3 . This describes D2-branes with fractional NS-NS 2-branes coming from the wrapping of 5-branes, which is supported by a non-normalisable harmonic 3-form on the 7-manifold. We prove that both types of solutions are supersymmetric, preserving 1/16 of the maximal supersymmetry and hence that they are dual to N=1 three-dimensional gauge theories. In each case, the spectrum for minimally-coupled scalars is discrete, indicating confinement in the infrared region of the dual gauge theories. We examine resolutions of other branes, and obtain necessary conditions for their regularity. The resolution of many of these seems to lie beyond supergravity. In the process of studying these questions, we construct new explicit examples of complete Ricci-flat metrics
Harmonic superpositions of M-branes
International Nuclear Information System (INIS)
Tseytlin, A.A.
1996-01-01
We present solutions describing supersymmetric configurations of 2 or 3 orthogonally intersecting 2-branes and 5-branes of D=11 supergravity. The configurations which preserve 1/4 or 1/8 of maximal supersymmetry are 2 perpendicular to 2, 5 perpendicular to 5, 2 perpendicular to 5, 2 perpendicular to 2 perpendicular to 2, 5 perpendicular to 5 perpendicular to 5, 2 perpendicular to 2 perpendicular to 5 and 2 perpendicular to 5 perpendicular to 5 (2 perpendicular to 2 stands for orthogonal intersection of two 2-branes over a point, etc.; p-branes of the same type intersect over (p-2)-branes). There exists a simple rule which governs the construction of composite supersymmetric p-brane solutions in D=10 and 11 with a separate harmonic function assigned to each constituent 1/2-supersymmetric p-brane. The resulting picture of intersecting p-brane solutions complements their D-brane interpretation in D=10 and seems to support possible existence of a D=11 analogue of D-brane description. The D=11 solution describing intersecting 2-brane and 5-brane reduces in D=10 to a type II string solution corresponding to a fundamental string lying within a solitonic 5-brane (which further reduces to an extremal D=5 black hole). We also discuss a particular D=11 embedding of the extremal D=4 dyonic black hole solution with finite area of horizon. (orig.)
Branes constrictions with White Dwarfs
International Nuclear Information System (INIS)
García-Aspeitia, Miguel A.
2015-01-01
We consider here a robust study of stellar dynamics for white dwarf stars with polytropic matter in the weak-field approximation using the Lane–Emden equation from the brane-world scenario. We also derive an analytical solution to the nonlocal energy density and show the behavior and sensitivity of these stars to the presence of extra dimensions. Similarly, we analyze stability and compactness, in order to show whether it is possible to agree with the conventional wisdom of white dwarfs dynamics. Our results predict an average value of the brane tension of <λ>≳84.818 MeV 4 , with a standard deviation σ≃82.021 MeV 4 , which comes from a sample of dwarf stars, being weaker than other astrophysical observations but remaining higher than cosmological results provided by nucleosynthesis among others
Modified geodetic brane cosmology
International Nuclear Information System (INIS)
Cordero, Rubén; Cruz, Miguel; Molgado, Alberto; Rojas, Efraín
2012-01-01
We explore the cosmological implications provided by the geodetic brane gravity action corrected by an extrinsic curvature brane term, describing a codimension-1 brane embedded in a 5D fixed Minkowski spacetime. In the geodetic brane gravity action, we accommodate the correction term through a linear term in the extrinsic curvature swept out by the brane. We study the resulting geodetic-type equation of motion. Within a Friedmann–Robertson–Walker metric, we obtain a generalized Friedmann equation describing the associated cosmological evolution. We observe that, when the radiation-like energy contribution from the extra dimension is vanishing, this effective model leads to a self-(non-self)-accelerated expansion of the brane-like universe in dependence on the nature of the concomitant parameter β associated with the correction, which resembles an analogous behaviour in the DGP brane cosmology. Several possibilities in the description for the cosmic evolution of this model are embodied and characterized by the involved density parameters related in turn to the cosmological constant, the geometry characterizing the model, the introduced β parameter as well as the dark-like energy and the matter content on the brane. (paper)
BlackMax: A black-hole event generator with rotation, recoil, split branes, and brane tension
International Nuclear Information System (INIS)
Dai Dechang; Starkman, Glenn; Stojkovic, Dejan; Issever, Cigdem; Tseng, Jeff; Rizvi, Eram
2008-01-01
We present a comprehensive black-hole event generator, BlackMax, which simulates the experimental signatures of microscopic and Planckian black-hole production and evolution at the LHC in the context of brane world models with low-scale quantum gravity. The generator is based on phenomenologically realistic models free of serious problems that plague low-scale gravity, thus offering more realistic predictions for hadron-hadron colliders. The generator includes all of the black-hole gray-body factors known to date and incorporates the effects of black-hole rotation, splitting between the fermions, nonzero brane tension, and black-hole recoil due to Hawking radiation (although not all simultaneously). The generator can be interfaced with Herwig and Pythia. The main code can be downloaded from http://www-pnp.physics.ox.ac.uk/~issever/BlackMax/blackmax.html.
D-branes in little string theory
International Nuclear Information System (INIS)
Israel, Dan; Pakman, Ari; Troost, Jan
2005-01-01
We analyze in detail the D-branes in the near-horizon limit of NS5-branes on a circle, the holographic dual of little string theory in a double scaling limit. We emphasize their geometry in the background of the NS5-branes and show the relation with D-branes in coset models. The exact one-point functions giving the coupling of the closed string states with the D-branes and the spectrum of open strings are computed. Using these results, we analyze several aspects of Hanany-Witten setups, using exact CFT analysis. In particular we identify the open string spectrum on the D-branes stretched between NS5-branes which confirms the low-energy analysis in brane constructions, and that allows to go to higher energy scales. As an application we show the emergence of the beta-function of the N=2 gauge theory on D4-branes stretching between NS5-branes from the boundary states describing the D4-branes. We also speculate on the possibility of getting a matrix model description of little string theory from the effective theory on the D1-branes. By considering D3-branes orthogonal to the NS5-branes we find a CFT incarnation of the Hanany-Witten effect of anomalous creation of D-branes. Finally we give an brief description of some non-BPS D-branes
Differential cross sections in a thick brane world scenario
Pedraza, Omar; Arceo, R.; López, L. A.; Cerón, V. E.
2018-04-01
The elastic differential cross section is calculated at low energies for the elements He and Ne using an effective 4D electromagnetic potential coming from the contribution of the massive Kaluza-Klein modes of the 5D vector field in a thick brane scenario. The length scale is adjusted in the potential to compare with known experimental data and to set bounds for the parameter of the model.
Giant graviton interactions and M2-branes ending on multiple M5-branes
Hirano, Shinji; Sato, Yuki
2018-05-01
We study splitting and joining interactions of giant gravitons with angular momenta N 1/2 ≪ J ≪ N in the type IIB string theory on AdS 5 × S 5 by describing them as instantons in the tiny graviton matrix model introduced by Sheikh-Jabbari. At large J the instanton equation can be mapped to the four-dimensional Laplace equation and the Coulomb potential for m point charges in an n-sheeted Riemann space corresponds to the m-to- n interaction process of giant gravitons. These instantons provide the holographic dual of correlators of all semi-heavy operators and the instanton amplitudes exactly agree with the pp-wave limit of Schur polynomial correlators in N = 4 SYM computed by Corley, Jevicki and Ramgoolam. By making a slight change of variables the same instanton equation is mathematically transformed into the Basu-Harvey equation which describes the system of M2-branes ending on M5-branes. As it turns out, the solutions to the sourceless Laplace equation on an n-sheeted Riemann space correspond to n M5-branes connected by M2-branes and we find general solutions representing M2-branes ending on multiple M5-branes. Among other solutions, the n = 3 case describes an M2-branes junction ending on three M5-branes. The effective theory on the moduli space of our solutions might shed light on the low energy effective theory of multiple M5-branes.
Branes constrictions with White Dwarfs
Energy Technology Data Exchange (ETDEWEB)
García-Aspeitia, Miguel A., E-mail: aspeitia@fisica.uaz.edu.mx [Consejo Nacional de Ciencia y Tecnología, Av, Insurgentes Sur 1582, Colonia Crédito Constructor, Del. Benito Juárez, C.P. 03940, Mexico, D.F. (Mexico); Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad esquina con Paseo a la Bufa S/N, C.P. 98060, Zacatecas (Mexico)
2015-11-06
We consider here a robust study of stellar dynamics for white dwarf stars with polytropic matter in the weak-field approximation using the Lane–Emden equation from the brane-world scenario. We also derive an analytical solution to the nonlocal energy density and show the behavior and sensitivity of these stars to the presence of extra dimensions. Similarly, we analyze stability and compactness, in order to show whether it is possible to agree with the conventional wisdom of white dwarfs dynamics. Our results predict an average value of the brane tension of <λ>≳84.818 MeV{sup 4}, with a standard deviation σ≃82.021 MeV{sup 4}, which comes from a sample of dwarf stars, being weaker than other astrophysical observations but remaining higher than cosmological results provided by nucleosynthesis among others.
Branes constrictions with White Dwarfs
Energy Technology Data Exchange (ETDEWEB)
Garcia-Aspeitia, Miguel A. [Consejo Nacional de Ciencia y Tecnologia, Mexico (Mexico); Unidad Academica de Fisica, Universidad Autonoma de Zacatecas (Mexico)
2015-11-15
We consider here a robust study of stellar dynamics for white dwarf stars with polytropic matter in the weak-field approximation using the Lane-Emden equation from the brane-world scenario. We also derive an analytical solution to the nonlocal energy density and show the behavior and sensitivity of these stars to the presence of extra dimensions. Similarly, we analyze stability and compactness, in order to show whether it is possible to agree with the conventional wisdom of white dwarfs dynamics. Our results predict an average value of the brane tension of left angle λ right angle >or similar 84.818 MeV{sup 4}, with a standard deviation σ ≅ 82.021 MeV{sup 4}, which comes from a sample of dwarf stars, being weaker than other astrophysical observations but remaining higher than cosmological results provided by nucleosynthesis among others. (orig.)
The calculation of warping spools of warp-knitting machines
Directory of Open Access Journals (Sweden)
Vitaliy V. Chaban
2014-12-01
Full Text Available The paper is devoted to the development of scientific bases of the knitting machine design, in particular, to the calculation of warping spools of warp-knitting machines. The method of calculating the operating parameters of warping spools and mode of winding is offered. A formula that is obtained allows to define relationship between the parameters of the threads wound on a warping spool, their pull, structural dimensions of spool barrel and the diameter of spooling. With the given spool design and the given value of permissible tension of the material of its barrel, the offered formula allows to determine the maximum tension of the threads in the process of their winding on a spool. By this formula the safe diameter of winding the threads onto the spool can be calculated at a given pull of the threads during winding.
Axion monodromy inflation with warped KK-modes
Energy Technology Data Exchange (ETDEWEB)
Hebecker, Arthur; Moritz, Jakob; Witkowski, Lukas T. [Heidelberg Univ. (Germany). Inst. for Theoretical Physics; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2015-12-15
We present a particularly simple model of axion monodromy inflation: Our axion is the lowest-lying KK-mode of the RR-2-form-potential C{sub 2} in the standard Klebanov-Strassler throat. One can think of this inflaton candidate as being defined by the integral of C{sub 2} over the S{sup 2} cycle of the throat. It obtains an exponentially small mass from the IR-region in which the S{sup 2} shrinks to zero size. Crucially, the S{sup 2} cycle has to be shared between two throats, such that the second locus where the S{sup 2} shrinks is also in a warped region. Well-known problems like the potentially dangerous back-reaction of brane/antibrane pairs and explicit supersymmetry breaking are not present in our scenario. The inflaton back-reaction on the geometry turns out to be controlled by the string coupling g{sub s}. We hope that our setting is simple enough for many critical consistency issues of large-field inflation in string theory to be addressed at a quantitative level.
Axion monodromy inflation with warped KK-modes
International Nuclear Information System (INIS)
Hebecker, Arthur; Moritz, Jakob; Witkowski, Lukas T.
2015-12-01
We present a particularly simple model of axion monodromy inflation: Our axion is the lowest-lying KK-mode of the RR-2-form-potential C 2 in the standard Klebanov-Strassler throat. One can think of this inflaton candidate as being defined by the integral of C 2 over the S 2 cycle of the throat. It obtains an exponentially small mass from the IR-region in which the S 2 shrinks to zero size. Crucially, the S 2 cycle has to be shared between two throats, such that the second locus where the S 2 shrinks is also in a warped region. Well-known problems like the potentially dangerous back-reaction of brane/antibrane pairs and explicit supersymmetry breaking are not present in our scenario. The inflaton back-reaction on the geometry turns out to be controlled by the string coupling g s . We hope that our setting is simple enough for many critical consistency issues of large-field inflation in string theory to be addressed at a quantitative level.
Axion monodromy inflation with warped KK-modes
Hebecker, Arthur; Moritz, Jakob; Westphal, Alexander; Witkowski, Lukas T.
2016-03-01
We present a particularly simple model of axion monodromy inflation: Our axion is the lowest-lying KK-mode of the RR-2-form-potential C2 in the standard Klebanov-Strassler throat. One can think of this inflaton candidate as being defined by the integral of C2 over the S2 cycle of the throat. It obtains an exponentially small mass from the IR-region in which the S2 shrinks to zero size. Crucially, the S2 cycle has to be shared between two throats, such that the second locus where the S2 shrinks is also in a warped region. Well-known problems like the potentially dangerous back-reaction of brane/antibrane pairs and explicit supersymmetry breaking are not present in our scenario. The inflaton back-reaction on the geometry turns out to be controlled by the string coupling gs. We hope that our setting is simple enough for many critical consistency issues of large-field inflation in string theory to be addressed at a quantitative level.
International Nuclear Information System (INIS)
Csaki, Csaba; Grossman, Yuval; Tanedo, Philip; Tsai, Yuhsin
2011-01-01
We present an analysis of the loop-induced magnetic dipole operator in the Randall-Sundrum model of a warped extra dimension with anarchic bulk fermions and an IR brane-localized Higgs. These operators are finite at one-loop order and we explicitly calculate the branching ratio for μ→eγ using the mixed position/momentum space formalism. The particular bound on the anarchic Yukawa and Kaluza-Klein (KK) scales can depend on the flavor structure of the anarchic matrices. It is possible for a generic model to either be ruled out or unaffected by these bounds without any fine-tuning. We quantify how these models realize this surprising behavior. We also review tree-level lepton flavor bounds in these models and show that these are on the verge of tension with the μ→eγ bounds from typical models with a 3 TeV Kaluza-Klein scale. Further, we illuminate the nature of the one-loop finiteness of these diagrams and show how to accurately determine the degree of divergence of a five-dimensional loop diagram using both the five-dimensional and KK formalism. This power counting can be obfuscated in the four-dimensional Kaluza-Klein formalism and we explicitly point out subtleties that ensure that the two formalisms agree. Finally, we remark on the existence of a perturbative regime in which these one-loop results give the dominant contribution.
Soliton models for thick branes
International Nuclear Information System (INIS)
Peyravi, Marzieh; Riazi, Nematollah; Lobo, Francisco S.N.
2016-01-01
In this work, we present new soliton solutions for thick branes in 4+1 dimensions. In particular, we consider brane models based on the sine-Gordon (SG), φ 4 and φ 6 scalar fields, which have broken Z 2 symmetry in some cases and are responsible for supporting and stabilizing the thick branes. The origin of the symmetry breaking in these models resides in the fact that the modified scalar field potential may have non-degenerate vacua. These vacua determine the cosmological constant on both sides of the brane. We also study the geodesic equations along the fifth dimension, in order to explore the particle motion in the neighborhood of the brane. Furthermore, we examine the stability of the thick branes, by determining the sign of the w 2 term in the expansion of the potential for the resulting Schroedinger-like equation, where w is the five-dimensional coordinate. It turns out that the φ 4 brane is stable, while there are unstable modes for certain ranges of the model parameters in the SG and φ 6 branes. (orig.)
Brane tilings and their applications
International Nuclear Information System (INIS)
Yamazaki, M.
2008-01-01
We review recent developments in the theory of brane tilings and four-dimensional N=1 supersymmetric quiver gauge theories. This review consists of two parts. In part I, we describe foundations of brane tilings, emphasizing the physical interpretation of brane tilings as fivebrane systems. In part II, we discuss application of brane tilings to AdS/CFT correspondence and homological mirror symmetry. More topics, such as orientifold of brane tilings, phenomenological model building, similarities with BPS solitons in supersymmetric gauge theories, are also briefly discussed. (Abstract Copyright [2008], Wiley Periodicals, Inc.)
Mass spectrum in 5D Warped Einstein Universe and El Naschie's quantum golden field theory
International Nuclear Information System (INIS)
Dariescu, Marina-Aura; Dariescu, Ciprian; Pirghie, Ana-Camelia
2009-01-01
The present paper deals with the massive bosons evolving in a 5D manifold, where the four-dimensional slices are the S 3 xR spacetime. By solving the Einstein equations with a perfect fluid source, we find the expression of the warp factor and write down the corresponding Gordon equation in the bulk, near one of the degenerated vacua of an effective potential with a spontaneously broken Z 2 -symmetry. We obtain the general form of the wave functions and analyze how the Kaluza-Klein-type spectrum is affecting the mass of the scalar on the brane. By inspecting the mass spectrum, we point out a connection with the golden mean based El Naschie's field theory.
Energy Technology Data Exchange (ETDEWEB)
Gonzalez-Diaz, Pedro F. [Colina de los Chopos, Centro de Fisica ' Miguel A. Catalan' , Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain)], E-mail: p.gonzalezdiaz@imaff.cfmac.csic.es
2007-09-20
In this Letter we consider a warp drive spacetime resulting from that suggested by Alcubierre when the spaceship can only travel faster than light. Restricting to the two dimensions that retains most of the physics, we derive the thermodynamic properties of the warp drive and show that the temperature of the spaceship rises up as its apparent velocity increases. We also find that the warp drive spacetime can be exhibited in a manifestly cosmological form.
Phenomenological aspects of D-branes
International Nuclear Information System (INIS)
Quevedo, F.
2003-01-01
A general overview is presented on string phenomenology, emphasizing the role played by D-branes. A general discussion of the main challenges for string phenomenology is followed by recent progress made in constructing realistic models from D-branes and anti-branes at singularities and also from intersecting D-branes. Some possible cosmological implications of these classes of string models are also mentioned. (author)
Phenomenological aspects of D-branes
Energy Technology Data Exchange (ETDEWEB)
Quevedo, F [Centre for Mathematical Sciences, DAMTP, University of Cambridge, Cambridge (United Kingdom)
2003-08-15
A general overview is presented on string phenomenology, emphasizing the role played by D-branes. A general discussion of the main challenges for string phenomenology is followed by recent progress made in constructing realistic models from D-branes and anti-branes at singularities and also from intersecting D-branes. Some possible cosmological implications of these classes of string models are also mentioned. (author)
Soliton models for thick branes
Energy Technology Data Exchange (ETDEWEB)
Peyravi, Marzieh [Ferdowsi University of Mashhad, Department of Physics, School of Sciences, Mashhad (Iran, Islamic Republic of); Riazi, Nematollah [Shahid Beheshti University, Physics Department, Tehran (Iran, Islamic Republic of); Lobo, Francisco S.N. [Faculdade de Ciencias da Universidade de Lisboa, Instituto de Astrofisica e Ciencias do Espaco, Lisbon (Portugal)
2016-05-15
In this work, we present new soliton solutions for thick branes in 4+1 dimensions. In particular, we consider brane models based on the sine-Gordon (SG), φ{sup 4} and φ{sup 6} scalar fields, which have broken Z{sub 2} symmetry in some cases and are responsible for supporting and stabilizing the thick branes. The origin of the symmetry breaking in these models resides in the fact that the modified scalar field potential may have non-degenerate vacua. These vacua determine the cosmological constant on both sides of the brane. We also study the geodesic equations along the fifth dimension, in order to explore the particle motion in the neighborhood of the brane. Furthermore, we examine the stability of the thick branes, by determining the sign of the w{sup 2} term in the expansion of the potential for the resulting Schroedinger-like equation, where w is the five-dimensional coordinate. It turns out that the φ{sup 4} brane is stable, while there are unstable modes for certain ranges of the model parameters in the SG and φ{sup 6} branes. (orig.)
Note on inflation with a tachyon rolling on the Gauss-Bonnet brane
International Nuclear Information System (INIS)
Paul, B.C.; Sami, M.
2004-01-01
In this paper we study the tachyonic inflation in brane world cosmology with Gauss-Bonnet term in the bulk. We obtain the exact solution of slow roll equations in case of exponential potential. We attempt to implement the proposal of J. E. Lidsey and N. J. Nunes [Phys. Rev. D 67, 103510 (2003)] for the tachyon condensate rolling on the Gauss-Bonnet brane and discuss the difficulties associated with the proposal
Swarup, Bob
2008-01-01
Warp drives are a staple of science fiction, transporting the heroes of shows like Star Trek between galaxies in a matter of hours. Now, increasing numbers of cosmologists are wondering whether this technology might eventually become science fact. Dozens of scientific papers on warp drives have appeared since 1994 when Miguel Alcubierre - a theoretical physicist then at the University of Wales in Cardiff - first argued that a warp drive was theoretically possible (Class. Quantum Grav. 11 L73)
Post-inflationary brane cosmology
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Mazumdar, Anupam
2001-01-01
The brane cosmology has invoked new challenges to the usual Big Bang cosmology. In this paper we present a brief account on thermal history of the post-inflationary brane cosmology. We have realized that it is not obvious that the post-inflationary brane cosmology would always deviate from the standard Big Bang cosmology. However, if it deviates some stringent conditions on the brane tension are to be satisfied. In this regard we study various implications on gravitino production and its abundance. We discuss Affleck-Dine mechanism for baryogenesis and make some comments on moduli and dilaton problems in this context
Non-BPS D-branes in light-cone Green-Schwarz formalism
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Mukhopadhyay, Partha
2005-01-01
Non-BPS D-branes are difficult to describe covariantly in a manifestly supersymmetric formalism. For definiteness we concentrate on type-IIB string theory in flat background in light-cone Green-Schwarz formalism. We study both the boundary state and the boundary conformal field theory descriptions of these D-branes with manifest SO(8) covariance and go through various consistency checks. We analyze Sen's original construction of non-BPS D-branes given in terms of an orbifold boundary conformal field theory. We also directly study the relevant world-sheet theory by deriving the open string boundary condition from the covariant boundary state. Both these methods give the same open string spectrum which is consistent with the boundary state, as required by the world-sheet duality. The boundary condition found in the second method is given in terms of bi-local fields that are quadratic in Green-Schwarz fermions. We design a special 'doubling trick' suitable to handle such boundary conditions and prescribe rules for computing all possible correlation functions without boundary insertions. This prescription has been tested by computing disk one-point functions of several classes of closed string states and comparing the results with the boundary state computation. (author)
Near-horizon solutions for D3-branes ending on 5-branes
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Aharony, Ofer; Berdichevsky, Leon; Berkooz, Micha; Shamir, Itamar
2011-01-01
We construct the type IIB supergravity solutions describing D3-branes ending on 5-branes, in the near-horizon limit of the D3-branes. Our solutions are holographically dual to the four dimensional (4D) N=4 SU(N) supersymmetric-Yang-Mills (SYM) theory on a half line, at large N and large 't Hooft coupling, with various boundary conditions that preserve half of the supersymmetry. The solutions are limiting cases of the general solutions with the same symmetries constructed in 2007 by D'Hoker, Estes and Gutperle. The classification of our solutions matches exactly with the general classification of boundary conditions for D3-branes ending on 5-branes by Gaiotto and Witten. We use the gravity duals to compute the one-point functions of some chiral operators in the N=4 SYM theory on a half line at strong coupling, and we find that they do not match with the expectation values of the same operators with the same boundary conditions at small 't Hooft coupling. Our solutions may also be interpreted as the gravity duals of 4D N=4 SYM on AdS 4 , with various boundary conditions.
On asymptotic behavior of anisotropic branes with induced gravity inspired by L(R) term
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Heydari-Fard, Malihe
2010-01-01
The DGP brane-world scenario provides the accelerated expansion of the universe at late-time by large-distance modification of general relativity without any need for dark energy. Using the method in reference [33], we investigate the asymptotic behavior of homogeneous and anisotropic cosmologies on a generalization of DGP scenario where the effective theory of gravity induced on the brane is given by a L(R) term. We show that for a constant induced curvature term on the brane all Bianchi models except type IX isotropize, like general relativity, if the effective energy density and E ab term satisfy some energy conditions. Finally, we compare the result of the model with the result of anisotropic DGP branes and general relativity
Rolling down the throat in NS5-brane background: the case of electrified D-brane
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Nakayama, Yu; Takayanagi, Hiromitsu; Panigrahi, Kamal L.; Rey, Soo-Jong
2005-01-01
We study rolling radion dynamics of electrified D-brane in NS5-brane background, both in effective field theory and in full open string theory. We construct exact boundary states and, from them, extract conserved Noether currents. We argue that T-duality and Lorentz boost offer an intuitive approach. In the limit of large number of NS5-branes, both boundary wave functions and conserved currents are sharply peaked and agree with those deduced from the effective field theory. As the number of NS5-branes is reduced, width around the peak becomes wider by string corrections. We also study radiative decay process. By applying Lorentz covariance, we show how the decay of electrified D-brane is related to that of bare D-brane. We compute spectral moments of final state energy and winding quantum number. Using Lorentz covariance argument, we explain in elementary way why winding quantum number should be included and derive rules how to do so. We conclude that Kutasov's 'geometric realization' between radion rolling dynamics and tachyon rolling dynamics holds universally, both for bare and electrified D-branes. (author)
Doǧan, S.; Nixon, C. J.; King, A. R.; Pringle, J. E.
2018-05-01
Accretion discs are generally warped. If a warp in a disc is too large, the disc can `break' apart into two or more distinct planes, with only tenuous connections between them. Further, if an initially planar disc is subject to a strong differential precession, then it can be torn apart into discrete annuli that precess effectively independently. In previous investigations, torque-balance formulae have been used to predict where and when the disc breaks into distinct parts. In this work, focusing on discs with Keplerian rotation and where the shearing motions driving the radial communication of the warp are damped locally by turbulence (the `diffusive' regime), we investigate the stability of warped discs to determine the precise criterion for an isolated warped disc to break. We find and solve the dispersion relation, which, in general, yields three roots. We provide a comprehensive analysis of this viscous-warp instability and the emergent growth rates and their dependence on disc parameters. The physics of the instability can be understood as a combination of (1) a term that would generally encapsulate the classical Lightman-Eardley instability in planar discs (given by ∂(νΣ)/∂Σ < 0) but is here modified by the warp to include ∂(ν1|ψ|)/∂|ψ| < 0, and (2) a similar condition acting on the diffusion of the warp amplitude given in simplified form by ∂(ν2|ψ|)/∂|ψ| < 0. We discuss our findings in the context of discs with an imposed precession, and comment on the implications for different astrophysical systems.
M5-brane as a Nambu-Poisson geometry of a multi-D1-brane theory
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De Castro, A.; Garcia del Moral, M.P.; Martin, I.; Restuccia, A.
2004-01-01
We introduce a Nambu-Poisson bracket in the geometrical description of the D=11 M5-brane. This procedure allows us, under some assumptions, to eliminate the local degrees of freedom of the antisymmetric field in the M5-brane Hamiltonian and to express it as a D=11 p-brane theory invariant under symplectomorphisms. The explicit expression of the Hamiltonian is obtained. The existence of nontrivial physical configurations annihilating the energy density is shown. Finally, a regularization of the M5-brane in terms of a multi D1-brane theory invariant under the SU(N)xSU(N) group in the limit when N→∞ is constructed
Inflation with improved D3-brane potential and the fine tunings associated with the model
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Ali, Amna; Sami, M.; Deshamukhya, Atri; Panda, Sudhakar
2011-01-01
We revisit our earlier investigations of the brane-antibrane inflation in a warped deformed conifold background, reported in Phys. Lett. B 674, 131 (2009), where now we include the contributions to the inflation potential arising from imaginary anti-self-dual (IASD) fluxes including the term with irrational scaling dimension discovered recently in arXiv:0912.4268 and arXiv:1001.5028. We observe that these corrections to the effective potential help in relaxing the severe fine tunings associated with the earlier analysis. Required number of e-folds, observational constraint on COBE normalization and low value of the tensor to scalar ratio are achieved which is consistent with WMAP seven years data. (orig.)
Near-horizon brane-scan revived
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Duff, M.J.
2009-01-01
In 1987 two versions of the brane-scan of D-dimensional super p-branes were put forward. The first pinpointed those (p,D) slots consistent with kappa-symmetric Green-Schwarz type actions; the second generalized the membrane at the end of the universe idea to all those superconformal groups describing p-branes on the boundary of AdS p+2 xS D-p-2 . Although the second version predicted D3- and M5-branes in addition to those of the first, it came unstuck because the 1/2 BPS solitonic branes failed to exhibit the required symmetry enhancement in the near-horizon limit, except in the non-dilatonic cases (p=2,D=11), (p=3,D=10) and (p=5,D=11). Just recently, however, it has been argued that the fundamental D=10 heterotic string does indeed display a near-horizon enhancement to OSp(8|2) as predicted by the brane-scan, provided α' corrections are taken into account. If this logic could be extended to the other strings and branes, it would resolve this 21-year-old paradox and provide a wealth of new AdS/CFT dualities, which we tabulate
Fundamental limitations on 'warp drive' spacetimes
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Lobo, Francisco S N; Visser, Matt
2004-01-01
'Warp drive' spacetimes are useful as 'gedanken-experiments' that force us to confront the foundations of general relativity, and among other things, to precisely formulate the notion of 'superluminal' communication. After carefully formulating the Alcubierre and Natario warp drive spacetimes, and verifying their non-perturbative violation of the classical energy conditions, we consider a more modest question and apply linearized gravity to the weak-field warp drive, testing the energy conditions to first and second orders of the warp-bubble velocity, v. Since we take the warp-bubble velocity to be non-relativistic, v << c, we are not primarily interested in the 'superluminal' features of the warp drive. Instead we focus on a secondary feature of the warp drive that has not previously been remarked upon-the warp drive (if it could be built) would be an example of a 'reaction-less drive'. For both the Alcubierre and Natario warp drives we find that the occurrence of significant energy condition violations is not just a high-speed effect, but that the violations persist even at arbitrarily low speeds. A particularly interesting feature of this construction is that it is now meaningful to think of placing a finite mass spaceship at the centre of the warp bubble, and then see how the energy in the warp field compares with the mass-energy of the spaceship. There is no hope of doing this in Alcubierre's original version of the warp field, since by definition the point at the centre of the warp bubble moves on a geodesic and is 'massless'. That is, in Alcubierre's original formalism and in the Natario formalism the spaceship is always treated as a test particle, while in the linearized theory we can treat the spaceship as a finite mass object. For both the Alcubierre and Natario warp drives we find that even at low speeds the net (negative) energy stored in the warp fields must be a significant fraction of the mass of the spaceship
Brane world cosmologies with varying speed of light
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Youm, Donam
2001-02-01
We study cosmologies in the Randall-Sundrum models, incorporating the possibility of time-varying speed of light and Newton's constant. The cosmologies with varying speed of light (VSL) were proposed by Moffat and by Albrecht and Magueijo as an alternative to inflation for solving the cosmological problems. We consider the case in which the speed of light varies with time after the radion or the scale of the extra dimension has been stabilized. We elaborate on the conditions under which the flatness problem and the cosmological constant problem can be resolved. Particularly, the VSL cosmologies may provide a possible mechanism for bringing the quantum corrections to the fine-tuned brane tensions after the SUSY breaking under control. (author)
On D-brane dynamics and moduli stabilization
Kitazawa, Noriaki
2017-09-01
We discuss the effect of the dynamics of D-branes on moduli stabilization in type IIB string theory compactifications, with reference to a concrete toy model of T6/Z 3 orientifold compactification with fractional D3-branes and anti-D3-branes at orbifold fixed points. The resulting attractive forces between anti-D3-branes and D3-branes, together with the repulsive forces between anti-D3-branes and O3-planes, can affect the stability of the compact space. There are no complex structure moduli in T6/Z 3 orientifold, which should thus capture some generic features of more general settings where all complex structure moduli are stabilized by three-form fluxes. The simultaneous presence of branes and anti-branes brings along the breaking of supersymmetry. Non-BPS combinations of this type are typical of “brane supersymmetry breaking” and are a necessary ingredient in the KKLT scenario for stabilizing the remaining Kähler moduli. The conclusion of our analysis is that, while mutual D-brane interactions sometimes help Kähler moduli stabilization, this is not always the case.
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Gregory, Ruth
2007-01-01
The study of braneworlds has been an area of intense activity over the past decade, with thousands of papers being written, and many important technical advances being made. This book focuses on a particular aspect of braneworlds, namely perturbative gravity in one specific model: the Randall-Sundrum model. The book starts with an overview of the Randall-Sundrum model, discussing anti-de Sitter (AdS) space and the Israel equations in some detail. It then moves on to discuss cosmological branes, focusing on branes with constant curvature. The book then turns to brane gravity, i.e. what do we, as brane observers, perceive the gravitational interaction to be on the brane as derived from the actual five-dimensional gravitational physics? After a derivation of the general brane equations from the Israel equations, the remainder of the book deals with perturbative gravity. This part of the book is extremely detailed, with calculations given explicitly. Overall, the book is quite pedagogical in style, with the aim being to explain in detail the topics it chooses to cover. While it is not unusual to have books written on current and extremely popular research areas, it is unusual to have calculations written so explicitly. This is both a strength and a weakness of this book. It is a strength because the calculations are presented in a detail that students learning the topic will definitely appreciate; however, the narrow focus of the book also means that it lacks perspective and fails to present the broader context. In choosing to focus on one particular aspect of Randall-Sundrum branes, the book has not managed to communicate why a large number of theorists have worked so intensively on this model. In its early stages, the explicit detail of the Randall-Sundrum model would be extremely useful for a student starting out in this research area. In addition, the calculational detail later in the computation of the graviton propagator on the brane would also be welcome not
Brane f(R) gravity and the dark side of the universe
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Borzou, A.; Sepangi, H. R.; Shahidi, S.; Yousefi, R.
2009-01-01
We consider a brane world scenario in which the bulk action is assumed to have the form of a generic function of the Ricci scalar f(R) and derive the resulting Einstein field equation on the brane. In a constant curvature bulk a conserved geometric quantity appears in the field equations which can be associated with matter. We present spherically symmetric solutions which account for galaxy rotation curves in a specific form. Then cosmological solutions by assuming a specific form for f(R) are derived which can explain an accelerated expanding universe.
Correlation functions of warped CFT
Song, Wei; Xu, Jianfei
2018-04-01
Warped conformal field theory (WCFT) is a two dimensional quantum field theory whose local symmetry algebra consists of a Virasoro algebra and a U(1) Kac-Moody algebra. In this paper, we study correlation functions for primary operators in WCFT. Similar to conformal symmetry, warped conformal symmetry is very constraining. The form of the two and three point functions are determined by the global warped conformal symmetry while the four point functions can be determined up to an arbitrary function of the cross ratio. The warped conformal bootstrap equation are constructed by formulating the notion of crossing symmetry. In the large central charge limit, four point functions can be decomposed into global warped conformal blocks, which can be solved exactly. Furthermore, we revisit the scattering problem in warped AdS spacetime (WAdS), and give a prescription on how to match the bulk result to a WCFT retarded Green's function. Our result is consistent with the conjectured holographic dualities between WCFT and WAdS.
U-duality and D-brane combinatorics
Pioline, B
1998-01-01
We investigate D-brane instanton contributions to R^4 couplings in any toroidal compactification of type II theories. Starting from the 11D supergravity one-loop four-graviton amplitude computed by Green, Gutperle and Vanhove, we derive the non-perturbative O(e^{-1/\\lambda}) corrections to R^4 couplings by a sequence of T-dualities, and interpret them as precise configurations of bound states of D-branes wrapping cycles of the compactification torus. Dp-branes explicitely appear as fluxes on D(p+2)-branes, and as gauge instantons on D(p+4)-branes. Specific rules for weighting these contributions are obtained, which should carry over to more general situations. Furthermore, it is shown that U-duality in D<=6 relates these D-brane configurations to O(e^{-1/\\lambda^2}) instantons for which a geometric interpretation is still lacking.
Brane solutions sourced by a scalar with vanishing potential and classification of scalar branes
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Cadoni, Mariano [Dipartimento di Fisica, Università di Cagliari,Cittadella Universitaria, 09042 Monserrato (Italy); INFN, Sezione di Cagliari,Cagliari (Italy); Franzin, Edgardo [Dipartimento di Fisica, Università di Cagliari,Cittadella Universitaria, 09042 Monserrato (Italy); INFN, Sezione di Cagliari,Cagliari (Italy); CENTRA, Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa,Avenida Rovisco Pais 1, 1049 Lisboa (Portugal); Serra, Matteo [Dipartimento di Matematica, Sapienza Università di Roma,Piazzale Aldo Moro 2, 00185 Roma (Italy)
2016-01-20
We derive exact brane solutions of minimally coupled Einstein-Maxwell-scalar gravity in d+2 dimensions with a vanishing scalar potential and we show that these solutions are conformal to the Lifshitz spacetime whose dual QFT is characterized by hyperscaling violation. These solutions, together with the AdS brane and the domain wall sourced by an exponential potential, give the complete list of scalar branes sourced by a generic potential having simple (scale-covariant) scaling symmetries not involving Galilean boosts. This allows us to give a classification of both simple and interpolating brane solution of minimally coupled Einstein-Maxwell-scalar gravity having no Schrödinger isometries, which may be very useful for holographic applications.
4D-flat compactifications with brane vorticities
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Randjbar Daemi, S.; Rubakov, V.
2004-07-01
We present solutions in six-dimensional gravity coupled to a sigma model, in the presence of three-brane sources. The space transverse to the branes is a compact non-singular manifold. The example of O(3) sigma model in the presence of two three-branes is worked out in detail. We show that the four-dimensional flatness is obtained with a single condition involving the brane tensions, which are in general different and may be both positive, and another characteristic of the branes, vorticity. We speculate that the adjustment of the effective four- dimensional cosmological constant may occur through the exchange of vorticity between the branes. We then give exact instanton type solutions for sigma models targeted on a general Kaehler manifold, and elaborate in this framework on multi-instantons of the O(3) sigma model. The latter have branes, possibly with vorticities, at the instanton positions, thus generalizing our two-brane solution. (author)
4d-flat compactifications with brane vorticities
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Randjbar-Daemi, Seif; Rubakov, Valery
2004-01-01
We present solutions in six-dimensional gravity coupled to a sigma model, in the presence of three-brane sources. The space transverse to the branes is a compact non-singular manifold. The example of O(3) sigma model in the presence of two three-branes is worked out in detail. We show that the four-dimensional flatness is obtained with a single condition involving the brane tensions, which are in general different and may be both positive, and another characteristic of the branes, vorticity. We speculate that the adjustment of the effective four-dimensional cosmological constant may occur through the exchange of vorticity between the branes. We then give exact instanton type solutions for sigma models targeted on a general Kaehler manifold, and elaborate in this framework on multi-instantons of the O(3) sigma model. The latter have branes, possibly with vorticities, at the instanton positions, thus generalizing our two-brane solution. (author)
Strings, Branes and Symmetries
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Westerberg, A.
1997-01-01
Recent dramatic progress in the understanding of the non-perturbative structure of superstring theory shows that extended objects of various kinds, collectively referred to as p-branes, are an integral part of the theory. In this thesis, comprising an introductory text and seven appended research papers, we study various aspects of p-branes with relevance for superstring theory. The first part of the introductory text is a brief review of string theory focussing on the role of p-branes. In particular, we consider the so-called D-branes which currently are attracting a considerable amount of attention. The purpose of this part is mainly to put into context the results of paper 4, 5 and 6 concerning action functionals describing the low-energy dynamics of D-branes. The discussion of perturbative string theory given in this part of the introduction is also intended to provide some background to paper 2 which contains an application of the Reggeon-sewing approach to the construction of string vertices. The second part covers a rather different subject, namely higher-dimensional loop algebras and their cohomology, with the aim of facilitating the reading of papers 1, 3 and 7. The relation to p-branes is to be found in paper 1 where we introduce a certain higher-dimensional generalization of the loop algebra and discuss its potential applicability as a symmetry algebra for p-branes. Papers 3 and 7 are mathematically oriented out-growths of this paper addressing the issue of realizing algebras of this kind, known in physics as current algebras, in terms of pseudo differential operators (PSDOs). The main result of paper 3 is a proof of the equivalence between certain Lie-algebra cocycles on the space of second-quantizable PSDOs
The D-instanton and other supersymmetric D-branes in IIB plane-wave string theory
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Gaberdiel, Matthias R.; Green, Michael B.
2003-01-01
A class of D-branes for the type IIB plane-wave background is considered that preserve half the dynamical supersymmetries of the light-cone gauge. The D-branes of this type are the Euclidean (or instantonic) (0,0), (0,4), and (4,0) branes (where (r,s) denotes a brane oriented with r axes in the first four directions transverse to the +, - light-cone, and s axes in the second four directions). Corresponding Lorentzian D-branes are (+,-;0,0), (+,-;0,4), and (+,-;4,0). These are constructed in two ways. The first uses a boundary state formalism which implements appropriate fermionic gluing conditions and the second is based on a direct quantization of the open strings ending on the branes. In distinction to the D-branes considered earlier these have massless world-volume fermions but do not possess kinematical supersymmetries. Cylinder diagrams describing the overlap between a pair of boundary states displaced by some distance are evaluated. The open-string description of this system involves mode frequencies that are, in general, given by irrational solutions to transcendental equations. The closed-string and open-string descriptions are shown to be equivalent by a nontrivial implementation of the S modular transformation. A classical description of the D-instanton (the (0,0) case) in light-cone gauge is also given
Micro-orbits in a many-brane model and deviations from Newton's 1/r^2 law
Donini, A.; Marimón, S. G.
2016-12-01
We consider a five-dimensional model with geometry M = M_4 × S_1, with compactification radius R. The Standard Model particles are localized on a brane located at y=0, with identical branes localized at different points in the extra dimension. Objects located on our brane can orbit around objects located on a brane at a distance d=y/R, with an orbit and a period significantly different from the standard Newtonian ones. We study the kinematical properties of the orbits, finding that it is possible to distinguish one motion from the other in a large region of the initial conditions parameter space. This is a warm-up to study if a SM-like mass distribution on one (or more) distant brane(s) may represent a possible dark matter candidate. After using the same technique to the study of orbits of objects lying on the same brane (d=0), we apply this method to the detection of generic deviations from the inverse-square Newton law. We propose a possible experimental setup to look for departures from Newtonian motion in the micro-world, finding that an order of magnitude improvement on present bounds can be attained at the 95% CL under reasonable assumptions.
Micro-orbits in a many-brane model and deviations from Newton's 1/r"2 law
International Nuclear Information System (INIS)
Donini, A.; Marimon, S.G.
2016-01-01
We consider a five-dimensional model with geometry M = M_4 x S_1, with compactification radius R. The Standard Model particles are localized on a brane located at y = 0, with identical branes localized at different points in the extra dimension. Objects located on our brane can orbit around objects located on a brane at a distance d = y/R, with an orbit and a period significantly different from the standard Newtonian ones. We study the kinematical properties of the orbits, finding that it is possible to distinguish one motion from the other in a large region of the initial conditions parameter space. This is a warm-up to study if a SM-like mass distribution on one (or more) distant brane(s) may represent a possible dark matter candidate. After using the same technique to the study of orbits of objects lying on the same brane (d = 0), we apply this method to the detection of generic deviations from the inverse-square Newton law. We propose a possible experimental setup to look for departures from Newtonian motion in the micro-world, finding that an order of magnitude improvement on present bounds can be attained at the 95% CL under reasonable assumptions. (orig.)
Non-abelian action of D0-branes from Matrix theory in the longitudinal 5-brane background
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Asano, Masako; Sekino, Yasuhiro
2002-01-01
We study one-loop effective action of Berkooz-Douglas Matrix theory and obtain non-abelian action of D0-branes in the background field produced by longitudinal 5-branes. Since these 5-branes do not have D0-brane charge and are not present in BFSS Matrix theory, our analysis provides an independent test for the coupling of D-branes to general weak backgrounds proposed by Taylor and Van Raamsdonk from the analysis of the BFSS model. The proposed couplings appear in the Berkooz-Douglas effective action precisely as expected, which suggests the consistency of the two matrix models. We also point out the existence of the terms which are not given by the symmetrized trace prescription in the Matrix theory effective action
Cosmological evolution of p-brane networks
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Sousa, L.; Avelino, P. P.
2011-01-01
In this paper we derive, directly from the Nambu-Goto action, the relevant components of the acceleration of cosmological featureless p-branes, extending previous analysis based on the field theory equations in the thin-brane limit. The component of the acceleration parallel to the velocity is at the core of the velocity-dependent one-scale model for the evolution of p-brane networks. We use this model to show that, in a decelerating expanding universe in which the p-branes are relevant cosmologically, interactions cannot lead to frustration, except for fine-tuned nonrelativistic networks with a dimensionless curvature parameter k<<1. We discuss the implications of our findings for the cosmological evolution of p-brane networks.
Thick branes with inner structure in mimetic gravity
Energy Technology Data Exchange (ETDEWEB)
Zhong, Yi; Zhang, Yu-Peng; Liu, Yu-Xiao [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China); Lanzhou University, Research Center of Gravitation, Lanzhou (China); Zhong, Yuan [Xi' an Jiaotong University, School of Science, Xi' an (China)
2018-01-15
In this paper, thick branes generated by mimetic scalar field are investigated. Three typical thick brane models are constructed and the linear tensor and scalar perturbations are analyzed. These branes have different inner structures, some of which are absent in general relativity. For each brane model, the solution is stable under both tensor and scalar perturbations. The tensor zero modes are localized on the branes, while the scalar perturbations do not propagate and they are not localized on the brane. As the branes split into multi sub-branes for specific parameters, the potentials of the tensor perturbations also split into multi-wells, and this may lead to new phenomenon in the resonance of the tensor perturbation and the localization of matter fields. (orig.)
A Gauged Open 2-Brane String in the p-Brane Background
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Monemzadeh, Majid; Sarvi, Fahimeh; Abarghouei Nejad, Salman
2016-01-01
We make a gauge theory from the Open p-brane system and map it into the Open 2-Brane one. Due to the presence of second-class constraints in this model, we encounter some problems during the procedure of quantization. In this regard, considering boundary conditions as Dirac conditions, one can drive the constrained structure of the model at first. Then, with the help of BFT formalism of constraint systems, the Open 2-Brane model is embedded into an extended phase space. For this purpose, we introduce some tensor fields to convert ungauged theory into the gauged one. This is the novel part of our research, while mostly scalar and vector fields are used to convert second-class constraints into first ones.
D3-brane shells to black branes on the Coulomb branch
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Giddings, Steven B.; Ross, Simon F.
2000-01-01
We use the AdS-CFT duality to study the special point on the Coulomb branch of N=4 SU(N) gauge theory which corresponds to a spherically symmetric shell of D3-branes. This point is of interest both because the spacetime region inside the shell is flat, and because this configuration gives a very simple example of the transition between D-branes in the perturbative string regime and the nonperturbative regime of black holes. We discuss how this geometry is described in the dual gauge theory, through its effect on the two-point functions and Wilson loops. In the calculation of the two-point function, we stress the importance of absorption by the branes. (c) 1999 The American Physical Society
Teleparallel loop quantum cosmology in a system of intersecting branes
Directory of Open Access Journals (Sweden)
Alireza Sepehri
2016-09-01
Full Text Available Recently, some authors have removed the big bang singularity in teleparallel Loop Quantum Cosmology (LQC and have shown that the universe may undergo a number of oscillations. We investigate the origin of this type of teleparallel theory in a system of intersecting branes in M-theory in which the angle between them changes with time. This system is constructed by two intersecting anti-D8-branes, one compacted D4-brane and a D3-brane. These branes are built by joining M0-branes which develop in decaying fundamental strings. The compacted D4-brane is located between two intersecting anti-D8 branes and glues to one of them. Our universe is located on the D3 brane which wraps around the D4 brane from one end and sticks to one of the anti-D8 branes from the other one. In this system, there are three types of fields, corresponding to compacted D4 branes, intersecting branes and D3-branes. These fields interact with each other and make the angle between branes oscillate. By decreasing this angle, the intersecting anti-D8 branes approach each other, the D4 brane rolls, the D3 brane wraps around the D4 brane, and the universe contracts. By separating the intersecting branes and increasing the angle, the D4 brane rolls in the opposite direction, the D3 brane separates from it and the expansion branch begins. Also, the interaction between branes in this system gives us the exact form of the relevant Lagrangian for teleparallel LQC.
Teleparallel loop quantum cosmology in a system of intersecting branes
Energy Technology Data Exchange (ETDEWEB)
Sepehri, Alireza, E-mail: alireza.sepehri@uk.ac.ir [Faculty of Physics, Shahid Bahonar University, P.O. Box 76175, Kerman (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of); Pradhan, Anirudh, E-mail: pradhan.anirudh@gmail.com [Department of Mathematics, Institute of Applied Sciences and Humanities, GLA University, Mathura-281 406, Uttar Pradesh (India); Beesham, Aroonkumar, E-mail: beeshama@unizulu.ac.za [Department of Mathematical Sciences, University of Zululand, Kwa-Dlangezwa 3886 (South Africa); Haro, Jaume de, E-mail: jaime.haro@upc.edu [Departament de Matemàtiques, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain)
2016-09-10
Recently, some authors have removed the big bang singularity in teleparallel Loop Quantum Cosmology (LQC) and have shown that the universe may undergo a number of oscillations. We investigate the origin of this type of teleparallel theory in a system of intersecting branes in M-theory in which the angle between them changes with time. This system is constructed by two intersecting anti-D8-branes, one compacted D4-brane and a D3-brane. These branes are built by joining M0-branes which develop in decaying fundamental strings. The compacted D4-brane is located between two intersecting anti-D8 branes and glues to one of them. Our universe is located on the D3 brane which wraps around the D4 brane from one end and sticks to one of the anti-D8 branes from the other one. In this system, there are three types of fields, corresponding to compacted D4 branes, intersecting branes and D3-branes. These fields interact with each other and make the angle between branes oscillate. By decreasing this angle, the intersecting anti-D8 branes approach each other, the D4 brane rolls, the D3 brane wraps around the D4 brane, and the universe contracts. By separating the intersecting branes and increasing the angle, the D4 brane rolls in the opposite direction, the D3 brane separates from it and the expansion branch begins. Also, the interaction between branes in this system gives us the exact form of the relevant Lagrangian for teleparallel LQC.
Tension perturbations of black brane spacetimes
International Nuclear Information System (INIS)
Traschen, Jennie; Fox, Daniel
2004-01-01
We consider black brane spacetimes that have at least one spatial translation Killing field that is tangent to the brane. A new parameter, the tension of a spacetime, is defined. The tension parameter is associated with spatial translations in much the same way that the ADM mass is associated with the time translation Killing field. In this work, we explore the implications of the spatial translation symmetry for small perturbations around a background black brane. For static-charged black branes we derive a law which relates the tension perturbation to the surface gravity times the change in the horizon area, plus terms that involve variations in the charges and currents. We find that as a black brane evaporates the tension decreases. We also give a simple derivation of a first law for black brane spacetimes. These constructions hold when the background stress-energy is governed by a Hamiltonian, and the results include arbitrary perturbative stress-energy sources
Brane brick models in the mirror
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Franco, Sebastián [Physics Department, The City College of the CUNY,160 Convent Avenue, New York, NY 10031 (United States); The Graduate School and University Center, The City University of New York,365 Fifth Avenue, New York NY 10016 (United States); Lee, Sangmin [Center for Theoretical Physics, Seoul National University,Seoul 08826 (Korea, Republic of); Department of Physics and Astronomy, Seoul National University,Seoul 08826 (Korea, Republic of); College of Liberal Studies, Seoul National University,Seoul 08826 (Korea, Republic of); Seong, Rak-Kyeong [School of Physics, Korea Institute for Advanced Study,Seoul 02455 (Korea, Republic of); Vafa, Cumrun [Jefferson Physical Laboratory, Harvard University,Cambridge, MA 02138 (United States)
2017-02-21
Brane brick models are Type IIA brane configurations that encode the 2dN=(0,2) gauge theories on the worldvolume of D1-branes probing toric Calabi-Yau 4-folds. We use mirror symmetry to improve our understanding of this correspondence and to provide a systematic approach for constructing brane brick models starting from geometry. The mirror configuration consists of D5-branes wrapping 4-spheres and the gauge theory is determined by how they intersect. We also explain how 2d(0,2) triality is realized in terms of geometric transitions in the mirror geometry. Mirror symmetry leads to a geometric unification of dualities in different dimensions, where the order of duality is n−1 for a Calabi-Yau n-fold. This makes us conjecture the existence of a quadrality symmetry in 0d. Finally, we comment on how the M-theory lift of brane brick models connects to the classification of 2d(0,2) theories in terms of 4-manifolds.
T-branes through 3d mirror symmetry
Energy Technology Data Exchange (ETDEWEB)
Collinucci, Andrés; Giacomelli, Simone [Physique Théorique et Mathématique and International Solvay Institutes,Université Libre de Bruxelles,C.P. 231, 1050 Bruxelles (Belgium); Savelli, Raffaele [Institut de Physique Théorique, CEA Saclay,Orme de Merisiers, F-91191 Gif-sur-Yvette (France); Valandro, Roberto [Dipartimento di Fisica, Università di Trieste,Strada Costiera 11, 34151 Trieste (Italy); INFN, Sezione di Trieste,Via Valerio 2, 34127 Trieste (Italy); Abdus Salam International Centre for Theoretical Physics,Strada Costiera 11, 34151 Trieste (Italy)
2016-07-19
T-branes are exotic bound states of D-branes, characterized by mutually non-commuting vacuum expectation values for the worldvolume scalars. The M/F-theory geometry lifting D6/D7-brane configurations is blind to the T-brane data. In this paper, we make this data manifest, by probing the geometry with an M2-brane. We find that the effect of a T-brane is to deform the membrane worldvolume superpotential with monopole operators, which partially break the three-dimensional flavor symmetry, and reduce supersymmetry from N=4 to N=2. Our main tool is 3d mirror symmetry. Through this language, a very concrete framework is developed for understanding T-branes in M-theory. This leads us to uncover a new class of N=2 quiver gauge theories, whose Higgs branches mimic those of membranes at ADE singularities, but whose Coulomb branches differ from their N=4 counterparts.
Kaste, P.; Lutken, C.A.; Walcher, Johannes
2000-01-01
B-type D-branes are constructed on two different K3-fibrations over IP_1 using boundary conformal field theory at the rational Gepner points of these models. The microscopic CFT charges are compared with the Ramond charges of D-branes wrapped on holomorphic cycles of the corresponding Calabi-Yau manifold. We study in particular D4-branes and bundles localized on the K3 fibers, and find agreement with expectations. This provides a further test of the boundary CFT approach to $D$-brane physics.
Directory of Open Access Journals (Sweden)
Dariush Kaviani
2016-09-01
Full Text Available We study the temperature of extended objects in string theory. Rotating probe D-branes admit horizons and temperatures a la Unruh effect. We find that the induced metrics on slow rotating probe D1-branes in holographic string solutions including warped Calabi–Yau throats have distinct thermal horizons with characteristic Hawking temperatures even if there is no black hole in the bulk Calabi–Yau. Taking the UV/IR limits of the solution, we show that the world volume black hole nucleation depends on the deformation and the warping of the throat. We find that world volume horizons and temperatures of expected features form not in the regular confining IR region but in the singular nonconfining UV solution. In the conformal limit of the UV, we find horizons and temperatures similar to those on rotating probes in the AdS throat found in the literature. In this case, we also find that activating a background gauge field form the U(1 R-symmetry modifies the induced metric with its temperature describing two different classes of black hole solutions.
Branes in Poisson sigma models
International Nuclear Information System (INIS)
Falceto, Fernando
2010-01-01
In this review we discuss possible boundary conditions (branes) for the Poisson sigma model. We show how to carry out the perturbative quantization in the presence of a general pre-Poisson brane and how this is related to the deformation quantization of Poisson structures. We conclude with an open problem: the perturbative quantization of the system when the boundary has several connected components and we use a different pre-Poisson brane in every component.
Warp drive with zero expansion
Energy Technology Data Exchange (ETDEWEB)
Natario, Jose [Department of Mathematics, Instituto Superior Tecnico (Portugal)
2002-03-21
It is commonly believed that Alcubierre's warp drive works by contracting space in front of the warp bubble and expanding the space behind it. We show that this contraction/expansion is but a marginal consequence of the choice made by Alcubierre and explicitly construct a similar spacetime where no contraction/expansion occurs. Global and optical properties of warp-drive spacetimes are also discussed.
International Nuclear Information System (INIS)
Obregon, Octavio; Quevedo, Hernando; Ryan, Michael P.
2004-01-01
We construct a family of time and angular dependent, regular S-brane solutions which corresponds to a simple analytical continuation of the Zipoy-Voorhees 4-dimensional vacuum spacetime. The solutions are asymptotically flat and turn out to be free of singularities without requiring a twist in space. They can be considered as the simplest non-singular generalization of the singular S0-brane solution. We analyze the properties of a representative of this family of solutions and show that it resembles to some extent the asymptotic properties of the regular Kerr S-brane. The R-symmetry corresponds, however, to the general lorentzian symmetry. Several generalizations of this regular solution are derived which include a charged S-brane and an additional dilatonic field. (author)
White, Harold
2011-01-01
This paper will begin with a short review of the Alcubierre warp drive metric and describes how the phenomenon might work based on the original paper. The canonical form of the metric was developed and published in [6] which provided key insight into the field potential and boost for the field which remedied a critical paradox in the original Alcubierre concept of operations. A modified concept of operations based on the canonical form of the metric that remedies the paradox is presented and discussed. The idea of a warp drive in higher dimensional space-time (manifold) will then be briefly considered by comparing the null-like geodesics of the Alcubierre metric to the Chung-Freese metric to illustrate the mathematical role of hyperspace coordinates. The net effect of using a warp drive technology coupled with conventional propulsion systems on an exploration mission will be discussed using the nomenclature of early mission planning. Finally, an overview of the warp field interferometer test bed being implemented in the Advanced Propulsion Physics Laboratory: Eagleworks (APPL:E) at the Johnson Space Center will be detailed. While warp field mechanics has not had a Chicago Pile moment, the tools necessary to detect a modest instance of the phenomenon are near at hand.
Inflation driven by single geometric tachyon with D-brane orbiting around NS5-branes
International Nuclear Information System (INIS)
Kwon, Pyung Seong; Jun, Gyeong Yun; Panigrahi, Kamal L.; Sami, M.
2012-01-01
We investigate models in which inflation is driven by a single geometrical tachyon. We assume that the D-brane as a probe brane in the background of NS5-branes has non-zero angular momentum which is shown to play similar role as the number of the scalar fields of the assisted inflation. We demonstrate that the angular momentum corrected effective potential allows to account for the observational constraint on COBE normalization, spectral index n S and the tensor to scalar ratio of perturbations consistent with WMAP seven years data.
Generalized Canonical Time Warping.
Zhou, Feng; De la Torre, Fernando
2016-02-01
Temporal alignment of human motion has been of recent interest due to its applications in animation, tele-rehabilitation and activity recognition. This paper presents generalized canonical time warping (GCTW), an extension of dynamic time warping (DTW) and canonical correlation analysis (CCA) for temporally aligning multi-modal sequences from multiple subjects performing similar activities. GCTW extends previous work on DTW and CCA in several ways: (1) it combines CCA with DTW to align multi-modal data (e.g., video and motion capture data); (2) it extends DTW by using a linear combination of monotonic functions to represent the warping path, providing a more flexible temporal warp. Unlike exact DTW, which has quadratic complexity, we propose a linear time algorithm to minimize GCTW. (3) GCTW allows simultaneous alignment of multiple sequences. Experimental results on aligning multi-modal data, facial expressions, motion capture data and video illustrate the benefits of GCTW. The code is available at http://humansensing.cs.cmu.edu/ctw.
International Nuclear Information System (INIS)
Anninos, Dionysios; Li Wei; Padi, Megha; Song Wei; Strominger, Andrew
2009-01-01
Three dimensional topologically massive gravity (TMG) with a negative cosmological constant -l -2 and positive Newton constant G admits an AdS 3 vacuum solution for any value of the graviton mass μ. These are all known to be perturbatively unstable except at the recently explored chiral point μl = 1. However we show herein that for every value of μl ≠ 3 there are two other (potentially stable) vacuum solutions given by SL(2,R) x U(1)-invariant warped AdS 3 geometries, with a timelike or spacelike U(1) isometry. Critical behavior occurs at μl = 3, where the warping transitions from a stretching to a squashing, and there are a pair of warped solutions with a null U(1) isometry. For μl > 3, there are known warped black hole solutions which are asymptotic to warped AdS 3 . We show that these black holes are discrete quotients of warped AdS 3 just as BTZ black holes are discrete quotients of ordinary AdS 3 . Moreover new solutions of this type, relevant to any theory with warped AdS 3 solutions, are exhibited. Finally we note that the black hole thermodynamics is consistent with the hypothesis that, for μl > 3, the warped AdS 3 ground state of TMG is holographically dual to a 2D boundary CFT with central charges c R -formula and c L -formula.
International Nuclear Information System (INIS)
Flachi, Antonino; Tanaka, Takahiro
2009-01-01
We consider the Casimir effect between two parallel plates localized on a brane. We argue that in order to properly compute the contribution to the Casimir energy due to any higher dimensional field, it is necessary to take into account the localization properties of the Kaluza-Klein modes. When the bulk field configuration is such that no massless mode appears in the spectrum, as, for instance, when the higher dimensional field obeys twisted boundary conditions across the branes, the correction to the Casimir energy is exponentially suppressed. When a massless mode is present in the spectrum, the correction to the Casimir energy can be, in principle, sizeable. However, when the bulk field is massless and strongly coupled to brane matter, the model is already excluded without resorting to any Casimir force experiment. The case which is in principle interesting is when the massless mode is not localized on the visible brane. We illustrate a method to compute the Casimir energy between two parallel plates, localized on the visible brane, approximating the Kaluza-Klein spectrum by truncation at the first excited mode. We treat this case by considering a pistonlike configuration and introduce a small parameter, ε, that takes into account the relative amplitude of the zero-mode wave function on the visible brane with respect to the massive excitation. We find that the Casimir energy is suppressed by two factors: at lowest order in ε, the correction to the Casimir energy comes entirely from the massive mode and turns out to be exponentially suppressed; the next-to-leading order correction in ε follows, instead, a power-law suppression due to the small wave-function overlap of the zero mode with matter confined on the visible brane. Generic comments on the constraints on new physics that may arise from Casimir force experiments are also made.
International Nuclear Information System (INIS)
Kaste, P.; Lerche, W.; Luetken, C.A.; Walcher, J.
2000-01-01
B-type D-branes are constructed on two different K3-fibrations over P 1 using boundary conformal field theory at the rational Gepner points of these models. The microscopic CFT charges are compared with the Ramond charges of D-branes wrapped on holomorphic cycles of the corresponding Calabi-Yau manifold. We study in particular D4-branes and bundles localized on the K3 fibers, and find from CFT that each irreducible component of a bundle on K3 gains one modulus upon fibration over P 1 . This is in agreement with expectations and so provides a further test of the boundary CFT approach to D-brane physics
Supersymmetry Breaking Casimir Warp Drive
Obousy, Richard K.; Cleaver, Gerald
2007-01-01
This paper utilizes a recent model which relates the cosmological constant to the Casimir energy of the extra dimensions in brane-world theories. The objective of this paper is to demonstrate that, given some sufficiently advanced civilization with the ability to manipulate the radius of the extra dimension, a local adjustment of the cosmological constant could be created. This adjustment would facilitate an expansion/contraction of the spacetime around a spacecraft creating an exotic form of field-propulsion. This idea is analogous to the Alcubierre bubble, but differs entirely in the approach, utilizing the physics of higher dimensional quantum field theory, instead of general relativity.
Wavefunctions on magnetized branes in the conifold
International Nuclear Information System (INIS)
Abe, Hiroyuki; Oikawa, Akane; Otsuka, Hajime
2016-01-01
We study wavefunctions on D7-branes with magnetic fluxes in the conifold. Since some supersymmetric embeddings of D-branes on the AdS_5×T"1","1 geometry are known, we consider one of the embeddings, especially the spacetime filling D7-branes in which (a part of) the standard model is expected to be realized. The explicit form of induced metric on the D7-branes allows us to solve the Laplace and Dirac equations to evaluate matter wavefunctions in extra dimensions analytically. We find that the zero-mode wavefunctions can be localized depending on the configuration of magnetic fluxes on D7-branes, and show some phenomenological aspects.
Five-brane superpotentials and heterotic/F-theory duality
International Nuclear Information System (INIS)
Grimm, Thomas W.; Ha, Tae-Won; Klemm, Albrecht; Klevers, Denis
2010-01-01
Under heterotic/F-theory duality it was argued that a wide class of heterotic five-branes is mapped into the geometry of an F-theory compactification manifold. In four-dimensional compactifications this identifies a five-brane wrapped on a curve in the base of an elliptically fibered Calabi-Yau threefold with a specific F-theory Calabi-Yau fourfold containing the blow-up of the five-brane curve. We argue that this duality can be reformulated by first constructing a non-Calabi-Yau heterotic threefold by blowing up the curve of the five-brane into a divisor with five-brane flux. Employing heterotic/F-theory duality this leads us to the construction of a Calabi-Yau fourfold and four-form flux. Moreover, we obtain an explicit map between the five-brane superpotential and an F-theory flux superpotential. The map of the open-closed deformation problem of a five-brane in a compact Calabi-Yau threefold into a deformation problem of complex structures on a dual Calabi-Yau fourfold with four-form flux provides a powerful tool to explicitly compute the five-brane superpotential.
D-Branes in the Background of NS Fivebranes
Elitzur, Shmuel; Rabinovici, Eliezer; Sarkisian, G; Kutasov, D; Elitzur, Shmuel; Giveon, Amit; Kutasov, David; Rabinovici, Eliezer; Sarkissian, Gor
2000-01-01
We study the dynamics of $D$-branes in the near-horizon geometry of $NS$ fivebranes. This leads to a holographically dual description of the physics of $D$-branes ending on and/or intersecting $NS5$-branes. We use it to verify some properties of such $D$-branes which were deduced indirectly in the past, and discuss some instabilities of non-supersymmetric brane configurations. Our construction also describes vacua of Little String Theory which are dual to open plus closed string theory in asymptotically linear dilaton spacetimes.
International Nuclear Information System (INIS)
Alberghi, Gian Luigi; Caceres, Elena; Goldstein, Kevin; Lowe, David A. . lowe@het.brown.edu
2001-08-01
We present a candidate supergravity solution for a stacked configuration of stable non-BPS D-branes in Type II string theory compactified on T 4 /Z 2 . This gives a supergravity description of nonabelian tachyon condensation on the brane woldvolume. (author)
Configurational entropy as a tool to select a physical thick brane model
Chinaglia, M.; Cruz, W. T.; Correa, R. A. C.; de Paula, W.; Moraes, P. H. R. S.
2018-04-01
We analize braneworld scenarios via a configurational entropy (CE) formalism. Braneworld scenarios have drawn attention mainly due to the fact that they can explain the hierarchy problem and unify the fundamental forces through a symmetry breaking procedure. Those scenarios localize matter in a (3 + 1) hypersurface, the brane, which is inserted in a higher dimensional space, the bulk. Novel analytical braneworld models, in which the warp factor depends on a free parameter n, were recently released in the literature. In this article we will provide a way to constrain this parameter through the relation between information and dynamics of a system described by the CE. We demonstrate that in some cases the CE is an important tool in order to provide the most probable physical system among all the possibilities. In addition, we show that the highest CE is correlated to a tachyonic sector of the configuration, where the solutions for the corresponding model are dynamically unstable.
Coupling brane fields to bulk supergravity
Energy Technology Data Exchange (ETDEWEB)
Parameswaran, Susha L. [Uppsala Univ. (Sweden). Theoretical Physics; Schmidt, Jonas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2010-12-15
In this note we present a simple, general prescription for coupling brane localized fields to bulk supergravity. We illustrate the procedure by considering 6D N=2 bulk supergravity on a 2D orbifold, with brane fields localized at the fixed points. The resulting action enjoys the full 6D N=2 symmetries in the bulk, and those of 4D N=1 supergravity at the brane positions. (orig.)
Nucleation of (4)R brane universes
International Nuclear Information System (INIS)
Cordero, Ruben; Rojas, EfraIn
2004-01-01
The creation of brane universes induced by a totally antisymmetric tensor living in a fixed background spacetime is presented, where a term involving the intrinsic curvature of the brane is considered. A canonical quantum mechanical approach employing the Wheeler-DeWitt equation is used. The probability nucleation for the brane is calculated by means of the corresponding instanton and the WKB approximation. Some cosmological implications from the model are presented
An, Xinliang; Wong, Willie Wai Yeung
2018-01-01
Many classical results in relativity theory concerning spherically symmetric space-times have easy generalizations to warped product space-times, with a two-dimensional Lorentzian base and arbitrary dimensional Riemannian fibers. We first give a systematic presentation of the main geometric constructions, with emphasis on the Kodama vector field and the Hawking energy; the construction is signature independent. This leads to proofs of general Birkhoff-type theorems for warped product manifolds; our theorems in particular apply to situations where the warped product manifold is not necessarily Einstein, and thus can be applied to solutions with matter content in general relativity. Next we specialize to the Lorentzian case and study the propagation of null expansions under the assumption of the dominant energy condition. We prove several non-existence results relating to the Yamabe class of the fibers, in the spirit of the black-hole topology theorem of Hawking–Galloway–Schoen. Finally we discuss the effect of the warped product ansatz on matter models. In particular we construct several cosmological solutions to the Einstein–Euler equations whose spatial geometry is generally not isotropic.
The geometry of warped product singularities
Stoica, Ovidiu Cristinel
In this article, the degenerate warped products of singular semi-Riemannian manifolds are studied. They were used recently by the author to handle singularities occurring in General Relativity, in black holes and at the big-bang. One main result presented here is that a degenerate warped product of semi-regular semi-Riemannian manifolds with the warping function satisfying a certain condition is a semi-regular semi-Riemannian manifold. The connection and the Riemann curvature of the warped product are expressed in terms of those of the factor manifolds. Examples of singular semi-Riemannian manifolds which are semi-regular are constructed as warped products. Applications include cosmological models and black holes solutions with semi-regular singularities. Such singularities are compatible with a certain reformulation of the Einstein equation, which in addition holds at semi-regular singularities too.
From p-branes to fluxbranes and back
Emparan, R; Emparan, Roberto; Gutperle, Michael
2001-01-01
In this note we study aspects of the interplay between fluxbranes and p-branes. We describe how a fluxbrane can be physically realized as a limit of a brane-antibrane configuration, in a manner similar to the way a uniform electric field appears in between the plates of a capacitor. We also study the evolution of a fluxbrane after nucleation of p-branes. We find that Kaluza-Klein fluxbranes do relax by forming brane-antibrane pairs or spherical branes, but we also find that for fluxtubes with dilaton coupling in a different range, the field strength does not relax, instead it becomes stronger after each nucleation bounce. We speculate on a possible runaway instability of such fluxtubes an an eventual breakdown of their classical description.
Progress in D-brane model building
International Nuclear Information System (INIS)
Marchesano, F.
2007-01-01
The state of the art in D-brane model building is briefly reviewed, focusing on recent achievements in the construction of D=4 N=1 type II string vacua with semi-realistic gauge sectors. Such progress relies on a better understanding of the spectrum of BPS D-branes, the effective field theory obtained from them and the explicit construction of vacua. We first consider D-branes in standard Calabi-Yau compactifications, and then the more involved case of compactifications with fluxes. We discuss how the non-trivial interplay between D-branes and fluxes modifies the previous model-building rules, as well as provides new possibilities to connect string theory to particle physics. (Abstract Copyright [2007], Wiley Periodicals, Inc.)
Level-rank duality of untwisted and twisted D-branes
International Nuclear Information System (INIS)
Naculich, Stephen G.; Schnitzer, Howard J.
2006-01-01
Level-rank duality of untwisted and twisted D-branes of WZW models is explored. We derive the relation between D0-brane charges of level-rank dual untwisted D-branes of su-bar (N) K and sp-bar (n) k , and of level-rank dual twisted D-branes of su-bar (2n+1) 2k+1 . The analysis of level-rank duality of twisted D-branes of su-bar (2n+1) 2k+1 is facilitated by their close relation to untwisted D-branes of sp-bar (n) k . We also demonstrate level-rank duality of the spectrum of an open string stretched between untwisted or twisted D-branes in each of these cases
Non-relativistic AdS branes and Newton-Hooke superalgebra
International Nuclear Information System (INIS)
Sakaguchi, Makoto; Yoshida, Kentaroh
2006-01-01
We examine a non-relativistic limit of D-branes in AdS 5 x S 5 and M-branes in AdS 4/7 x S 7/4 . First, Newton-Hooke superalgebras for the AdS branes are derived from AdS x S superalgebras as Inoenue-Wigner contractions. It is shown that the directions along which the AdS-brane worldvolume extends are restricted by requiring that the isometry on the AdS-brane worldvolume and the Lorentz symmetry in the transverse space naturally extend to the super-isometry. We also derive Newton-Hooke superalgebras for pp-wave branes and show that the directions along which a brane worldvolume extends are restricted. Then the Wess-Zumino terms of the AdS branes are derived by using the Chevalley-Eilenberg cohomology on the super-AdS x S algebra, and the non-relativistic limit of the AdS-brane actions is considered. We show that the consistent limit is possible for the following branes: Dp (even,even) for p = 1 mod 4 and Dp (odd,odd) for p = 3 mod 4 in AdS 5 x S 5 , and M2 (0,3), M2 (2,1), M5 (1,5) and M5 (3,3) in AdS 4 x S 7 and S 4 x AdS 7 . We furthermore present non-relativistic actions for the AdS branes
Fundamental limitations on 'warp drive' spacetimes
Energy Technology Data Exchange (ETDEWEB)
Lobo, Francisco S N [Centro de Astronomia e AstrofIsica da Universidade de Lisboa, Campo Grande, Ed. C8 1749-016 Lisbon (Portugal); Visser, Matt [School of Mathematical and Computing Sciences, Victoria University of Wellington, PO Box 600, Wellington (New Zealand)
2004-12-21
'Warp drive' spacetimes are useful as 'gedanken-experiments' that force us to confront the foundations of general relativity, and among other things, to precisely formulate the notion of 'superluminal' communication. After carefully formulating the Alcubierre and Natario warp drive spacetimes, and verifying their non-perturbative violation of the classical energy conditions, we consider a more modest question and apply linearized gravity to the weak-field warp drive, testing the energy conditions to first and second orders of the warp-bubble velocity, v. Since we take the warp-bubble velocity to be non-relativistic, v << c, we are not primarily interested in the 'superluminal' features of the warp drive. Instead we focus on a secondary feature of the warp drive that has not previously been remarked upon-the warp drive (if it could be built) would be an example of a 'reaction-less drive'. For both the Alcubierre and Natario warp drives we find that the occurrence of significant energy condition violations is not just a high-speed effect, but that the violations persist even at arbitrarily low speeds. A particularly interesting feature of this construction is that it is now meaningful to think of placing a finite mass spaceship at the centre of the warp bubble, and then see how the energy in the warp field compares with the mass-energy of the spaceship. There is no hope of doing this in Alcubierre's original version of the warp field, since by definition the point at the centre of the warp bubble moves on a geodesic and is 'massless'. That is, in Alcubierre's original formalism and in the Natario formalism the spaceship is always treated as a test particle, while in the linearized theory we can treat the spaceship as a finite mass object. For both the Alcubierre and Natario warp drives we find that even at low speeds the net (negative) energy stored in the warp fields must be a significant fraction
Fate of black branes in Einstein-Gauss-Bonnet gravity
International Nuclear Information System (INIS)
Suranyi, P.; Wijewardhana, L. C. R.; Vaz, C.
2009-01-01
Black branes are studied in Einstein-Gauss-Bonnet gravity. Evaporation drives black branes toward one of two singularities depending on the sign of α, the Gauss-Bonnet coupling. For positive α and sufficiently large ratio √(α)/L, where L/2π is the radius of compactification, black branes avoid the Gregory-Laflamme (GL) instability before reaching a critical state. No black branes with the radius of horizon smaller than the critical value can exist. Approaching the critical state branes have a nonzero Hawking temperature. For negative α all black branes encounter the GL instability. No black branes may exist outside of the interval of the critical values 0≤β h 2 and r h is the radius of horizon of the black brane. The first order phase transition line of GL transitions ends in a second order phase transition point at β=0.
Higgs decays and brane gravi-vectors
International Nuclear Information System (INIS)
Clark, T. E.; Liu Boyang; Love, S. T.; Xiong, C.; Veldhuis, T. ter
2008-01-01
Higgs boson decays in flexible brane world models with stable, massive gravi-vectors are considered. Such vectors couple bilinearly to the standard model fields through either the standard model energy-momentum tensor, the weak hypercharge field strength, or the Higgs scalar. The role of the coupling involving the extrinsic curvature is highlighted. It is found that within the presently allowed parameter space, the decay rate of the Higgs into two gravi-vectors (which would appear as an invisible Higgs decay) can be comparable to the rate for any of the standard model decay modes.
Janson, Siegfried
2017-01-01
A Brane Craft is a membrane spacecraft with solar cells, command and control electronics, communications systems, antennas, propulsion systems, attitude and proximity sensors, and shape control actuators as thin film structures manufactured on 10 micron thick plastic sheets. This revolutionary spacecraft design can have a thickness of tens of microns with a surface area of square meters to maximize area-to-mass ratios for exceptionally low-mass spacecraft. Communications satellites, solar power satellites, solar electric propulsion stages, and solar sails can benefit from Brane Craft design. It also enables new missions that require low-mass spacecraft with exceptionally high delta-V. Active removal of orbital debris from Earth orbit is the target application for this study.
Schimmrigk, Rolf
2012-01-01
In this paper the problem of constructing spacetime from string theory is addressed in the context of D-brane physics. It is suggested that the knowledge of discrete configurations of D-branes is sufficient to reconstruct the motivic building blocks of certain Calabi-Yau varieties. The collections of D-branes involved have algebraic base points, leading to the notion of K-arithmetic D-crystals for algebraic number fields K. This idea can be tested for D0-branes in the framework of toroidal compactifications via the conjectures of Birch and Swinnerton-Dyer. For the special class of D0-crystals of Heegner type these conjectures can be interpreted as formulae that relate the canonical Neron-Tate height of the base points of the D-crystals to special values of the motivic L-function at the central point. In simple cases the knowledge of the D-crystals of Heegner type suffices to uniquely determine the geometry.
Time-dependent AdS backgrounds from S-branes
Energy Technology Data Exchange (ETDEWEB)
Deger, Nihat Sadik, E-mail: sadik.deger@boun.edu.tr [Department of Mathematics, Bogazici University, Bebek, 34342, Istanbul (Turkey); Feza Gursey Center for Physics and Mathematics, Bogazici University, Kandilli, 34684, Istanbul (Turkey)
2016-11-10
We construct time and radial dependent solutions that describe p-branes in chargeless S-brane backgrounds. In particular, there are some new M5- and D3-branes among our solutions which have AdS limits and contain a cosmological singularity as well. We also find a time-dependent version of the dyonic membrane configuration in 11-dimensions by applying a Lunin–Maldacena deformation to our new M5-brane solution.
The Hierarchy Problem and the Self-Localized Higgs
Burgess, C P; van Nierop, Leo
2008-01-01
We examine brane-world scenarios in which all the observed Standard Model particles reside on a brane but the Higgs is an elementary extra-dimensional scalar in the bulk. We show that, for codimension 2 branes, often-neglected interactions between the bulk Higgs and the branes cause two novel effects. First, they cause to depend only logarithmically on the UV-sensitive coefficient, m_B^2, of the mass term, m_B^2 H^*H, of the bulk potential, thus providing a new mechanism for tackling the hierarchy problem. Second, the Higgs brane couplings cause the lowest mass KK mode to localize near the brane without any need for geometrical effects like warping. We explore some preliminary implications such models have for the Higgs signature at the LHC, both in the case where the extra dimensions arise at the TeV scale, and in ADD models having Large Extra Dimensions. Novel Higgs features include couplings to fermions which are generically stronger than the Standard Model values, m_f/v, despite the fermions acquiring th...
Effective Field Theories and Matching for Codimension-2 Branes
Burgess, C P; De Rham, C; Tasinato, G
2009-01-01
It is generic for the bulk fields sourced by branes having codimension two and higher to diverge at the brane position, much as does the Coulomb potential at the position of its source charge. This complicates finding the relation between brane properties and the bulk geometries they source. (These complications do not arise for codimension-1 sources, such as in RS geometries, because of the special properties unique to codimension one.) Understanding these relations is a prerequisite for phenomenological applications involving higher-codimension branes. Using codimension-2 branes in extra-dimensional scalar-tensor theories as an example, we identify the classical matching conditions that relate the near-brane asymptotic behaviour of bulk fields to the low-energy effective actions describing how space-filling codimension-2 branes interact with the surrounding extra-dimensional bulk. We do so by carefully regulating the near-brane divergences, and show how these may be renormalized in a general way. Among the ...
Penrose limits, pp waves, and deformed M2-branes
International Nuclear Information System (INIS)
Cvetic, M.; Lue, H.; Pope, C.N.
2004-01-01
Motivated by the recent discussions of the Penrose limit of AdS 5 xS 5 , we examine a more general class of supersymmetric pp-wave solutions of the type IIB theory, with a larger number of nonvanishing structures in the self-dual 5-form. One of the pp-wave solutions can be obtained as a Penrose limit of a D3-D3 intersection. In addition to 16 standard supersymmetries these backgrounds always allow for supernumerary supersymmetries. The latter are in one-to-one correspondence with the linearly realized world-sheet supersymmetries of the corresponding exactly solvable type IIB string action. The pp-waves provide new examples where supersymmetries will survive in a T-duality transformation on the x + coordinate. The T-dual solutions can be lifted to give supersymmetric deformed M2-branes in D=11. The deformed M2-brane is dual to a three-dimensional field theory whose renormalization group flow runs from the conformal fixed point in the infrared regime to a nonconformal theory as the energy increases. At a certain intermediate energy scale there is a phase transition associated with a naked singularity of the M2-brane. In the ultraviolet limit the theory is related by T duality to an exactly solvable massive type IIB string theory
Dynamical Formation of Horizons in Recoiling D Branes
Ellis, Jonathan Richard; Nanopoulos, Dimitri V; Ellis, John
2000-01-01
A toy calculation of string/D-particle interactions within a world-sheet approach indicates that quantum recoil effects - reflecting the gravitational back-reaction on space-time foam due to the propagation of energetic particles - induces the appearance of a microscopic event horizon, or `bubble', inside which stable matter can exist. The scattering event causes this horizon to expand, but we expect quantum effects to cause it to contract again, in a `bounce' solution. Within such `bubbles', massless matter propagates with an effective velocity that is less than the velocity of light in vacuo, which may lead to observable violations of Lorentz symmetry that may be tested experimentally. The conformal invariance conditions in the interior geometry of the bubbles select preferentially three for the number of the spatial dimensions, corresponding to a consistent formulation of the interaction of D3 branes with recoiling D particles, which are allowed to fluctuate independently only on the D3-brane hypersurface.
A holographic bound for D3-brane
Energy Technology Data Exchange (ETDEWEB)
Momeni, Davood; Myrzakul, Aizhan; Myrzakulov, Ratbay [Eurasian National University, Eurasian International Center for Theoretical Physics, Astana (Kazakhstan); Eurasian National University, Department of General Theoretical Physics, Astana (Kazakhstan); Faizal, Mir [University of British Columbia-Okanagan, Irving K. Barber School of Arts and Sciences, Kelowna, BC (Canada); University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada); Bahamonde, Sebastian [University College London, Department of Mathematics, London (United Kingdom)
2017-06-15
In this paper, we will regularize the holographic entanglement entropy, holographic complexity and fidelity susceptibility for a configuration of D3-branes. We will also study the regularization of the holographic complexity from the action for a configuration of D3-branes. It will be demonstrated that for a spherical shell of D3-branes the regularized holographic complexity is always greater than or equal to the regularized fidelity susceptibility. Furthermore, we will also demonstrate that the regularized holographic complexity is related to the regularized holographic entanglement entropy for this system. Thus, we will obtain a holographic bound involving regularized holographic complexity, regularized holographic entanglement entropy and regularized fidelity susceptibility of a configuration of D3-brane. We will also discuss a bound for regularized holographic complexity from action, for a D3-brane configuration. (orig.)
Left-right entanglement entropy of Dp-branes
Energy Technology Data Exchange (ETDEWEB)
Zayas, Leopoldo A. Pando [The Abdus Salam International Centre for Theoretical Physics,Strada Costiera 11, 34014 Trieste (Italy); Michigan Center for Theoretical Physics, Randall Laboratory of Physics,The University of Michigan,450 Church Street, Ann Arbor, MI 48109-1120 (United States); Quiroz, Norma [Departamento de Ciencias Exactas, Tecnología y Metodología,Centro Universitario del Sur, Universidad de Guadalajara,Enrique Arreola Silva 883, C.P. 49000, Cd. Guzmán, Jalisco (Mexico)
2016-11-04
We compute the left-right entanglement entropy for Dp-branes in string theory. We employ the CFT approach to string theory Dp-branes, in particular, its presentation as coherent states of the closed string sector. The entanglement entropy is computed as the von Neumann entropy for a density matrix resulting from integration over the left-moving degrees of freedom. We discuss various crucial ambiguities related to sums over spin structures and argue that different choices capture different physics; however, we advance a themodynamic argument that seems to favor a particular choice of replica. We also consider Dp branes on compact dimensions and verify that the effects of T-duality act covariantly on the Dp brane entanglement entropy. We find that generically the left-right entanglement entropy provides a suitable generalization of boundary entropy and of the D-brane tension.
V = 1 super quantum chromodynamics and fractional branes
Indian Academy of Sciences (India)
The orbifold group acts on the directions x4,...,x9 transverse to the world-volume of the stack of the N D3-branes. The Z2 group is characterized by two elements 1, h , with h2 = 1, hence the four elements of the tensor product Z2 ¢Z2 are easily obtained. The non-trivial elements act on the complex vector z = (z1 = x4 + ix5, ...
Ring relations and mirror map from branes
Energy Technology Data Exchange (ETDEWEB)
Assel, Benjamin [Theoretical Physics Department, CERN,CH-1211 Geneva 23 (Switzerland)
2017-03-29
We study the space of vacua of three-dimensional N=4 theories from a novel approach building on the type IIB brane realization of the theory and in which the insertion of local chiral operators in the path integral is obtained from integrating out light modes in appropriate brane setups. Most of our analysis focuses on abelian quiver theories which can be realized as the low-energy theory of D3-D5-NS5 brane arrays. Their space of vacua contains a Higgs branch, parametrized by the vevs of half-BPS meson operators, and a Coulomb branch, parametrized by the vevs of half-BPS monopole operators. We show that the Higgs operators are inserted by adding F1 strings and D3 branes, while Coulomb operators are inserted by adding D1 strings and D3 branes, with specific orientations, to the initial brane setup of the theory. This approach has two main advantages. First the ring relations describing the Higgs and Coulomb branches can be derived by looking at specific brane setups with multiple interpretations in terms of operator insertions. This provides a new derivation of the Coulomb branch quantum relations. Secondly the map between the Higgs and Coulomb operators of mirror dual theories can be derived in a trivial way from IIB S-duality.
Wireless Augmented Reality Prototype (WARP)
Devereaux, A. S.
1999-01-01
Initiated in January, 1997, under NASA's Office of Life and Microgravity Sciences and Applications, the Wireless Augmented Reality Prototype (WARP) is a means to leverage recent advances in communications, displays, imaging sensors, biosensors, voice recognition and microelectronics to develop a hands-free, tetherless system capable of real-time personal display and control of computer system resources. Using WARP, an astronaut may efficiently operate and monitor any computer-controllable activity inside or outside the vehicle or station. The WARP concept is a lightweight, unobtrusive heads-up display with a wireless wearable control unit. Connectivity to the external system is achieved through a high-rate radio link from the WARP personal unit to a base station unit installed into any system PC. The radio link has been specially engineered to operate within the high- interference, high-multipath environment of a space shuttle or space station module. Through this virtual terminal, the astronaut will be able to view and manipulate imagery, text or video, using voice commands to control the terminal operations. WARP's hands-free access to computer-based instruction texts, diagrams and checklists replaces juggling manuals and clipboards, and tetherless computer system access allows free motion throughout a cabin while monitoring and operating equipment.
Intersecting Branes Flip SU(5)
Ellis, Jonathan Richard; Nanopoulos, Dimitri V; Ellis, John
2002-01-01
Within a toroidal orbifold framework, we exhibit intersecting brane-world constructions of flipped SU(5) \\times U(1) GUT models with various numbers of generations, other chiral matter representations and Higgs representations. We exhibit orientifold constructions with integer winding numbers that yield 8 or more conventional SU(5) generations, and orbifold constructions with fractional winding numbers that yield flipped SU(5) \\times U(1) models with just 3 conventional generations. Some of these models have candidates for the 5 and {\\bar 5} Higgs representations needed for electroweak symmetry breaking, but not for the 10 and {\\bar 10} representations needed for GUT symmetry breaking, or vice-versa.
Quantum effects in warp drives
Directory of Open Access Journals (Sweden)
Finazzi Stefano
2013-09-01
Full Text Available Warp drives are interesting configurations that, at least theoretically, provide a way to travel at superluminal speed. Unfortunately, several issues seem to forbid their realization. First, a huge amount of exotic matter is required to build them. Second, the presence of quantum fields propagating in superluminal warp-drive geometries makes them semiclassically unstable. Indeed, a Hawking-like high-temperature flux of particles is generated inside the warp-drive bubble, which causes an exponential growth of the energy density measured at the front wall of the bubble by freely falling observers. Moreover, superluminal warp drives remain unstable even if the Lorentz symmetry is broken by the introduction of regulating higher order terms in the Lagrangian of the quantum field. If the dispersion relation of the quantum field is subluminal, a black-hole laser phenomenon yields an exponential amplification of the emitted flux. If it is superluminal, infrared effects cause a linear growth of this flux.
Constraining brane tension using rotation curves of galaxies
García-Aspeitia, Miguel A.; Rodríguez-Meza, Mario A.
2018-04-01
We present in this work a study of brane theory phenomenology focusing on the brane tension parameter, which is the main observable of the theory. We show the modifications steaming from the presence of branes in the rotation curves of spiral galaxies for three well known dark matter density profiles: Pseudo isothermal, Navarro-Frenk-White and Burkert dark matter density profiles. We estimate the brane tension parameter using a sample of high resolution observed rotation curves of low surface brightness spiral galaxies and a synthetic rotation curve for the three density profiles. Also, the fittings using the brane theory model of the rotation curves are compared with standard Newtonian models. We found that Navarro-Frenk-White model prefers lower values of the brane tension parameter, on the average λ ∼ 0.73 × 10‑3eV4, therefore showing clear brane effects. Burkert case does prefer higher values of the tension parameter, on the average λ ∼ 0.93 eV4 ‑ 46 eV4, i.e., negligible brane effects. Whereas pseudo isothermal is an intermediate case. Due to the low densities found in the galactic medium it is almost impossible to find evidence of the presence of extra dimensions. In this context, we found that our results show weaker bounds to the brane tension values in comparison with other bounds found previously, as the lower value found for dwarf stars composed of a polytropic equation of state, λ ≈ 104 MeV4.
D-branes in a non-critical superstrings and minimal super Yang-Mills in various dimensions
International Nuclear Information System (INIS)
Ashok, S.K.; Murthy, S.; Troost, J.
2005-11-01
We construct and analyze D-branes in superstring theories in even dimensions less than ten. The backgrounds under study are supersymmetric R d-1,1 x SL(2,R) k /U(1) where the level of the supercoset is tuned such as to provide bona fide string theory backgrounds. We provide exact boundary states for D-branes that are localized at the tip of the cigar SL(2,R)/U(1) supercoset conformal field theory. We analyze the spectra of open strings on these D-branes and show explicitly that they are consistent with supersymmetry in d = 2,4 and 6. The low energy theory on the world-volume of the D-brane in each case is pure Yang-Mills theory with minimal supersymmetry. In the case with four macroscopic flat directions d = 4, we realize an N = 1 super Yang-Mills theory, and we interpret the backreaction for the dilaton as the running of the gauge coupling, and study the relation between R-symmetry breaking in the gauge theory and the backreaction on the Rr axion. (author)
International Nuclear Information System (INIS)
Lee, Peter; Ooguri, Hirosi.; Park, Jongwon; Tannenhauser, Jonathan
2001-01-01
We study the spectrum of open strings on AdS 2 branes in AdS 3 in an NS-NS background, using the SL(2,R) WZW model. When the brane carries no fundamental string charge, the open string spectrum is the holomorphic square root of the spectrum of closed strings in AdS 3 . It contains short and long strings, and is invariant under spectral flow. When the brane carries fundamental string charge, the open string spectrum again contains short and long strings in all winding sectors. However, branes with fundamental string charge break half the spectral flow symmetry. This has different implications for short and long strings. As the fundamental string charge increases, the brane approaches the boundary of AdS 3 . In this limit, the induced electric field on the worldvolume reaches its critical value, producing noncommutative open string theory on AdS 2
Universal aspects of gravity localized on thick branes
International Nuclear Information System (INIS)
Csaki, Csaba; Erlich, Joshua; Hollowood, Timothy J.; Shirman, Yuri
2000-01-01
We study gravity in backgrounds that are smooth generalizations of the Randall-Sundrum model, with and without scalar fields. These generalizations include three-branes in higher dimensional spaces which are not necessarily anti-de Sitter far from the branes, intersecting brane configurations and configurations involving negative tension branes. We show that under certain mild assumptions there is a universal equation for the gravitational fluctuations. We study both the graviton ground state and the continuum of Kaluza-Klein modes and we find that the four-dimensional gravitational mode is localized precisely when the effects of the continuum modes decouple at distances larger than the fundamental Planck scale. The decoupling is contingent only on the long-range behaviour of the metric from the brane and we find a universal form for the corrections to Newton's law. We also comment on the possible contribution of resonant modes. Given this, we find general classes of metrics which maintain localized four-dimensional gravity. We find that three-brane metrics in five dimensions can arise from a single scalar field source, and we rederive the BPS type conditions without any a priori assumptions regarding the form of the scalar potential. We also show that a single scalar field cannot produce conformally-flat locally intersecting brane configurations or a p-brane in greater than (p+2)-dimensions
Geometry and physics of branes
Energy Technology Data Exchange (ETDEWEB)
Gal' tsov, D V
2003-03-21
The book brings together the contents of lecture courses delivered at the school 'Geometry and Physics of Branes' which took place at the Center 'Alessandro Volta' (Como, Italy) in the spring of 2001. The purpose of the school was to provide an introduction to some lines of research, related to the notion of branes in superstring theory, which are in the focus of attention both in the physical and mathematical communities. The book is structured into three parts: the first contains an elementary introduction to branes, the second is devoted to physical aspects (conformal field theory on open and unoriented surfaces and topics in string tachyon dynamics), and the last contains some more formal mathematical developments. An introduction to branes is given in a remarkably lucid contribution by A Lerda. It opens with a construction of p-brane solutions in classical IIA and IIB supergravities with particular emphasis on the 'fundamental string' solution, the NS5-brane and the D3-brane. Then, the quantum description of D-branes is discussed in terms of boundary states of the closed superstring, which is an alternative to the more common description in terms of open strings with Dirichlet boundary conditions in the transverse to the brane directions. When a constant gauge field is present in the D-brane worldvolume, the boundary states are coherent states of the string oscillators depending on the field strength tensor. The couplings of the brane to the bulk fields - the graviton, the dilaton, and the Kalb-Ramond fields - are then extracted and shown to be precisely the ones that are produced by the Dirac-Born-Infeld action governing the low-energy dynamics of the D-brane derived using the open strings formalism. It is also shown that in the classical limit, the boundary states correctly reproduce the parameters of the corresponding classical solutions. The second part of the book starts with a contribution by Y S Stanev devoted to the two
RELAXATION OF WARPED DISKS: THE CASE OF PURE HYDRODYNAMICS
Energy Technology Data Exchange (ETDEWEB)
Sorathia, Kareem A.; Krolik, Julian H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Hawley, John F. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)
2013-05-10
Orbiting disks may exhibit bends due to a misalignment between the angular momentum of the inner and outer regions of the disk. We begin a systematic simulational inquiry into the physics of warped disks with the simplest case: the relaxation of an unforced warp under pure fluid dynamics, i.e., with no internal stresses other than Reynolds stress. We focus on the nonlinear regime in which the bend rate is large compared to the disk aspect ratio. When warps are nonlinear, strong radial pressure gradients drive transonic radial motions along the disk's top and bottom surfaces that efficiently mix angular momentum. The resulting nonlinear decay rate of the warp increases with the warp rate and the warp width, but, at least in the parameter regime studied here, is independent of the sound speed. The characteristic magnitude of the associated angular momentum fluxes likewise increases with both the local warp rate and the radial range over which the warp extends; it also increases with increasing sound speed, but more slowly than linearly. The angular momentum fluxes respond to the warp rate after a delay that scales with the square root of the time for sound waves to cross the radial extent of the warp. These behaviors are at variance with a number of the assumptions commonly used in analytic models to describe linear warp dynamics.
Holographic cosmology from a system of M2–M5 branes
International Nuclear Information System (INIS)
Sepehri, Alireza; Faizal, Mir; Setare, Mohammad Reza; Ali, Ahmed Farag
2016-01-01
In this paper, we analyze the holographic cosmology using a M2–M5 brane configuration. In this configuration, a M2-brane will be placed in between a M5-brane and an anti-M5-brane. The M2-brane will act as a channel for energy to flow from an anti-M5-brane to a M5-brane, and this will increase the degrees of freedom on the M5-brane causing inflation. The inflation will end when the M5-brane and anti-M5-brane get separated. However, at a later stage the distance between the M5-brane and the anti-M5-bran can reduce and this will cause the formation of tachyonic states. These tachyonic states will again open a bridge between the M5-branes and the anti-M5-branes, which will cause further acceleration of the universe.
Holographic cosmology from a system of M2–M5 branes
Energy Technology Data Exchange (ETDEWEB)
Sepehri, Alireza, E-mail: alireza.sepehri@uk.ac.ir [Faculty of Physics, Shahid Bahonar University, P.O. Box 76175, Kerman (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Faizal, Mir, E-mail: f2mir@uwaterloo.ca [Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, N2L 3G1 (Canada); Setare, Mohammad Reza, E-mail: rezakord@ipm.ir [Department of Science, Campus of Bijar, University of Kurdistan, Bijar (Iran, Islamic Republic of); Ali, Ahmed Farag, E-mail: afali@fsu.edu [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Department of Physics, Faculty of Science, Benha University, Benha 13518 (Egypt)
2016-05-15
In this paper, we analyze the holographic cosmology using a M2–M5 brane configuration. In this configuration, a M2-brane will be placed in between a M5-brane and an anti-M5-brane. The M2-brane will act as a channel for energy to flow from an anti-M5-brane to a M5-brane, and this will increase the degrees of freedom on the M5-brane causing inflation. The inflation will end when the M5-brane and anti-M5-brane get separated. However, at a later stage the distance between the M5-brane and the anti-M5-bran can reduce and this will cause the formation of tachyonic states. These tachyonic states will again open a bridge between the M5-branes and the anti-M5-branes, which will cause further acceleration of the universe.
Statistical anisotropy from vector curvaton in D-brane inflation
International Nuclear Information System (INIS)
Dimopoulos, Konstantinos; Wills, Danielle; Zavala, Ivonne
2013-01-01
We investigate the possibility of embedding the vector curvaton paradigm in D-brane models of inflation in type IIB string theory in a simple toy model. The vector curvaton is identified with the U(1) gauge field that lives on the world volume of a D3-brane, which may be stationary or undergoing general motion in the internal space. The dilaton is considered as a spectator field which modulates the evolution of the vector field. In this set-up, the vector curvaton is able to generate measurable statistical anisotropy in the spectrum and bispectrum of the curvature perturbation assuming that the dilaton evolves as e −φ ∝a 2 where a(t) is the scale factor. Our work constitutes a first step towards exploring how such distinctive features may arise from the presence of several light fields that naturally appear in string theory models of cosmology.
One-loop adjoint masses for non-supersymmetric intersecting branes
Energy Technology Data Exchange (ETDEWEB)
Anastasopoulos, P. [Technische Univ., Vienna (Austria). 1. Inst. fuer Theoretische Physik; Antoniadis, I. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Benakli, K. [CNRS, UPMC Univ. Paris (France). Lab. de Physique Theorique et Haute Energies; Goodsell, M.D. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Vichi, A. [Institute de Theorie des Phenomenes Physiques, EPFL, Lausanne (Switzerland)
2011-05-15
We consider breaking of supersymmetry in intersecting D-brane configurations by slight deviation of the angles from their supersymmetric values. We compute the masses generated by radiative corrections for the adjoint scalars on the brane world-volumes. In the open string channel, the string two-point function receives contributions only from the infrared and the ultraviolet limits. The latter is due to tree-level closed string uncanceled NS-NS tadpoles, which we explicitly reproduce from the effective Born-Infeld action. On the other hand, the infrared region reproduces the one-loop mediation of supersymmetry breaking in the effective gauge theory, via messengers and their Kaluza-Klein excitations. In the toroidal set-up considered here, it receives contributions only from N {approx} 4 and N {approx} 2 supersymmetric configurations, and thus always leads at leading order to a tachyonic direction, in agreement with effective field theory expectations. (orig.)
Dielectric (p,q) strings in a throat
International Nuclear Information System (INIS)
Firouzjahi, Hassan
2006-01-01
We calculate the (p,q) string spectrum in a warped deformed conifold using the dielectric brane method. The spectrum is shown to have the same functional form as in the dual picture of a wrapped D3-brane with electric and magnetic fluxes on its world volume. The agreement is exact in the limit where q is large. We also calculate the dielectric spectrum in the S-dual picture. The spectrum in the S-dual picture has the same form as in the original picture but it is not exactly S-dual invariant due to an interchange of Casimirs of the non-Abelian gauge symmetries. We argue that in order to restore S-duality invariance the non-Abelian brane action should be refined, probably by a better prescription for the non-Abelian trace operation
Negative branes, supergroups and the signature of spacetime
Dijkgraaf, Robbert; Heidenreich, Ben; Jefferson, Patrick; Vafa, Cumrun
2018-02-01
We study the realization of supergroup gauge theories using negative branes in string theory. We show that negative branes are intimately connected with the possibility of timelike compactification and exotic spacetime signatures previously studied by Hull. Isolated negative branes dynamically generate a change in spacetime signature near their worldvolumes, and are related by string dualities to a smooth M-theory geometry with closed timelike curves. Using negative D3-branes, we show that SU(0| N) supergroup theories are holographically dual to an exotic variant of type IIB string theory on {dS}_{3,2}× {\\overline{S}}^5 , for which the emergent dimensions are timelike. Using branes, mirror symmetry and Nekrasov's instanton calculus, all of which agree, we derive the Seiberg-Witten curve for N=2 SU( N | M ) gauge theories. Together with our exploration of holography and string dualities for negative branes, this suggests that supergroup gauge theories may be non-perturbatively well-defined objects, though several puzzles remain.
Brane surgery: energy conditions, traversable wormholes, and voids
International Nuclear Information System (INIS)
Barcelo, Carlos; Visser, Matt
2000-01-01
Branes are ubiquitous elements of any low-energy limit of string theory. We point out that negative tension branes violate all the standard energy conditions of the higher-dimensional spacetime they are embedded in; this opens the door to very peculiar solutions of the higher-dimensional Einstein equations. Building upon the (3+1)-dimensional implementation of fundamental string theory, we illustrate the possibilities by considering a toy model consisting of a (2+1)-dimensional brane propagating through our observable (3+1)-dimensional universe. Developing a notion of 'brane surgery', based on the Israel-Lanczos-Sen 'thin shell' formalism of general relativity, we analyze the dynamics and find traversable wormholes, closed baby universes, voids (holes in the spacetime manifold), and an evasion (not a violation) of both the singularity theorems and the positive mass theorem. These features appear generic to any brane model that permits negative tension branes: This includes the Randall-Sundrum models and their variants
Semiclassical instability of warp drives
Energy Technology Data Exchange (ETDEWEB)
Barcelo, C [Instituto de Astrofisica de Andalucia, IAA-CSIC, Glorieta de la Astronomia s/n, 18008 Granada (Spain); Finazzi, S; Liberati, S, E-mail: carlos@iaa.e, E-mail: finazzi@sissa.i, E-mail: liberati@sissa.i
2010-05-01
Warp drives, at least theoretically, provide a way to travel at superluminal speeds. However, even if one succeeded in providing the necessary exotic matter to construct them, it would still be necessary to check whether they would survive to the switching on of quantum effects. In this contribution we will report on the behaviour of the Renormalized Stress-Energy Tensor (RSET) in the spacetimes associated with superluminal warp drives. We find that the RSET will exponentially grow in time close to the front wall of the superluminal bubble, hence strongly supporting the conclusion that the warp-drive geometries are unstable against semiclassical back-reaction.
Small numbers from tunneling between brane throats
International Nuclear Information System (INIS)
Kaloper, Nemanja
2003-01-01
In generic string compactifications with branes, the regions of space in the vicinity of brane horizons, or brane throats, support effective potential barriers, raised by the back-ground gravitational fields. A familiar example is the AdS brane throats in the Randall-Sundrum model. The barriers obstruct the interaction of observers inside different throats, whose communication is effectively described by tunneling through the barriers. Consequently the interactions between different throats are exponentially weak. This provides for a new mechanism for explaining small numbers in Nature. We review the applications to the hierarchy problem where supersymmetry breaking scale is reduced by tunneling, long-lived cold dark matter particles which decay into hot CFT, and consider the implications for holography. We finally discuss the important interplay between the tunneling suppression and our recent conjecture that black holes stuck on a brane in AdS D+1 should be interpreted as duals of quantum-corrected D-dimensional black holes, rather than classical ones, of a CFT coupled to gravity. (author)
Axion production from gravitons off interacting 0-branes
International Nuclear Information System (INIS)
Hussain, F.; Iengo, R.; Nunez, C.
1997-01-01
We study axion-graviton scattering from a system of two D0-branes in a type II superstring theory, a process which does not occur on a single brane. The two D0-branes interact via the exchange of closed string states which form a cylinder joining them. By compactifying on the Z 3 orbifold we find a non-vanishing amplitude coming from the odd spin structure sector, thus from the exchanged RR states. We compute, in particular, the leading term of the amplitude at large distance from the branes, which corresponds to taking a field theory limit. This seems to suggest that the process takes place through the coupling of an axion to the RR states exchanged between the 0-branes. (orig.)
Brane configurations and 4D field theory dualities
International Nuclear Information System (INIS)
Brandhuber, A.; Sonnenschein, J.; Yankielowicz, S.
1997-01-01
We study brane configurations which correspond to field theories in four dimension with N=2 and N=1 supersymmetry. In particular we discuss brane motions that translate to Seiberg's duality in N=1 models recently studied by Elitzur, Giveon and Kutasov. We investigate, using the brane picture, the moduli spaces of the dual theories. Deformations of these models like mass terms and vacuum expectation values of scalar fields can be identified with positions of branes. The map of these deformations between the electric and dual magnetic theories is clarified. The models we study reproduce known field theory results and we provide an example of new dual pairs with N=1 supersymmetry. Possible relations between brane configurations and non-supersymmetric field theories are discussed. (orig.)
Energy Technology Data Exchange (ETDEWEB)
2016-10-25
Sirepo is an open source framework for cloud computing. The graphical user interface (GUI) for Sirepo, also known as the client, executes in any HTML5 compliant web browser on any computing platform, including tablets. The client is built in JavaScript, making use of the following open source libraries: Bootstrap, which is fundamental for cross-platform web applications; AngularJS, which provides a model–view–controller (MVC) architecture and GUI components; and D3.js, which provides interactive plots and data-driven transformations. The Sirepo server is built on the following Python technologies: Flask, which is a lightweight framework for web development; Jin-ja, which is a secure and widely used templating language; and Werkzeug, a utility library that is compliant with the WSGI standard. We use Nginx as the HTTP server and proxy, which provides a scalable event-driven architecture. The physics codes supported by Sirepo execute inside a Docker container. One of the codes supported by Sirepo is Warp. Warp is a particle-in-cell (PIC) code de-signed to simulate high-intensity charged particle beams and plasmas in both the electrostatic and electromagnetic regimes, with a wide variety of integrated physics models and diagnostics. At pre-sent, Sirepo supports a small subset of Warp’s capabilities. Warp is open source and is part of the Berkeley Lab Accelerator Simulation Toolkit.
Nucleation of {sup (4)}R brane universes
Energy Technology Data Exchange (ETDEWEB)
Cordero, Ruben [Departamento de FIsica, Escuela Superior de FIsica y Matematicas del IPN, Unidad Adolfo Lopez Mateos, Edificio 9, 07738 Mexico, DF (Mexico); Rojas, EfraIn [Facultad de FIsica e Inteligencia Artificial, Universidad Veracruzana, Sebastian Camacho 5, Xalapa, Veracruz, 91000 (Mexico)
2004-09-07
The creation of brane universes induced by a totally antisymmetric tensor living in a fixed background spacetime is presented, where a term involving the intrinsic curvature of the brane is considered. A canonical quantum mechanical approach employing the Wheeler-DeWitt equation is used. The probability nucleation for the brane is calculated by means of the corresponding instanton and the WKB approximation. Some cosmological implications from the model are presented.
Deriving all p-brane superalgebras via integrability
Grasso, D. T.; McArthur, I. N.
2018-03-01
In previous work we demonstrated that the enlarged super-Poincare algebras which underlie p-brane and D-brane actions in superstring theory can be directly determined based on the integrability of supersymmetry transformations assigned to fields appearing in Wess-Zumino terms. In that work we derived p-brane superalgebras for p = 2 and 3. Here we extend our previous results and give a compact expression for superalgebras for all valid p.
Superluminal warp drive and dark energy
Energy Technology Data Exchange (ETDEWEB)
Gonzalez-Diaz, Pedro F. [Colina de los Chopos, Centro de Fisica ' Miguel A. Catalan' , Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain)], E-mail: p.gonzalezdiaz@imaff.cfmac.csic.es
2007-11-29
In this Letter we consider a warp drive spacetime where the spaceship can only travel faster than light. Restricting to the two-dimensional case, we find that if the warp drive is placed in an accelerating universe the warp bubble size increases in a comoving way to the expansion of the universe in which it is immersed. Also shown is the result that the apparent velocity of the ship steadily increases with time as phantom energy is accreted onto it.
Hydro-elastic complementarity in black branes at large D
Energy Technology Data Exchange (ETDEWEB)
Emparan, Roberto [ICREA, Passeig Lluís Companys 23, E-08010 Barcelona (Spain); Departament de Física Fonamental, Institut de Ciències del Cosmos, Universitat de Barcelona,Martí i Franquès 1, E-08028 Barcelona (Spain); Izumi, Keisuke; Luna, Raimon [Departament de Física Fonamental, Institut de Ciències del Cosmos, Universitat de Barcelona,Martí i Franquès 1, E-08028 Barcelona (Spain); Suzuki, Ryotaku [Department of Physics, Osaka City University, Osaka 558-8585 (Japan); Tanabe, Kentaro [Theory Center, Institute of Particles and Nuclear Studies, KEK,Tsukuba, Ibaraki, 305-0801 (Japan)
2016-06-21
We obtain the effective theory for the non-linear dynamics of black branes — both neutral and charged, in asymptotically flat or Anti-deSitter spacetimes — to leading order in the inverse-dimensional expansion. We find that black branes evolve as viscous fluids, but when they settle down they are more naturally viewed as solutions of an elastic soap-bubble theory. The two views are complementary: the same variable is regarded in one case as the energy density of the fluid, in the other as the deformation of the elastic membrane. The large-D theory captures finite-wavelength phenomena beyond the conventional reach of hydrodynamics. For asymptotically flat charged black branes (either Reissner-Nordstrom or p-brane-charged black branes) it yields the non-linear evolution of the Gregory-Laflamme instability at large D and its endpoint at stable non-uniform black branes. For Reissner-Nordstrom AdS black branes we find that sound perturbations do not propagate (have purely imaginary frequency) when their wavelength is below a certain charge-dependent value. We also study the polarization of black branes induced by an external electric field.
On the localisation of four-dimensional brane-world black holes: II. The general case
International Nuclear Information System (INIS)
Kanti, P; Pappas, T; Pappas, N
2016-01-01
We perform a comprehensive analysis of a number of scalar field theories in an attempt to find analytically five-dimensional, localised-on-the-brane, black-hole solutions. Extending a previous analysis, we assume a generalised Vaidya ansatz for the five-dimensional metric tensor that allows for a time-dependent, non-trivial profile of the mass function in terms of the bulk coordinate and a deviation from the over-restricting Schwarzschild-type solution on the brane. In order to support such a solution, we study a variety of theories including single or multiple scalar fields, with canonical or non-canonical kinetic terms, minimally or non-minimally coupled to gravity. We demonstrate that for such a metric ansatz and for a carefully chosen energy-momentum tensor which is non-isotropic in five dimensions, solutions that have the form of a Schwarzschild–(anti)de Sitter or Reissner–Nordstrom type of solution do emerge. However, the resulting profile of the mass function along the bulk coordinate, when allowed, is not the correct one for eliminating bulk singularities. (paper)
On the localisation of four-dimensional brane-world black holes: II. The general case
Kanti, P.; Pappas, N.; Pappas, T.
2016-01-01
We perform a comprehensive analysis of a number of scalar field theories in an attempt to find analytically five-dimensional, localised-on-the-brane, black-hole solutions. Extending a previous analysis, we assume a generalised Vaidya ansatz for the five-dimensional metric tensor that allows for a time-dependent, non-trivial profile of the mass function in terms of the bulk coordinate and a deviation from the over-restricting Schwarzschild-type solution on the brane. In order to support such a solution, we study a variety of theories including single or multiple scalar fields, with canonical or non-canonical kinetic terms, minimally or non-minimally coupled to gravity. We demonstrate that for such a metric ansatz and for a carefully chosen energy-momentum tensor which is non-isotropic in five dimensions, solutions that have the form of a Schwarzschild-(anti)de Sitter or Reissner-Nordstrom type of solution do emerge. However, the resulting profile of the mass function along the bulk coordinate, when allowed, is not the correct one for eliminating bulk singularities.
On the problem of vacuum energy in brane theories
International Nuclear Information System (INIS)
Gurwich, Ilya; Rubin, Shimon; Davidson, Aharon
2009-01-01
We point out that modern brane theories suffer from a severe vacuum energy problem. To be specific, the Casimir energy associated with the matter fields confined to the brane, is stemming from the one and the same localization mechanism which forms the brane itself, and is thus generically unavoidable. Possible practical solutions are discussed, including in particular spontaneously broken supersymmetry, and quantum mechanically induced brane tension.
Warped products and black holes
International Nuclear Information System (INIS)
Hong, Soon-Tae
2005-01-01
We apply the warped product space-time scheme to the Banados-Teitelboim-Zanelli black holes and the Reissner-Nordstroem-anti-de Sitter black hole to investigate their interior solutions in terms of warped products. It is shown that there exist no discontinuities of the Ricci and Einstein curvatures across event horizons of these black holes
Criticality for charged black branes
Hennigar, Robie A.
2017-09-01
We show that the inclusion of higher curvature terms in the gravitational action can lead to phase transitions and critical behaviour for charged black branes. The higher curvature terms considered here belong to the recently constructed generalized quasi-topological class [arXiv:1703.01631], which possess a number of interesting properties, such as being ghost-free on constant curvature backgrounds and non-trivial in four dimensions. We show that critical behaviour is a generic feature of the black branes in all dimensions d ≥ 4, and contextualize the results with a review of the properties of black branes in Lovelock and quasi-topological gravity, where critical behaviour is not possible. These results may have interesting implications for the CFTs dual to this class of theories.
From the currency rate quotations onto strings and brane world scenarios
Horváth, D.; Pincak, R.
2012-11-01
In the paper, we study the projections of the real exchange rate dynamics onto the string-like topology. Our approach is inspired by the contemporary movements in the string theory. The string map of data is defined here by the boundary conditions, characteristic length, real valued and the method of redistribution of information. As a practical matter, this map represents the detrending and data standardization procedure. We introduced maps onto 1-end-point and 2-end-point open strings that satisfy the Dirichlet and Neumann boundary conditions. The questions of the choice of extra-dimensions, symmetries, duality and ways to the partial compactification are discussed. Subsequently, we pass to higher dimensional and more complex objects. The 2D-Brane was suggested which incorporated bid-ask spreads. Polarization by the spread was considered which admitted analyzing arbitrage opportunities on the market where transaction costs are taken into account. The model of the rotating string which naturally yields calculation of angular momentum is suitable for tracking of several currency pairs. The systematic way which allows one suggest more structured maps suitable for a simultaneous study of several currency pairs was analyzed by means of the Gâteaux generalized differential calculus. The effect of the string and brane maps on test data was studied by comparing their mean statistical characteristics. The study revealed notable differences between topologies. We review the dependence on the characteristic string length, mean fluctuations and properties of the intra-string statistics. The study explores the coupling of the string amplitude and volatility. The possible utilizations of the string theory approach in financial markets are slight.
Goldberger-Wise variations: stabilizing brane models with a bulk scalar
Sorbo, L; Lesgourgues, Julien; Sorbo, Lorenzo
2004-01-01
Braneworld scenarios with compact extra-dimensions need the volume of the extra space to be stabilized. Goldberger and Wise have introduced a simple mechanism, based on the presence of a bulk scalar field, able to stabilize the radius of the Randall-Sundrum model. Here, we transpose the same mechanism to generic single-brane and two-brane models, with one extra dimension and arbitrary scalar potentials in the bulk and on the branes. The single-brane construction turns out to be always unstable, independently of the bulk and brane potentials. In the case of two branes, we derive some generic criteria ensuring the stabilization or destabilization of the system.
Goldberger-Wise variations: Stabilizing brane models with a bulk scalar
International Nuclear Information System (INIS)
Lesgourgues, Julien; Sorbo, Lorenzo
2004-01-01
Braneworld scenarios with compact extra dimensions need the volume of the extra space to be stabilized. Goldberger and Wise have introduced a simple mechanism, based on the presence of a bulk scalar field, able to stabilize the radius of the Randall-Sundrum model. Here, we transpose the same mechanism to generic single-brane and two-brane models, with one extra dimension and arbitrary scalar potentials in the bulk and on the branes. The single-brane construction turns out to be always unstable, independently of the bulk and brane potentials. In the case of two branes, we derive some generic criteria ensuring the stabilization or destabilization of the system
Seamless warping of diffusion tensor fields
DEFF Research Database (Denmark)
Xu, Dongrong; Hao, Xuejun; Bansal, Ravi
2008-01-01
To warp diffusion tensor fields accurately, tensors must be reoriented in the space to which the tensors are warped based on both the local deformation field and the orientation of the underlying fibers in the original image. Existing algorithms for warping tensors typically use forward mapping...... of seams, including voxels in which the deformation is extensive. Backward mapping, however, cannot reorient tensors in the template space because information about the directional orientation of fiber tracts is contained in the original, unwarped imaging space only, and backward mapping alone cannot...... transfer that information to the template space. To combine the advantages of forward and backward mapping, we propose a novel method for the spatial normalization of diffusion tensor (DT) fields that uses a bijection (a bidirectional mapping with one-to-one correspondences between image spaces) to warp DT...
Mirror symmetry in the presence of branes
Energy Technology Data Exchange (ETDEWEB)
Mertens, Adrian
2011-10-11
This work deals with mirror symmetry for N=1 compactifications on compact Calabi-Yau threefolds with branes. The mayor tool is a combined deformation space for the Calabi-Yau and a hypersurface within it. Periods of this deformation space contain information about B-type branes within the hypersurface in addition to the usual closed string data. To study these periods we generalize techniques used in closed string mirror symmetry. We derive the Picard-Fuchs system and encode the information in extended toric polytopes. Solutions of the Picard-Fuchs equations give superpotentials for certain brane configurations. This is an efficient way to calculate superpotentials. The deformations we consider are massive for all branes with non trivial superpotential. Depending on a choice of a family of hypersurfaces, the superpotential of the effective low energy theory depends on different massive fields. A priori there is no reason for these fields to be lighter then other fields that are not included. We find however examples where the superpotential is nearly at. In these examples we use the Gauss-Manin connection on the combined deformation space to define an open string mirror map. We find instanton generated superpotentials of A-type branes. This gives predictions for Ooguri-Vafa invariants counting holomorphic disks that end on a Lagrangian brane on the Quintic. A second class of examples does not have preferred nearly massless deformations and different families of hypersurfaces can be used to calculate the same on-shell superpotential. We calculate examples of superpotentials for branes in Calabi-Yau manifolds with several moduli. The on-shell superpotentials are mapped to the mirror A-model to study the instanton expansion and to obtain predictions for disk invariants. The combined deformation spaces are equivalent to the quantum corrected Kaehler deformation spaces of certain non compact Calabi-Yau fourfolds. These fourfolds are fibrations of Calabi-Yau threefolds
Mirror symmetry in the presence of branes
International Nuclear Information System (INIS)
Mertens, Adrian
2011-01-01
This work deals with mirror symmetry for N=1 compactifications on compact Calabi-Yau threefolds with branes. The mayor tool is a combined deformation space for the Calabi-Yau and a hypersurface within it. Periods of this deformation space contain information about B-type branes within the hypersurface in addition to the usual closed string data. To study these periods we generalize techniques used in closed string mirror symmetry. We derive the Picard-Fuchs system and encode the information in extended toric polytopes. Solutions of the Picard-Fuchs equations give superpotentials for certain brane configurations. This is an efficient way to calculate superpotentials. The deformations we consider are massive for all branes with non trivial superpotential. Depending on a choice of a family of hypersurfaces, the superpotential of the effective low energy theory depends on different massive fields. A priori there is no reason for these fields to be lighter then other fields that are not included. We find however examples where the superpotential is nearly at. In these examples we use the Gauss-Manin connection on the combined deformation space to define an open string mirror map. We find instanton generated superpotentials of A-type branes. This gives predictions for Ooguri-Vafa invariants counting holomorphic disks that end on a Lagrangian brane on the Quintic. A second class of examples does not have preferred nearly massless deformations and different families of hypersurfaces can be used to calculate the same on-shell superpotential. We calculate examples of superpotentials for branes in Calabi-Yau manifolds with several moduli. The on-shell superpotentials are mapped to the mirror A-model to study the instanton expansion and to obtain predictions for disk invariants. The combined deformation spaces are equivalent to the quantum corrected Kaehler deformation spaces of certain non compact Calabi-Yau fourfolds. These fourfolds are fibrations of Calabi-Yau threefolds
Some comments on N=1 gauge theories from wrapped branes
International Nuclear Information System (INIS)
Apreda, R.; Bigazzi, F.; Petrini, M.; Cotrone, A.L.; Zaffaroni, A.
2001-12-01
We discuss various aspects of gauge theories realized on the world-volume of wrapped branes. In particular we analyze the coupling of SYM operators to space-time fields both in N=1 and N=2 models and give a description of the gluino condensate in the Maldacena-Nunez N=1 solution. We also explore the seven dimensional BPS equations relevant for these solutions and their generalizations. (author)
Supergravity solutions for D-branes in Hpp-wave backgrounds
International Nuclear Information System (INIS)
Bain, P.; Meessen, P.; Zamaklar, M.
2002-05-01
We derive two families of supergravity solutions describing D-branes in the maximally supersymmetric Hpp-wave background. The first family of solutions corresponds to quarter-BPS D-branes. These solutions are delocalised along certain directions transverse to the pp-wave The second family corresponds to the non-supersymmetric D-branes. These solutions are fully localised. A peculiar feature of the nonsupersymmetric solutions is that gravity becomes repulsive close to the core of the D-brane. Both families preserve the amount of supersymmetry predicted by the D-brane probe/CFT analysis. All solutions are written in Brinkman coordinates. To construct these kind of solutions it is crucial to identify the coordinates in which the ansatz looks the simplest. We argue that the natural coordinates to get the supergravity description of the half-BPS branes are the Rosen coordinates. (author)
Localizing gravity on exotic thick 3-branes
International Nuclear Information System (INIS)
Castillo-Felisola, Oscar; Melfo, Alejandra; Pantoja, Nelson; Ramirez, Alba
2004-01-01
We consider localization of gravity on thick branes with a nontrivial structure. Double walls that generalize the thick Randall-Sundrum solution, and asymmetric walls that arise from a Z 2 symmetric scalar potential, are considered. We present a new asymmetric solution: a thick brane interpolating between two AdS 5 spacetimes with different cosmological constants, which can be derived from a 'fake supergravity' superpotential, and show that it is possible to confine gravity on such branes
Sepehri, Alireza
2016-07-01
Recently, some authors (Cruz and Rojas, 2013 [1]) have constructed a Born-Infeld type action which may be written in terms of the Lovelock brane Lagrangians for a given dimension p. We reconsider their model in M-theory and study the process of birth and growth of nonlinear spinor and bosonic gravity during the construction of Mp-branes. Then, by application of this idea to BIonic system, we construct a BIonic superconductor in the background of nonlinear gravity. In this model, first, M0-branes link to each other and build an M5-brane and an anti-M5-brane connected by an M2-brane. M0-branes are zero dimensional objects that only scalars are attached to them. By constructing higher dimensional branes from M0-branes, gauge fields are produced. Also, if M0-branes don't link to each other completely, the symmetry of system is broken and fermions are created. The curvature produced by fermions has the opposite sign the curvature produced by gauge fields. Fermions on M5-branes and M2 plays the role of bridge between them. By passing time, M2 dissolves in M5's and nonlinear bosonic and spinor gravities are produced. By closing M5-branes towards each other, coupling of two identical fermions on two branes to each other causes that the square mass of their system becomes negative and some tachyonic states are created. For removing these tachyons, M5-branes compact, the sign of gravity between branes reverses, anti-gravity is produced which causes that branes and identical fermions get away from each other. This is the reason for the emergence of Pauli exclusion principle in Bionic system. Also, the spinor gravity vanishes and its energy builds a new M2 between M5-branes. We obtain the resistivity in this system and find that its value decreases by closing M5 branes to each other and shrinks to zero at colliding point of branes. This idea has different applications. For example, in cosmology, universes are located on M5-branes and M2-brane has the role of bridge between
Constraining the age of the NGC 4565 H I disk WARP: Determining the origin of gas WARPS
Energy Technology Data Exchange (ETDEWEB)
Radburn-Smith, David J.; Dalcanton, Julianne J.; Stilp, Adrienne M. [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); De Jong, Roelof S.; Streich, David [Leibniz-Institut für Astrophysik Potsdam, D-14482 Potsdam (Germany); Bell, Eric F.; Monachesi, Antonela [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Dolphin, Andrew E. [Raytheon, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Holwerda, Benne W. [European Space Agency, ESTEC, 2200 AG Noordwijk (Netherlands); Bailin, Jeremy [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States)
2014-01-01
We have mapped the distribution of young and old stars in the gaseous H I warp of NGC 4565. We find a clear correlation of young stars (<600 Myr) with the warp but no coincident old stars (>1 Gyr), which places an upper limit on the age of the structure. The formation rate of the young stars, which increased ∼300 Myr ago relative to the surrounding regions, is (6.3{sub −1.5}{sup +2.5})×10{sup −5} M {sub ☉} yr{sup –1} kpc{sup –2}. This implies a ∼60 ± 20 Gyr depletion time of the H I warp, similar to the timescales calculated for the outer H I disks of nearby spiral galaxies. While some stars associated with the warp fall into the asymptotic giant branch (AGB) region of the color-magnitude diagram, where stars could be as old as 1 Gyr, further investigation suggests that they may be interlopers rather than real AGB stars. We discuss the implications of these age constraints for the formation of H I warps and the gas fueling of disk galaxies.
Energy Technology Data Exchange (ETDEWEB)
Sepehri, Alireza, E-mail: alireza.sepehri@uk.ac.ir [Faculty of Physics, Shahid Bahonar University, P.O. Box 76175, Kerman (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of)
2016-07-01
Recently, some authors (Cruz and Rojas, 2013 [1]) have constructed a Born–Infeld type action which may be written in terms of the Lovelock brane Lagrangians for a given dimension p. We reconsider their model in M-theory and study the process of birth and growth of nonlinear spinor and bosonic gravity during the construction of Mp-branes. Then, by application of this idea to BIonic system, we construct a BIonic superconductor in the background of nonlinear gravity. In this model, first, M0-branes link to each other and build an M5-brane and an anti-M5-brane connected by an M2-brane. M0-branes are zero dimensional objects that only scalars are attached to them. By constructing higher dimensional branes from M0-branes, gauge fields are produced. Also, if M0-branes don't link to each other completely, the symmetry of system is broken and fermions are created. The curvature produced by fermions has the opposite sign the curvature produced by gauge fields. Fermions on M5-branes and M2 plays the role of bridge between them. By passing time, M2 dissolves in M5's and nonlinear bosonic and spinor gravities are produced. By closing M5-branes towards each other, coupling of two identical fermions on two branes to each other causes that the square mass of their system becomes negative and some tachyonic states are created. For removing these tachyons, M5-branes compact, the sign of gravity between branes reverses, anti-gravity is produced which causes that branes and identical fermions get away from each other. This is the reason for the emergence of Pauli exclusion principle in Bionic system. Also, the spinor gravity vanishes and its energy builds a new M2 between M5-branes. We obtain the resistivity in this system and find that its value decreases by closing M5 branes to each other and shrinks to zero at colliding point of branes. This idea has different applications. For example, in cosmology, universes are located on M5-branes and M2-brane has the role of bridge
International Nuclear Information System (INIS)
Sepehri, Alireza
2016-01-01
Recently, some authors (Cruz and Rojas, 2013 [1]) have constructed a Born–Infeld type action which may be written in terms of the Lovelock brane Lagrangians for a given dimension p. We reconsider their model in M-theory and study the process of birth and growth of nonlinear spinor and bosonic gravity during the construction of Mp-branes. Then, by application of this idea to BIonic system, we construct a BIonic superconductor in the background of nonlinear gravity. In this model, first, M0-branes link to each other and build an M5-brane and an anti-M5-brane connected by an M2-brane. M0-branes are zero dimensional objects that only scalars are attached to them. By constructing higher dimensional branes from M0-branes, gauge fields are produced. Also, if M0-branes don't link to each other completely, the symmetry of system is broken and fermions are created. The curvature produced by fermions has the opposite sign the curvature produced by gauge fields. Fermions on M5-branes and M2 plays the role of bridge between them. By passing time, M2 dissolves in M5's and nonlinear bosonic and spinor gravities are produced. By closing M5-branes towards each other, coupling of two identical fermions on two branes to each other causes that the square mass of their system becomes negative and some tachyonic states are created. For removing these tachyons, M5-branes compact, the sign of gravity between branes reverses, anti-gravity is produced which causes that branes and identical fermions get away from each other. This is the reason for the emergence of Pauli exclusion principle in Bionic system. Also, the spinor gravity vanishes and its energy builds a new M2 between M5-branes. We obtain the resistivity in this system and find that its value decreases by closing M5 branes to each other and shrinks to zero at colliding point of branes. This idea has different applications. For example, in cosmology, universes are located on M5-branes and M2-brane has the role of bridge between
Natural four-generation mass textures in MSSM brane worlds
International Nuclear Information System (INIS)
Lebed, Richard F.; Mayes, Van E.
2011-01-01
A fourth generation of standard model fermions is usually considered unlikely due to constraints from direct searches, electroweak precision measurements, and perturbative unitarity. We show that fermion mass textures consistent with all constraints may be obtained naturally in a model with four generations constructed from intersecting D6-branes on a T 6 /(Z 2 xZ 2 ) orientifold. The Yukawa matrices of the model are rank 2, so that only the third- and fourth-generation fermions obtain masses at the trilinear level. The first two generations obtain masses via higher-order couplings and are therefore naturally lighter. In addition, we find that the third and fourth generations automatically split in mass, but do not mix at leading order. Furthermore, the standard model gauge couplings automatically unify at the string scale, and all the hidden-sector gauge groups become confining in the range 10 13 -10 16 GeV, so that the model becomes effectively a four-generation minimal supersymmetric standard model at low energies.
Gravitational wave constraints on multi-brane inflation
International Nuclear Information System (INIS)
Huston, Ian; Lidsey, James E; Thomas, Steven; Ward, John
2008-01-01
A class of non-canonical inflationary models is identified, where the leading-order contribution to the non-Gaussianity of the curvature perturbation is determined by the sound speed of the fluctuations in the inflaton field. Included in this class of models is the effective action for multiple coincident branes in the finite n limit. The action for this configuration is determined using a powerful iterative technique, based upon the fundamental representation of SU(2). In principle the upper bounds on the tensor–scalar ratio that arise in the standard, single-brane DBI inflationary scenario can be relaxed in such multi-brane configurations if a large and detectable non-Gaussianity is generated. Moreover models with a small number of coincident branes could generate a gravitational wave background that will be observable in future experiments
Gravitational wave constraints on multi-brane inflation
Energy Technology Data Exchange (ETDEWEB)
Huston, Ian; Lidsey, James E [Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Thomas, Steven [Centre for Research in String Theory, Department of Physics, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Ward, John, E-mail: I.Huston@qmul.ac.uk, E-mail: J.E.Lidsey@qmul.ac.uk, E-mail: S.Thomas@qmul.ac.uk, E-mail: jwa@uvic.ca [Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1 (Canada)
2008-05-15
A class of non-canonical inflationary models is identified, where the leading-order contribution to the non-Gaussianity of the curvature perturbation is determined by the sound speed of the fluctuations in the inflaton field. Included in this class of models is the effective action for multiple coincident branes in the finite n limit. The action for this configuration is determined using a powerful iterative technique, based upon the fundamental representation of SU(2). In principle the upper bounds on the tensor-scalar ratio that arise in the standard, single-brane DBI inflationary scenario can be relaxed in such multi-brane configurations if a large and detectable non-Gaussianity is generated. Moreover models with a small number of coincident branes could generate a gravitational wave background that will be observable in future experiments.
Can codimension-two branes solve the cosmological constant problem?
International Nuclear Information System (INIS)
Vinet, Jeremie; Cline, James M.
2004-01-01
It has been suggested that codimension-two braneworlds might naturally explain the vanishing of the 4D effective cosmological constant, due to the automatic relation between the deficit angle and the brane tension. To investigate whether this cancellation happens dynamically, and within the context of a realistic cosmology, we study a codimension-two braneworld with spherical extra dimensions compactified by magnetic flux. Assuming Einstein gravity, we show that when the brane contains matter with an arbitrary equation of state, the 4D metric components are not regular at the brane, unless the brane has nonzero thickness. We construct explicit 6D solutions with thick branes, treating the brane matter as a perturbation, and find that the universe expands consistently with standard Friedmann-Robertson-Walker (FRW) cosmology. The relation between the brane tension and the bulk deficit angle becomes Δ=2πG 6 (ρ-3p) for a general equation of state. However, this relation does not imply a self-tuning of the effective 4D cosmological constant to zero; perturbations of the brane tension in a static solution lead to deSitter or anti-deSitter braneworlds. Our results thus confirm other recent work showing that codimension-two braneworlds in nonsupersymmetric Einstein gravity do not lead to a dynamical relaxation of the cosmological constant, but they leave open the possibility that supersymmetric versions can be compatible with self-tuning
Classical solutions of the p-branes
International Nuclear Information System (INIS)
Stoyanov, D.T.
1988-11-01
An appropriate subsidiary condition is introduced in the classical actions of the p-branes (p arbitrary). A general class of exact solutions of the resulting nonlinear equations of motion are obtained which yield a broad class of characteristics for the original covariant equations of the p-branes. (author). 11 refs
Defects and permutation branes in the Liouville field theory
DEFF Research Database (Denmark)
Sarkissian, Gor
2009-01-01
The defects and permutation branes for the Liouville field theory are considered. By exploiting cluster condition, equations satisfied by permutation branes and defects reflection amplitudes are obtained. It is shown that two types of solutions exist, discrete and continuous families.......The defects and permutation branes for the Liouville field theory are considered. By exploiting cluster condition, equations satisfied by permutation branes and defects reflection amplitudes are obtained. It is shown that two types of solutions exist, discrete and continuous families....
Delocalization of brane gravity by a bulk black hole
International Nuclear Information System (INIS)
Seahra, Sanjeev S; Clarkson, Chris; Maartens, Roy
2005-01-01
We investigate the analogue of the Randall-Sundrum braneworld in the case when the bulk contains a black hole. Instead of the static vacuum Minkowski brane of the RS model, we have an Einstein static vacuum brane. We find that the presence of the bulk black hole has a dramatic effect on the gravity that is felt by brane observers. In the RS model, the 5D graviton has a stable localized zero mode that reproduces 4D gravity on the brane at low energies. With a bulk black hole, there is no such solution-gravity is delocalized by the 5D horizon. However, the brane does support a discrete spectrum of metastable massive bound states, or quasinormal modes, as was recently shown to be the case in the RS scenario. These states should dominate the high frequency component of the bulk gravity wave spectrum on a cosmological brane. We expect our results to generalize to any bulk spacetime containing a Killing horizon. (letter to the editor)
D-brane physics. From weak to strong coupling
Energy Technology Data Exchange (ETDEWEB)
Vieira Lopes, Daniel Ordine
2013-01-10
In this thesis we discuss two aspects of branes relevant to high-energy phenomenology. First, we consider a single D6-brane wrapping a special Lagrangian cycle and the background space compactified in a Calabi-Yau orientifold the conditions needed to obtain a four-dimensional N=1 supersymmetric theory. We calculate the bosonic part of the effective action by performing a Kaluza-Klein reduction of the brane seven-dimensional action, and obtain the N=1 characteristic data. To discuss the moduli, we first fix the moduli from deformations of the background Calabi-Yau and study the D-brane deformation moduli space. We next allow for Calabi-Yau deformations, and show that the moduli space for complex structure deformations is corrected by the fields living on the D6-brane. We also calculate the scalar potential from D- and F-terms generated from brane and background configurations that would break the supersymmetry condition. We then, via Mirror Symmetry, relate the spectrum obtained in our work to the spectrum in Type IIB effective theory with D3- D5- and D7-branes, and we propose a Kaehler potential for the moduli space of brane deformations in Type IIB theories. In the second part of the thesis we discuss effects of brane intersections when the string coupling can become strong, and we work in the framework of F-theory. After reviewing the basics of F-theory constructions and a particular SU(5) model already discussed in the literature, we construct a model which contains a point of E{sub 8} singularity, and curves of E{sub 6} singularity. By explicitly resolving the space, we show that the resolution requires the introduction of higher dimensional fibers, and argue how we can circumvent this problem for the E{sub 6} curve, leading to the expected resolution that generate an E{sub 6} group, while at the E{sub 8} point we cannot make the resolution lead to an expected E{sub 8} structure.
Quantum billiards in multidimensional models with branes
Energy Technology Data Exchange (ETDEWEB)
Ivashchuk, V.D.; Melnikov, V.N. [VNIIMS, Center for Gravitation and Fundamental Metrology, Moscow (Russian Federation); Peoples' Friendship University of Russia, Institute of Gravitation and Cosmology, Moscow (Russian Federation)
2014-03-15
gravitational D-dimensional model with l scalar fields and several forms is considered. When a cosmological-type diagonal metric is chosen, an electromagnetic composite brane ansatz is adopted and certain restrictions on the branes are imposed; the conformally covariant Wheeler-DeWitt (WDW) equation for the model is studied. Under certain restrictions asymptotic solutions to WDW equation are found in the limit of the formation of the billiard walls which reduce the problem to the so-called quantum billiard on the (D+l-2)-dimensional Lobachevsky space. Two examples of quantum billiards are considered. The first one deals with 9-dimensional quantum billiard for D = 11 model with 330 four-forms which mimic space-like M2- and M5-branes of D = 11 supergravity. The second one deals with the 9-dimensional quantum billiard for D = 10 gravitational model with one scalar field, 210 four-forms and 120 three-forms which mimic space-like D2-, D4-, FS1- and NS5-branes in D = 10 IIA supergravity. It is shown that in both examples wave functions vanish in the limit of the formation of the billiard walls (i.e. we get a quantum resolution of the singularity for 11D model) but magnetic branes could not be neglected in calculations of quantum asymptotic solutions while they are irrelevant for classical oscillating behavior when all 120 electric branes are present. (orig.)
Five-dimensional Nernst branes from special geometry
Energy Technology Data Exchange (ETDEWEB)
Dempster, P.; Errington, D. [Department of Mathematical Sciences, University of LiverpoolPeach Street, Liverpool L69 7ZL (United Kingdom); Gutowski, J. [Department of Mathematics, University of Surrey,Guildford, GU2 7XH (United Kingdom); Mohaupt, T. [Department of Mathematical Sciences, University of LiverpoolPeach Street, Liverpool L69 7ZL (United Kingdom)
2016-11-21
We construct Nernst brane solutions, that is black branes with zero entropy density in the extremal limit, of FI-gauged minimal five-dimensional supergravity coupled to an arbitrary number of vector multiplets. While the scalars take specific constant values and dynamically determine the value of the cosmological constant in terms of the FI-parameters, the metric takes the form of a boosted AdS Schwarzschild black brane. This metric can be brought to the Carter-Novotný-Horský form that has previously been observed to occur in certain limits of boosted D3-branes. By dimensional reduction to four dimensions we recover the four-dimensional Nernst branes of arXiv:1501.07863 and show how the five-dimensional lift resolves all their UV singularities. The dynamics of the compactification circle, which expands both in the UV and in the IR, plays a crucial role. At asymptotic infinity, the curvature singularity of the four-dimensional metric and the run-away behaviour of the four-dimensional scalar combine in such a way that the lifted solution becomes asymptotic to AdS{sub 5}. Moreover, the existence of a finite chemical potential in four dimensions is related to fact that the compactification circle has a finite minimal value. While it is not clear immediately how to embed our solutions into string theory, we argue that the same type of dictionary as proposed for boosted D3-branes should apply, although with a lower amount of supersymmetry.
Born–Infeld extension of Lovelock brane gravity
International Nuclear Information System (INIS)
Cruz, Miguel; Rojas, Efraín
2013-01-01
We present a Born–Infeld-type theory to describe the evolution of p-branes propagating in an N = (p + 2)-dimensional Minkowski spacetime. The expansion of the BI-type volume element gives rise to the (p + 1) Lovelock brane invariants associated with the worldvolume swept out by the brane. Contrary to the Lovelock theory in gravity, the number of Lovelock brane Lagrangians differs in this case, depending on the dimension of the worldvolume as a consequence that we consider the embedding functions, instead of the metric, as the field variables. This model depends on the intrinsic and the extrinsic geometries of the worldvolume and in consequence is a second-order theory as shown in the main text. A classically equivalent action is discussed and we comment on its Weyl invariance in any dimension which naturally requires the introduction of some auxiliary fields. (paper)
Geometry and physics of branes
International Nuclear Information System (INIS)
Gal'tsov, D V
2003-01-01
The book brings together the contents of lecture courses delivered at the school 'Geometry and Physics of Branes' which took place at the Center 'Alessandro Volta' (Como, Italy) in the spring of 2001. The purpose of the school was to provide an introduction to some lines of research, related to the notion of branes in superstring theory, which are in the focus of attention both in the physical and mathematical communities. The book is structured into three parts: the first contains an elementary introduction to branes, the second is devoted to physical aspects (conformal field theory on open and unoriented surfaces and topics in string tachyon dynamics), and the last contains some more formal mathematical developments. An introduction to branes is given in a remarkably lucid contribution by A Lerda. It opens with a construction of p-brane solutions in classical IIA and IIB supergravities with particular emphasis on the 'fundamental string' solution, the NS5-brane and the D3-brane. Then, the quantum description of D-branes is discussed in terms of boundary states of the closed superstring, which is an alternative to the more common description in terms of open strings with Dirichlet boundary conditions in the transverse to the brane directions. When a constant gauge field is present in the D-brane worldvolume, the boundary states are coherent states of the string oscillators depending on the field strength tensor. The couplings of the brane to the bulk fields - the graviton, the dilaton, and the Kalb-Ramond fields - are then extracted and shown to be precisely the ones that are produced by the Dirac-Born-Infeld action governing the low-energy dynamics of the D-brane derived using the open strings formalism. It is also shown that in the classical limit, the boundary states correctly reproduce the parameters of the corresponding classical solutions. The second part of the book starts with a contribution by Y S Stanev devoted to the two-dimensional conformal field
The scales of brane nucleation processes
International Nuclear Information System (INIS)
Alwis, S.P. de
2007-01-01
The scales associated with Brown-Teitelboim-Bousso-Polchinski processes of brane nucleation, which result in changes of the flux parameters and the number of D-branes, are discussed in the context of type IIB models with all moduli stabilized. It is argued that such processes are unlikely to be described by effective field theory
Emergence and oscillation of cosmic space by joining M1-branes
Energy Technology Data Exchange (ETDEWEB)
Sepehri, Alireza [Shahid Bahonar University, Faculty of Physics, Kerman (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Rahaman, Farook [Jadavpur University, Department of Mathematics, Kolkata, West Bengal (India); Capozziello, Salvatore [Universita di Napoli Federico II, Dipartimento di Fisica ' ' E. Pancini' ' , Naples (Italy); Gran Sasso Science Institute (INFN), L' Aquila (Italy); Tomsk State Pedagogical University, Tomsk (Russian Federation); INFN Sezione di Napoli, Naples (Italy); Ali, Ahmed Farag [Benha University, Department of Physics, Faculty of Science, Benha (Egypt); Pradhan, Anirudh [G L A University, Department of Mathematics, Institute of Applied Sciences and Humanities, Mathura, Uttar Pradesh (India)
2016-05-15
Recently, it has been proposed by Padmanabhan that the difference between the number of degrees of freedom on the boundary surface and the number of degrees of freedom in a bulk region leads to the expansion of the universe. Now, a natural question arises; how could this model explain the oscillation of the universe between contraction and expansion branches? We try to address this issue in the framework of a BIonic system. In this model, M0-branes join to each other and give rise to a pair of M1-anti-M1-branes. The fields which live on these branes play the roles of massive gravitons that cause the emergence of a wormhole between them and formation of a BIon system. This wormhole dissolves into M1-branes and causes a divergence between the number of degrees of freedom on the boundary surface of M1 and the bulk leading to an expansion of M1-branes. When M1-branes become close to each other, the square energy of their system becomes negative and some tachyonic states emerge. To remove these states, M1-branes become compact, the sign of compacted gravity changes, causing anti-gravity to arise: in this case, branes get away from each other. By articulating M1-BIons, an M3-brane and an anti-M3-brane are created and connected by three wormholes forming an M3-BIon. This new system behaves like the initial system and by closing branes to each other, they become compact and, by getting away from each other, they open. Our universe is located on one of these M3-branes and, by compactifying the M3-brane, it contracts and, by opening it, it expands. (orig.)
Emergence and oscillation of cosmic space by joining M1-branes
International Nuclear Information System (INIS)
Sepehri, Alireza; Rahaman, Farook; Capozziello, Salvatore; Ali, Ahmed Farag; Pradhan, Anirudh
2016-01-01
Recently, it has been proposed by Padmanabhan that the difference between the number of degrees of freedom on the boundary surface and the number of degrees of freedom in a bulk region leads to the expansion of the universe. Now, a natural question arises; how could this model explain the oscillation of the universe between contraction and expansion branches? We try to address this issue in the framework of a BIonic system. In this model, M0-branes join to each other and give rise to a pair of M1-anti-M1-branes. The fields which live on these branes play the roles of massive gravitons that cause the emergence of a wormhole between them and formation of a BIon system. This wormhole dissolves into M1-branes and causes a divergence between the number of degrees of freedom on the boundary surface of M1 and the bulk leading to an expansion of M1-branes. When M1-branes become close to each other, the square energy of their system becomes negative and some tachyonic states emerge. To remove these states, M1-branes become compact, the sign of compacted gravity changes, causing anti-gravity to arise: in this case, branes get away from each other. By articulating M1-BIons, an M3-brane and an anti-M3-brane are created and connected by three wormholes forming an M3-BIon. This new system behaves like the initial system and by closing branes to each other, they become compact and, by getting away from each other, they open. Our universe is located on one of these M3-branes and, by compactifying the M3-brane, it contracts and, by opening it, it expands. (orig.)
Hydrodynamics and Elasticity of Charged Black Branes
DEFF Research Database (Denmark)
Gath, Jakob
We consider long-wavelength perturbations of charged black branes to first order in a uidelastic derivative expansion. At first order the perturbations decouple and we treat the hydrodynamic and elastic perturbations separately. To put the results in a broader perspective, we present the rst...... as a seed solution, we obtain a class of charged black brane geometries carrying smeared Maxwell charge in Einstein-Maxwell-dilaton theory. In the specific case of ten-dimensional space-time we furthermore use T-duality to generate bent black branes with higher-form charge, including smeared D...
Brane gases in the early Universe
International Nuclear Information System (INIS)
Alexander, S.; Brandenberger, R.; Easson, D.
2000-01-01
Over the past decade it has become clear that fundamental strings are not the only fundamental degrees of freedom in string theory. D-branes are also part of the spectrum of fundamental states. In this paper we explore some possible effects of D-branes on early Universe string cosmology, starting with two key assumptions: firstly that the initial state of the Universe corresponded to a dense, hot gas in which all degrees of freedom were in thermal equilibrium, and secondly that the topology of the background space admits one-cycles. We argue by t duality that in this context the cosmological singularities are not present. We derive the equation of state of the brane gases and apply the results to suggest that, in an expanding background, the winding modes of fundamental strings will play the most important role at late times. In particular, we argue that the string winding modes will only allow four space-time dimensions to become large. The presence of brane winding modes with p>1 may lead to a hierarchy in the sizes of the extra dimensions
Entropy of N=2 black holes and their M-brane description
International Nuclear Information System (INIS)
Behrndt, K.; Mohaupt, T.
1997-01-01
In this paper we discuss the M-brane description for an N=2 black hole. This solution is a result of the compactification of M-5-brane configurations over a Calabi-Yau threefold with arbitrary intersection numbers C ABC . In analogy with the D-brane description where one counts open string states we count here open M-2-branes which end on the M-5-brane. copyright 1997 The American Physical Society
Microstates of black holes in expanding universe from interacting branes
Energy Technology Data Exchange (ETDEWEB)
Shiba, Shotaro [Theory Center, High Energy Accelerator Research Organization (KEK),1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
2017-05-15
Thermodynamics of the near extremal black p-branes can be described by collective motions of gravitationally interacting branes. This proposal is called the p-soup model. In this paper, we check this proposal in the case of black brane system which is asymptotically Friedmann-Lemaître-Robertson-Walker universe in an infinite distance. As a result, we can show that the gravitationally interacting branes explain free energy, entropy, temperature and other physical quantities in these systems. This implies that the microstates of this kind of brane system can be also understood in the p-soup model.
Branes, superpotentials and superconformal fixed points
International Nuclear Information System (INIS)
Aharony, O.
1997-01-01
We analyze various brane configurations corresponding to field theories in three, four and five dimensions. We find brane configurations which correspond to three-dimensional N=2 and four-dimensional N=1 supersymmetric QCD theories with quartic superpotentials, in which what appear to be ''hidden parameters'' play an important role. We discuss the construction of five-dimensional N=1 supersymmetric gauge theories and superconformal fixed points using branes, which leads to new five-dimensional N=1 superconformal field theories. The same five-dimensional theories are also used, in a surprising way, to describe new superconformal fixed points of three-dimensional N=2 supersymmetric theories, which have both ''electric'' and ''magnetic'' Coulomb branches. (orig.)
Bifid Throats for Axion Monodromy Inflation
International Nuclear Information System (INIS)
Retolaza, Ander
2015-04-01
We construct a simple explicit local geometry providing a 'bifid throat' for 5-brane axion monodromy. A bifid throat is a throat that splits into two daughter throats in the IR, containing a homologous 2-cycle family reaching down into each daughter throat. Our example consists of a deformed Z 3 x Z 2 orbifold of the conifold, which provides us with an explicit holographic dual of the bifid throat including D3-branes and fractional 5-branes at the toric singularities of our setup. Having the holographic description in terms of the dual gauge theory allows us to address the effect of 5-brane-antibrane pair backreaction including the warping effects. This leads to the size of the backreaction being small and controllable after imposing proper normalization of the inflaton potential and hence the warping scales.
Non-linear realizations and bosonic branes
International Nuclear Information System (INIS)
West, P.
2001-01-01
In this very short note, following hep-th/0001216, we express the well known bosonic brane as a non-linear realization. The reader may also consult hep-th/9912226, 0001216 and 0005270 where the branes of M theory are constructed as a non-linear realisation. The automorphisms of the supersymmetry algebra play an essential role. (author)
The WARP Code: Modeling High Intensity Ion Beams
International Nuclear Information System (INIS)
Grote, D P; Friedman, A; Vay, J L; Haber, I
2004-01-01
The Warp code, developed for heavy-ion driven inertial fusion energy studies, is used to model high intensity ion (and electron) beams. Significant capability has been incorporated in Warp, allowing nearly all sections of an accelerator to be modeled, beginning with the source. Warp has as its core an explicit, three-dimensional, particle-in-cell model. Alongside this is a rich set of tools for describing the applied fields of the accelerator lattice, and embedded conducting surfaces (which are captured at sub-grid resolution). Also incorporated are models with reduced dimensionality: an axisymmetric model and a transverse ''slice'' model. The code takes advantage of modern programming techniques, including object orientation, parallelism, and scripting (via Python). It is at the forefront in the use of the computational technique of adaptive mesh refinement, which has been particularly successful in the area of diode and injector modeling, both steady-state and time-dependent. In the presentation, some of the major aspects of Warp will be overviewed, especially those that could be useful in modeling ECR sources. Warp has been benchmarked against both theory and experiment. Recent results will be presented showing good agreement of Warp with experimental results from the STS500 injector test stand. Additional information can be found on the web page http://hif.lbl.gov/theory/WARP( ) summary.html
The dual formulation of M5-brane action
Energy Technology Data Exchange (ETDEWEB)
Ko, Sheng-Lan; Vanichchapongjaroen, Pichet [The Institute for Fundamental Study “The Tah Poe Academia Institute' ,Naresuan University, Phitsanulok 65000 (Thailand)
2016-06-06
We construct a dual formulation, with respect to the conventional PST formalism, of the M5-brane action propagating in a generic 11d supergravity background. Constraint analysis is performed to further justify that our theory has the correct number of degrees of freedom. Comparison of this action with the existing M5-brane actions is carried out. We also show that a conventional D4-brane action is obtained upon double dimensional reduction.
Discrete Torsion, (Anti) de Sitter D4-Brane and Tunneling
Singh, Abhishek K.; Pandey, P. K.; Singh, Sunita; Kar, Supriya
2014-06-01
We obtain quantum geometries on a vacuum created pair of a (DDbar)3-brane, at a Big Bang singularity, by a local two form on a D4-brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an effective non-perturbative curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the effective curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of (DDbar)-instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D4-brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole.
Discrete Torsion, (Anti) de Sitter D4-Brane and Tunneling
International Nuclear Information System (INIS)
Singh, Abhishek K.; Pandey, P.K.; Singh, Sunita; Kar, Supriya
2014-01-01
We obtain quantum geometries on a vacuum created pair of a (DD ¯ ) 3 -brane, at a Big Bang singularity, by a local two form on a D 4 -brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an effective non-perturbative curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the effective curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of (DD ¯ )-instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D 4 -brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole
Finite temperature corrections to tachyon mass in intersecting D-branes
International Nuclear Information System (INIS)
Sethi, Varun; Chowdhury, Sudipto Paul; Sarkar, Swarnendu
2017-01-01
We continue with the analysis of finite temperature corrections to the Tachyon mass in intersecting branes which was initiated in https://www.doi.org/10.1007/JHEP09(2014)063. In this paper we extend the computation to the case of intersecting D3 branes by considering a setup of two intersecting branes in flat-space background. A holographic model dual to BCS superconductor consisting of intersecting D8 branes in D4 brane background was proposed in https://www.doi.org/10.1016/j.nuclphysb.2011.07.011. The background considered here is a simplified configuration of this dual model. We compute the one-loop Tachyon amplitude in the Yang-Mills approximation and show that the result is finite. Analyzing the amplitudes further we numerically compute the transition temperature at which the Tachyon becomes massless. The analytic expressions for the one-loop amplitudes obtained here reduce to those for intersecting D1 branes obtained in https://www.doi.org/10.1007/JHEP09(2014)063 as well as those for intersecting D2 branes.
Finite temperature corrections to tachyon mass in intersecting D-branes
Energy Technology Data Exchange (ETDEWEB)
Sethi, Varun [Department of Physics and Astrophysics, University of Delhi,Delhi 110007 (India); Chowdhury, Sudipto Paul [Institute of Physics, Sachivalaya Marg,Bhubaneswar 751005 (India); Sarkar, Swarnendu [Department of Physics and Astrophysics, University of Delhi,Delhi 110007 (India)
2017-04-19
We continue with the analysis of finite temperature corrections to the Tachyon mass in intersecting branes which was initiated in https://www.doi.org/10.1007/JHEP09(2014)063. In this paper we extend the computation to the case of intersecting D3 branes by considering a setup of two intersecting branes in flat-space background. A holographic model dual to BCS superconductor consisting of intersecting D8 branes in D4 brane background was proposed in https://www.doi.org/10.1016/j.nuclphysb.2011.07.011. The background considered here is a simplified configuration of this dual model. We compute the one-loop Tachyon amplitude in the Yang-Mills approximation and show that the result is finite. Analyzing the amplitudes further we numerically compute the transition temperature at which the Tachyon becomes massless. The analytic expressions for the one-loop amplitudes obtained here reduce to those for intersecting D1 branes obtained in https://www.doi.org/10.1007/JHEP09(2014)063 as well as those for intersecting D2 branes.
Poisson-Lie T-duality open strings and D-branes
Klimcik, C.
1996-01-01
Global issues of the Poisson-Lie T-duality are addressed. It is shown that oriented open strings propagating on a group manifold G are dual to D-brane - anti-D-brane pairs propagating on the dual group manifold \\ti G. The D-branes coincide with the symplectic leaves of the standard Poisson structure induced on the dual group \\ti G by the dressing action of the group G. T-duality maps the momentum of the open string into the mutual distance of the D-branes in the pair. The whole picture is then extended to the full modular space M(D) of the Poisson-Lie equivalent \\si-models which is the space of all Manin triples of a given Drinfeld double.T-duality rotates the zero modes of pairs of D-branes living on targets belonging to M(D). In this more general case the D-branes are preimages of symplectic leaves in certain Poisson homogeneous spaces of their targets and, as such, they are either all even or all odd dimensional.
Kastor, David; Ray, Sourya; Traschen, Jennie
2017-10-01
We study the problem of finding brane-like solutions to Lovelock gravity, adopting a general approach to establish conditions that a lower dimensional base metric must satisfy in order that a solution to a given Lovelock theory can be constructed in one higher dimension. We find that for Lovelock theories with generic values of the coupling constants, the Lovelock tensors (higher curvature generalizations of the Einstein tensor) of the base metric must all be proportional to the metric. Hence, allowed base metrics form a subclass of Einstein metrics. This subclass includes so-called ‘universal metrics’, which have been previously investigated as solutions to quantum-corrected field equations. For specially tuned values of the Lovelock couplings, we find that the Lovelock tensors of the base metric need to satisfy fewer constraints. For example, for Lovelock theories with a unique vacuum there is only a single such constraint, a case previously identified in the literature, and brane solutions can be straightforwardly constructed.
International Nuclear Information System (INIS)
Kastor, David; Traschen, Jennie; Ray, Sourya
2017-01-01
We study the problem of finding brane-like solutions to Lovelock gravity, adopting a general approach to establish conditions that a lower dimensional base metric must satisfy in order that a solution to a given Lovelock theory can be constructed in one higher dimension. We find that for Lovelock theories with generic values of the coupling constants, the Lovelock tensors (higher curvature generalizations of the Einstein tensor) of the base metric must all be proportional to the metric. Hence, allowed base metrics form a subclass of Einstein metrics. This subclass includes so-called ‘universal metrics’, which have been previously investigated as solutions to quantum-corrected field equations. For specially tuned values of the Lovelock couplings, we find that the Lovelock tensors of the base metric need to satisfy fewer constraints. For example, for Lovelock theories with a unique vacuum there is only a single such constraint, a case previously identified in the literature, and brane solutions can be straightforwardly constructed. (paper)
Universality in all-{alpha}{sup Prime} order corrections to BPS/non-BPS brane world volume theories
Energy Technology Data Exchange (ETDEWEB)
Hatefi, Ehsan, E-mail: ehatefi@ictp.it [International Centre for Theoretical Physics, Strada Costiera 11, Trieste (Italy); Park, I.Y., E-mail: inyongpark05@gmail.com [Department of Natural and Physical Sciences, Philander Smith College, Little Rock, AR 72223 (United States)
2012-11-21
Knowledge of all-{alpha}{sup Prime} higher derivative corrections to leading order BPS and non-BPS brane actions would serve in future endeavor of determining the complete form of the non-abelian BPS and tachyonic effective actions. In this paper, we note that there is a universality in the all-{alpha}{sup Prime} order corrections to BPS and non-BPS branes. We compute amplitudes between one Ramond-Ramond C-field vertex operator and several SYM gauge/scalar vertex operators. Specifically, we evaluate in closed form string correlators of two-point amplitudes A{sup C{phi}}, A{sup CA}, a three-point amplitude A{sup C{phi}{phi}}, and a four-point amplitude A{sup C{phi}{phi}{phi}}. We carry out pole and contact term analysis. In particular we reproduce some of the contact terms and the infinite massless poles of A{sup C{phi}{phi}{phi}} by SYM vertices obtained through the universality.
Conformal boundaries of warped products
DEFF Research Database (Denmark)
Kokkendorff, Simon Lyngby
2006-01-01
In this note we prove a result on how to determine the conformal boundary of a type of warped product of two length spaces in terms of the individual conformal boundaries. In the situation, that we treat, the warping and conformal distortion functions are functions of distance to a base point....... The result is applied to produce examples of CAT(0)-spaces, where the conformal and ideal boundaries differ in interesting ways....
Strong coupling in F-theory and geometrically non-Higgsable seven-branes
Directory of Open Access Journals (Sweden)
James Halverson
2017-06-01
Full Text Available Geometrically non-Higgsable seven-branes carry gauge sectors that cannot be broken by complex structure deformation, and there is growing evidence that such configurations are typical in F-theory. We study strongly coupled physics associated with these branes. Axiodilaton profiles are computed using Ramanujan's theories of elliptic functions to alternative bases, showing explicitly that the string coupling is O(1 in the vicinity of the brane; that it sources nilpotent SL(2,Z monodromy and therefore the associated brane charges are modular; and that essentially all F-theory compactifications have regions with order one string coupling. It is shown that non-perturbative SU(3 and SU(2 seven-branes are related to weakly coupled counterparts with D7-branes via deformation-induced Hanany–Witten moves on (p,q string junctions that turn them into fundamental open strings; only the former may exist for generic complex structure. D3-brane near these and the Kodaira type II seven-branes probe Argyres–Douglas theories. The BPS states of slightly deformed theories are shown to be dyonic string junctions.
Scalar field localization on a brane with cosmological constant
International Nuclear Information System (INIS)
Ghoroku, Kazuo; Yahiro, Masanobu
2003-01-01
We investigate the localization of a massive scalar for both dS and AdS branes, where the scalar mass is varied from the massive-particle region to the tachyon region. We find that the eigenmass m of the localized mode satisfies a simple relation m 2 = cM 2 with a positive constant c for the dS brane, and m 2 = c 1 M 2 + c 2 with positive constants c 1 and c 2 for the AdS brane. We discuss the relation of these results to the stability of the brane and also some cosmological problems
Non-Lagrangian theories from brane junctions
Energy Technology Data Exchange (ETDEWEB)
Bao, Ling [Chalmers Univ. of Technology, Goeteborg (Sweden); Mitev, Vladimir [Humboldt Univ., Berlin (Germany). Inst. fuer Mathematik und Inst. fuer Physik; Pomoni, Elli [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany). Theory Group; Taki, Masato [RIKEN Nishina Center, Saitama (Japan). Mathematical Physics Lab.; Yagi, Futoshi [International School of Advanced Studies (SISSA), Trieste (Italy); INFN, Trieste (Italy); Korea Institute for Advanced Study (KIAS), Seoul (Korea, Republic of)
2013-10-15
In this article we use 5-brane junctions to study the 5D T{sub N} SCFTs corresponding to the 5D N=1 uplift of the 4D N=2 strongly coupled gauge theories, which are obtained by compactifying N M5 branes on a sphere with three full punctures. Even though these theories have no Lagrangian description, by using the 5-brane junctions proposed by Benini, Benvenuti and Tachikawa, we are able to derive their Seiberg-Witten curves and Nekrasov partition functions. We cross-check our results with the 5D superconformal index proposed by Kim, Kim and Lee. Through the AGTW correspondence, we discuss the relations between 5D superconformal indices and n-point functions of the q-deformed W{sub N} Toda theories.
Non-Lagrangian theories from brane junctions
International Nuclear Information System (INIS)
Bao, Ling; Mitev, Vladimir
2013-10-01
In this article we use 5-brane junctions to study the 5D T N SCFTs corresponding to the 5D N=1 uplift of the 4D N=2 strongly coupled gauge theories, which are obtained by compactifying N M5 branes on a sphere with three full punctures. Even though these theories have no Lagrangian description, by using the 5-brane junctions proposed by Benini, Benvenuti and Tachikawa, we are able to derive their Seiberg-Witten curves and Nekrasov partition functions. We cross-check our results with the 5D superconformal index proposed by Kim, Kim and Lee. Through the AGTW correspondence, we discuss the relations between 5D superconformal indices and n-point functions of the q-deformed W N Toda theories.
Emergence and expansion of cosmic space as due to M0-branes
Energy Technology Data Exchange (ETDEWEB)
Sepehri, Alireza, E-mail: alireza.sepehri@uk.ac.ir [Faculty of Physics, Shahid Bahonar University, P.O. Box 76175, Kerman (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of); Setare, Mohammad Reza, E-mail: rezakord@ipm.ir [Department of Science, University of Kurdistan, Campus of Bijar, Bijar (Iran, Islamic Republic of); Capozziello, Salvatore, E-mail: capozziello@na.infn.it [Dipartimento di Fisica, Universita di Napoli Federico II, 80126, Naples (Italy); INFN Sez. di Napoli, Compl. Univ. di Monte S. Angelo, Edificio G, 80126, Naples (Italy); Gran Sasso Science Institute (INFN), Viale F. Crispi, 7, 67100, L’Aquila (Italy)
2015-12-29
Recently, Padmanabhan discussed that the difference between the number of degrees of freedom on the boundary surface and the number of degrees of freedom in a bulk region causes the accelerated expansion of the universe. The main question arising is: what is the origin of this inequality between the surface degrees of freedom and the bulk degrees of freedom? We answer this question in M-theory. In our model, first M0-branes are compactified on one circle and ND0-branes are created. Then ND0-branes join each other, grow, and form one D5-branes. Next, the D5-brane is compactified on two circles and our universe’s D3-brane, two D1-branes and some extra energies are produced. After that, one of the D1-branes, which is closer to the universe’s brane, gives its energy into it, and this leads to an increase in the difference between the numbers of degrees of freedom and the occurring inflation era. With the disappearance of this D1-brane, the number of degrees of freedom of boundary surface and bulk region become equal and inflation ends. At this stage, extra energies that are produced due to the compactification cause an expansion of the universe and deceleration epoch. Finally, another D1-brane dissolves in our universe’s brane, leads to an inequality between degrees of freedom, and there occurs a new phase of acceleration.
Emergence and expansion of cosmic space as due to M0-branes
International Nuclear Information System (INIS)
Sepehri, Alireza; Setare, Mohammad Reza; Capozziello, Salvatore
2015-01-01
Recently, Padmanabhan discussed that the difference between the number of degrees of freedom on the boundary surface and the number of degrees of freedom in a bulk region causes the accelerated expansion of the universe. The main question arising is: what is the origin of this inequality between the surface degrees of freedom and the bulk degrees of freedom? We answer this question in M-theory. In our model, first M0-branes are compactified on one circle and ND0-branes are created. Then ND0-branes join each other, grow, and form one D5-branes. Next, the D5-brane is compactified on two circles and our universe’s D3-brane, two D1-branes and some extra energies are produced. After that, one of the D1-branes, which is closer to the universe’s brane, gives its energy into it, and this leads to an increase in the difference between the numbers of degrees of freedom and the occurring inflation era. With the disappearance of this D1-brane, the number of degrees of freedom of boundary surface and bulk region become equal and inflation ends. At this stage, extra energies that are produced due to the compactification cause an expansion of the universe and deceleration epoch. Finally, another D1-brane dissolves in our universe’s brane, leads to an inequality between degrees of freedom, and there occurs a new phase of acceleration
Moshe RozaliDepartment of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Darren Smyth(Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada)
2014-01-01
We discuss finite density configurations on probe D-branes, in the presence of worldvolume fermions. To this end we consider a phenomenological model whose bosonic sector is governed by the DBI action, and whose charged sector is purely fermionic. In this model, we demonstrate the existence of a compact worldvolume embedding, stabilized by a Fermi surface on the D- brane. The finite density state in the boundary QFT is a Fermi-like liquid. We comment on the possibility of realizing non-Fermi ...
Method for adjusting warp measurements to a different board dimension
William T. Simpson; John R. Shelly
2000-01-01
Warp in lumber is a common problem that occurs while lumber is being dried. In research or other testing programs, it is sometimes necessary to compare warp of different species or warp caused by different process variables. If lumber dimensions are not the same, then direct comparisons are not possible, and adjusting warp to a common dimension would be desirable so...
Conformal Vector Fields on Doubly Warped Product Manifolds and Applications
Directory of Open Access Journals (Sweden)
H. K. El-Sayied
2016-01-01
Full Text Available This article aimed to study and explore conformal vector fields on doubly warped product manifolds as well as on doubly warped spacetime. Then we derive sufficient conditions for matter and Ricci collineations on doubly warped product manifolds. A special attention is paid to concurrent vector fields. Finally, Ricci solitons on doubly warped product spacetime admitting conformal vector fields are considered.
DigiWarp: a method for deformable mouse atlas warping to surface topographic data
International Nuclear Information System (INIS)
Joshi, Anand A; Shattuck, David W; Toga, Arthur W; Chaudhari, Abhijit J; Li Changqing; Cherry, Simon R; Dutta, Joyita; Leahy, Richard M
2010-01-01
For pre-clinical bioluminescence or fluorescence optical tomography, the animal's surface topography and internal anatomy need to be estimated for improving the quantitative accuracy of reconstructed images. The animal's surface profile can be measured by all-optical systems, but estimation of the internal anatomy using optical techniques is non-trivial. A 3D anatomical mouse atlas may be warped to the estimated surface. However, fitting an atlas to surface topography data is challenging because of variations in the posture and morphology of imaged mice. In addition, acquisition of partial data (for example, from limited views or with limited sampling) can make the warping problem ill-conditioned. Here, we present a method for fitting a deformable mouse atlas to surface topographic range data acquired by an optical system. As an initialization procedure, we match the posture of the atlas to the posture of the mouse being imaged using landmark constraints. The asymmetric L 2 pseudo-distance between the atlas surface and the mouse surface is then minimized in order to register two data sets. A Laplacian prior is used to ensure smoothness of the surface warping field. Once the atlas surface is normalized to match the range data, the internal anatomy is transformed using elastic energy minimization. We present results from performance evaluation studies of our method where we have measured the volumetric overlap between the internal organs delineated directly from MRI or CT and those estimated by our proposed warping scheme. Computed Dice coefficients indicate excellent overlap in the brain and the heart, with fair agreement in the kidneys and the bladder.
Matching conditions for a brane of arbitrary codimension
International Nuclear Information System (INIS)
Charmousis, Christos; Zegers, Robin
2005-01-01
We present matching conditions for distributional sources of arbitrary codimension in the context of Lovelock gravity. Then we give examples, treating maximally symmetric distributional p-branes, embedded in flat, de Sitter and anti-de Sitter spacetime. Unlike Einstein theory, distributional defects of locally smooth geometry and codimension greater than 2 are demonstrated to exist in Lovelock theories. The form of the matching conditions depends on the parity of the brane codimension. For odd codimension, the matching conditions involve discontinuities of Chern-Simons forms and are thus similar to junction conditions for hypersurfaces. For even codimension, the bulk Lovelock densities induce intrinsic Lovelock densities on the brane. In particular, this results in the appearance of the induced Einstein tensor for p>2. For the matching conditions we present, the effect of the bulk is reduced to an overall topological solid angle defect which sets the Planck scale on the brane and to extrinsic curvature terms. Moreover, for topological matching conditions and solid deficit angle, we find that the equations of motion are obtained from an exact p+1 dimensional action, which reduces to an induced Lovelock theory for large codimension. In essence, this signifies that the distributional part of the Lovelock bulk equations can naturally give rise to induced gravity terms on a brane of even co-dimension. We relate our findings to recent results on codimension 2 branes
D-branes in N=2 Liouville theory and its mirror
International Nuclear Information System (INIS)
Israel, Dan; Pakman, Ari; Troost, Jan
2005-01-01
We study D-branes in the mirror pair N=2 Liouville/supersymmetric SL(2,R)/U(1) coset superconformal field theories. We build D0-, D1- and D2-branes, on the basis of the boundary state construction for the H 3 + conformal field theory. We also construct D0-branes in an orbifold that rotates the angular direction of the cigar. We show how the poles of correlators associated to localized states and bulk interactions naturally decouple in the one-point functions of localized and extended branes. We stress the role played in the analysis of D-brane spectra by primaries in SL(2,R)/U(1) which are descendents of the parent theory
Dynamics of warped flux compactifications
International Nuclear Information System (INIS)
Shiu, Gary; Underwood, Bret; Torroba, Gonzalo; Douglas, Michael R.
2008-01-01
We discuss the four dimensional effective action for type IIB flux compactifications, and obtain the quadratic terms taking warp effects into account. The analysis includes both the 4-d zero modes and their KK excitations, which become light at large warping. We identify an 'axial' type gauge for the supergravity fluctuations, which makes the four dimensional degrees of freedom manifest. The other key ingredient is the existence of constraints coming from the ten dimensional equations of motion. Applying these conditions leads to considerable simplifications, enabling us to obtain the low energy lagrangian explicitly. In particular, the warped Kaehler potential for metric moduli is computed and it is shown that there are no mixings with the KK fluctuations and the result differs from previous proposals. The four dimensional potential contains a generalization of the Gukov-Vafa-Witten term, plus usual mass terms for KK modes.
D-branes in a big bang/big crunch universe: Misner space
International Nuclear Information System (INIS)
Hikida, Yasuaki; Nayak, Rashmi R.; Panigrahi, Kamal L.
2005-01-01
We study D-branes in a two-dimensional lorentzian orbifold R 1,1 /Γ with a discrete boost Γ. This space is known as Misner or Milne space, and includes big crunch/big bang singularity. In this space, there are D0-branes in spiral orbits and D1-branes with or without flux on them. In particular, we observe imaginary parts of partition functions, and interpret them as the rates of open string pair creation for D0-branes and emission of winding closed strings for D1-branes. These phenomena occur due to the time-dependence of the background. Open string 2→2 scattering amplitude on a D1-brane is also computed and found to be less singular than closed string case
D-branes in a big bang/big crunch universe: Misner space
Energy Technology Data Exchange (ETDEWEB)
Hikida, Yasuaki [Theory Group, High Energy Accelerator Research Organization (KEK), Tukuba, Ibaraki 305-0801 (Japan); Nayak, Rashmi R. [Dipartimento di Fisica and INFN, Sezione di Roma 2, ' Tor Vergata' , Rome 00133 (Italy); Panigrahi, Kamal L. [Dipartimento di Fisica and INFN, Sezione di Roma 2, ' Tor Vergata' , Rome 00133 (Italy)
2005-09-01
We study D-branes in a two-dimensional lorentzian orbifold R{sup 1,1}/{gamma} with a discrete boost {gamma}. This space is known as Misner or Milne space, and includes big crunch/big bang singularity. In this space, there are D0-branes in spiral orbits and D1-branes with or without flux on them. In particular, we observe imaginary parts of partition functions, and interpret them as the rates of open string pair creation for D0-branes and emission of winding closed strings for D1-branes. These phenomena occur due to the time-dependence of the background. Open string 2{yields}2 scattering amplitude on a D1-brane is also computed and found to be less singular than closed string case.
Emergence and expansion of cosmic space as due to M0-branes
Energy Technology Data Exchange (ETDEWEB)
Sepehri, Alireza [Shahid Bahonar University, Faculty of Physics, Kerman (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Setare, Mohammad Reza [University of Kurdistan, Department of Science, Bijar (Iran, Islamic Republic of); Capozziello, Salvatore [Universita di Napoli Federico II, Dipartimento di Fisica, Naples (Italy); Complutense Univ. di Monte S. Angelo, Naples (Italy); Gran Sasso Science Institute (INFN), L' Aquila (Italy); INFN Sezione di Napoli, Naples (Italy)
2015-12-15
Recently, Padmanabhan (arXiv:1206.4916 [hepth]) discussed that the difference between the number of degrees of freedom on the boundary surface and the number of degrees of freedom in a bulk region causes the accelerated expansion of the universe. The main question arising is: what is the origin of this inequality between the surface degrees of freedom and the bulk degrees of freedom? We answer this question in M-theory. In our model, first M0-branes are compactified on one circle and N D0-branes are created. Then N D0-branes join each other, grow, and form one D5-branes. Next, the D5-brane is compactified on two circles and our universe's D3-brane, two D1-branes and some extra energies are produced. After that, one of the D1-branes, which is closer to the universe's brane, gives its energy into it, and this leads to an increase in the difference between the numbers of degrees of freedom and the occurring inflation era. With the disappearance of this D1-brane, the number of degrees of freedom of boundary surface and bulk region become equal and inflation ends. At this stage, extra energies that are produced due to the compactification cause an expansion of the universe and deceleration epoch. Finally, another D1-brane dissolves in our universe's brane, leads to an inequality between degrees of freedom, and there occurs a new phase of acceleration. (orig.)
The WARP Code: Modeling High Intensity Ion Beams
International Nuclear Information System (INIS)
Grote, David P.; Friedman, Alex; Vay, Jean-Luc; Haber, Irving
2005-01-01
The Warp code, developed for heavy-ion driven inertial fusion energy studies, is used to model high intensity ion (and electron) beams. Significant capability has been incorporated in Warp, allowing nearly all sections of an accelerator to be modeled, beginning with the source. Warp has as its core an explicit, three-dimensional, particle-in-cell model. Alongside this is a rich set of tools for describing the applied fields of the accelerator lattice, and embedded conducting surfaces (which are captured at sub-grid resolution). Also incorporated are models with reduced dimensionality: an axisymmetric model and a transverse ''slice'' model. The code takes advantage of modern programming techniques, including object orientation, parallelism, and scripting (via Python). It is at the forefront in the use of the computational technique of adaptive mesh refinement, which has been particularly successful in the area of diode and injector modeling, both steady-state and time-dependent. In the presentation, some of the major aspects of Warp will be overviewed, especially those that could be useful in modeling ECR sources. Warp has been benchmarked against both theory and experiment. Recent results will be presented showing good agreement of Warp with experimental results from the STS500 injector test stand
Chiral vortical effect from the compactified D4-branes with smeared D0-brane charge
Energy Technology Data Exchange (ETDEWEB)
Wu, Chao; Chen, Yidian [Institute of High Energy Physics, Chinese Academy of Sciences,Beijing 100049 (China); Huang, Mei [Institute of High Energy Physics, Chinese Academy of Sciences,Beijing 100049 (China); University of Chinese Academy of Sciences,Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences,Beijing 100049 (China)
2017-03-15
By using the boundary derivative expansion formalism of fluid/gravity correspondence, we study the chiral vortical effect from the compactified D4-branes with smeared D0-brane charge. This background corresponds to a strongly coupled, nonconformal relativistic fluid with a conserved vector current. The presence of the chiral vortical effect is induced by the addition of a Chern-Simons term in the bulk action. Except that the non-dissipative anomalous viscous coefficient and the sound speed rely only on the chemical potential, most of the other thermal and hydrodynamical quantities of the first order depend both on the temperature and the chemical potential. According to our result, the way that the chiral vortical effect coefficient depends on the chemical potential seems irrelevant with whether the relativistic fluid is conformal or not. Stability analysis shows that this anomalous relativistic fluid is stable and the doping of the smeared D0-brane charge will slow down the sound speed.
Spiked instantons from intersecting D-branes
Directory of Open Access Journals (Sweden)
Nikita Nekrasov
2017-01-01
Full Text Available The moduli space of spiked instantons that arises in the context of the BPS/CFT correspondence [22] is realised as the moduli space of classical vacua, i.e. low-energy open string field configurations, of a certain stack of intersecting D1-branes and D5-branes in Type IIB string theory. The presence of a constant B-field induces an interesting dynamics involving the tachyon condensation.
Conformal symmetry for rotating D-branes
International Nuclear Information System (INIS)
Cao Liming; Matsuo, Yoshinori; Tsukioka, Takuya; Yoo, Chul-Moon
2009-01-01
We apply the Kerr/CFT correspondence to the rotating black p-brane solutions. These solutions give the simplest examples from string theory point of view. Their near horizon geometries have structures of AdS, even though black p-brane solutions do not have AdS-like structures in the non-rotating case. The microscopic entropy which can be calculated via the Cardy formula exactly agrees with Bekenstein-Hawking entropy.
Coincident brane nucleation and the neutralization of Λ
International Nuclear Information System (INIS)
Garriga, Jaume; Megevand, Ariel
2004-01-01
Nucleation of branes by a four-form field has recently been considered in string motivated scenarios for the neutralization of the cosmological constant. An interesting question in this context is whether the nucleation of stacks of coincident branes is possible, and if so, at what rate does it proceed. Feng et al. have suggested that, at high ambient de Sitter temperature, the rate may be strongly enhanced, due to large degeneracy factors associated with the number of light species living on the worldsheet. This might facilitate the quick relaxation from a large effective cosmological constant down to the observed value. Here, we analyze this possibility in some detail. In four dimensions, and after the moduli are stabilized, branes interact via repulsive long range forces. Because of that, the Coleman-de Luccia (CdL) instanton for coincident brane nucleation may not exist, unless there is some short range interaction that keeps the branes together. If the CdL instanton exists, we find that the degeneracy factor depends only mildly on the ambient de Sitter temperature, and does not switch off even in the case of tunneling from flat space. This would result in catastrophic decay of the present vacuum. If, on the contrary, the CdL instanton does not exist, coincident brane nucleation may still proceed through a 'static' instanton, representing pair creation of critical bubbles--a process somewhat analogous to thermal activation in flat space. In that case, the branes may stick together due to thermal symmetry restoration, and the pair creation rate depends exponentially on the ambient de Sitter temperature, switching off sharply as the temperature approaches zero. Such a static instanton may be well suited for the 'saltatory' relaxation scenario proposed by Feng et al
Brane solutions of gravity-dilaton-axion systems
Bergshoeff, E; Collinucci, A; Gran, U; Roest, D; Vandoren, S; Lukierski, J; Sorokin, D
2005-01-01
We consider general properties of brane solutions of gravity-dilaton-axion systems. We focus on the case of 7-branes and instantons. In both cases we show that besides the standard solutions there are new deformed solutions whose charges take value in any of the three conjugacy classes of SL(2, R).
Warping methods for spectroscopic and chromatographic signal alignment: A tutorial
Energy Technology Data Exchange (ETDEWEB)
Bloemberg, Tom G., E-mail: T.Bloemberg@science.ru.nl [Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Radboud University Nijmegen, Education Institute for Molecular Sciences, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Gerretzen, Jan; Lunshof, Anton [Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Wehrens, Ron [Centre for Research and Innovation, Fondazione Edmund Mach, Via E. Mach, 1, 38010 San Michele all’Adige, TN (Italy); Buydens, Lutgarde M.C. [Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands)
2013-06-05
Highlights: •The concepts of warping and alignment are introduced. •The most important warping methods are critically reviewed and explained. •Reference selection, evaluation and place of warping in preprocessing are discussed. •Some pitfalls, especially for LC–MS and similar data, are addressed. •Examples are provided, together with programming scripts to rework and extend them. -- Abstract: Warping methods are an important class of methods that can correct for misalignments in (a.o.) chemical measurements. Their use in preprocessing of chromatographic, spectroscopic and spectrometric data has grown rapidly over the last decade. This tutorial review aims to give a critical introduction to the most important warping methods, the place of warping in preprocessing and current views on the related matters of reference selection, optimization, and evaluation. Some pitfalls in warping, notably for liquid chromatography–mass spectrometry (LC–MS) data and similar, will be discussed. Examples will be given of the application of a number of freely available warping methods to a nuclear magnetic resonance (NMR) spectroscopic dataset and a chromatographic dataset. As part of the Supporting Information, we provide a number of programming scripts in Matlab and R, allowing the reader to work the extended examples in detail and to reproduce the figures in this paper.
Thermodynamics of spinning branes and their dual field theories
DEFF Research Database (Denmark)
Harmark, Troels; Obers, N. A.
2000-01-01
We discuss general spinning p-branes of string and M-theory and use their thermodynamics along with the correspondence between near-horizon brane solutions and field theories with 16 supercharges to describe the thermodynamic behavior of these theories in the presence of voltages under the R......-symmetry. The thermodynamics is used to provide two pieces of evidence in favor of a smooth interpolation function between the free energy at weak and strong coupling of the field theory. (i) A computation of the boundaries of stability shows that for the D2, D3, D4, M2 and M5-branes the critical values of Omega/T in the two...... limits are remarkably close and (ii) The tree-level R^4 corrections to the spinning D3-brane generate a decrease in the free energy at strong coupling towards the weak coupling result. We also comment on the generalization to spinning brane bound states and their thermodynamics, which are relevant...
D-brane propagation in two-dimensional black hole geometries
International Nuclear Information System (INIS)
Nakayama, Yu; Rey, Soo-Jong; Sugawara, Yuji
2005-01-01
We study propagation of D0-brane in two-dimensional lorentzian black hole backgrounds by the method of boundary conformal field theory of SL(2,R)/U(1) supercoset at level k. Typically, such backgrounds arise as near-horizon geometries of k coincident non-extremal NS5-branes, where 1/k measures curvature of the backgrounds in string unit and hence size of string worldsheet effects. At classical level, string worldsheet effects are suppressed and D0-brane propagation in the lorentzian black hole geometry is simply given by the Wick rotation of D1-brane contour in the euclidean black hole geometry. Taking account of string worldsheet effects, boundary state of the lorentzian D0-brane is formally constructible via Wick rotation from that of the euclidean D1-brane. However, the construction is subject to ambiguities in boundary conditions. We propose exact boundary states describing the D0-brane, and clarify physical interpretations of various boundary states constructed from different boundary conditions. As it falls into the black hole, the D0-brane radiates off to the horizon and to the infinity. From the boundary states constructed, we compute physical observables of such radiative process. We find that part of the radiation to infinity is in effective thermal distribution at the Hawking temperature. We also find that part of the radiation to horizon is in the Hagedorn distribution, dominated by massive, highly non-relativistic closed string states, much like the tachyon matter. Remarkably, such distribution emerges only after string worldsheet effects are taken exactly into account. From these results, we observe that nature of the radiation distribution changes dramatically across the conifold geometry k = 1 (k = 3 for the bosonic case), exposing the 'string - black hole transition' therein
DigiWarp: a method for deformable mouse atlas warping to surface topographic data
Energy Technology Data Exchange (ETDEWEB)
Joshi, Anand A; Shattuck, David W; Toga, Arthur W [Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, CA 90095 (United States); Chaudhari, Abhijit J [Department of Radiology, UC Davis School of Medicine, Sacramento, CA 95817 (United States); Li Changqing; Cherry, Simon R [Department of Biomedical Engineering, University of California-Davis, Davis, CA 95616 (United States); Dutta, Joyita; Leahy, Richard M, E-mail: anand.joshi@loni.ucla.ed, E-mail: leahy@sipi.usc.ed [Signal and Image Processing Institute, University of Southern California, Los Angeles, CA 90089 (United States)
2010-10-21
For pre-clinical bioluminescence or fluorescence optical tomography, the animal's surface topography and internal anatomy need to be estimated for improving the quantitative accuracy of reconstructed images. The animal's surface profile can be measured by all-optical systems, but estimation of the internal anatomy using optical techniques is non-trivial. A 3D anatomical mouse atlas may be warped to the estimated surface. However, fitting an atlas to surface topography data is challenging because of variations in the posture and morphology of imaged mice. In addition, acquisition of partial data (for example, from limited views or with limited sampling) can make the warping problem ill-conditioned. Here, we present a method for fitting a deformable mouse atlas to surface topographic range data acquired by an optical system. As an initialization procedure, we match the posture of the atlas to the posture of the mouse being imaged using landmark constraints. The asymmetric L{sup 2} pseudo-distance between the atlas surface and the mouse surface is then minimized in order to register two data sets. A Laplacian prior is used to ensure smoothness of the surface warping field. Once the atlas surface is normalized to match the range data, the internal anatomy is transformed using elastic energy minimization. We present results from performance evaluation studies of our method where we have measured the volumetric overlap between the internal organs delineated directly from MRI or CT and those estimated by our proposed warping scheme. Computed Dice coefficients indicate excellent overlap in the brain and the heart, with fair agreement in the kidneys and the bladder.
Supersymmetric codimension-two branes in six-dimensional gauged supergravity
International Nuclear Information System (INIS)
Lee, Hyun Min; Papazoglou, Antonios
2008-01-01
We consider the six-dimensional Salam-Sezgin supergravity in the presence of codimension-2 branes. In the case that the branes carry only tension, we provide a way to supersymmetrise them by adding appropriate localised Fayet-Iliopoulos terms and modifying accordingly the supersymmetry transformations. The resulting brane action has N = 1 supersymmetry (SUSY). We find the axisymmetric vacua of the system and show that one has unwarped background solutions with 'football'-shaped extra dimensions which always respect N = 1 SUSY, in contrast with the non-supersymmetric brane action background. Finally, we generically find multiple zero modes of the gravitino in this background and discuss how one could obtain a single chiral zero mode present in the low energy spectrum
Collective excitations of massive flavor branes
Directory of Open Access Journals (Sweden)
Georgios Itsios
2016-08-01
Full Text Available We study the intersections of two sets of D-branes of different dimensionalities. This configuration is dual to a supersymmetric gauge theory with flavor hypermultiplets in the fundamental representation of the gauge group which live on the defect of the unflavored theory determined by the directions common to the two types of branes. One set of branes is dual to the color degrees of freedom, while the other set adds flavor to the system. We work in the quenched approximation, i.e., where the flavor branes are considered as probes, and focus specifically on the case in which the quarks are massive. We study the thermodynamics and the speeds of first and zero sound at zero temperature and non-vanishing chemical potential. We show that the system undergoes a quantum phase transition when the chemical potential approaches its minimal value and we obtain the corresponding non-relativistic critical exponents that characterize its critical behavior. In the case of (2+1-dimensional intersections, we further study alternative quantization and the zero sound of the resulting anyonic fluid. We finally extend these results to non-zero temperature and magnetic field and compute the diffusion constant in the hydrodynamic regime. The numerical results we find match the predictions by the Einstein relation.
Branes in the GL(1 vertical stroke 1) WZNW-Model
Energy Technology Data Exchange (ETDEWEB)
Creutzig, T.; Schomerus, V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Quella, T. [Amsterdam Univ. (Netherlands). KdV Inst. for Mathematics
2007-08-15
We initiate a systematic study of boundary conditions in conformal field theories with target space supersymmetry. The WZNW model on GL(1 vertical stroke 1) is used as a prototypical example for which we find the complete set of maximally symmetric branes. This includes a unique brane of maximal super-dimension 2 vertical stroke 2, a 2-parameter family of branes with super-dimension 0 vertical stroke 2 and an infinite set of fully localized branes possessing a single modulus. Members of the latter family can only exist along certain lines on the bosonic base, much like fractional branes at orbifold singularities. Our results establish that all essential algebraic features of Cardy-type boundary theories carry over to the non-rational logarithmic WZNW model on GL(1 vertical stroke 1). (orig.)
Study of Strongly Coupled Systems via Probe Brane Constructions
Chang, Han-Chih
In this thesis, we present our study towards better understanding of the strongly coupled systems with extra matter content in the fundamental representation of some prescribed global symmetry group in the quenched approximation, with the toolkit of holography via a probe brane construction. Specically, for the defect conformal systems, we unearth and quantify the phase trasition diagram, and novel supersymmetric vacua in the top-down model of the D3/D5 probe brane system. For further quantify various non-Fermi quantum liquid phases realized through the holographical probe brane construction, we then propose and verify the method to include the backreaction of entanglement entropy due to the probe branes at the leading order, which can potentially be used to detect topological phase transitions. We will recapitulate the main results of our works, in collaboration with Prof. Andreas Karch, published in the following journals: "Minimal Submanifolds asymptotic to AdS4 xS2 in AdS5xS5', JHEP, vol.1404, p.037, 2014; "The Novel Solutions of Finite-Density D3/D5 Probe Brane System and Their Implications for Stability'', JHEP, vol.1210, p.060, 2014; "Entanglement Entropy for Probe Branes'', JHEP, vol.1401, p.180, 2014.
D0-branes in black hole attractors
International Nuclear Information System (INIS)
Gaiotto, Davide; Simons, Aaron; Strominger, Andrew; Yin Xi
2006-01-01
Configurations of N probe D0-branes in a Calabi-Yau black hole are studied. A large degeneracy of near-horizon bound states are found which can be described as lowest Landau levels tiling the horizon of the black hole. These states preserve some of the enhanced supersymmetry of the near-horizon AdS 2 x S 2 x CY 3 attractor geometry, but not of the full asymptotically flat solution. Supersymmetric non-abelian configurations are constructed which, via the Myers effect, develop charges associated with higher-dimensional branes wrapping CY 3 cycles. An SU(1,1/2) superconformal quantum mechanics describing D0-branes in the attractor geometry is explicitly constructed
Localization and mass spectra of various matter fields on Weyl thin brane
Energy Technology Data Exchange (ETDEWEB)
Sui, Tao-Tao; Zhao, Li; Zhang, Yu-Peng [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China); Xie, Qun-Ying [Lanzhou University, School of Information Science and Engineering, Lanzhou (China)
2017-06-15
It has been shown that the thin brane model in a five-dimensional Weyl gravity can deal with the wrong-signed Friedmann-like equation in the Randall-Sundrum-1 (RS1) model. In the Weyl brane model, there are also two branes with opposite brane tensions, but the four-dimensional graviton (the gravity zero mode) is localized near the negative tension brane, while our four-dimensional universe is localized on the positive tension brane. In this paper, we consider the mass spectra of various bulk matter fields (i.e., scalar, vector, and fermion fields) on the Weyl brane. It is shown that the zero modes of those matter fields can be localized on the positive tension brane under some conditions. The mass spectra of the bulk matter fields are equidistant for the higher excited states, and relatively sparse for the lower excited states. The size of the extra dimension determines the gap of the mass spectra. We also consider the correction to the Newtonian potential in this model and it is proportional to 1/r{sup 3}. (orig.)
Brane cosmology as a dynamical system
International Nuclear Information System (INIS)
Lara, Luis; Castagnino, Mario
2004-01-01
We investigate the qualitative dynamical properties of a brane model for the flat isotropic universe with a single matter component represented by a scalar field. We study the flat and quadratic potential. Three classes of behaviors of the scale factor are determined. In particular, in the case of the brane with dark negative radiation, via a fine tuning, the existence of oscillatory solutions is shown, which is not possible in the traditional flat FRW model
Defect branes as Alice strings
International Nuclear Information System (INIS)
Okada, Takashi; Sakatani, Yuho
2015-01-01
There exist various defect-brane backgrounds in supergravity theories which arise as the low energy limit of string theories. These backgrounds typically have non-trivial monodromies, and if we move a charged probe around the center of a defect, its charge will be changed by the action of the monodromy. During the process, the charge conservation law seems to be violated. In this paper, to resolve this puzzle, we examine a dynamics of the charge changing process and show that the missing charge of the probe is transferred to the background. We then explicitly construct the resultant background after the charge transfer process by utilizing dualities. This background has the same monodromy as the original defect brane, but has an additional charge which does not have any localized source. In the literature, such a charge without localized source is known to appear in the presence of Alice strings. We argue that defect branes can in fact be regarded as a realization of Alice strings in string theory and examine the charge transfer process from that perspective.
Defect branes as Alice strings
Energy Technology Data Exchange (ETDEWEB)
Okada, Takashi [Theoretical Biology Laboratory, RIKEN,Wako 351-0198 (Japan); Sakatani, Yuho [Department of Physics and Astronomy,Seoul National University, Seoul 151-747 (Korea, Republic of)
2015-03-25
There exist various defect-brane backgrounds in supergravity theories which arise as the low energy limit of string theories. These backgrounds typically have non-trivial monodromies, and if we move a charged probe around the center of a defect, its charge will be changed by the action of the monodromy. During the process, the charge conservation law seems to be violated. In this paper, to resolve this puzzle, we examine a dynamics of the charge changing process and show that the missing charge of the probe is transferred to the background. We then explicitly construct the resultant background after the charge transfer process by utilizing dualities. This background has the same monodromy as the original defect brane, but has an additional charge which does not have any localized source. In the literature, such a charge without localized source is known to appear in the presence of Alice strings. We argue that defect branes can in fact be regarded as a realization of Alice strings in string theory and examine the charge transfer process from that perspective.
Discrete Torsion, (Anti) de Sitter D{sub 4}-Brane and Tunneling
Energy Technology Data Exchange (ETDEWEB)
Singh, Abhishek K.; Pandey, P.K.; Singh, Sunita; Kar, Supriya, E-mail: skkar@physics.du.ac.in
2014-06-15
We obtain quantum geometries on a vacuum created pair of a (DD{sup ¯}){sub 3}-brane, at a Big Bang singularity, by a local two form on a D{sub 4}-brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an effective non-perturbative curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the effective curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of (DD{sup ¯})-instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D{sub 4}-brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole.
Probe branes thermalization in external electric and magnetic fields
International Nuclear Information System (INIS)
Ali-Akbari, M.; Ebrahim, H.; Rezaei, Z.
2014-01-01
We study thermalization on rotating probe branes in AdS 5 ×S 5 background in the presence of constant external electric and magnetic fields. In the AdS/CFT framework this corresponds to thermalization in the flavour sector in field theory. The horizon appears on the worldvolume of the probe brane due to its rotation in one of the sphere directions. For both electric and magnetic fields the behaviour of the temperature is independent of the probe brane dimension. We also study the open string metric and the fluctuations of the probe brane in such a set-up. We show that the temperatures obtained from open string metric and observed by the fluctuations are larger than the one calculated from the induced metric
F-theory and the landscape of intersecting D7-branes
Energy Technology Data Exchange (ETDEWEB)
Braun, Andreas
2010-02-05
In this work, the moduli of D7-branes in type IIB orientifold compactifications and their stabilization by fluxes is studied from the perspective of F-theory. In F-theory, the moduli of the D7-branes and the moduli of the orientifold are unified in the moduli space of an elliptic Calabi-Yau manifold. This makes it possible to study flux the stabilization of D7-branes in an elegant manner. To answer phenomenological questions, one has to translate the deformations of the elliptic Calabi-Yau manifold of F-theory back to the positions and the shape of the D7-branes. We address this problem by constructing the homology cycles that are relevant for the deformations of the elliptic Calabi-Yau manifold.We show the viability of our approach for the case of elliptic two- and three-folds. Furthermore, we discuss a consistency conditions related to the intersections between D7-branes and orientifold planes which is automatically fulfilled in F-theory. Finally, we use our results to study the flux stabilization of D7-branes on the orientifold K3 x T{sup 2}/Z{sub 2} using F-theory on K3 x K3. In this context, we derive conditions on the fluxes to stabilize a given configuration of D7-branes. (orig.)
Running with rugby balls: bulk renormalization of codimension-2 branes
Williams, M.; Burgess, C. P.; van Nierop, L.; Salvio, A.
2013-01-01
We compute how one-loop bulk effects renormalize both bulk and brane effective interactions for geometries sourced by codimension-two branes. We do so by explicitly integrating out spin-zero, -half and -one particles in 6-dimensional Einstein-Maxwell-Scalar theories compactified to 4 dimensions on a flux-stabilized 2D geometry. (Our methods apply equally well for D dimensions compactified to D - 2 dimensions, although our explicit formulae do not capture all divergences when D > 6.) The renormalization of bulk interactions are independent of the boundary conditions assumed at the brane locations, and reproduce standard heat-kernel calculations. Boundary conditions at any particular brane do affect how bulk loops renormalize this brane's effective action, but not the renormalization of other distant branes. Although we explicitly compute our loops using a rugby ball geometry, because we follow only UV effects our results apply more generally to any geometry containing codimension-two sources with conical singularities. Our results have a variety of uses, including calculating the UV sensitivity of one-loop vacuum energy seen by observers localized on the brane. We show how these one-loop effects combine in a surprising way with bulk back-reaction to give the complete low-energy effective cosmological constant, and comment on the relevance of this calculation to proposed applications of codimension-two 6D models to solutions of the hierarchy and cosmological constant problems.
F-theory and the landscape of intersecting D7-branes
International Nuclear Information System (INIS)
Braun, Andreas
2010-01-01
In this work, the moduli of D7-branes in type IIB orientifold compactifications and their stabilization by fluxes is studied from the perspective of F-theory. In F-theory, the moduli of the D7-branes and the moduli of the orientifold are unified in the moduli space of an elliptic Calabi-Yau manifold. This makes it possible to study flux the stabilization of D7-branes in an elegant manner. To answer phenomenological questions, one has to translate the deformations of the elliptic Calabi-Yau manifold of F-theory back to the positions and the shape of the D7-branes. We address this problem by constructing the homology cycles that are relevant for the deformations of the elliptic Calabi-Yau manifold.We show the viability of our approach for the case of elliptic two- and three-folds. Furthermore, we discuss a consistency conditions related to the intersections between D7-branes and orientifold planes which is automatically fulfilled in F-theory. Finally, we use our results to study the flux stabilization of D7-branes on the orientifold K3 x T 2 /Z 2 using F-theory on K3 x K3. In this context, we derive conditions on the fluxes to stabilize a given configuration of D7-branes. (orig.)
A de Sitter tachyon thick braneworld
Energy Technology Data Exchange (ETDEWEB)
Germán, Gabriel; Herrera-Aguilar, Alfredo; Malagón-Morejón, Dagoberto [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apdo. Postal 48-3, 62251, Cuernavaca, Morelos (Mexico); Mora-Luna, Refugio Rigel [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Ciudad Universitaria, C.P. 58040, Morelia, Michoacán (Mexico); Rocha, Roldão da, E-mail: gabriel@fis.unam.mx, E-mail: aha@fis.unam.mx, E-mail: malagon@ifm.umich.mx, E-mail: rigel@ifm.umich.mx, E-mail: roldao.rocha@ufabc.edu.br [Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, Rua Santa Adélia, 166 09210-170, Santo André, SP (Brazil)
2013-02-01
Among the multiple 5D thick braneworld models that have been proposed in the last years, in order to address several open problems in modern physics, there is a specific one involving a tachyonic bulk scalar field. Delving into this framework, a thick braneworld with a cosmological background induced on the brane is here investigated. The respective field equations — derived from the model with a warped 5D geometry — are highly non-linear equations, admitting a non-trivial solution for the warp factor and the tachyon scalar field as well, in a de Sitter 4D cosmological background. Moreover, the non-linear tachyonic scalar field, that generates the brane in complicity with warped gravity, has the form of a kink-like configuration. Notwithstanding, the non-linear field equations restricting character does not allow one to easily find thick brane solutions with a decaying warp factor which leads to the localization of 4D gravity and other matter fields. We derive such a thick brane configuration altogether in this tachyon-gravity setup. When analyzing the spectrum of gravity fluctuations in the transverse traceless sector, the 4D gravity is shown to be localized due to the presence of a single zero mode bound state, separated by a continuum of massive Kaluza-Klein (KK) modes by a mass gap. It contrasts with previous results, where there is a KK massive bound excitation providing no clear physical interpretation. The mass gap is determined by the scale of the metric parameter H. Finally, the corrections to Newton's law in this model are computed and shown to decay exponentially. It is in full compliance to corrections reported in previous results (up to a constant factor) within similar braneworlds with induced 4D de Sitter metric, despite the fact that the warp factor and the massive modes have a different form.
Thermodynamics of Lovelock-Lifshitz black branes
International Nuclear Information System (INIS)
Dehghani, M. H.; Mann, R. B.
2010-01-01
We investigate the thermodynamics of Lovelock-Lifshitz black branes. We begin by introducing the finite action of third order Lovelock gravity in the presence of a massive vector field for a flat boundary, and use it to compute the energy density of these black branes. Using the field equations, we find a conserved quantity along the r coordinate that relates the metric parameters at the horizon and at infinity. Remarkably, though the subleading large-r behavior of Lovelock-Lifshitz black branes differs substantively from their Einsteinian Lifshitz counterparts, we find that the relationship between the energy density, temperature, and entropy density is unchanged from Einsteinian gravity. Using the first law of thermodynamics to obtain the relationship between entropy and temperature, we find that it too is the same as the Einsteinian case, apart from a constant of integration that depends on the Lovelock coefficients.
Decoupling limit and throat geometry of non-susy D3 brane
Energy Technology Data Exchange (ETDEWEB)
Nayek, Kuntal, E-mail: kuntal.nayek@saha.ac.in; Roy, Shibaji, E-mail: shibaji.roy@saha.ac.in
2017-03-10
Recently it has been shown by us that, like BPS Dp branes, bulk gravity gets decoupled from the brane even for the non-susy Dp branes of type II string theories indicating a possible extension of AdS/CFT correspondence for the non-supersymmetric case. In that work, the decoupling of gravity on the non-susy Dp branes has been shown numerically for the general case as well as analytically for some special case. Here we discuss the decoupling limit and the throat geometry of the non-susy D3 brane when the charge associated with the brane is very large. We show that in the decoupling limit the throat geometry of the non-susy D3 brane, under appropriate coordinate change, reduces to the Constable–Myers solution and thus confirming that this solution is indeed the holographic dual of a (non-gravitational) gauge theory discussed there. We also show that when one of the parameters of the solution takes a specific value, it reduces, under another coordinate change, to the five-dimensional solution obtained by Csaki and Reece, again confirming its gauge theory interpretation.
Energy Technology Data Exchange (ETDEWEB)
Craps, Ben [Theoretische Natuurkunde, Vrije Universiteit Brussel and The International Solvay Institutes, Pleinlaan 2, B-1050 Brussels (Belgium); Evnin, Oleg [California Institute of Technology 452-48, Pasadena, CA 91125 (United States); Nakamura, Shin [Physics Department, Hanyang University, Seoul, 133-791 (Korea, Republic of)
2006-12-15
One-loop string scattering amplitudes computed using the standard D0-brane conformal field theory (CFT) suffer from infrared divergences associated with recoil. A systematic framework to take recoil into account is the worldline formalism, where fixed boundary conditions are replaced by dynamical D0-brane worldlines. We show that, in the worldline formalism, the divergences that plague the CFT are automatically cancelled in a non-trivial way. The amplitudes derived in the worldline formalism can be reproduced by deforming the CFT with a specific 'recoil operator', which is bilocal and different from the ones previously suggested in the literature.
On the microcanonical description D-brane thermodynamics
International Nuclear Information System (INIS)
Meana, Marco Laucelli; Penalba, Jesus Puente
1999-01-01
We study the microcanonical description of string gases in the presence of D-branes. We obtain exact expressions for the single string density of states and draw the regions in phase space where asymptotic approximations are valid. We are able to describe the whole range of energies including the SYM phase of the D-branes and we remark the importance of the infrared cut-off used in the high energy approximations. With the complete expression we can obtain the density of states of the multiple string gas and study its thermal properties, showing that the Hagedorn temperature is maximum for every system and there is never a phase transition whenever there is thermal contact among the strings attached to different D-branes
Global embeddings for branes at toric singularities
Balasubramanian, Vijay; Braun, Volker; García-Etxebarria, Iñaki
2012-01-01
We describe how local toric singularities, including the Toric Lego construction, can be embedded in compact Calabi-Yau manifolds. We study in detail the addition of D-branes, including non-compact flavor branes as typically used in semi-realistic model building. The global geometry provides constraints on allowable local models. As an illustration of our discussion we focus on D3 and D7-branes on (the partially resolved) (dP0)^3 singularity, its embedding in a specific Calabi-Yau manifold as a hypersurface in a toric variety, the related type IIB orientifold compactification, as well as the corresponding F-theory uplift. Our techniques generalize naturally to complete intersections, and to a large class of F-theory backgrounds with singularities.
Galactic warps and the shape of heavy halos
International Nuclear Information System (INIS)
Sparke, L.S.
1984-01-01
The outer disks of many spiral galaxies are bent away from the plane of the inner disk; the abundance of these warps suggests that they are long-lived. Isolated galactic disks have long been thought to have no discrete modes of vertical oscillation under their own gravity, and so to be incapable of sustaining persistent warps. However, the visible disk contains only a fraction of the galactic mass; an invisible galactic halo makes up the rest. This paper presents an investigation of vertical warping modes in self-gravitating disks, in the imposed potential due to an axisymmetric unseen massive halo. If the halo matter is distributed so that the free precession rate of a test particle decreases with radius near the edge of the disk, then the disk has a discrete mode of vibration; oblate halos which become rapidly more flattened at large radii, and uniformly prolate halos, satisfy this requirement. Otherwise, the disk has no discrete modes and so cannot maintain a long-lived warp, unless the edge is sharply truncated. Computed mode shapes which resemble the observed warps can be found for halo masses consistent with those inferred from galactic rotation curves
Nonsingular 4d-flat branes in six-dimensional supergravities
International Nuclear Information System (INIS)
Nair, V.P.; Randjbar-Daemi, S.
2005-01-01
We show that six-dimensional supergravity models admit nonsingular solutions in the presence of flat three-brane sources with positive tensions. The models studied in this paper involve nonlinear sigma model scalar fields targeted on noncompact manifolds. For the particular solutions of the scalar field equations which we consider, only two brane sources are possible which are positioned at those points where the scalar field densities diverge, without creating a divergence in the Ricci scalar or the total energy. These solutions are invariant under 1/2 of D=6 supersymmetries far away from the branes, which, however, do not integrate to global Killing spinors. Other branes can be introduced by hand by allowing for local deficit angles in the transverse space without generating any kind of curvature singularities. (author)
N{sup 3} entropy of M5 branes from dielectric effect
Energy Technology Data Exchange (ETDEWEB)
Hatefi, E., E-mail: ehatefi@ictp.it [International Centre for Theoretical Physics, Strada Costiera 11, Trieste (Italy); Nurmagambetov, A.J., E-mail: ajn@kipt.kharkov.ua [A.I. Akhiezer Institute for Theoretical Physics of NSC KIPT, 1 Akademicheskaya St., Kharkov, UA 61108 (Ukraine); Park, I.Y., E-mail: inyongpark05@gmail.com [Department of Natural and physical Sciences, Philander Smith College, Little Rock, AR 72223 (United States)
2013-01-01
We observe that the N{sup 3} entropy behavior of near-extremal M5 branes can be reproduced from SYM side with the role of Myers' terms. We start by generalizing the Klebanov-Tseytlin (KT) supergravity solution that displays the N{sup 3} entropy behavior. The new feature of the general solution is visibility of the 'internal' degrees of the M5 branes, i.e., the M0 branes and the M2 branes. With the rationale provided by the supergravity analysis, we consider a D0 brane quantum mechanical setup with Myers' terms. Using localization technique, we show that the leading N{sup 3} behavior of the free energy comes from the 'classical contribution' with the rest subleading.
Point-based warping with optimized weighting factors of displacement vectors
Pielot, Ranier; Scholz, Michael; Obermayer, Klaus; Gundelfinger, Eckart D.; Hess, Andreas
2000-06-01
The accurate comparison of inter-individual 3D image brain datasets requires non-affine transformation techniques (warping) to reduce geometric variations. Constrained by the biological prerequisites we use in this study a landmark-based warping method with weighted sums of displacement vectors, which is enhanced by an optimization process. Furthermore, we investigate fast automatic procedures for determining landmarks to improve the practicability of 3D warping. This combined approach was tested on 3D autoradiographs of Gerbil brains. The autoradiographs were obtained after injecting a non-metabolized radioactive glucose derivative into the Gerbil thereby visualizing neuronal activity in the brain. Afterwards the brain was processed with standard autoradiographical methods. The landmark-generator computes corresponding reference points simultaneously within a given number of datasets by Monte-Carlo-techniques. The warping function is a distance weighted exponential function with a landmark- specific weighting factor. These weighting factors are optimized by a computational evolution strategy. The warping quality is quantified by several coefficients (correlation coefficient, overlap-index, and registration error). The described approach combines a highly suitable procedure to automatically detect landmarks in autoradiographical brain images and an enhanced point-based warping technique, optimizing the local weighting factors. This optimization process significantly improves the similarity between the warped and the target dataset.
Canonical formulation of IIB D-branes
International Nuclear Information System (INIS)
Kamimura, K.
1998-01-01
We find Wess-Zumino actions for kappa invariant type IIB D-branes in explicit forms. A simple and compact expression is obtained by the use of spinor variables which are defined as power series of differential forms. Using the Wess-Zumino actions we develop the canonical formulation and find the complete set of the constraint equations for generic type IIB Dp-branes. The conserved global supersymmetry charges are determined and the algebra containing the central charges can be obtained explicitly. (orig.)
Zhang, Dongliang; Wang, Xin; Huang, Yunsong; Schuster, Gerard T.
2014-01-01
The quality of migration images depends on the accuracy of the velocity model. For large velocity errors, the migration image is strongly distorted, which unflattens events in the common image gathers and consequently leads to a blurring in the stacked migration image. To mitigate this problem, we propose dynamic image warping to flatten the common image gathers before stacking and to enhance the signal-to-noise ratio of the migration image. Numerical tests on the Marmousi model and GOM data show that image warping of the prestack images followed by stacking leads to much better resolved reflectors than the original migration image. The problem, however, is that the reflector locations have increased uncertainty because the wrong velocity model is still used.
Zhang, Dongliang
2014-08-05
The quality of migration images depends on the accuracy of the velocity model. For large velocity errors, the migration image is strongly distorted, which unflattens events in the common image gathers and consequently leads to a blurring in the stacked migration image. To mitigate this problem, we propose dynamic image warping to flatten the common image gathers before stacking and to enhance the signal-to-noise ratio of the migration image. Numerical tests on the Marmousi model and GOM data show that image warping of the prestack images followed by stacking leads to much better resolved reflectors than the original migration image. The problem, however, is that the reflector locations have increased uncertainty because the wrong velocity model is still used.
Universal hydrodynamics of non-conformal branes
International Nuclear Information System (INIS)
Kanitscheider, Ingmar; Skenderis, Kostas
2009-01-01
We examine the hydrodynamic limit of non-conformal branes using the recently developed precise holographic dictionary. We first streamline the discussion of holography for backgrounds that asymptote locally to non-conformal brane solutions by showing that all such solutions can be obtained from higher dimensional asymptotically locally AdS solutions by suitable dimensional reduction and continuation in the dimension. As a consequence, many holographic results for such backgrounds follow from the corresponding results of the Asymptotically AdS case. In particular, the hydrodynamics of non-conformal branes is fully determined in terms of conformal hydrodynamics. Using previous results on the latter we predict the form of the non-conformal hydrodynamic stress tensor to second order in derivatives. Furthermore we show that the ratio between bulk and shear viscosity is fixed by the generalized conformal structure to be ζ/η = 2(1/(d-1)-c s 2 ), where c s is the speed of sound in the fluid.
Statistics of galaxy warps in the HDF North and South
Reshetnikov, [No Value; Battaner, E; Combes, F; Jimenez-Vicente, J
We present a statistical study of the presence of galaxy warps in the Hubble deep fields. Among a complete sample of 45 edge-on galaxies above a diameter of 1."3, we find 5 galaxies to be certainly warped and 6 galaxies as good candidates. In addition, 4 galaxies reveal a characteristic U-warp.
International Nuclear Information System (INIS)
Kallosh, R.; Rajaraman, A.
1996-01-01
We suggest a duality-invariant formula for the entropy and temperature of nonextreme black holes in supersymmetric string theory. The entropy is given in terms of the duality-invariant parameter of the deviation from extremality and 56 SU(8) covariant central charges. It interpolates between the entropies of Schwarzschild solution and extremal solutions with various amount of unbroken supersymmetries, and therefore, serves for classification of black holes in supersymmetric string theories. We introduce the second auxiliary 56 via an E(7) symmetric constraint. The symmetric and antisymmetric combinations of these two multiplets are related via moduli to the corresponding two fundamental representations of E(7): brane and antibrane open-quote open-quote numbers.close-quote close-quote Using the CPT as well as C symmetry of the entropy formula and duality one can explain the mysterious simplicity of the nonextreme black hole area formula in terms of branes and antibranes. copyright 1996 The American Physical Society
Namaste (counterbalancing) technique: Overcoming warping in costal cartilage.
Agrawal, Kapil S; Bachhav, Manoj; Shrotriya, Raghav
2015-01-01
Indian noses are broader and lack projection as compared to other populations, hence very often need augmentation, that too by large volume. Costal cartilage remains the material of choice in large volume augmentations and repair of complex primary and secondary nasal deformities. One major disadvantage of costal cartilage grafts (CCG) which offsets all other advantages is the tendency to warp and become distorted over a period of time. We propose a simple technique to overcome this menace of warping. We present the data of 51 patients of rhinoplasty done using CCG with counterbalancing technique over a period of 4 years. No evidence of warping was found in any patient up to a maximum follow-up period of 4 years. Counterbalancing is a useful technique to overcome the problem of warping. It gives liberty to utilize even unbalanced cartilage safely to provide desired shape and use the cartilage without any wastage.
Mechanical properties of 3D printed warped membranes
Kosmrlj, Andrej; Xiao, Kechao; Weaver, James C.; Vlassak, Joost J.; Nelson, David R.
2015-03-01
We explore how a frozen background metric affects the mechanical properties of solid planar membranes. Our focus is a special class of ``warped membranes'' with a preferred random height profile characterized by random Gaussian variables h (q) in Fourier space with zero mean and variance q-m . It has been shown theoretically that in the linear response regime, this quenched random disorder increases the effective bending rigidity, while the Young's and shear moduli are reduced. Compared to flat plates of the same thickness t, the bending rigidity of warped membranes is increased by a factor hv / t while the in-plane elastic moduli are reduced by t /hv , where hv =√{ } describes the frozen height fluctuations. Interestingly, hv is system size dependent for warped membranes characterized with m > 2 . We present experimental tests of these predictions, using warped membranes prepared via high resolution 3D printing.
Surface Casimir densities and induced cosmological constant on parallel branes in AdS spacetime
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Saharian, Aram A.
2004-01-01
Vacuum expectation value of the surface energy-momentum tensor is evaluated for a massive scalar field with general curvature coupling parameter subject to Robin boundary conditions on two parallel branes located on (D+1)-dimensional anti-de Sitter bulk. The general case of different Robin coefficients on separate branes is considered. As a regularization procedure the generalized zeta function technique is used, in combination with contour integral representations. The surface energies on the branes are presented in the form of the sums of single brane and second brane-induced parts. For the geometry of a single brane both regions, on the left (L-region) and on the right (R-region), of the brane are considered. The surface densities for separate L- and R-regions contain pole and finite contributions. For an infinitely thin brane taking these regions together, in odd spatial dimensions the pole parts cancel and the total surface energy is finite. The parts in the surface densities generated by the presence of the second brane are finite for all nonzero values of the interbrane separation. It is shown that for large distances between the branes the induced surface densities give rise to an exponentially suppressed cosmological constant on the brane. In the Randall-Sundrum braneworld model, for the interbrane distances solving the hierarchy problem between the gravitational and electroweak mass scales, the cosmological constant generated on the visible brane is of the right order of magnitude with the value suggested by the cosmological observations
Brane classical and quantum cosmology from an effective action
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Seahra, Sanjeev S.; Sepangi, H.R.; Ponce de Leon, J.
2003-01-01
Motivated by the Randall-Sundrum braneworld scenario, we discuss the classical and quantum dynamics of a (d+1)-dimensional boundary wall between a pair of (d+2)-dimensional topological Schwarzschild-AdS black holes. We assume there are quite general--but not completely arbitrary--matter fields living on the boundary 'brane universe', and that its geometry is that of a Friedmann-Lemaitre-Robertson-Walker (FLRW) model. The effective action governing the model in the minisuperspace approximation is derived. We find that the presence of black hole horizons in the bulk gives rise to a complex action for certain classically allowed brane configurations, but that the imaginary contribution plays no role in the equations of motion. Classical and instanton brane trajectories are examined in general and for special cases, and we find a subset of configuration space that is not allowed at the classical or semiclassical level; this subset corresponds to spacelike branes carrying tachyonic matter. The Hamiltonization and Dirac quantization of the model is then performed for the general case; the latter involves the manipulation of the Hamiltonian constraint before it is transformed into an operator that annihilates physical state vectors. The ensuing covariant Wheeler-DeWitt equation is examined at the semiclassical level, and we consider the possible localization of the brane universe's wave function away from the cosmological singularity. This is easier to achieve for branes with low density and/or spherical spatial sections
Brane classical and quantum cosmology from an effective action
Seahra, Sanjeev S.; Sepangi, H. R.; Ponce de Leon, J.
2003-09-01
Motivated by the Randall-Sundrum braneworld scenario, we discuss the classical and quantum dynamics of a (d+1)-dimensional boundary wall between a pair of (d+2)-dimensional topological Schwarzschild-AdS black holes. We assume there are quite general—but not completely arbitrary—matter fields living on the boundary “brane universe,” and that its geometry is that of a Friedmann-Lemaître-Robertson-Walker (FLRW) model. The effective action governing the model in the minisuperspace approximation is derived. We find that the presence of black hole horizons in the bulk gives rise to a complex action for certain classically allowed brane configurations, but that the imaginary contribution plays no role in the equations of motion. Classical and instanton brane trajectories are examined in general and for special cases, and we find a subset of configuration space that is not allowed at the classical or semiclassical level; this subset corresponds to spacelike branes carrying tachyonic matter. The Hamiltonization and Dirac quantization of the model is then performed for the general case; the latter involves the manipulation of the Hamiltonian constraint before it is transformed into an operator that annihilates physical state vectors. The ensuing covariant Wheeler-DeWitt equation is examined at the semiclassical level, and we consider the possible localization of the brane universe’s wave function away from the cosmological singularity. This is easier to achieve for branes with low density and/or spherical spatial sections.
Brane big bang brought on by a bulk bubble
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Gen, Uchida; Ishibashi, Akihiro; Tanaka, Takahiro
2002-01-01
We propose an alternative inflationary universe scenario in the context of Randall-Sundrum braneworld cosmology. In this new scenario the existence of extra dimension(s) plays an essential role. First, the brane universe is initially in the inflationary phase driven by the effective cosmological constant induced by a small mismatch between the vacuum energy in the five-dimensional bulk and the brane tension. This mismatch arises since the bulk is initially in a false vacuum. Then, false vacuum decay occurs, nucleating a true vacuum bubble with negative energy inside the bulk. The nucleated bubble expands in the bulk and consequently hits the brane, causing a hot big-bang brane universe of the Randall-Sundrum type. Here, the termination of the inflationary phase is due to the change of the bulk vacuum energy. The bubble kinetic energy heats up the universe. As a simple realization, we propose a model in which we assume an interaction between the brane and the bubble. We derive the constraints on the model parameters taking into account the following requirements: solving the flatness problem, no force which prohibits the bubble from colliding with the brane, a sufficiently high reheating temperature for the standard nucleosynthesis to work, and the recovery of Newton's law up to 1 mm. We find that a fine-tuning is needed in order to satisfy the first and the second requirements simultaneously, although the other constraints are satisfied in a wide range of the model parameters
Dirichlet branes and nonperturbative aspects of supersymmetric string and gauge theories
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Yin, Zheng
1999-01-01
In chapter 1 the author reviews some elements of string theory relevant to the rest of this report. He touches on both the classical, i.e. perturbative, string physics before D-branes rise to prominence, and some of the progresses they brought forth. In chapter 2 he proceeds to give an exact algebraic formulation of D-branes in curved spaces. This allows one to classify them in backgrounds of interest and study their geometric properties. He applies this formalism to string theory on Calabi-Yau and other supersymmetry preserving manifolds. Then he studies the behavior of the D-branes under mirror symmetry in chapter 3. Mirror symmetry is known to be a symmetry of string theory perturbatively. He finds evidence for its nonperturbative validity when D-branes are also considered and compute some dynamical consequences. In chapter 4 he turns to examine the consistency of curved and/or intersecting D-brane configurations. They have been used recently to extract information about the field theories that arise in certain limits. It turns out that there are potential quantum mechanical inconsistencies associated with them. What saves the day are certain subtle topological properties of D-branes. This resolution has implications for the conserved charges carried by the D-branes, which he computes for the cases studied in chapter 2. In chapter 5 he uses intersecting brane configurations to study three dimensional supersymmetric gauge theories. There is also a mirror symmetry there that, among other things, exchanges classical and quantum mechanical quantities of a (mirror) pair of theories. It has an elegant realization in term of a symmetry of string theory involving D-branes. The author employs it to study a wide class of 3d models. He also predicts new mirror pairs and unconventional 3d field theories without Lagrangian descriptions
A compact codimension-two braneworld with precisely one brane
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Akerblom, Nikolas; Cornelissen, Gunther
2010-01-01
Building on earlier work on football-shaped extra dimensions, we construct a compact codimension-two braneworld with precisely one brane. The two extra dimensions topologically represent a 2-torus which is stabilized by a bulk cosmological constant and magnetic flux. The torus has positive constant curvature almost everywhere, except for a single conical singularity at the location of the brane. In contradistinction to the football-shaped case, there is no fine-tuning required for the brane tension. We also present some plausibility arguments why the model should not suffer from serious stability issues.
Cosmological perturbations on the phantom brane
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Bag, Satadru; Sahni, Varun [Inter-University Centre for Astronomy and Astrophysics, Pune (India); Viznyuk, Alexander; Shtanov, Yuri, E-mail: satadru@iucaa.in, E-mail: viznyuk@bitp.kiev.ua, E-mail: shtanov@bitp.kiev.ua, E-mail: varun@iucaa.in [Bogolyubov Institute for Theoretical Physics, Kiev 03680 (Ukraine)
2016-07-01
We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, w {sub eff} < −1, but no big-rip future singularity. In addition to matter and radiation, the braneworld possesses a new effective degree of freedom—the 'Weyl fluid' or 'dark radiation'. Setting initial conditions on super-Hubble spatial scales at the epoch of radiation domination, we evolve perturbations of radiation, pressureless matter and the Weyl fluid until the present epoch. We observe a gradual decrease in the amplitude of the Weyl-fluid perturbations after Hubble-radius crossing, which results in a negligible effect of the Weyl fluid on the evolution of matter perturbations on spatial scales relevant for structure formation. Consequently, the quasi-static approximation of Koyama and Maartens provides a good fit to the exact results during the matter-dominated epoch. We find that the late-time growth of density perturbations on the brane proceeds at a faster rate than in ΛCDM. Additionally, the gravitational potentials Φ and Ψ evolve differently on the brane than in ΛCDM, for which Φ = Ψ. On the brane, by contrast, the ratio Φ/Ψ exceeds unity during the late matter-dominated epoch ( z ∼< 50). These features emerge as smoking gun tests of phantom brane cosmology and allow predictions of this scenario to be tested against observations of galaxy clustering and large-scale structure.
D-brane description of new open string solutions in AdS5
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Kluson, J.
2008-01-01
In this Letter we find D-brane descriptions of some of new open string solutions that were found in (0804.3438 [hep-th]). These D5-brane and D3-brane configurations give gravitational dual descriptions of Wilson loops in some particular representations
Namaste (counterbalancing technique: Overcoming warping in costal cartilage
Directory of Open Access Journals (Sweden)
Kapil S Agrawal
2015-01-01
Full Text Available Background: Indian noses are broader and lack projection as compared to other populations, hence very often need augmentation, that too by large volume. Costal cartilage remains the material of choice in large volume augmentations and repair of complex primary and secondary nasal deformities. One major disadvantage of costal cartilage grafts (CCG which offsets all other advantages is the tendency to warp and become distorted over a period of time. We propose a simple technique to overcome this menace of warping. Materials and Methods: We present the data of 51 patients of rhinoplasty done using CCG with counterbalancing technique over a period of 4 years. Results: No evidence of warping was found in any patient up to a maximum follow-up period of 4 years. Conclusion: Counterbalancing is a useful technique to overcome the problem of warping. It gives liberty to utilize even unbalanced cartilage safely to provide desired shape and use the cartilage without any wastage.
Charged rotating black holes on a 3-brane
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Aliev, A.N.; Guemruekcueoglu, A.E.
2005-01-01
We study exact stationary and axisymmetric solutions describing charged rotating black holes localized on a 3-brane in the Randall-Sundrum braneworld. The charges of the black holes are considered to be of two types, the first being an induced tidal charge that appears as an imprint of nonlocal gravitational effects from the bulk space and the second is a usual electric charge arising due to a Maxwell field trapped on the brane. We assume a special ansatz for the metric on the brane taking it to be of the Kerr-Schild form and show that the Kerr-Newman solution of ordinary general relativity in which the electric charge is superseded by a tidal charge satisfies a closed system of the effective gravitational field equations on the brane. It turns out that the negative tidal charge may provide a mechanism for spinning up the black hole so that its rotation parameter exceeds its mass. This is not allowed in the framework of general relativity. We also find a new solution that represents a rotating black hole on the brane carrying both charges. We show that for a rapid enough rotation the combined influence of the rotational dynamics and the local bulk effects of the 'squared' energy-momentum tensor on the brane distort the horizon structure of the black hole in such a way that it can be thought of as composed of nonuniformly rotating null circles with growing radii from the equatorial plane to the poles. We finally study the geodesic motion of test particles in the equatorial plane of a rotating black hole with tidal charge. We show that the effects of negative tidal charge tend to increase the horizon radius, as well as the radii of the limiting photon orbit, the innermost bound and the innermost stable circular orbits for both direct and retrograde motions of the particles
A stringy origin of M2 brane Chern-Simons theories
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Aganagic, Mina
2010-01-01
We show that string duality relates M-theory on a local Calabi-Yau fourfold singularity X 4 to type IIA string theory on a Calabi-Yau threefold X 3 fibered over a real line, with RR 2-form fluxes turned on. The RR flux encodes how the M-theory circle is fibered over the IIA geometry. The theories on N D2 branes probing X 3 are the well-known quiver theories with N=2 supersymmetry in three dimensions. We show that turning on fluxes, and fibering the X 3 over a direction transverse to the branes, corresponds to turning on N=2 Chern-Simons couplings. String duality implies that, in the strong coupling limit, the N D2 branes on X 3 in this background become N M2 branes on X 4 . This provides a string theory derivation for the recently conjectured description of the M2 brane theories on Calabi-Yau fourfolds in terms of N=2 quiver Chern-Simons theories. We also provide a new N=2 Chern-Simons theory dual to AdS 4 xQ 1,1,1 . Type IIA/M-theory duality also relates IIA string theory on X 3 with only the RR fluxes turned on, to M-theory on a G 2 holonomy manifold. We show that this implies that the N M2 branes probing the G 2 manifold are described by the quiver Chern-Simons theory originating from the D2 branes probing X 3 , except that now Chern-Simons terms preserve only N=1 supersymmetry in three dimensions.
D-brane potentials from multi-trace deformations in AdS/CFT
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Bernamonti, Alice; Craps, Ben
2009-01-01
It is known that certain AdS boundary conditions allow smooth initial data to evolve into a big crunch. To study this type of cosmological singularity, one can use the dual quantum field theory, where the non-standard boundary conditions are reflected by the presence of a multi-trace potential unbounded below. For specific AdS 4 and AdS 5 models, we provide a D-brane (or M-brane) interpretation of the unbounded potential. Using probe brane computations, we show that the AdS boundary conditions of interest cause spherical branes to be pushed to the boundary of AdS in finite time, and that the corresponding potential agrees with the multi-trace deformation of the dual field theory. Systems with expanding spherical D3-branes are related to big crunch supergravity solutions by a phenomenon similar to geometric transition.
An N=1 superfield action for M2 branes
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Mauri, Andrea; Petkou, Anastasios C.
2008-01-01
We present an octonionic N=1 superfield action that reproduces in components the action of Bagger and Lambert for M2 branes. By giving an expectation value to one of the scalars we obtain the maximally supersymmetric superfield action for D2 branes
Tachyon tube on non BPS D-branes
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Huang Wunghong
2004-01-01
We report our searches for a single tubular tachyonic solution of regular profile on unstable non BPS D3-branes. We first show that some extended Dirac-Born-Infeld tachyon actions in which new contributions are added to avoid the Derrick's no-go theorem still could not have a single regular tube solution. Next we use the Minahan-Zwiebach tachyon action to find the regular tube solutions with circular or elliptic cross section. With a critical electric field, the energy of the tube comes entirely from the D0 and strings, while the energy associated to the tubular D2-brane tension is vanishing. We also show that fluctuation spectrum around the tube solution does not contain tachyonic mode. The results are consistent with the identification of the tubular configuration as a BPS D2-brane. (author)
Localization of abelian gauge fields on thick branes
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Vaquera-Araujo, Carlos A. [Universidad de Colima, Facultad de Ciencias, CUICBAS, Colima (Mexico); Corradini, Olindo [Universidad Autonoma de Chiapas, Ciudad Universitaria, Facultad de Ciencias en Fisica y Matematicas, Tuxtla Gutierrez (Mexico); Universita di Modena e Reggio Emilia, Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Modena (Italy)
2015-02-01
In this work, we explore a mechanism for abelian gauge field localization on thick branes based on a five-dimensional Stueckelberg-like action. A normalizable zero mode is found through the identification of a suitable coupling function between the brane and the gauge field. The same mechanism is studied for the localization of the abelian Kalb-Ramond field. (orig.)
Merger transitions in brane-black-hole systems: Criticality, scaling, and self-similarity
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Frolov, Valeri P.
2006-01-01
We propose a toy model for studying merger transitions in a curved spacetime with an arbitrary number of dimensions. This model includes a bulk N-dimensional static spherically symmetric black hole and a test D-dimensional brane (D≤N-1) interacting with the black hole. The brane is asymptotically flat and allows a O(D-1) group of symmetry. Such a brane-black-hole (BBH) system has two different phases. The first one is formed by solutions describing a brane crossing the horizon of the bulk black hole. In this case the internal induced geometry of the brane describes a D-dimensional black hole. The other phase consists of solutions for branes which do not intersect the horizon, and the induced geometry does not have a horizon. We study a critical solution at the threshold of the brane-black-hole formation, and the solutions which are close to it. In particular, we demonstrate that there exists a striking similarity of the merger transition, during which the phase of the BBH system is changed, both with the Choptuik critical collapse and with the merger transitions in the higher dimensional caged black-hole-black-string system
Brane Gas-Driven Bulk Expansion as a Precursor Stage to Brane Inflation
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Shuhmaher, Natalia; Brandenberger, Robert
2006-01-01
We propose a new way of obtaining slow-roll inflation in the context of higher dimensional models motivated by string and M theory. In our model, all extra spatial dimensions are orbifolded. The initial conditions are taken to be a hot dense bulk brane gas which drives an initial phase of isotropic bulk expansion. This phase ends when a weak potential between the orbifold fixed planes begins to dominate. For a wide class of potentials, a period during which the bulk dimensions decrease sufficiently slowly to lead to slow-roll inflation of the three dimensions parallel to the orbifold fixed planes will result. Once the separation between the orbifold fixed planes becomes of the string scale, a repulsive potential due to string effects takes over and leads to a stabilization of the radion modes. The conversion of bulk branes into radiation during the phase of bulk contraction leads to reheating
Anomalies and inflow on D-branes and O-planes
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Scrucca, Claudio A.; Serone, Marco
1999-01-01
We derive the general form of the anomaly for chiral spinors and self-dual antisymmetric tensors living on D-brane and O-plane intersections, using both path-integral and index theorem methods. We then show that the anomalous couplings to RR forms of D-branes and O-planes in a general background are precisely those required to cancel these anomalies through the inflow mechanism. This allows, for instance, for local anomaly cancellation in generic orientifold models, the relevant Green-Schwarz term being given by the sum of the anomalous couplings of all the D-branes and O-planes in the model
Quantum effective action in spacetimes with branes and boundaries
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Barvinsky, A.O.; Nesterov, D.V.
2006-01-01
We construct quantum effective action in spacetime with branes/boundaries. This construction is based on the reduction of the underlying Neumann type boundary value problem for the propagator of the theory to that of the much more manageable Dirichlet problem. In its turn, this reduction follows from the recently suggested Neumann-Dirichlet duality which we extend beyond the tree-level approximation. In the one-loop approximation this duality suggests that the functional determinant of the differential operator subject to Neumann boundary conditions factorizes into the product of its Dirichlet counterpart and the functional determinant of a special operator on the brane--the inverse of the brane-to-brane propagator. As a byproduct of this relation we suggest a new method for surface terms of the heat kernel expansion. This method allows one to circumvent well-known difficulties in the heat kernel theory on manifolds with boundaries for a wide class of generalized Neumann boundary conditions. In particular, we easily recover several lowest-order surface terms in the case of Robin and oblique boundary onditions. We briefly discuss multiloop applications of the suggested Dirichlet reduction and the prospects of constructing the universal background-field method for systems with branes/boundaries, analogous to the Schwinger-DeWitt technique
Gerbes, M5-brane anomalies and E8 gauge theory
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Aschieri, Paolo; Jurco, Branislav
2004-01-01
Abelian gerbes and twisted bundles describe the topology of the NS 3-form gauge field strength H. We review how they have been usefully applied to study and resolve global anomalies in open string theory. Abelian 2-gerbes and twisted nonabelian gerbes describe the topology of the 4-form field strength G of M-theory. We show that twisted nonabelian gerbes are relevant in the study and resolution of global anomalies of multiple coinciding M5-branes. Global anomalies for one M5-brane have been studied by Witten and by Diaconescu, Freed and Moore. The structure and the differential geometry of twisted nonabelian gerbes (i.e. modules for 2-gerbes) is defined and studied. The nonabelian 2-form gauge potential living on multiple coinciding M5-branes arises as curving (curvature) of twisted nonabelian gerbes. The nonabelian group is in general Ω-tildeE 8 , the central extension of the E 8 loop group. The twist is in general necessary to cancel global anomalies due to the non-triviality of the 11-dimensional 4-form field strength G and due to the possible torsion present in the cycles the M5-branes wrap. Our description of M5-branes global anomalies leads to the D4-branes one upon compactification of M-theory to Type IIA theory. (author)
Gerbes, M5-Brane Anomalies and E8 Gauge Theory
Aschieri, Paolo; Jurco, Branislav
2004-10-01
Abelian gerbes and twisted bundles describe the topology of the NS 3-form gauge field strength H. We review how they have been usefully applied to study and resolve global anomalies in open string theory. Abelian 2-gerbes and twisted nonabelian gerbes describe the topology of the 4-form field strength G of M-theory. We show that twisted nonabelian gerbes are relevant in the study and resolution of global anomalies of multiple coinciding M5-branes. Global anomalies for one M5-brane have been studied by Witten and by Diaconescu, Freed and Moore. The structure and the differential geometry of twisted nonabelian gerbes (i.e. modules for 2-gerbes) is defined and studied. The nonabelian 2-form gauge potential living on multiple coinciding M5-branes arises as curving (curvature) of twisted nonabelian gerbes. The nonabelian group is in general tilde OmegaE8, the central extension of the E8 loop group. The twist is in general necessary to cancel global anomalies due to the nontriviality of the 11-dimensional 4-form field strength G and due to the possible torsion present in the cycles the M5-branes wrap. Our description of M5-branes global anomalies leads to the D4-branes one upon compactification of M-theory to Type IIA theory.
The cosmological constant, branes and non-geometry
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Gautason, Fridhrik Freyr
2014-01-01
In this thesis we derive an equation for the classical cosmological constant in general string compactifications by employing scaling symmetries present in string theory. We find that in heterotic string theory, a perturbatively small, but non-vanishing, cosmological constant is impossible unless non-perturbative and/or string loop corrections are taken into account. In type II string theory we show that the classical cosmological constant is given by a sum of two terms, the source actions evaluated on-shell, and a certain combination of non-vanishing fluxes integrated over spacetime. In many cases we can express the classical cosmological constant in terms of only the source contributions by exploiting two scaling symmetries. This result can be used in two ways. First one can simply predict the classical cosmological constant in a given setup without solving all equations of motion. A second application is to give constraints on the near brane behavior of supergravity fields when the cosmological constant is known. In particular we motivate that energy densities of some fields diverge in the well-known KKLT scenario for de Sitter solutions in type IIB string theory. More precisely, we show, using our results and minimal assumptions, that energy densities of the three-form fluxes diverge in the near-source region of internal space. This divergence is unusual, since these fields do not directly couple to the source, and has been interpreted as a hint of instability of the solution. In the last chapter of the thesis we discuss the worldvolume actions of exotic five-branes. Using a specific chain of T- and S-dualities in a spacetime with two circular isometries, we derive the DBI and WZ actions of the so-called 5 2 2 - and 5 2 3 -brane. These actions describe the dynamics of the branes as well as their couplings to the ten-dimensional gauge potentials. We propose a modified Bianchi identity for the non-geometric Q-flux due to one of the branes. Q-flux often appears
Poisson sigma model with branes and hyperelliptic Riemann surfaces
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Ferrario, Andrea
2008-01-01
We derive the explicit form of the superpropagators in the presence of general boundary conditions (coisotropic branes) for the Poisson sigma model. This generalizes the results presented by Cattaneo and Felder [''A path integral approach to the Kontsevich quantization formula,'' Commun. Math. Phys. 212, 591 (2000)] and Cattaneo and Felder ['Coisotropic submanifolds in Poisson geometry and branes in the Poisson sigma model', Lett. Math. Phys. 69, 157 (2004)] for Kontsevich's angle function [Kontsevich, M., 'Deformation quantization of Poisson manifolds I', e-print arXiv:hep.th/0101170] used in the deformation quantization program of Poisson manifolds. The relevant superpropagators for n branes are defined as gauge fixed homotopy operators of a complex of differential forms on n sided polygons P n with particular ''alternating'' boundary conditions. In the presence of more than three branes we use first order Riemann theta functions with odd singular characteristics on the Jacobian variety of a hyperelliptic Riemann surface (canonical setting). In genus g the superpropagators present g zero mode contributions
Fixing D7-brane positions by F-theory fluxes
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Braun, A.P.; Hebecker, A.; Luedeling, C.; Valandro, R.
2009-01-01
To do realistic model building in type IIB supergravity, it is important to understand how to fix D7-brane positions by the choice of fluxes. More generally, F-theory model building requires the understanding of how fluxes determine the singularity structure (and hence gauge group and matter content) of the compactification. We analyse this problem in the simple setting of M-theory on K3xK3. Given a certain flux which is consistent with the F-theory limit, we can explicitly derive the positions at which D7 branes or stacks of D7 branes are stabilised. The analysis is based on a parameterization of the moduli space of type IIB string theory on T 2 /Z 2 (including D7-brane positions) in terms of the periods of integral cycles of M-theory on K3. This allows us, in particular, to select a specific desired gauge group by the choice of flux numbers.
D-branes in non-critical superstrings and duality in N = 1 gauge theories with flavor
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Murthy, S.; Troost, J.
2006-06-01
We study D-branes in the superstring background R 3,1 x SL(2, R) k =1/U(1) which are extended in the cigar direction. Some of these branes are new. The branes realize flavor in the four dimensional N = 1 gauge theories on the D-branes localized at the tip of the cigar. We study the analytic properties of the boundary conformal field theories on these branes with respect to their defining parameter and find non- trivial monodromies in this parameter. Through this approach, we gain a better understanding of the brane set-ups in ten dimensions involving wrapped NS5-branes. As one application, using the boundary conformal field theory description of the electric and magnetic D-branes, we can understand electric-magnetic (Seiberg) duality in N = 1 SQCD microscopically in a string theoretic context. (author)
Cold dark matter in brane cosmology scenario
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Dahab, Eiman Abou El; Khalil, Shaaban
2006-01-01
We analyze the dark matter problem in the context of brane cosmology. We investigate the impact of the non-conventional brane cosmology on the relic abundance of non-relativistic stable particles in high and low reheating temperature scenarios. We show that in case of high reheating temperature, the brane cosmology may enhance the dark matter relic density by many order of magnitudes and a stringent lower bound on the five dimensional scale is obtained. We also consider low reheating temperature scenarios with chemical equilibrium and non-equilibrium. We emphasize that in non-equilibrium case, the resulting relic density is very small. While with equilibrium, it is increased by a factor of O(10 2 ) with respect to the standard thermal production. Therefore, dark matter particles with large cross section, which is favored by detection expirements, can be consistent with the recent relic density observational limits
Hamilton-Jacobi equations and brane associated Lagrangians
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Baker, L.M.; Fairlie, D.B.
2001-01-01
This article seeks to relate a recent proposal for the association of a covariant Field Theory with a string or brane Lagrangian to the Hamilton-Jacobi formalism for strings and branes. It turns out that since in this special case, the Hamiltonian depends only upon the momenta of the Jacobi fields and not the fields themselves, it is the same as a Lagrangian, subject to a constancy constraint. We find that the associated Lagrangians for strings or branes have a covariant description in terms of the square root of the same Lagrangian. If the Hamilton-Jacobi function is zero, rather than a constant, then it is in in one dimension lower, reminiscent of the 'holographic' idea. In the second part of the paper, we discuss properties of these Lagrangians, which lead to what we have called 'Universal Field Equations', characteristic of covariant equations of motion
Electromagnetic dipole radiation of oscillating D-branes
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Savvidy, G.K.
2000-01-01
I emphasize analogy between Dp-branes in string theories and solitons in gauge theories comparing their common properties and showing differences. In string theory we do not have the full set of equations which define the theory in all orders of coupling constant as it was in gauge theories, nevertheless such solutions have been found as solutions of low energy superstring effective action carrying the RR charges. The existence of dynamical RR charged extended objects in string theory has been deduced also by considering string theory with mixed boundary conditions, when type II closed superstring theory is enriched by open strings with Neumann boundary conditions on p + 1 directions and Dirichlet conditions on the remaining 9-p transverse directions. We will show that for certain excitations of the string/D3-brane system Neumann boundary conditions emerge from the Born-Infeld dynamics. Here the excitations which are coming down the string with a polarization along a direction parallel to the brane are almost completely reflected just as in the case of all-normal Dirichlet excitations considered by Callan and Maldacena, but now the end of the string moves freely on the 3-brane realizing Polchinski's open string Neumann boundary condition dynamically. In the low energy limit ω → 0, i.e. for wavelengths much larger than the string scale only a small fraction ∼ ω 4 of the energy escapes in the form of dipole radiation. The physical interpretation is that a string attached to the 3-brane manifests itself as an electric charge, and waves on the string cause the end point of the string to freely oscillate and produce e.m. dipole radiation in the asymptotic outer region. The magnitude of emitted power is in fact exactly equal to the one given by Thomson formula in electrodynamics
Supersymmetric codimension-two branes and U(1)R mediation in 6D gauged supergravity
International Nuclear Information System (INIS)
Lee, Hyun Min
2008-01-01
We construct a consistent supersymmetric action for brane chiral and vector multiplets in a six-dimensional chiral gauged supergravity. A nonzero brane tension can be accommodated by allowing for a brane-localized Fayet-Iliopoulos term proportional to the brane tension. When the brane chiral multiplet is charged under the bulk U(1) R , we obtain a nontrivial coupling to the extra component of the U(1) R gauge field strength and a singular scalar self-interaction term. Dimensionally reducing to 4D on a football supersymmetric solution, we discuss the implication of such interactions for obtaining the U(1) R D-term in the 4D effective supergravity. By assuming the bulk gaugino condensates and nonzero brane F- and/or D-term for the uplifting potential, we have all the moduli stabilized with a vanishing cosmological constant. The brane scalar with nonzero R charge then gets a soft mass of order the gravitino mass. The overall sign of the soft mass squared depends on the sign of the R charge as well as whether the brane F- or D-term dominates.
A nonperturbative test of M2-brane theory
International Nuclear Information System (INIS)
Hosomichi, Kazuo; Lee, Ki-Myeong; Lee, Sungjay; Yi, Piljin; Lee, Sangmin; Park, Jaemo
2008-01-01
We discuss non-perturbative effects in the ABJM model due to monopole instantons. We begin by constructing the instanton solutions in the U(2) x U(2) model, explicitly, and computing the Euclidean action. The Wick-rotated Lagrangian is complex and its BPS monopole instantons are found to be a delicate version of the usual 't Hooft-Polyakov monopole solutions. They are generically 1/3 BPS but become 1/2 BPS at special locus in the moduli space of two M2-branes, yet each instanton carries eight fermionic zero modes, regardless of the vacuum choice. The low energy effective action induced by monopole instantons are quartic order in derivatives. The resulting vertices are nonperturbative in 1/k, as expected, but are rational functions of the vacuum moduli. We also analyze the system of two M2-branes in the supergravity framework and compute the higher order interactions via 11-dimensional supergraviton exchange. The comparison of the two shows that the instanton vertices are precisely reproduced by this M2-brane picture, supporting the proposal that the ABJM model describes multiple M2-branes.
Intersecting branes, Higgs sector, and chirality from N = 4 SYM with soft SUSY breaking
Sperling, Marcus; Steinacker, Harold C.
2018-04-01
We consider SU( N ) N = 4 super Yang-Mills with cubic and quadratic soft SUSY breaking potential, such that the global SU(4) R is broken to SU(3) or further. As shown recently, this set-up supports a rich set of non-trivial vacua with the geometry of self-intersecting SU(3) branes in 6 extra dimensions. The zero modes on these branes can be interpreted as 3 generations of bosonic and chiral fermionic strings connecting the branes at their intersections. Here, we uncover a large class of exact solutions consisting of branes connected by Higgs condensates, leading to Yukawa couplings between the chiral fermionic zero modes. Under certain decoupling conditions, the backreaction of the Higgs on the branes vanishes exactly. The resulting physics is that of a spontaneously broken chiral gauge theory on branes with fluxes. In particular, we identify combined brane plus Higgs configurations which lead to gauge fields that couple to chiral fermions at low energy. This turns out to be quite close to the Standard Model and its constructions via branes in string theory. As a by-product, we construct a G 2-brane solution corresponding to a squashed fuzzy coadjoint orbit of G 2.
Experimental Signatures of Strings and Branes
Antoniadis, I.
2007-01-01
Type I string theory provides a D-brane world description of our universe and leads to two new scenaria for physics beyond the Standard Model: low string scale and plit supersymmetry. Lowering the string scale in the TeV region provides a heoretical framework for solving the mass hierarchy problem and unifymg all interactions. The apparent weakn'ess of gravity can then be accounted by the existence of large internal dimensions, in the submillimeter region, and transverse to a braneworld where we must be confined. I review the main properties of this scenario and its implications for observations at both particle cofiders, and in non-accelerator gravity experiments. I also review the main properties of split supersymmetry and present a concrete string realization which guarantees gauge coupling unification at the conventional scale $M_{GUT}\\approx2$ x $10^{16}$GeV.
Heterotic/type I duality and D-brane instantons
Bachas, C.; Fabre, C.; Kiritsis, E.; Obers, N. A.; Vanhove, P.
1998-01-01
We study heterotic/type I duality in d = 8, 9 uncompactified dimensions. We consider the special ("BPS-saturated") F4 and R4 terms in the effective one-loop heterotic action, which are expected to be non-perturbatively exact. Under the standard duality map these translate to tree-level, perturbative and non-perturbative contributions on the type I side. We check agreement with the one-loop open string calculation, and discuss the higher-order perturbative contributions, which arise because of the mild non-holomorphicities of the heterotic elliptic genus. We put the heterotic world-sheet instanton corrections in a form that can be motivated as arising from a D-brane instanton calculation on the type I side.
Heterotic/type I duality and D-brane instantons
International Nuclear Information System (INIS)
Bachas, C.; Fabre, C.; Vanhove, P.
1998-01-01
We study heterotic/type I duality in d=8,9 uncompactified dimensions. We consider the special (''BPS-saturated'') F 4 and R 4 terms in the effective one-loop heterotic action, which are expected to be non-perturbatively exact. Under the standard duality map these translate to tree-level, perturbative and non-perturbative contributions on the type I side. We check agreement with the one-loop open string calculation, and discuss the higher-order perturbative contributions, which arise because of the mild non-holomorphicities of the heterotic elliptic genus. We put the heterotic world-sheet instanton corrections in a form that can be motivated as arising from a D-brane instanton calculation on the type I side. (orig.)
Heterotic / type-I duality and D-brane instantons
Bachas, C P; Kiritsis, Elias B; Obers, N A; Vanhove, P
1998-01-01
We study heterotic/type-I duality in d=8,9 uncompactified dimensions. We consider the special (``BPS saturated'') F^4 and R^4 terms in the effective one-loop heterotic action, which are expected to be non-perturbatively exact. Under the standard duality map these translate to tree-level, perturbative and non-perturbative contributions on the type I side. We check agreement with the one-loop open string calculation, and discuss the higher-order perturbative contributions, which arise because of the mild non-holomorphicities of the heterotic elliptic genus. We put the heterotic world-sheet instanton corrections in a form that can be recognized easily as arising from a D-brane instanton calculation on the type-I side.
Atlas warping for brain morphometry
Machado, Alexei M. C.; Gee, James C.
1998-06-01
In this work, we describe an automated approach to morphometry based on spatial normalizations of the data, and demonstrate its application to the analysis of gender differences in the human corpus callosum. The purpose is to describe a population by a reduced and representative set of variables, from which a prior model can be constructed. Our approach is rooted in the assumption that individual anatomies can be considered as quantitative variations on a common underlying qualitative plane. We can therefore imagine that a given individual's anatomy is a warped version of some referential anatomy, also known as an atlas. The spatial warps which transform a labeled atlas into anatomic alignment with a population yield immediate knowledge about organ size and shape in the group. Furthermore, variation within the set of spatial warps is directly related to the anatomic variation among the subjects. Specifically, the shape statistics--mean and variance of the mappings--for the population can be calculated in a special basis, and an eigendecomposition of the variance performed to identify the most significant modes of shape variation. The results obtained with the corpus callosum study confirm the existence of substantial anatomical differences between males and females, as reported in previous experimental work.
Superdualities, brane tensions and massive IIA/IIB duality
International Nuclear Information System (INIS)
Lavrinenko, I.V.; Lue, H.; Pope, C.N.; Stelle, K.S.
1999-01-01
The gauge transformations of p-form fields in supergravity theories acquire a non-commuting character when one introduces potentials both for the theory's original field strengths and for their duals. This has previously been shown in the 'doubled' formalism for maximal supergravities, where a generalised duality relation between original and dual field strengths replaces the equations of motion. In the doubled formalism, the gauge transformations generate a superalgebra, and the corresponding symmetries have accordingly been called 'superdualities'. The corresponding Noether charges form a representation of the cohomology ring on the space-time manifold. In this paper, we show that the gauge symmetry superalgebra implies certain non-trivial relations among the various p-brane tensions, which can straightforwardly be read off from the superalgebra commutation relations. This provides an elegant derivation of the brane-tension relations purely within a given theory, without the need to make use of duality relations between different theories, such as the type IIA/IIB T-duality, although the results are consistent with such dualities. We present the complete set of brane-tension relations in M-theory, in the type IIA and type IIB theories, and in all the lower-dimensional maximal supergravities. We also construct a doubled formalism for massive type IIA supergravity, and this enables us to obtain the brane-tension relations involving the D8-brane, purely within the framework of the massive IIA theory. We also obtain explicit transformations for the nine-dimensional T-duality between the massive type IIA theory and the Scherk-Schwarz reduced type IIB theory
U duality, D-branes, and black hole emission rates: Agreements and disagreements
International Nuclear Information System (INIS)
Dowker, F.; Kastor, D.; Traschen, J.
1998-01-01
An expression for the spacetime absorption coefficient of a scalar field in a five-dimensional, near-extremal black hole background is derived, which has the same form as that presented by Maldacena and Strominger, but is valid over a larger, U-duality invariant region of parameter space and in general disagrees with the corresponding D-brane result. We develop an argument, based on D-brane thermodynamics, which specifies the range of parameters over which agreement should be expected. For neutral emission, the spacetime and D-brane results agree over this range. However, for charged emission, we find disagreement in the 'fat black hole' regime, in which charge is quantized in smaller units on the brane than in the bulk of spacetime. We indicate a possible problem with the D-brane model in this regime. We also use the Born approximation to study the high frequency limit of the absorption coefficient and find that it approaches unity, for large black hole backgrounds, at frequencies still below the string scale, again in disagreement with D-brane results. copyright 1998 The American Physical Society
Superluminal warp drives are semiclassically unstable
Energy Technology Data Exchange (ETDEWEB)
Finazzi, S; Liberati, S [SISSA, via Beirut 2-4, Trieste 34151, Italy and INFN sezione di Trieste (Italy); Barcelo, C, E-mail: finazzi@sissa.i, E-mail: liberati@sissa.i, E-mail: carlos@iaa.e [Instituto de Astrofisica de AndalucIa, CSIC, Camino Bajo de Huetor 50, 18008 Granada (Spain)
2010-04-01
Warp drives are very interesting configurations of General Relativity: they provide a way to travel at superluminal speeds, albeit at the cost of requiring exotic matter to build them. Even if one succeeded in providing the necessary exotic matter, it would still be necessary to check whether they would survive to the switching on of quantum effects. Semiclassical corrections to warp-drive geometries created out of an initially flat spacetime have been analyzed in a previous work by the present authors in special locations, close to the wall of the bubble and in its center. Here, we present an exact numerical analysis of the renormalized stress-energy tensor (RSET) in the whole bubble. We find that the the RSET will exponentially grow in time close to the front wall of the superluminal bubble, after some transient terms have disappeared, hence strongly supporting our previous conclusion that the warp-drive geometries are unstable against semiclassical back-reaction. This result seems to implement the chronology protection conjecture, forbiddig the set up of a structure potentially dangerous for causality.
The bosonic mother of fermionic D-branes
Chattaraputi, Auttakit; Englert, Francois; Houart, Laurent; Taormina, Anne
2002-01-01
We extend the search for fermionic subspaces of the bosonic string compactified on E8 X SO(16) lattices to include all fermionic D-branes. This extension constraints the truncation procedure previously proposed and relates the fermionic strings, supersymmetric or not, to the global structure of the SO(16) group. The specific properties of all the fermionic D-branes are found to be encoded in its universal covering, whose maximal toroid defines the configuration space torus of their mother bos...
Brane decay and an initial spacelike singularity.
Kawai, Shinsuke; Keski-Vakkuri, Esko; Leigh, Robert G; Nowling, Sean
2006-01-27
We present a novel string theory scenario where matter in a spacetime originates from a decaying brane at the origin of time. The decay could be considered as a big-bang-like event at X0=0. The closed string interpretation is a time-dependent spacetime with a semi-infinite time direction, with the initial energy of the brane converted into energy flux from the origin. The open string interpretation can be viewed as a string theoretic nonsingular initial condition.
International Nuclear Information System (INIS)
Cai Ronggen; Li Tong; Li Xueqian; Wang Xun
2007-01-01
Motivated by the alpha-magnetic-spectrometer (AMS) project, we assume that after the big bang or inflation epoch, antimatter was repelled onto one brane which is separated from our brane where all the observational matter resides. It is suggested that CP may be spontaneously broken, the two branes would correspond to ground states for matter and antimatter, respectively. Generally a complex scalar field which is responsible for the spontaneous CP violation, exists in the space between the branes. The matter and antimatter on the two branes attract each other via gravitational force, meanwhile the scalar field causes a Casimir effect to result in a repulsive force against the gravitation. We find that the Casimir force is much stronger than the gravitational force, as long as the separation of the two branes is small. Thus at early epoch after the big bang, the two branes were closer and then have been separated by the Casimir repulsive force from each other. The trend will continue until the separation is sufficiently large and then the gravitational force observed in our four-space would obviously deviate from the Newton's universal gravitational law. We suppose that there is a potential barrier at the brane boundary, which is similar to the surface tension for a water membrane. The barrier prevents the matter (antimatter) particles from entering the space between two branes and jump from one brane to another. However, by the quantum tunneling, a sizable antimatter flux may come to our brane and be observed by the AMS. In this work by considering two possible models, i.e. the naive flat space-time and Randall-Sundrum models, and using the observational data on the visible matter in our universe as inputs, we derive the antimatter flux which comes to our detector in the nonrelativistic approximation and make a rough numerical estimate of possible numbers of antihelium at AMS
Time Warp Operating System (TWOS)
Bellenot, Steven F.
1993-01-01
Designed to support parallel discrete-event simulation, TWOS is complete implementation of Time Warp mechanism - distributed protocol for virtual time synchronization based on process rollback and message annihilation.
Brane/Flux Annihilation and the String Dual of a Non-Supersymmetric Field Theory
International Nuclear Information System (INIS)
Kachru, Shamit
2002-01-01
We consider the dynamics of p anti-D3 branes inside the Klebanov-Strassler geometry, the deformed conifold with M units of RR 3-form flux around the S 3 . We find that for p << M the system relaxes to a nonsupersymmetric NS 5-brane ''giant graviton'' configuration, which is classically stable, but quantum mechanically can tunnel to a nearby supersymmetric vacuum with M - p D3 branes. This decay mode is exponentially suppressed and proceeds via the nucleation of an NS 5-brane bubble wall. They propose a dual field theory interpretation of the decay as the transition between a nonsupersymmetric baryonic branch and a supersymmetric mesonic branch of the corresponding SU(2M-p) x SU(M-p) low energy gauge theory. The NS 5-brane tunneling process also provides a simple visualization of the geometric transition by which D3-branes can dissolve into 3-form flux
Evaluation of the Intel iWarp parallel processor for space flight applications
Hine, Butler P., III; Fong, Terrence W.
1993-01-01
The potential of a DARPA-sponsored advanced processor, the Intel iWarp, for use in future SSF Data Management Systems (DMS) upgrades is evaluated through integration into the Ames DMS testbed and applications testing. The iWarp is a distributed, parallel computing system well suited for high performance computing applications such as matrix operations and image processing. The system architecture is modular, supports systolic and message-based computation, and is capable of providing massive computational power in a low-cost, low-power package. As a consequence, the iWarp offers significant potential for advanced space-based computing. This research seeks to determine the iWarp's suitability as a processing device for space missions. In particular, the project focuses on evaluating the ease of integrating the iWarp into the SSF DMS baseline architecture and the iWarp's ability to support computationally stressing applications representative of SSF tasks.
Superworld volume dynamics of super branes from nonlinear realizations
International Nuclear Information System (INIS)
Bellucci, S.; Ivanov, E.; Krivonos, S.
2000-01-01
Based on the concept of the partial breaking of global supersymmetry (PBGS), it has been derived the world volume superfield equations of motion for N=1, D=4 supermembrane, as well as for the space-time filling D2- and D3-branes, from nonlinear realizations of the corresponding supersymmetries. It has been argued that it is of no need to take care of the relevant automorphism groups when being interested in the dynamical equations. This essentially facilitates computations. As a by-product, it has been obtained a new polynomial representation for the d=3,4 Born-Infeld equations, with merely a cubic nonlinearity
T-branes and α{sup ′}-corrections
Energy Technology Data Exchange (ETDEWEB)
Marchesano, Fernando; Schwieger, Sebastian [Instituto de Física Teórica UAM-CSIC,Cantoblanco, 28049 Madrid (Spain)
2016-11-21
We study α’-corrections in multiple D7-brane configurations with non-commuting profiles for their transverse position fields. We focus on T-brane systems, crucial in F-theory GUT model building. There α{sup ′}-corrections modify the D-term piece of the BPS equations which, already at leading order, require a non-primitive Abelian worldvolume flux background. We find that α{sup ′}-corrections may either i) leave this flux background invariant, ii) modify the Abelian non-primitive flux profile, or iii) deform it to a non-Abelian profile. The last case typically occurs when primitive fluxes, a necessary ingredient to build 4d chiral models, are added to the system. We illustrate these three cases by solving the α{sup ′}-corrected D-term equations in explicit examples, and describe their appearance in more general T-brane backgrounds. Finally, we discuss implications of our findings for F-theory GUT local models.
Indian Academy of Sciences (India)
K Sridhar
2017-10-05
Oct 5, 2017 ... fields localized on the IR brane. Thus, mass scales which suppress dangerous higher-dimensional opera- tors responsible for proton decay or neutrino masses also become small which spells a disaster for the RS model. One way out of this is to realize that to solve the gauge-hierarchy problem one needs ...
Radius stabilization and brane running in the Randall-Sundrum type 1 model
International Nuclear Information System (INIS)
Brevik, Iver; Ghoroku, Kazuo; Yahiro, Masanobu
2004-01-01
We study the effective potential of a scalar field based on the 5D gauged supergravity for the Randall-Sundrum type one brane model in terms of the brane running method. The scalar couples to the brane such that the Bogomolnyi-Prasad-Sommerfield conditions are satisfied for the bulk configuration. The resulting effective potential implies that the interbrane distance is undetermined in this case, and we need a small Bogomolnyi-Prasad-Sommerfield breaking term on the brane to stabilize the interbrane distance at a finite length. We also discuss the relationship to the Goldberger-Wise model
Some examples of image warping for low vision prosthesis
Juday, Richard D.; Loshin, David S.
1988-01-01
NASA has developed an image processor, the Programmable Remapper, for certain functions in machine vision. The Remapper performs a highly arbitrary geometric warping of an image at video rate. It might ultimately be shrunk to a size and cost that could allow its use in a low-vision prosthesis. Coordinate warpings have been developed for retinitis pigmentosa (tunnel vision) and for maculapathy (loss of central field) that are intended to make best use of the patient's remaining viable retina. The rationales and mathematics are presented for some warpings that we will try in clinical studies using the Remapper's prototype.
Asymptotically spacelike warped anti-de Sitter spacetimes in generalized minimal massive gravity
International Nuclear Information System (INIS)
Setare, M R; Adami, H
2017-01-01
In this paper we show that warped AdS 3 black hole spacetime is a solution of the generalized minimal massive gravity (GMMG) and introduce suitable boundary conditions for asymptotically warped AdS 3 spacetimes. Then we find the Killing vector fields such that transformations generated by them preserve the considered boundary conditions. We calculate the conserved charges which correspond to the obtained Killing vector fields and show that the algebra of the asymptotic conserved charges is given as the semi direct product of the Virasoro algebra with U (1) current algebra. We use a particular Sugawara construction to reconstruct the conformal algebra. Thus, we are allowed to use the Cardy formula to calculate the entropy of the warped black hole. We demonstrate that the gravitational entropy of the warped black hole exactly coincides with what we obtain via Cardy’s formula. As we expect, the warped Cardy formula also gives us exactly the same result as we obtain from the usual Cardy’s formula. We calculate mass and angular momentum of the warped black hole and then check that obtained mass, angular momentum and entropy to satisfy the first law of the black hole mechanics. According to the results of this paper we believe that the dual theory of the warped AdS 3 black hole solution of GMMG is a warped CFT. (paper)
Towards a classification of branes in theories with eight supercharges
Bergshoeff, Eric A.; Riccioni, Fabio; Romano, Luca
2014-01-01
We provide a classification of half-supersymmetric branes in quarter-maximal supergravity theories with scalars parametrising coset manifolds. We show that the results previously obtained for the half-maximal theories give evidence that half-supersymmetric branes correspond to the real longest
Non-linear dynamics in galactic disks: the spiral-warps connection
International Nuclear Information System (INIS)
Masset, Frederic
1997-01-01
After a recall on warp theories and on warp waves, this research thesis reports a linear study of warp waves with an assessment of the role of gas compressibility when taking the galactic disk thickness into account. Then, the author reports an analytical study of the non-linear coupling between warp waves and density waves, in order to calculate coupling efficiency, to identify areas of the galactic disk in which it is efficient, and to discuss concurrent physical processes (such as Landau absorption) and the validity of assumptions made to perform the calculations. The next part reports numerical simulations which have been performed to check the coupling mechanism. The author notably comments evolutions brought to existing codes, and finally presents the three-dimensional version of the developed code, and discusses choices made for this code (presence of gas, choice of hydrodynamics algorithms and of gas mesh geometry, and so on). Numerical results are then presented and discussed: they actually show the existence of a coupling between density waves and warp waves [fr
Inflation and late-time acceleration in braneworld cosmological models with varying brane tension
International Nuclear Information System (INIS)
Wong, K.C.; Cheng, K.S.; Harko, T.
2010-01-01
Braneworld models with variable brane tension λ introduce a new degree of freedom that allows for evolving gravitational and cosmological constants, the latter being a natural candidate for dark energy. We consider a thermodynamic interpretation of the varying brane tension models, by showing that the field equations with variable λ can be interpreted as describing matter creation in a cosmological framework. The particle creation rate is determined by the variation rate of the brane tension, as well as by the brane-bulk energy-matter transfer rate. We investigate the effect of a variable brane tension on the cosmological evolution of the Universe, in the framework of a particular model in which the brane tension is an exponentially dependent function of the scale factor. The resulting cosmology shows the presence of an initial inflationary expansion, followed by a decelerating phase, and by a smooth transition towards a late accelerated de Sitter type expansion. The varying brane tension is also responsible for the generation of the matter in the Universe (reheating period). The physical constraints on the model parameters, resulting from the observational cosmological data, are also investigated. (orig.)
Warped Kähler potentials and fluxes
International Nuclear Information System (INIS)
Martucci, Luca
2017-01-01
The four-dimensional effective theory for type IIB warped flux compactifications proposed in https://www.doi.org/10.1007/JHEP03(2015)067 is completed by taking into account the backreaction of the Kähler moduli on the three-form fluxes. The only required modification consists in a flux-dependent contribution to the chiral fields parametrising the Kähler moduli. The resulting supersymmetric effective theory satisfies the no-scale condition and consistently combines previous partial results present in the literature. Similar results hold for M-theory warped compactifications on Calabi-Yau fourfolds, whose effective field theory and Kähler potential are also discussed.
Warped Kähler potentials and fluxes
Energy Technology Data Exchange (ETDEWEB)
Martucci, Luca [Dipartimento di Fisica ed Astronomia “Galileo Galilei' ,Università di Padova & I.N.F.N. Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy)
2017-01-13
The four-dimensional effective theory for type IIB warped flux compactifications proposed in https://www.doi.org/10.1007/JHEP03(2015)067 is completed by taking into account the backreaction of the Kähler moduli on the three-form fluxes. The only required modification consists in a flux-dependent contribution to the chiral fields parametrising the Kähler moduli. The resulting supersymmetric effective theory satisfies the no-scale condition and consistently combines previous partial results present in the literature. Similar results hold for M-theory warped compactifications on Calabi-Yau fourfolds, whose effective field theory and Kähler potential are also discussed.
Seamless warping of diffusion tensor fields
DEFF Research Database (Denmark)
Xu, Dongrong; Hao, Xuejun; Bansal, Ravi
2008-01-01
deformations in an attempt to ensure that the local deformations in the warped image remains true to the orientation of the underlying fibers; forward mapping, however, can also create "seams" or gaps and consequently artifacts in the warped image by failing to define accurately the voxels in the template...... space where the magnitude of the deformation is large (e.g., |Jacobian| > 1). Backward mapping, in contrast, defines voxels in the template space by mapping them back to locations in the original imaging space. Backward mapping allows every voxel in the template space to be defined without the creation...
M-theory inflation from multi M5-brane dynamics
International Nuclear Information System (INIS)
Becker, Katrin; Becker, Melanie; Krause, Axel
2005-01-01
We derive inflation from M-theory on S 1 /Z 2 via the non-perturbative dynamics of N M5-branes. The open membrane instanton interactions between the M5-branes give rise to exponential potentials which are too steep for inflation individually but lead to inflation when combined together. The resulting type of inflation, known as assisted inflation, facilitates considerably the requirement of having all moduli, except the inflaton, stabilized at the beginning of inflation. During inflation the distances between the M5-branes, which correspond to the inflatons, grow until they reach the size of the S 1 /Z 2 orbifold. At this stage the M5-branes will reheat the universe by dissolving into the boundaries through small instanton transitions. Further flux and non-perturbative contributions become important at this late stage, bringing inflation to an end and stabilizing the moduli. We find that with moderate values for N, one obtains both a sufficient amount of e-foldings and the right size for the spectral index
Brane inflation: A field theory approach in background supergravity
International Nuclear Information System (INIS)
Choudhury, Sayantan; Pal, Supratik
2012-01-01
We propose a model of inflation in the framework of brane cosmology driven by background supergravity. Starting from bulk supergravity we construct the inflaton potential on the brane and employ it to investigate for the consequences to inflationary paradigm. To this end, we derive the expressions for the important parameters in brane inflation, which are somewhat different from their counterparts in standard cosmology, using the one loop radiative corrected potential. We further estimate the observable parameters and find them to fit well with recent observational data. We have studied extensively reheating phenomenology, which explains the thermal history of the universe and leptogenesis through the production of thermal gravitino pertaining to the particle physics phenomenology of the early universe.
Hair-brane ideas on the horizon
International Nuclear Information System (INIS)
Martinec, Emil J.; Niehoff, Ben E.
2015-01-01
We continue an examination of the microstate geometries program begun in arXiv:1409.6017, focussing on the role of branes that wrap the cycles which degenerate when a throat in the geometry deepens and a horizon forms. An associated quiver quantum mechanical model of minimally wrapped branes exhibits a non-negligible fraction of the gravitational entropy, which scales correctly as a function of the charges. The results suggest a picture of AdS_3/CFT_2 duality wherein the long string that accounts for BTZ black hole entropy in the CFT description, can also be seen to inhabit the horizon of BPS black holes on the gravity side.
Hair-brane ideas on the horizon
Energy Technology Data Exchange (ETDEWEB)
Martinec, Emil J. [Enrico Fermi Institute and Department of Physics, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637-1433 (United States); Niehoff, Ben E. [Department of Applied Mathematics and Theoretical Physics, University of Cambridge,Centre for Mathematical Sciences,Wilberforce Rd., Cambridge, CB3 0WA (United Kingdom)
2015-11-27
We continue an examination of the microstate geometries program begun in arXiv:1409.6017, focussing on the role of branes that wrap the cycles which degenerate when a throat in the geometry deepens and a horizon forms. An associated quiver quantum mechanical model of minimally wrapped branes exhibits a non-negligible fraction of the gravitational entropy, which scales correctly as a function of the charges. The results suggest a picture of AdS{sub 3}/CFT{sub 2} duality wherein the long string that accounts for BTZ black hole entropy in the CFT description, can also be seen to inhabit the horizon of BPS black holes on the gravity side.
Dirac relaxation of the Israel junction conditions: Unified Randall-Sundrum brane theory
International Nuclear Information System (INIS)
Davidson, Aharon; Gurwich, Ilya
2006-01-01
Following Dirac's brane variation prescription, the brane must not be deformed during the variation process, or else the linearity of the variation may be lost. Alternatively, the variation of the brane is done, in a special Dirac frame, by varying the bulk coordinate system itself. Imposing appropriate Dirac-style boundary conditions on the constrained 'sandwiched' gravitational action, we show how Israel junction conditions get relaxed, but remarkably, all solutions of the original Israel equations are still respected. The Israel junction conditions are traded, in the Z 2 -symmetric case, for a generalized Regge-Teitelboim type equation (plus a local conservation law), and in the generic Z 2 -asymmetric case, for a pair of coupled Regge-Teitelboim equations. The Randall-Sundrum model and its derivatives, such as the Dvali-Gabadadze-Porrati and the Collins-Holdom models, get generalized accordingly. Furthermore, Randall-Sundrum and Regge-Teitelboim brane theories appear now to be two different faces of the one and the same unified brane theory. Within the framework of unified brane cosmology, we examine the dark matter/energy interpretation of the effective energy/momentum deviations from general relativity
The impact of emerging technology on nursing care: warp speed ahead.
Huston, Carol
2013-05-31
While myriad forces are changing the face of contemporary healthcare, one could argue that nothing will change the way nursing is practiced more than current advances in technology. Indeed, technology is changing the world at warp speed and nowhere is this more evident than in healthcare settings. This article identifies seven emerging technologies that will change the practice of nursing; three skill sets nurses will need to develop to acquire, use, and integrate these emerging technologies; and four challenges nurse leaders will face in integrating this new technology.
D-brane disformal coupling and thermal dark matter
Dutta, Bhaskar; Jimenez, Esteban; Zavala, Ivonne
2017-11-01
Conformal and disformal couplings between a scalar field and matter occur naturally in general scalar-tensor theories. In D-brane models of cosmology and particle physics, these couplings originate from the D-brane action describing the dynamics of its transverse (the scalar) and longitudinal (matter) fluctuations, which are thus coupled. During the post-inflationary regime and before the onset of big bang nucleosynthesis (BBN), these couplings can modify the expansion rate felt by matter, changing the predictions for the thermal relic abundance of dark matter particles and thus the annihilation rate required to satisfy the dark matter content today. We study the D-brane-like conformal and disformal couplings effect on the expansion rate of the Universe prior to BBN and its impact on the dark matter relic abundance and annihilation rate. For a purely disformal coupling, the expansion rate is always enhanced with respect to the standard one. This gives rise to larger cross sections when compared to the standard thermal prediction for a range of dark matter masses, which will be probed by future experiments. In a D-brane-like scenario, the scale at which the expansion rate enhancement occurs depends on the string coupling and the string scale.