Configurational entropy in brane-world models
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
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
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.)
Solar system tests of brane world models
Boehmer, Christian G; Lobo, Francisco S N
2008-01-01
The classical tests of general relativity (perihelion precession, deflection of light, and the radar echo delay) are considered for the Dadhich, Maartens, Papadopoulos and Rezania (DMPR) solution of the spherically symmetric static vacuum field equations in brane world models. For this solution the metric in the vacuum exterior to a brane world star is similar to the Reissner-Nordstrom form of classical general relativity, with the role of the charge played by the tidal effects arising from projections of the fifth dimension. The existing observational solar system data on the perihelion shift of Mercury, on the light bending around the Sun (obtained using long-baseline radio interferometry), and ranging to Mars using the Viking lander, constrain the numerical values of the bulk tidal parameter and of the brane tension.
Clustering of Galaxies in Brane World Models
Hameeda, Mir; Faizal, Mir; Ali, Ahmed Farag
2015-01-01
In this paper, we analyze the clustering of galaxies using a modified Newtonian potential. This modification of the Newtonian potential occurs due to the existence of extra dimensions in brane world models. We will analyze a system of galaxies interacting with each other through this modified Newtonian potential. The partition function for this system of galaxies will be calculated, and this partition function will be used to calculate the free energy of this system of galaxies. The entropy a...
Modeling a network of brane worlds
We study junctions of supersymmetric domain walls in N=1 supergravity theories in four dimensions, coupled to a chiral superfield with quartic superpotential having Z3 symmetry. After deriving a BPS equation of the domain wall junction, we consider a stable hexagonal configuration of network of brane junctions, which are only approximately locally BPS. We propose a model for a mechanism of supersymmetry breaking without loss of stability, where a messenger for the SUSY breaking comes from the neighboring anti-BPS junction world, propagating along the domain walls connection them. (author)
Clustering of Galaxies in Brane World Models
Hameeda, Mir; Ali, Ahmed Farag
2015-01-01
In this paper, we analyze the clustering of galaxies using a modified Newtonian potential. This modification of the Newtonian potential occurs due to the existence of extra dimensions in brane world models. We will analyze a system of galaxies interacting with each other through this modified Newtonian potential. The partition function for this system of galaxies will be calculated, and this partition function will be used to calculate the free energy of this system of galaxies. The entropy and the chemical potential for this system will also be calculated. We will derive an explicit expression for the clustering parameter for this system. This parameter will determine the behavior of this system, and we will be able to express various thermodynamic quantities using this clustering parameter. Thus, we will be able to explicitly analyze the effect that modifying the Newtonian potential can have on the clustering of galaxies.
Clustering of galaxies in brane world models
Hameeda, Mir; Faizal, Mir; Ali, Ahmed Farag
2016-04-01
In this paper, we analyze the clustering of galaxies using a modified Newtonian potential. This modification of the Newtonian potential occurs due to the existence of extra dimensions in brane world models. We will analyze a system of galaxies interacting with each other through this modified Newtonian potential. The partition function for this system of galaxies will be calculated, and this partition function will be used to calculate the free energy of this system of galaxies. The entropy and the chemical potential for this system will also be calculated. We will derive explicit expression for the clustering parameter for this system. This parameter will determine the behavior of this system, and we will be able to express various thermodynamic quantities using this clustering parameter. Thus, we will be able to explicitly analyze the effect that modifying the Newtonian potential can have on the clustering of galaxies. We also analyse the effect of extra dimensions on the two-point functions between galaxies.
Dileep P Jatkar
2003-02-01
We review proposals of brane world models which attempt to combine gauge theories with gravity at TeV scale by conﬁning the gauge theory to a three-brane embedded in higher dimensional bulk. Gravity, however, propagates in the directions transverse to the brane as well.
Brane-World Black Holes in Randall-Sundrum Models
Kim, W T; Oh, M K; Yoon, M S; Kim, Won Tae; Oh, John J.; Oh, Marie K.; Yoon, Myung Seok
2000-01-01
We study brane-world black holes from Randall-Sundrum(RS) models in ($D+1$)-dimensional anti-de Sitter spacetimes. The solutions are directly obtained by using a slightly modified RS metric ansatz in $D+1$ dimensions. The metric of the brane world can be described by the Schwarzschild solution promoted to the black cigar solution in $D+1$ dimensions, which is compatible with the recently suggested black cigar solution for D=4. Furthermore, we show that the Ricci flat condition for the brane can be easily derived from the effective gravity defined on the brane by using the RS dimensional reduction. Especially, it is shown that in two dimensions the effective gravity on the brane is described by the Polyakov action.
Inflation in Brane World Gravity
Banerjee, Argha
2015-01-01
We study the inflationary dynamics in Brane World gravity and look for observational signatures of any deviation from the standard General Relativity based results of Cosmological Perturbation Theory. We first review the standard paradigm of General Relativity based inflationary dynamics and cosmological perturbation theory and then go on to review Brane World gravity. Finally we look at the high energy corrections for some chosen models and compare the results with the Planck and WMAP (9 year) data. Then we make a summary of our results and point out certain interesting features of Brane World gravity based calculations and infer it's implications on Brane World gravity itself.
Maartens Roy
2004-01-01
Full Text Available The observable universe could be a 1+3-surface (the "brane" embedded in a 1+3+$d$-dimensional spacetime (the "bulk", with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the $d$ extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak ($sim$TeV level. This revolutionary picture arises in the framework of recent developments in M theory. The 1+10-dimensional M theory encompasses the known 1+9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. General relativity cannot describe gravity at high enough energies and must be replaced by a quantum gravity theory, picking up significant corrections as the fundamental energy scale is approached. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review discusses the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall-Sundrum models.
Wands, David
1999-01-01
A simple model of the brane-world cosmology has been proposed, which is characterized by four parameters, the bulk cosmological constant, the spatial curvature of the universe, the radiation strength arising from bulk space-time and the breaking parameter of $Z_2$-symmetry. The bulk space-time is assumed to be locally static five-dimensional analogue of the Schwarzschild-anti-de Sitter space-time, and then the location of three-brane is determined by metric junction. The resulting Friedmann e...
Sarrazin, M; Sarrazin, Michael; Petit, Fabrice
2004-01-01
In recent few years, there has been a number of papers devoted to the brane world theories which appear to be of potential interest for explaining several puzzling physical phenomena. Inspired from those models, we propose in this paper to consider relevant extensions of the Dirac and Pauli equations for a two brane universe. This model assumes that the branes are embedded in a 5D bulk where the fifth dimension is restricted to only two points. In previous attempts to describe quantum effects involving branes, graviton oscillations have been suggested as well as the possibility for highly energetic particles to escape into the 5D bulk. In this paper, we predict that usual matter particles can oscillate between the two branes as well. It is suggested that this phenomenon, which is a low energy one, might be enhanced using electromagnetic fields and could perhaps be demonstrated at a laboratory scale.
Gravitomagnetism in Brane-Worlds
Nayeri, Ali; Reynolds, Adam
2001-01-01
In this paper we discuss a physical observable which is drastically different in a brane-world scenario. To date, the Randall-Sundrum model seems to be consistent with all experimental tests of general relativity. Specifically, we examine the so-called gravitomagnetic effect in the context of the Randall-Sundrum (RS) model. This treatment, of course, assumes the recovery of the Kerr metric in brane-worlds which we have found to the first order in the ratio of the brane separation to the radiu...
Fermions in five-dimensional brane world models
Smolyakov, Mikhail N
2016-01-01
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...
Simple inflationary models in Gauss–Bonnet brane-world cosmology
Okada, Nobuchika; Okada, Satomi
2016-06-01
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.
The virial theorem and the dynamics of clusters of galaxies in the brane world models
Harko, T.; Cheng, K. S.
2007-01-01
A version of the virial theorem, which takes into account the effects of the non-compact extra-dimensions, is derived in the framework of the brane world models. In the braneworld scenario, the four dimensional effective Einstein equation has some extra terms, called dark radiation and dark pressure, respectively, which arise from the embedding of the 3-brane in the bulk. To derive the generalized virial theorem we use a method based on the collisionless Boltzmann equation. The dark radiation...
Enveloping branes and brane-world singularities
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.)
On Closed Timelike Curves and Warped Brane World Models
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.
Rotating Brane World Black Holes
Modgil, Moninder Singh; Panda, Sukanta; Sengupta, Gautam
2001-01-01
A five dimensional rotating black string in a Randall-Sundrum brane world is considered. The black string intercepts the three brane in a four dimensional rotating black hole. The geodesic equations and the asymptotics in this background are discussed.
Gravitomagnetism in Brane-Worlds
Nayeri, A; Nayeri, Ali; Reynolds, Adam
2001-01-01
In this paper we discuss a physical observable which is drastically different in a brane-world scenario. To date, the Randall-Sundrum model seems to be consistent with all experimental tests of general relativity. Specifically, we examine the so-called gravitomagnetic effect in the context of the Randall-Sundrum (RS) model. This treatment, of course, assumes the recovery of the Kerr metric in brane-worlds which we have found to the first order in the ratio of the brane separation to the radius of the AdS$_5$, $(\\ell/r)$. We first show that the second Randall-Sundrum model of one brane leaves the gravitomagnetic effect unchanged. Then, we consider the two-brane scenario of the original Randall-Sundrum proposal and show that the magnitude of the gravitomagnetic effect depends heavily on the ratio of $(\\ell/r)$. Such dependence is a result of the geometrodynamic spacetime and does not appear in static scenarios. We hope that we will be able to test this proposal experimentally with data from NASA's Gravity Probe...
On cross-section computation in the brane-world models
We present Mathematica7 numerical simulation of the process pp → jet + E/Tin the framework of modified Randall-Sundrum brane-world model with one infinite and n compact extra dimension. We compare the energy missing signature with the standard model background pp → jet + v v-bar , which was simulated at CompHep. We show that the models with numbers of compact extra dimensions greater than 4 can be probed at the protons center-of-mass energy equal 14 TeV. We also find that testing the brane-world models at 7 TeV on the LHC appears to hopeless
Metric factorizability and equivalence of brane world models with Brans-Dicke theory
Chakraborty, Sumanta
2015-01-01
In the standard brane world models, the bulk metric ansatz is usually assumed to be factorizable in brane and bulk coordinates. However it is not self evident that it is always possible to factorize the bulk metric. Using gradient expansion scheme, which involves, expansion of bulk quantities in terms of the brane to bulk curvature ratio, as perturbative parameter, we have explicitly shown that upto second order in perturbative expansion, metric factorizability is a valid assumption. We have also argued from our result that the same should be true for all orders in the perturbation scheme. We further establish that the non-local terms present in the bulk gravitational field equation can be replaced by radion field and the effective action on the brane obtained thereof resembles Brans-Dicke theory of gravity.
A varying-e brane world cosmology
We study a varying electric charge brane world cosmology in the RS2 model obtained from a varying-speed-of-light brane world cosmology by redefining the system of units. We elaborate conditions under which the flatness problem and the cosmological constant problem can be resolved by such cosmological model (author)
Higgs-radion mixing in stabilized brane world models
Boos, Edward E; Perfilov, Maxim A; Smolyakov, Mikhail N; Volobuev, Igor P
2015-01-01
We consider a quartic interaction of the Higgs and Goldberger-Wise fields, which connects the mechanism of the extra dimension size stabilization with spontaneous symmetry breaking on our brane and gives rise to a coupling of the Higgs field to the radion and its KK tower. We estimate a possible influence of this coupling on the Higgs-radion mixing and study its experimental consequences.
Fine-tuning problem in five-dimensional brane world models
Fine tuning may be called a main disadvantage of the Randall-sundrum model, being the most popular brane world model, constructed quite artificially in the five-dimensional space-time. It needs a bare multidimensional cosmological constant, which is related strictly to the four-dimensional tension. We try to avoid this problem of naturalness, introducing a perfect fluid with arbitrary linear equations of state in both three-dimensional external and one-dimensional internal spaces. This model represents the direct generalization of the Randall-Sundrum one. We derive equations for background metric coefficients, determining a wide class of new exact solutions, and discuss uselessness of subsequent development of brane world models in view of their unjustified plurality
Vacuum solutions of the gravitational field equations in the brane world model
Mak, MK; Harko, TC
2004-01-01
We consider some classes of solutions of the static, spherically symmetric gravitational field equations in the vacuum in the brane world scenario, in which our Universe is a three-brane embedded in a higher dimensional space-time. The vacuum field equations on the brane are reduced to a system of two ordinary differential equations, which describe all the geometric properties of the vacuum as functions of the dark pressure and dark radiation terms (the projections of the Weyl curvature of th...
Brane world corrections to Newton's law
Bronnikov, K. A.; Kononogov, S. A.; Melnikov, V. N.
2006-01-01
We discuss possible variations of the effective gravitational constant with length scale, predicted by most of alternative theories of gravity and unified models of physical interactions. After a brief general exposition, we review in more detail the predicted corrections to Newton's law of gravity in diverse brane world models. We consider various configurations in 5 dimensions (flat, de Sitter and AdS branes in Einstein and Einstein-Gauss-Bonnet theories, with and without induced gravity an...
Cosmological Evolution of Brane World Moduli
Brax, P; Davis, A C; Rhodes, C S; Brax, Ph.
2003-01-01
We study cosmological consequences of non-constant brane world moduli in five dimensional brane world models with bulk scalars and two boundary branes. We focus on the case where the brane tension is an exponential function of the bulk scalar field, $U_b \\propto \\exp{(\\alpha \\phi)}$. In the limit $\\alpha \\to 0$, the model reduces to the two-brane model of Randall-Sundrum, whereas larger values of $\\alpha$ allow for a less warped bulk geometry. Using the moduli space approximation we derive the four-dimensional low-energy effective action from a supergravity-inspired five-dimensional theory. For arbitrary values of $\\alpha$, the resulting theory has the form of a bi-scalar-tensor theory. We show that, in order to be consistent with local gravitational observations, $\\alpha$ has to be small (less than $10^{-2}$) and the separation of the branes must be large. We study the cosmological evolution of the interbrane distance and the bulk scalar field for different matter contents on each branes. Our findings indica...
Brane-world cosmology and inflation
Misao Sasaki
2004-10-01
There has been substantial progress in brane-world cosmology in recent years. Much attention has been particularly paid to the second Randall–Sundrum (RS2) scenario in which a single positive-tension brane is embedded in a five-dimensional space-time, called the bulk, with a negative cosmological constant. 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 in the five-dimensional bulk, the so-called bulk inflaton model. An intriguing feature of this model is that the projection of the bulk inflaton on the brane behaves just like an ordinary inflaton in four dimensions in the low energy regime, 2 ℓ2 ≪ 1, where is the Hubble expansion rate of the brane and ℓ is the curvature radius of the bulk. We then discuss the cosmological perturbation on superhorizon scales in this model. We find that, even under the presence of spatial inhomogeneities, the model is indistinguishable from the standard four-dimensional inflation to (2 ℓ2). That is, the difference may appear only at O(4 ℓ4).
Consistency Conditions for Brane Worlds in Arbitrary Dimensions
Leblond, F; Winters, D J; Leblond, Frederic; Myers, Robert C.; Winters, David J.
2001-01-01
We consider ``brane world sum rules'' for compactifications involving an arbitrary number of spacetime dimensions. One of the most striking results derived from such consistency conditions is the necessity for negative tension branes to appear in five--dimensional scenarios. We show how this result is easily evaded for brane world models with more than five dimensions. As an example, we consider a novel realization of the Randall--Sundrum scenario in six dimensions involving only positive tension branes.
Fine-tuning of the cosmological constant in brane worlds
We discuss how the fine-tuning of the cosmological constant enters brane world setups. After presenting the Randall Sundrum model as a prototype case, we focus on single brane models with curvature singularities which are separated from the brane in the additional dimension. Finally, the issue of the existence of nearby curved solutions is addressed. (orig.)
Brane-world cosmology with black strings
Gergely, L A
2006-01-01
We consider the simplest scenario when black strings (cigars) penetrate the cosmological brane. As a result, the brane has a Swiss-cheese structure, with Schwarzschild black holes immersed in a Friedmann-Lema\\^{\\i}tre-Robertson-Walker brane. There is no dark radiation in the model, the cosmological regions of the brane are characterized by a cosmological constant $\\Lambda$ and flat spatial sections. Regardless of the value of $\\Lambda$, these brane-world universes forever expand and forever decelerate. The totality of source terms in the modified Einstein equation sum up to a dust, establishing a formal equivalence with the general relativistic Einstein-Straus model. However in this brane-world scenario with black strings the evolution of the cosmological fluid strongly depends on $\\Lambda$. For $\\Lambda$ less or equal to zero it has positive energy density $\\rho$ and negative pressure $p$ and at late times it behaves as in the Einstein-Straus model. For (not too high) positive values of $\\Lambda$ the cosmolo...
Chamblin, A; Reall, H S
2000-01-01
Gravitational collapse of matter trapped on a brane will produce a black hole on the brane. We discuss such black holes in the models of Randall and Sundrum where our universe is viewed as a domain wall in five dimensional anti-de Sitter space. We present evidence that a non-rotating uncharged black hole on the domain wall is described by a ``black cigar'' solution in five dimensions.
Chamblin, A.; Hawking, S. W.; Reall, H. S.
2000-03-01
Gravitational collapse of matter trapped on a brane will produce a black hole on the brane. We discuss such black holes in the models of Randall and Sundrum where our universe is viewed as a domain wall in five-dimensional anti-de Sitter space. We present evidence that a non-rotating uncharged black hole on the domain wall is described by a ``black cigar'' solution in five dimensions.
A varying-α brane world cosmology
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)
A Varying-alpha Brane World Cosmology
Youm, Donam
2001-01-01
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.
Enveloping branes and brane-world singularities
Antoniadis, Ignatios; Klaoudatou, Ifigeneia
2014-01-01
The existence of envelopes is studied for systems of differential equations in connection with the method of asymptotic splittings which allows to determine the singularity structure of the solutions. The result is applied to braneworlds consisting of a 3-brane in a five-dimensional bulk, in the presence of an analog of a bulk perfect fluid parametrizing 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.
Brane World Dynamics and Adiabatic Matter creation
Gopakumar, P
2006-01-01
We have treated the adiabatic matter creation process in various three-brane models by applying thermodynamics of open systems. The matter creation rate is found to affect the evolution of scale factor and energy density of the universe. We find modification at early stages of cosmic dynamics. In GB and RS brane worlds, by chosing appropriate parameters we obtain standard scenario, while the warped DGP model has different Friedmann equations. During later stages, since the matter creation is negligible the evolution reduces to FRW expansion, in RS and GB models.
Phantomlike behavior in a brane-world model with curvature effects
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.
Hawking, Stephen William; Reall, H S
2000-01-01
We study a Randall-Sundrum cosmological scenario consisting of a domain wallin anti-de Sitter space with a strongly coupled large $N$ conformal fieldtheory living on the wall. The AdS/CFT correspondence allows a fully quantummechanical treatment of this CFT, in contrast with the usual treatment ofmatter fields in inflationary cosmology. The conformal anomaly of the CFTprovides an effective tension which leads to a de Sitter geometry for thedomain wall. This is the analogue of Starobinsky's four dimensional model ofanomaly driven inflation. Studying this model in a Euclidean setting gives anatural choice of boundary conditions at the horizon. We calculate the gravitoncorrelator using the Hartle-Hawking ``No Boundary'' proposal and analyticallycontinue to Lorentzian signature. We find that the CFT strongly suppressesmetric perturbations on all but the largest angular scales. This is trueindependently of how the de Sitter geometry arises, i.e., it is also true forfour dimensional Einstein gravity. Since generic ...
Hawking, S. W.; Hertog, T.; Reall, H. S.
2000-08-01
We study a Randall-Sundrum cosmological scenario consisting of a domain wall in anti-de Sitter space with a strongly coupled large N conformal field theory living on the wall. The AdS-CFT correspondence allows a fully quantum mechanical treatment of this CFT, in contrast with the usual treatment of matter fields in inflationary cosmology. The conformal anomaly of the CFT provides an effective tension which leads to a de Sitter geometry for the domain wall. This is the analogue of Starobinsky's four dimensional model of anomaly driven inflation. Studying this model in a Euclidean setting gives a natural choice of boundary conditions at the horizon. We calculate the graviton correlator using the Hartle-Hawking ``no boundary'' proposal and analytically continue to Lorentzian signature. We find that the CFT strongly suppresses metric perturbations on all but the largest angular scales. This is true independently of how the de Sitter geometry arises, i.e., it is also true for four dimensional Einstein gravity. Since generic matter would be expected to behave like a CFT on small scales, our results suggest that tensor perturbations on small scales are far smaller than predicted by all previous calculations, which have neglected the effects of matter on tensor perturbations.
Bare and effective fluid description in brane world cosmology
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.)
Randall-Sundrum brane-world in modified gravity
Nakada, Hiroshi
2016-01-01
We modify Randall-Sundrum model of brane-world (with two branes) by adding the scalar curvature squared term in five dimensions. We find that it does not destabilize Randall-Sundrum solution to the hierarchy problem of the Standard Model in particle physics.
Gravity on codimension 2 brane worlds
Navarro, Ignacio; /Durham U., IPPP; Santiago, Jose; /Durham U., IPPP /Fermilab
2004-11-01
The authors compute the matching conditions for a general thick codimension 2 brane, a necessary previous step towards the investigation of gravitational phenomena in co-dimension 2 braneworlds. They show that, provided the brane is weakly curved, they are specified by the integral in the extra dimensions of the brane energy-momentum, independently of its detailed internal structure. These general matching conditions can then be used as boundary conditions for the bulk solution. By evaluating Einstein equations at the brane boundary they are able to write an evolution equation for the induced metric on the brane depending only on physical brane parameters and the bulk energy-momentum tensor. They particularize to a cosmological metric and show that a realistic cosmology can be obtained in the simplest case of having just a non-zero cosmological constant in the bulk. They point out several parallelisms between this case and the codimension 1 brane worlds in an AdS space.
Smolyakov, Mikhail N.; Volobuev, Igor P.
2016-01-01
In this paper we examine, from the purely theoretical point of view and in a model-independent way, the case, when matter, gauge and Higgs fields are allowed to propagate in the bulk of five-dimensional brane world models with compact extra dimension, and the Standard Model fields and their interactions are supposed to be reproduced by the corresponding zero Kaluza-Klein modes. An unexpected result is that in order to avoid possible pathological behavior in the fermion sector, it is necessary to impose constraints on the fermion field Lagrangian. In the case when the fermion zero modes are supposed to be localized at one of the branes, these constraints imply an additional relation between the vacuum profile of the Higgs field and the form of the background metric. Moreover, this relation between the vacuum profile of the Higgs field and the form of the background metric results in the exact reproduction of the gauge boson and fermion sectors of the Standard Model by the corresponding zero mode four-dimensional effective theory in all the physically relevant cases, allowed by the absence of pathologies. Meanwhile, deviations from these conditions can lead either back to pathological behavior in the fermion sector or to a variance between the resulting zero mode four-dimensional effective theory and the Standard Model, which, depending on the model at hand, may, in principle, result in constraints putting the theory out of the reach of the present day experiments.
Creation of a brane world with a Gauss-Bonnet term
Here we study the creation of a brane world using an instanton solution with Hartle-Hawking's no-boundary approach. We analyze brane models with a Gauss-Bonnet term in a bulk spacetime. The curvature of 3-brane is assumed to be closed, flat, or open. We construct instanton solutions with branes for our models, and calculate the value of the actions to discuss the initial state of a brane universe
Null geodesics in brane world universe
We study null bulk geodesic motion in the brane world cosmology in the RS2 scenario and in the static universe in the bulk of the charged topological AdS black hole. We obtain equations describing the null bulk geodesic motion as observed in one lower dimensions. We find that the null geodesic motion in the bulk of the brane world cosmology in the RS2 scenario is observed to be under the additional influence of extra non-gravitational force by the observer on the three-brane, if the brane universe does not possess the Z2 symmetry. As for the null geodesic motion in the static universe in the bulk of the charged AdS black hole, the extra force is realized even when the brane universe has the Z2 symmetry. (author)
Holographic Cosmic Quintessence on Dilatonic Brane World
Chen, B; Chen, Bin; Lin, Feng-Li
2002-01-01
Recently quintessence is proposed to explain the observation data of supernova indicating a time-varying cosmological constant and accelerating universe. Inspired by this and its mysterious origin, we look for the possibility of quintessence as the holographic dark matters dominated in the late time in the brane world scenarios. We consider both the cases of static and moving brane in a dilaton gravity background. For the static brane we use the Hamilton-Jacobi method to study the intrinsic FRW cosmology on the brane and find out the constraint on the bulk potential for the quintessence. We find the similar constraint for the moving brane cases and that the quintessence on it has the effect as a mildly time-varying Newton constant.
Warped brane worlds in critical gravity
We investigate the brane models in arbitrary dimensional critical gravity presented in Lu and Pope (Phys Rev Lett 106:181302, 2011). For the models of the thin branes with codimension one, the Gibbons-Hawking surface term and the junction conditions are derived, with which the analytical solutions for the flat, AdS, and dS branes are obtained at the critical point of the critical gravity. It is found that all these branes are embedded in an AdSn spacetime, but, in general, the effective cosmological constant Λ of the AdSn spacetime is not equal to the naked one Λ0 in the critical gravity, which can be positive, zero, and negative. Another interesting result is that the brane tension can also be positive, zero, or negative, depending on the symmetry of the thin brane and the values of the parameters of the theory, which is very different from the case in general relativity. It is shown that the mass hierarchy problem can be solved in the braneworld model in the higher-derivative critical gravity. We also study the thick brane model and find analytical and numerical solutions of the flat, AdS, and dS branes. It is found that some branes will have inner structure when some parameters of the theory are larger than their critical values, which may result in resonant KK modes for some bulk matter fields. The flat branes with positive energy density and AdS branes with negative energy density are embedded in an n-dimensional Minkowski one. (orig.)
Nojiri, S; Nojiri, Shin'ichi; Odintsov, Sergei D.
2001-01-01
In this report we consider brane-world universe (New Brane World) where an arbitrary large $N$ quantum CFT exists on the domain wall. This corresponds to implementing of Randall-Sundrum compactification within the context of AdS/CFT correspondence. Using anomaly induced effective action for domain wall CFT, the possibility of self-consistent quantum creation of 4d de Sitter wall universe (inflation) is demonstrated. In case of maximally SUSY Yang-Mills theory the exact correspondence with radius and effective tension found by Hawking-Hertog-Reall is obtained. We also discuss the bosonic sector of 5d gauged supergravity with single scalar and taking the boundary action as predicted by supersymmetry and discuss the possibility to supersymmetrize dilatonic New Brane World. It is demonstrated that for a number of superpotentials the flat SUSY dilatonic brane-world (with dynamically induced brane dilaton) or quantum-induced de Sitter dilatonic brane-world (not Anti-de Sitter one) where SUSY is broken by the quantu...
Tensor Perturbations from Brane-World Inflation with Curvature Effects
Bouhmadi-Lopez, Mariam; Liu, Yen-Wei; IZUMI, KEISUKE; Chen, Pisin(Graduate Institute of Astrophysics, National Taiwan University, Taipei, 10617, Taiwan)
2013-01-01
The brane-world scenario provides an intriguing possibility to explore the phenomenological cosmology implied by string/M theory. In this paper, we consider a modified Randall-Sundrum single brane model with two natural generalizations: a Gauss-Bonnet term in the five-dimensional bulk action as well as an induced gravity term in the four-dimensional brane action, which are the leading-order corrections to the Randall-Sundrum model. We study the influence of these combined effects on the evolu...
Electromagnetic perturbations in new brane world scenarios
Molina, C; Torrejon, T E M
2016-01-01
In this work we consider electromagnetic dynamics in Randall-Sundrum branes. It is derived a family of four-dimensional spacetimes compatible with Randall-Sundrum brane worlds, focusing on asymptotic flat backgrounds. Maximal extensions of the solutions are constructed and their causal structures are discussed. These spacetimes include singular, non-singular and extreme black holes. Maxwell's electromagnetic field is introduced and its evolution is studied in an extensive numerical survey. Electromagnetic quasinormal mode spectra are derived and analyzed with time-dependent and high order WKB methods. Our results indicate that the black holes in the brane are electromagnetically stable.
Electromagnetic perturbations in new brane world scenarios
Molina, C.; Pavan, A. B.; Medina Torrejón, T. E.
2016-06-01
In this work, we consider electromagnetic dynamics in Randall-Sundrum branes. It is derived from a family of four-dimensional spacetimes compatible with Randall-Sundrum brane worlds, focusing on asymptotic flat backgrounds. Maximal extensions of the solutions are constructed, and their causal structures are discussed. These spacetimes include singular, nonsingular, and extreme black holes. Maxwell's electromagnetic field is introduced, and its evolution is studied in an extensive numerical survey. Electromagnetic quasinormal mode spectra are derived and analyzed with time-dependent and high-order WKB methods. Our results indicate that the black holes in the brane are electromagnetically stable.
Electromagnetic perturbations in new brane world scenarios
Molina, C.; Pavan, A. B.; Torrejon, T. E. M.
2016-01-01
In this work we consider electromagnetic dynamics in Randall-Sundrum branes. It is derived a family of four-dimensional spacetimes compatible with Randall-Sundrum brane worlds, focusing on asymptotic flat backgrounds. Maximal extensions of the solutions are constructed and their causal structures are discussed. These spacetimes include singular, non-singular and extreme black holes. Maxwell's electromagnetic field is introduced and its evolution is studied in an extensive numerical survey. El...
Randall-Sundrum model with {lambda}<0 and bulk brane viscosity
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.
Warped Brane worlds in Critical Gravity
Zhong, Yi; Chen, Feng-Wei; Xie, Qun-Ying
2014-01-01
We investigate the brane models in arbitrary dimensional critical gravity presented in [Phys. Rev. Lett. 106, 181302 (2011)]. For the model of the thin branes with codimension one, the Gibbons-Hawking surface term and the junction conditions are derived, with which the analytical solutions for the flat, AdS, and dS branes are obtained at the critical point of the critical gravity. It is found that all these branes are embedded in an AdS$_{n}$ spacetime, but, in general, the effective cosmological constant $\\Lambda$ of the AdS$_{n}$ spacetime is not equal to the naked one $\\Lambda_0$ in the critical gravity, which can be positive, zero, and negative. Another interesting result is that the brane tension can also be positive, zero, or negative, depending on the symmetry of the thin brane and the values of the parameters of the theory, which is very different from the case in general relativity. It is shown that the mass hierarchy problem can be solved in the higher-order braneworld model in the critical gravity....
The Cosmological Constant Problem from a Brane-World Perspective
Förste, S; Lavignac, Stephane; Nilles, Hans Peter; Forste, Stefan; Lalak, Zygmunt; Lavignac, St\\'ephane; Nilles, Hans Peter
2000-01-01
We point out several subtleties arising in brane-world scenarios of cosmological constant cancellation. We show that solutions with curvature singularities are inconsistent, unless the contribution to the effective four-dimentional cosmological constant of the physics that resolves the singularities is fine-tuned. This holds for both flat and curved branes. Irrespective of this problem, we then study an isolated class of flat solutions in models where a bulk scalar field with a vanishing potential couples to a 3-brane. We give an example where the introduction of a bulk scalar potential results in a nonzero cosmological constant. Finally we comment on the stability of classical solutions of the brane system with respect to quantum corrections.
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
Davis, Stephen; Bréchet, 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.
Bounded Scalar Perturbations in Bouncing Brane World Cosmologies
Maier, Rodrigo; Soares, Ivano Damião
2013-01-01
We examine the dynamics of scalar perturbations in closed Friedmann-Lema\\^itre-Robertson- Walker (FLRW) universes in the framework of Brane World theory with a timelike extra dimension. In this scenario, the unperturbed Friedmann equations contain additional terms arising from the bulk-brane interaction that implement non-singular bounces in the models with a cosmological constant and non-interacting perfect fluids. The structure of the phase-space of the models allows for two basic configurations, namely, one bounce solutions or eternal universes. Assuming that the matter content of the model is given by dust and radiation, we derive the dynamical field equations for scalar hydrodynamical perturbations considering either a conformally flat (de Sitter) bulk or a perturbed bulk. We perform a numerical analysis which can shed some light on the study of cosmological scalar perturbations in bouncing brane world models. From a mathematical point of view we show that although the bounce enhances the amplitudes of s...
Branes And Brane Worlds In M-theory
Vázquez-Poritz, J F
2001-01-01
The search for a theory which unifies all fundamental physics has culminated in M-theory, whose solitonic p-brane solutions offer a wealth of non- perturbative phenomena. In a particular regime of M- theory, there is a duality between gauge theories and the near-horizon region of certain p- branes, a concrete example of which is the AdS/CFT correspondence. I find a new class of warped Anti-de Sitter solutions which arise as the near-horizon region of various semi- localized brane intersections. This provides an example of AdS5 originating in eleven-dimensional supergravity, as well as AdS4 and AdS 6 in Type IIB string theory, cases which do not arise from direct products of spaces. This enables us to study four-dimensional gauge theories which are dual to eleven-dimensional supergravity solutions. The dual gauge theories of AdS in warped spacetimes have reduced supersymmetry, which is pertinent to the study of viable supersymmetric extensions of the Standard Model. In addition, I probe various supergravity s...
Classical and quantum aspects of brane-world cosmology
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.
Schwarzschild black branes and strings in higher-dimensional brane worlds
We consider branes embedded in spacetimes of codimension 1 and 2, with a warped metric tensor for the subspace parallel to the brane. We study a variety of brane-world solutions arising by introducing a Schwarzschild-like black hole metric on the brane and we investigate the properties of the corresponding higher-dimensional spacetime. We demonstrate that normalizable bulk modes lead to a vanishing flow of energy through the naked singularities. From this point of view, these singularities are harmless
Brane worlds in gravity with auxiliary fields
Recently, Pani et al. explored a new theory of gravity by adding nondynamical fields, i.e., gravity with auxiliary fields (Phys Rev D 88:121502, 2013). In this gravity theory, higher-order derivatives of matter fields generically appear in the field equations. In this paper we extend this theory to any dimensions and discuss the thick braneworld model in five dimensions. Domain wall solutions are obtained numerically. The stability of the brane system under tensor perturbations is analyzed. We find that the system is stable under tensor perturbations and the gravity zero mode is localized on the brane. Therefore, the four-dimensional Newtonian potential can be realized on the brane. (orig.)
Brane worlds in gravity with auxiliary fields
Guo, Bin; Liu, Yu-Xiao; Yang, Ke [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China)
2015-02-01
Recently, Pani et al. explored a new theory of gravity by adding nondynamical fields, i.e., gravity with auxiliary fields (Phys Rev D 88:121502, 2013). In this gravity theory, higher-order derivatives of matter fields generically appear in the field equations. In this paper we extend this theory to any dimensions and discuss the thick braneworld model in five dimensions. Domain wall solutions are obtained numerically. The stability of the brane system under tensor perturbations is analyzed. We find that the system is stable under tensor perturbations and the gravity zero mode is localized on the brane. Therefore, the four-dimensional Newtonian potential can be realized on the brane. (orig.)
Asymptotically Lifshitz brane-world black holes
We study the gravity dual of a Lifshitz field theory in the context of a RSII brane-world scenario, taking into account the effects of the extra dimension through the contribution of the electric part of the Weyl tensor. We study the thermodynamical behavior of such asymptotically Lifshitz black holes. It is shown that the entropy imposes the critical exponent z to be bounded from above. This maximum value of z corresponds to a positive infinite entropy as long as the temperature is kept positive. The stability and phase transition for different spatial topologies are also discussed. - Highlights: ► Studying the gravity dual of a Lifshitz field theory in the context of brane-world scenario. ► Studying the thermodynamical behavior of asymptotically Lifshitz black holes. ► Showing that the entropy imposes the critical exponent z to be bounded from above. ► Discussing the phase transition for different spatial topologies.
Asymptotically Lifshitz Brane-World Black Holes
Ranjbar, Arash; Shahidi, Shahab
2012-01-01
We study the gravity dual of a Lifshitz field theory in the context of a RSII brane-world scenario, taking into account the effects of the extra dimension through the contribution of the electric part of the Weyl tensor. We show that although the Lifshitz space-time cannot be considered as a vacuum solution of the RSII brane-world, the asymptotically Lifshitz solution can. We then study the thermodynamical behavior of such asymptotically Lifshitz black holes. It is shown that the condition on the positivity of entropy imposes an upper bound on the critical exponent $z$. This maximum value of $z$ corresponds to a positive infinite entropy as long as the temperature is kept positive. The stability and phase transition for different spatial topologies are also discussed.
Grand unification in the heterotic brane world
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 Z6-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 Z3 singularities in the local and in the compact case. Finally, we exemplify this procedure with the resolution of a Z3 MSSM candidate. (orig.)
Grand unification in the heterotic brane world
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.)
Variable-speed-of-light cosmology from brane world scenario
We argue that the four-dimensional universe on the TeV brane of the Randall-Sundrum scenario takes the bimetric structure of Clayton and Moffat, with gravitons traveling faster than photons instead, while the radion varies with time. We show that such brane world bimetric model can thereby solve the flatness and the cosmological constant problems, provided the speed of a graviton decreases to the present day value rapidly enough. The resolution of other cosmological problems such as the horizon problem and the monopole problem requires supplementation by inflation, which may be achieved by the radion field provided the radion potential satisfies the slow-roll approximation. (author)
Tensor Perturbations from Brane-World Inflation with Curvature Effects
Bouhmadi-Lopez, Mariam; Izumi, Keisuke; Chen, Pisin
2013-01-01
The brane-world scenario provides an intriguing possibility to explore the phenomenological cosmology implied by string/M theory. In this paper, we consider a modified Randall-Sundrum single brane model with two natural generalizations: a Gauss-Bonnet term in the five-dimensional bulk action as well as an induced gravity term in the four-dimensional brane action, which are the leading-order corrections to the Randall-Sundrum model. We study the influence of these combined effects on the evolution of the primordial gravitational waves generated during an extreme slow-roll inflation on the brane. The background, for the early inflationary era, is then modeled through a de Sitter brane embedded within an anti-de Sitter bulk. In this framework, we show that both effects tend to suppress the Randall-Sundrum enhancement of the amplitude of the tensor perturbations at relatively high energies. Moreover, the Gauss-Bonnet effect, relative to standard general relativity, will abruptly enhance the tensor-to-scalar ratio...
Soliton models for thick branes
Peyravi, Marzieh; Riazi, Nematollah; Lobo, Francisco S. N.
2016-05-01
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 Z2 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 Schrödinger-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.
The fate of Newton's law in brane-world scenarios
We consider brane-world scenarios embedded into string theory. We find that the D-brane backreaction induces a large increase in the open string's proper length. Consequently the stringy nature of elementary particles can be detected at distances much larger than the fundamental string scale. As an example, we compute the gravitational potential between two open strings ending on backreacting D3-branes in four-dimensional compactifications of type II string theory. We find that the Newtonian potential receives a correction that goes like 1/r but that is not proportional to the inertial masses of the open strings, implying a violation of the equivalence principle in the effective gravitational theory. This stringy correction is screened by thermal effects when the distance between the strings is greater than the inverse temperature. This suggests new experimental tests for many phenomenological models in type II string theory.
Radion and moduli stabilization from induced brane actions in higher-dimensional brane worlds
Charmousis, C.; U. Ellwanger
2004-01-01
We consider a 4+N-dimensional brane world with 2 co-dimension 1 branes in an empty bulk. The two branes have N-1 of their extra dimensions compactified on a sphere S^(N-1), whereas the ordinary 4 spacetime directions are Poincare invariant. An essential input are induced stress-energy tensors on the branes providing different tensions for the spherical and flat part of the branes. The junction conditions - notably through their extra dimensional components - fix both the distance between the ...
Soliton models for thick branes
Peyravi, Marzieh; Lobo, Francisco S N
2015-01-01
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 ($SG$), $\\varphi^{4}$ and $\\varphi^{6}$ 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 vacuua. These vacuua 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 neighbourhood 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 Schrodinger-like equation, where $w$ is the 5-dimensional coordinate. It turns out that the $\\phi^4$ brane is stable, while there are unstable modes for certain ranges of the model param...
A Brane World Perspective on the Cosmological Constant and the Hierarchy Problems
Flanagan, Eanna; Jones, Nicholas; Stoica, Horace; Tye, S.-H. Henry; Wasserman, Ira
2000-01-01
We elaborate on the recently proposed static brane world scenario, where the effective 4-D 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. Besides an exponentially small effective 4-D 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 ...
In this talk, I present and discuss a number of attempts to construct black hole solutions in models with Warped Extra Dimensions. Then, a contact is made with models with Large Extra Dimensions, where black-hole solutions are easily constructed - here the focus will be on the properties of microscopic black holes and the possibility of using phenomena associated with them, such as the emission of Hawking radiation, to discover fundamental properties of our spacetime.
Isotropic singularity in inhomogeneous brane cosmological models
We discuss the asymptotic dynamical evolution of spatially inhomogeneous brane-world cosmological models close to the initial singularity. By introducing suitable scale-invariant dependent variables and a suitable gauge, we write the evolution equations of the spatially inhomogeneous G2 brane cosmological models with one spatial degree of freedom as a system of autonomous first-order partial differential equations. We study the system numerically, and we find that there always exists an initial singularity, which is characterized by the fact that spatial derivatives are dynamically negligible. More importantly, from the numerical analysis we conclude that there is an initial isotropic singularity in all these spatially inhomogeneous brane cosmologies for a range of parameter values which include the physically important cases of radiation and a scalar field source. The numerical results are supported by a qualitative dynamical analysis and a calculation of the past asymptotic decay rates. Although the analysis is local in nature, the numerics indicate that the singularity is isotropic for all relevant initial conditions. Therefore this analysis, and a preliminary investigation of general inhomogeneous (G0) models, indicates that it is plausible that the initial singularity is isotropic in spatially inhomogeneous brane-world cosmological models and consequently that brane cosmology naturally gives rise to a set of initial data that provide the conditions for inflation to subsequently take place
Topics in brane world and quantum field theory
Corradini, Olindo
In the first part of the thesis we study various issues in the Brane World scenario with particular emphasis on gravity and the cosmological constant problem. First, we study localization of gravity on smooth domain-wall solutions of gravity coupled to a scalar field. In this context we discuss how the aforementioned localization is affected by including higher curvature terms in the theory, pointing out among other things that, general combinations of such terms lead to delocalization of gravity with the only exception of the Gauss-Bonnet combination (and its higher dimensional counterparts). We then find a solitonic 3-brane solution in 6D bulk in the Einstein-Hilbert-Gauss-Bonnet theory of gravity. Near to the brane the metric is that for a product of the 4D flat Minkowski space with a 2D wedge whose deficit angle is proportional to the brane tension. Consistency tests imposed on such backgrounds appear to require the localized matter on the brane to be conformal. We then move onto infinite volume extra dimension Brane World scenarios where we study gravity in a codimension-2 model, generalizing the work of Dvali, Gabadadze and Porrati to tensionful branes. We point out that, in the presence of the bulk Gauss-Bonnet combination, the Einstein-Hilbert term is induced on the brane already at the classical level. Consistency tests are presented here as well. To conclude we discuss, using String Theory, an interesting class of large-N gauge theories which have vanishing energy density even though these theories are non-covariant and non-supersymmetric. In the second part of the thesis we study a formulation of Quantum Mechanical Path Integrals in curved space. Such Path Integrals present superficial divergences which need to be regulated. We perform a three-loop calculation in mode regularization as a nontrivial check of the non-covariant counterterms required by such scheme. We discover that dimensional regularization can be successfully adopted to evaluate the
Supergravity, Non-Conformal Field Theories and Brane-Worlds
Gherghetta, Tony(ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, The University of Melbourne, Melbourne, Victoria, 3010, Australia); Oz, Yaron
2001-01-01
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 ...
Black strings from minimal geometric deformation in a variable tension brane-world
We study brane-world models with variable brane tension and compute corrections to the horizon of a black string along the extra dimension. The four-dimensional geometry of the black string on the brane is obtained by means of the minimal geometric deformation approach, and the bulk corrections are then encoded in additional terms involving the covariant derivatives of the variable brane tension. Our investigation shows that the variable brane tension strongly affects the shape and evolution of the black string horizon along the extra dimension, at least in a near-brane expansion. In particular, we apply our general analysis to a model motivated by the Eötvös branes, where the variable brane tension is related to the Friedmann–Robertson–Walker brane-world cosmology. We show that for some stages in the evolution of the universe, the black string warped horizon collapses to a point and the black string has correspondingly finite extent along the extra dimension. Furthermore, we show that in the minimal geometric deformation of a black hole on the variable tension brane, the black string has a throat along the extra dimension, whose area tends to zero as time goes to infinity. (paper)
Black strings from minimal geometric deformation in a variable tension brane-world
Casadio, R.; Ovalle, J.; da Rocha, Roldão
2014-02-01
We study brane-world models with variable brane tension and compute corrections to the horizon of a black string along the extra dimension. The four-dimensional geometry of the black string on the brane is obtained by means of the minimal geometric deformation approach, and the bulk corrections are then encoded in additional terms involving the covariant derivatives of the variable brane tension. Our investigation shows that the variable brane tension strongly affects the shape and evolution of the black string horizon along the extra dimension, at least in a near-brane expansion. In particular, we apply our general analysis to a model motivated by the Eötvös branes, where the variable brane tension is related to the Friedmann-Robertson-Walker brane-world cosmology. We show that for some stages in the evolution of the universe, the black string warped horizon collapses to a point and the black string has correspondingly finite extent along the extra dimension. Furthermore, we show that in the minimal geometric deformation of a black hole on the variable tension brane, the black string has a throat along the extra dimension, whose area tends to zero as time goes to infinity.
Asymptotically Lifshitz brane-world black holes
Ranjbar, Arash, E-mail: a_ranjbar@sbu.ac.ir; Sepangi, Hamid Reza, E-mail: hr-sepangi@sbu.ac.ir; Shahidi, Shahab, E-mail: s_shahidi@sbu.ac.ir
2012-12-15
We study the gravity dual of a Lifshitz field theory in the context of a RSII brane-world scenario, taking into account the effects of the extra dimension through the contribution of the electric part of the Weyl tensor. We study the thermodynamical behavior of such asymptotically Lifshitz black holes. It is shown that the entropy imposes the critical exponent z to be bounded from above. This maximum value of z corresponds to a positive infinite entropy as long as the temperature is kept positive. The stability and phase transition for different spatial topologies are also discussed. - Highlights: Black-Right-Pointing-Pointer Studying the gravity dual of a Lifshitz field theory in the context of brane-world scenario. Black-Right-Pointing-Pointer Studying the thermodynamical behavior of asymptotically Lifshitz black holes. Black-Right-Pointing-Pointer Showing that the entropy imposes the critical exponent z to be bounded from above. Black-Right-Pointing-Pointer Discussing the phase transition for different spatial topologies.
World-Volume Potentials on D-branes
Garousi, M R
2000-01-01
By evaluating string scattering amplitudes, we investigate various low energy interactions for the massless scalars on a nonabelian Dirichlet brane. We confirm the existence of couplings of closed string fields to the world-volume scalars, involving commutators of the latter. Our results are consistent with the recently proposed nonabelian world-volume actions for Dp-branes.
Brane-world cosmological perturbations a covariant approach
Maartens, R
2002-01-01
The standard cosmological model, based on general relativity with an inflationary era, is very effective in accounting for a broad range of observed features of the universe. However, the ongoing puzzles about the nature of dark matter and dark energy, together with the problem of a fundamental theoretical framework for inflation, indicate that cosmology may be probing the limits of validity of general relativity. The early universe provides a testing ground for theories of gravity, since gravitational dynamics can lead to characteristic imprints on the CMB and other cosmological observations. Precision cosmology is in principle a means to constrain and possibly falsify candidate quantum gravity theories like M theory. Generalized Randall-Sundrum brane-worlds provide a phenomenological means to test aspects of M theory. I outline the 1+3-covariant approach to cosmological perturbations in these brane-worlds, and its application to CMB anisotropies.
Black Strings from Minimal Geometric Deformation in a Variable Tension Brane-World
Casadio, Roberto; da Rocha, Roldao
2013-01-01
We study brane-world models with variable brane tension and compute corrections to the horizon of a black string along the extra dimension. The four-dimensional geometry of the black string on the brane is obtained by means of the minimal geometric deformation approach, and the bulk corrections are then encoded in additional terms involving the covariant derivatives of the variable brane tension. Our investigation shows that the variable brane tension strongly affects the shape and evolution of the black string horizon along the extra dimension, at least in a near-brane expansion. In particular, we apply our general analysis to a model motivated by the E\\"otv\\"os branes, where the variable brane tension is related to the Friedmann-Robertson-Walker brane-world cosmology. We show that for some stages in the evolution of the universe, the black string warped horizon collapses to a point and the black string has correspondingly finite extent along the extra dimension. Furthermore, we show that in the minimal geom...
Effective contact interactions in a stabilized RS1 brane world model
We consider the effective Lagrangian due to the exchange of heavy Kaluza-Klein (KK) tensor graviton and scalar radion states in a stabilized Randall-Sundrum model (RS1) and compute explicitly the corresponding effective coupling constants. The Drell-Yan lepton pair production at the Tevatron and the LHC is analyzed in two situations, when the first KK resonance is too heavy to be directly detected at the colliders, and when the first KK resonance is visible but other states are still too heavy. In the first case the effective Lagrangian reduces to a contact interaction of Standard Model (SM) particles, whereas in the second case it includes a coupling of SM particles to the first KK mode and a contact interaction due to the exchange of all the heavier modes. It is shown that in both cases the contribution from the invisible KK tower leads to a modification of final particles distributions. In particular, for the second case a nontrivial interference between the first KK mode and the rest KK tower takes place. Expected 95% C.L. limits for model parameters for the Tevatron and the LHC are given. The numerical results are obtained by means of the CompHEP code, in which all new effective interactions are implemented providing a tool for simulation of corresponding events and a more detailed analysis.
Nontrival cosmological constant in brane worlds with unorthodox lagrangians
In self-tuning brane-world models with extra dimensions, large contributions to the cosmological constant are absorbed into the curvature of extra dimensions and consistent with flat 4d geometry. In models with conventional Lagrangians fine-tuning is needed nevertheless to ensure a finite effective Planck mass. Here, we consider a class of models with non conventional Lagrangian in which known problems can be avoided. Unfortunately these models are found to suffer from tachyonic instabilities. An attempt to cure these instabilities leads to the prediction of a positive cosmological constant, which in turn needs a fine-tuning to be consistent with observations
Chiral symmetry breaking in brane models
We discuss the chiral symmetry breaking in general intersecting Dq/Dp brane models consisting of Nc Dq-branes and a single Dp-brane with an s-dimensional intersection. There exists a QCD-like theory localized at the intersection and the Dq/Dp model gives a holographic description of it. The rotational symmetry of directions transverse to both of the Dq and Dp-branes can be identified with a chiral symmetry, which is non-Abelian for certain cases. The asymptotic distance between the Dq-branes and the Dp-brane corresponds to a quark mass. By studying the probe Dp-brane dynamics in a Dq-brane background in the near horizon and large Nc limit we find that the chiral symmetry is spontaneously broken and there appear (pseudo-)Nambu-Goldstone bosons. We also discuss the models at finite temperature
Regular Bulk Solutions in Brane-worlds with Inhomogeneous Dust and Generalized Dark Radiation
Herrera-Aguilar, A; da Rocha, Roldao
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 physical soft singularities.
Regular Bulk Solutions in Brane-Worlds with Inhomogeneous Dust and Generalized Dark Radiation
A. Herrera-Aguilar
2015-01-01
Full Text Available 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.
Brane-world stars and (microscopic) black holes
Casadio, R., E-mail: casadio@bo.infn.it [Dipartimento di Fisica, Universita di Bologna, via Irnerio 46, 40126 Bologna (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, via Irnerio 46, 40126 Bologna (Italy); Ovalle, J., E-mail: jovalle@usb.ve [Departamento de Fisica, Universidad Simon Bolivar, Apartado 89000, Caracas 1080A (Venezuela, Bolivarian Republic of)
2012-08-29
We study stars in the brane-world by employing the principle of minimal geometric deformation and find that brane-world black hole metrics with a tidal charge can be consistently recovered in a suitable limit. This procedure allows us to determine the tidal charge as a function of the ADM mass of the black hole (and brane tension). A minimum mass for semiclassical microscopic black holes can then be derived, with a relevant impact for the description of black hole events at the LHC.
Brane-world stars and (microscopic) black holes
We study stars in the brane-world by employing the principle of minimal geometric deformation and find that brane-world black hole metrics with a tidal charge can be consistently recovered in a suitable limit. This procedure allows us to determine the tidal charge as a function of the ADM mass of the black hole (and brane tension). A minimum mass for semiclassical microscopic black holes can then be derived, with a relevant impact for the description of black hole events at the LHC.
Brane-world stars with solid crust and vacuum exterior
Ovalle, Jorge; Gergely, László Á; Casadio, Roberto
2014-01-01
The minimal geometric deformation approach is employed to show the existence of brane-world stellar distributions with vacuum Schwarzschild exterior, thus without energy leaking from the exterior of the brane-world star into the extra dimension. The interior satisfies all elementary criteria of physical acceptability for a stellar solution, namely, it is regular at the origin, the pressure and density are positive and decrease monotonically with increasing radius, finally all energy condition...
Brane-world generalizations of the Einstein static universe
A static Friedmann brane in a five-dimensional bulk (Randall-Sundrum-type scenario) can have a very different relation between the density, pressure, curvature and cosmological constant than in the case of the general relativistic Einstein static universe. In particular, static Friedmann branes with zero cosmological constant and 3-curvature, but satisfying ρ > 0 and ρ + 3p > 0, are possible. Furthermore, we find static Friedmann branes in a bulk that satisfies the Einstein equations but is not Schwarzschild-anti-de Sitter or its specializations. In the models with negative bulk cosmological constant, a positive brane tension leads to negative density and 3-curvature
Holographic cosmic quintessence on the dilatonic brane world
Chen, Bin; Lin, Feng-Li
2002-02-01
Recently quintessence has been proposed to explain the observation data of supernovae indicating a time-varying cosmological constant and accelerating universe. Inspired by this and its mysterious origin, we look for the possibility that quintessence is the holographic dark matter dominating in the late time in the brane world scenarios. We consider both the cases of a static and moving brane in a dilaton gravity background. For the static brane we use the Hamilton-Jacobi method motivated by holographic renormalization group to study the intrinsic FRW cosmology on the brane and find the constraint on the bulk potential for quintessence. This constraint requires a negative slowly varying bulk potential which implies an anti-de Sitter-like bulk geometry and could be possibly realized from higher dimensional supergravities or string theory. We find a similar constraint for the moving brane cases and that the quintessence on it has the effect of a mildly time-varying Newton constant.
Brane-world dark stars with solid crust
Ovalle, Jorge; Casadio, Roberto
2014-01-01
The minimal geometric deformation approach is employed to show the existence of brane-world stellar distributions with vacuum Schwarzschild exterior, thus without energy leaking from the exterior of the brane-world star into the extra dimension. The interior satisfies all elementary criteria of physical acceptability for a stellar solution, namely, it is regular at the origin, the pressure and density are positive and decrease monotonically with increasing radius, finally all energy conditions are fulfilled. A very thin solid crust with negative radial pressure separates the interior from the exterior, having a thickness $\\Delta $ inversely proportional to both the brane tension $\\sigma $ and the radius $R$ of the star, i.e. $\\Delta ^{-1}\\sim R\\,\\sigma $. This brane-world star with Schwarzschild exterior would appear dark to a distant observer and be fully compatible with the stringent constraints imposed on stellar parameters by observations of gravitational lensing, orbital evolutions or properties of accre...
World-volume Effective Actions of Exotic Five-branes
Kimura, Tetsuji; Yata, Masaya
2014-01-01
We construct world-volume effective actions of exotic $5^2_2$-branes in type IIA and IIB string theories. The effective actions are given in fully space-time covariant forms with two Killing vectors associated with background isometries. The effective theories are governed by the six-dimensional $\\mathcal{N}=(2,0)$ tensor multiplet and $\\mathcal{N}=(1,1)$ vector multiplet, respectively. Performing the S-duality transformation to the $5^2_2$-brane effective action in type IIB string theory, we also work out the world-volume action of the $5^2_3$-brane. We discuss some additional issues relevant to the exotic five-branes in type I and heterotic string theories.
Quantization of scalar perturbations in brane-world inflation
We consider a quantization of scalar perturbations about a de Sitter brane in a 5-dimensional anti-de Sitter (AdS) bulk spacetime. We first derive the second order action for a master variable Ω for 5-dimensional gravitational perturbations. For a vacuum brane, there is a continuum of normalizable Kaluza-Klein (KK) modes with m>3H/2. There is also a light radion mode with m=√(2)H which satisfies the junction conditions for two branes, but is non-normalizable for a single brane model. We perform the quantization of these bulk perturbations and calculate the effective energy density of the projected Weyl tensor on the brane. If there is a test scalar field perturbation on the brane, the m2=2H2 mode together with the zero-mode and an infinite ladder of discrete tachyonic modes become normalizable in a single brane model. This infinite ladder of discrete modes as well as the continuum of KK modes with m>3H/2 introduce corrections to the scalar field perturbations at first-order in a slow-roll expansion. We derive the second order action for the Mukhanov-Sasaki variable coupled to the bulk perturbations which is needed to perform the quantization and determine the amplitude of scalar perturbations generated during inflation on the brane
World-Volume Interactions on D-Branes
Garousi, M R
1999-01-01
We examine in detail various string scattering amplitudes in order to extract the world-volume interactions of massless fields on a Dirichlet brane. We find that the leading low-energy interactions are consistent with the Born-Infeld and Chern-Simons actions. In particular, our results confirm that the background closed string fields appearing in these actions must be treated as functionals of the non-abelian scalar fields describing transverse fluctuations of the D-brane.
Matter localization on brane-worlds generated by deformed defects
Bernardini, Alex E
2016-01-01
Localization and mass spectrum of bosonic and fermionic matter fields of some novel families of asymmetric thick brane configurations generated by deformed defects are investigated. The localization profiles of spin 0, spin 1/2 and spin 1 bulk fields are identified for novel matter field potentials supported by thick branes with internal structures. The condition for localization is constrained by the brane thickness of each model such that thickest branes strongly induces matter localization. The bulk mass terms for both fermion and boson fields are included in the global action as to produce some imprints on mass-independent potentials of the Kaluza-Klein modes associated to the corresponding Schr\\"odinger equations. In particular, for spin 1/2 fermions, a complete analytical profile of localization is obtained for the four classes of superpotentials here discussed. Regarding the localization of fermion fields, our overall conclusion indicates that thick branes produce a left-right asymmetric chiral localiz...
Mass gap in Kaluza-Klein spectrum in a network of brane worlds
We consider the Newton's force law for brane world consisting of periodic configuration of branes. We show that it supports a massless graviton. Furthermore, this massless mode is well separated from the Kaluza-Klein spectrum by a mass gap. Thus most of the problems in phenomenology coming from continuum of Kaluza-Klein modes without mass gap are potentially cured in such a model. (author)
Brane world in a topological black holes in asymptotically flat spacetime
We study static brane configurations in the bulk background of the topological black holes in asymptotically flat spacetime. We find that such configurations are possible even for flat black hole horizon, unlike the AdS black hole case. We construct the brane world model with an orbifold structure S1/Z2 in such bulk background. We also study massless bulk scalar field. (author)
Metastable Supersymmetry Breaking Vacua on Abelian Brane Models
Halyo, Edi
2009-01-01
We construct Abelian brane models with metastable vacua which are obtained from deformations of ${\\cal N}=2$ supersymmetric brane configurations. One such model lives on a D4 brane stretched between two displaced and rotated NS5 branes. Another one lives on a D5 brane wrapped on a deformed and fibered $A_2$ singularity.
David Bailin
2003-02-01
I brieﬂy outline previous work on getting the (supersymmetric) standard model from string theory, and then describe two ecent attempts using D-branes. The ﬁrst uses D3- and D7- branes and gives a supersymmetric standard model with extra vector-like matter and an intermediate uniﬁcation scale. The second uses intersecting D4-branes and yields a non-supersymmetric spectrum with TeV-scale uniﬁcation.
Wave function of the radion in a brane world
Charmousis, Christos; Gregory, Ruth; Rubakov, Valery A.
1999-01-01
We calculate the linearized metric perturbation corresponding to a massless four-dimensional scalar field, the radion, in a five-dimensional two-brane model of Randall and Sundrum. In this way we obtain relative strengths of the radion couplings to matter residing on each of the branes. The results are in agreement with the analysis of Garriga and Tanaka of gravitational and Brans--Dicke forces between matter on the branes. We also introduce a model with infinite fifth dimension and ``almost'...
Self-tuning and de Sitter brane intersections in 6-dimensional brane models
We study the self-tuning of general brane junctions and brane networks on 6-dimensional space-time. For general brane junctions, there may exist one fine-tuning among the brane tensions. For the brane networks, similar to the 5-dimensional self-tuning brane models, the brane tensions can be set arbitrarily and there exists a singularity for the metric and bulk scalar. If we want to regularize the singularity, we will introduce fine-tuning among the brane tensions. In addition, because the 4-dimensional cosmological constant we observe may be positive and very small, we discuss the brane network with de Sitter brane intersections by introducing a bulk scalar. (orig.)
The hoop conjecture and cosmic censorship in the brane-world
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∼<4πGM, black holes with horizons can form on the brane-world of the Randall-Sundrum scenario
New black holes in the brane world?
It is known that the Einstein field equations in five dimensions admit more general spherically symmetric black holes on the brane than four-dimensional general relativity. We propose two families of analytic solutions (with gtt≠-grr-1), parametrized by the Arnowitt-Deser-Misner mass and the parametrized post-Newtonian parameter β, which reduce to Schwarzschild for β=1. Agreement with observations requires vertical bar β-1 vertical bar ∼ verical bar η vertical bar 0). In the latter case, we find a family of black hole space-times completely regular
Brane-world stars from minimal geometric deformation, and black holes
Casadio, Roberto; Ovalle, Jorge
2014-02-01
Using the effective four-dimensional Einstein field equations, we build analytical models of spherically symmetric stars in the brane-world, in which the external space-time contains both an ADM mass and a tidal charge. In order to determine the interior geometry, we apply the principle of minimal geometric deformation, which allows one to map general relativistic solutions to solutions of the effective four-dimensional brane-world equations. We further restrict our analysis to stars with a radius linearly related to the total general relativistic mass, and obtain a general relation between the latter, the brane-world ADM mass and the tidal charge. In these models, the value of the star's radius can then be taken to zero smoothly, thus obtaining brane-world black hole metrics with a tidal charge solely determined by the mass of the source and the brane tension. We find configurations which entail a partial screening of the gravitational mass, and general conclusions regarding the minimum mass for semiclassical black holes are also drawn.
Modified large distance Newton potential on a Gauss-Bonnet brane world
Gravity on a brane world with higher order curvature terms and a conformally coupled bulk scalar field is investigated. Solutions with nonstandard large distance gravity are described. It is not necessary to include a scalar field potential in order to obtain the solutions. The resulting Newton potential is qualitatively similar to that of the Dvali-Gabadadze-Porrati (DGP) model. For suitable parameter choices the model is ghost free. Like many other brane gravity models with modified large distance Newton potentials, the short distance gravity is scalar-tensor. The scalar couples with gravitational strength, and so the model is not compatible with observation
Models of Inflation on D-Branes
Halyo, E
2003-01-01
We obtain models of chaotic, slow--roll, hybrid and D--term inflation from the Hanany--Witten brane configuration and its deformations. The deformations are given by the different orientations of the branes and control the parameters of the scalar potential such as the inflaton mass, Yukawa couplings and the anomalous D--term. The different inflationary models are continuously connected and arise in different limits of the parameter space. We describe a compactified version of the brane construction that also leads to models of inflation.
On the localization of four-dimensional brane-world black holes
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)
Brane-world black holes with post-Newtonian parameter: astrophysical signatures
The existence of the many unanswered questions in fundamental physics, in particular, in astrophysics allows for a great variety of theories to remain viable candidates for becoming the correct theory at energies not accessible in current experiments. One special class of these type of theories is the class of extra-dimensional brane-world models. Besides answering many fundamental problems, for instance, the hierarchy problem, they may produce testable predictions. In this work, we find and investigate brane-world induced black string horizon corrections, when the black hole solution has a post-Newtonian parameter. For suitable choices of such a parameter, the Hawking radiation on the brane is precluded, and the Hawking radiation in the bulk causes the black hole to slightly recoil into the bulk, which modifies the black hole apparent horizon. It has an impact on quasars luminosity and, therefore, might be detected and measured.
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. PMID:14683226
Quantum billiards in multidimensional models with branes
Ivashchuk, V. D.; Melnikov, V. N.
2013-01-01
A 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...
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.
Generalized virial theorem in warped DGP brane-world
Heydari-Fard, Malihe; Heydari-Fard, Mohaddese
2012-01-01
We generalize the virial theorem to the warped DGP brane world scenario and consider its implications on the virail mass. In this theory the four dimensional scalar curvature term is included in the bulk action and the resulting four dimensional effective Einstein equation is augmented with extra terms which can be interpreted as geometrical mass, contributing to the gravitational energy. Estimating the geometrical mass using the observational data, we show that these geometric terms may acco...
Quantum billiards in multidimensional models with branes
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.)
Brane Brick Models in the Mirror
Franco, Sebastian; Seong, Rak-Kyeong; Vafa, Cumrun
2016-01-01
Brane brick models are Type IIA brane configurations that encode the $2d$ $\\mathcal{N}=(0,2)$ 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.
Brane world models with a nonminimally coupled bulk scalar field have been studied recently. In this paper we consider metric fluctuations around an arbitrary gravity-scalar background solution, and we show that the corresponding spectrum includes a localized zero mode which strongly depends on the profile of the background scalar field. For a special class of solutions, with a warp factor of the RS form, we solve the linearized Einstein equations, for a pointlike mass source on the brane, by using the brane bending formalism. We see that general relativity on the brane is recovered only if we impose restrictions on the parameter space of the models under consideration
Brane world perspective on the cosmological constant and the hierarchy problems
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
Quantum cosmology, inflationary brane-world creation and dS/CFT correspondence
The creation of 4d de Sitter (inflationary) boundary gluing two d5 de Sitter bulks on the classical as well as on quantum level (with account of brane QFT via corresponding trace anomaly induced effective action) is discussed. Quantum effects decrease the classical de Sitter brane radius or create new de Sitter brane with even smaller radius. It is important that brane CFT may be chosen to be dual to one of 5d de Sitter bulks, making the explicit relation of de Sitter brane-world with dS/CFT correspondence. Moving (time-dependent) de Sitter brane in d5 SdS BH is considered. In the special coordinate system where brane equations look like quantum-corrected FRW equations the comparison with similar brane equations in SAdS BH bulk is done. (author)
Casimir force in brane worlds: Coinciding results from Green's and zeta function approaches
Casimir force encodes the structure of the field modes as vacuum fluctuations and so it is sensitive to the extra dimensions of brane worlds. Now, in flat spacetimes of arbitrary dimension the two standard approaches to the Casimir force, Green's function, and zeta function yield the same result, but for brane world models this was only assumed. In this work we show that both approaches yield the same Casimir force in the case of universal extra dimensions and Randall-Sundrum scenarios with one and two branes added by p compact dimensions. Essentially, the details of the mode eigenfunctions that enter the Casimir force in the Green's function approach get removed due to their orthogonality relations with a measure involving the right hypervolume of the plates, and this leaves just the contribution coming from the zeta function approach. The present analysis corrects previous results showing a difference between the two approaches for the single brane Randall-Sundrum; this was due to an erroneous hypervolume of the plates introduced by the authors when using the Green's function. For all the models we discuss here, the resulting Casimir force can be neatly expressed in terms of two four-dimensional Casimir force contributions: one for the massless mode and the other for a tower of massive modes associated with the extra dimensions.
Bulk scalar field in brane-worlds with induced gravity inspired by the L(R) term
Heydari-Fard, M. [Department of Physics, The University of Qom, Qom 37185-359 (Iran, Islamic Republic of); Sepangi, H.R., E-mail: heydarifard@qom.ac.ir, E-mail: hr-sepangi@sbu.ac.ir [Department of Physics, Shahid Beheshti University, Evin, Tehran 19839 (Iran, Islamic Republic of)
2009-01-15
We obtain the effective field equations in a brane-world scenario within the framework of a DGP model where the action on the brane is an arbitrary function of the Ricci scalar, L(R), and the bulk action includes a scalar field in the matter Lagrangian. We obtain the Friedmann equations and acceleration conditions in the presence of the bulk scalar field for the R{sup n} term in four-dimensional gravity.
Extra Dimensions, Brane Worlds, and the Vanishing of Axion Contributions to Inflation?
Beckwith, A. W.
2006-01-01
We examine from first principles the implications of the 5th Randall-Sundrum Brane world dimension in terms of setting initial conditions for chaotic inflationary physics. Our model pre supposes that the inflationary potential pioneered by Guth is equivalent in magnitute in its initial inflationary state to the effective potential presented in the Randall-Sundrum model. We also consider an axion contribution to chaotic inflation(which may have a temperature dependence) which partly fades out ...
Generalized virial theorem in warped DGP brane-world
Heydari-Fard, Malihe
2012-01-01
We generalize the virial theorem to the warped DGP brane world scenario and consider its implications on the virail mass. In this theory the four dimensional scalar curvature term is included in the bulk action and the resulting four dimensional effective Einstein equation is augmented with extra terms which can be interpreted as geometrical mass, contributing to the gravitational energy. Estimating the geometrical mass using the observational data, we show that these geometric terms may account for the virial mass discrepancy in clusters of galaxies. Finally, we obtain the radial velocity dispersion of galaxy clusters and show that it is compatible with the radial velocity dispersion profle of such clusters.
World-volume Effective Action of Exotic Five-brane in M-theory
Kimura, Tetsuji; 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 (M$5^3$-brane) in eleven dimensions. The supermultiplet of the world-volume theory is the $\\mathcal{N} = (2, 0)$ tensor multiplet in six dimensions. The world-volume action contains three Killing vectors $\\hat{k}_{\\hat{I}} {}^M \\ (\\hat{I} =1,2,3)$ 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 M$5^3$-brane. We also show that our action provides the source term for the M$5^3$-brane geometry in eleven-dimensional supergravity
Strong Gravitational Lensing in a Brane-World Black Hole
Li, GuoPing; Feng, Zhongwen; Zu, Xiaotao
2015-01-01
Adopting the strong field limit approach, we investigated the strong gravitational lensing in a Brane-World black hole, which means that the strong field limit coefficients and the deflection angle in this gravitational field are obtained. With this result, it can be said with certainly that the strong gravitational lensing is related to the metric of gravitational fields closely, the cosmology parameter {\\alpha} and the dark matter parameter \\b{eta} come from the Brane-World black hole exerts a great influence on it. Comparing with the Schwarzschild-AdS spacetime and the Schwarzschild-XCMD spacetime, the parameters {\\alpha}, \\b{eta} of black holes have the similar effects on the gravitational lensing. In some way, we infer that the real gravitational fields in our universe can be described by this metric, so the results of the strong gravitational lensing in this spacetime will be more reasonable for us to observe. Finally, it has to be noticed that the influence which the parameters {\\alpha}, \\b{eta} exerte...
Generalized Israel junction conditions for a Gauss-Bonnet brane world
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
Generalised Israel Junction Conditions for a Gauss-Bonnet Brane World
Davis, Stephen C.
2002-01-01
In spacetimes of dimension greater than four it is natural to consider higher order (in R) corrections to the Einstein equations. In this letter generalized Israel junction conditions for a membrane in such a theory are derived. This is achieved by generalising 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.
The Fermi Paradox in the light of the Inflationary and Brane World Cosmologies
Gato-Rivera, Beatriz
2006-01-01
The Fermi Paradox is discussed in the light of the inflationary and brane world cosmologies. We conclude that some brane world cosmologies may be of relevance for the problem of civilizations spreading across our galaxy, strengthening the Fermi Paradox, but not the inflationary cosmologies, as has been proposed.
Brane Brick Models and 2d (0,2) Triality
Franco, Sebastian; Seong, Rak-Kyeong
2016-01-01
We provide a brane realization of 2d (0,2) Gadde-Gukov-Putrov triality in terms of brane brick models. These are Type IIA brane configurations that are T-dual to D1-branes over singular toric Calabi-Yau 4-folds. Triality translates into a local transformation of brane brick models, whose simplest representative is a cube move. We present explicit examples and construct their triality networks. We also argue that the classical mesonic moduli space of brane brick model theories, which corresponds to the probed Calabi-Yau 4-fold, is invariant under triality. Finally, we discuss triality in terms of phase boundaries, which play a central role in connecting Calabi-Yau 4-folds to brane brick models.
The landscape of intersecting brane models
Douglas, Michael R. [NHETC and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08855-0849 (United States); Taylor, Washington [Center for Theoretical Physics, MIT, Cambridge, MA 02139 (United States)
2007-01-15
We develop tools for analyzing the space of intersecting brane models. We apply these tools to a particular T{sup 6}/Z{sup 2}{sub 2} orientifold which has been used for model building. We prove that there are a finite number of intersecting brane models on this orientifold which satisfy the Diophantine equations coming from supersymmetry. We give estimates for numbers of models with specific gauge groups, which we confirm numerically. We analyze the distributions and correlations of intersection numbers which characterize the numbers of generations of chiral fermions, and show that intersection numbers are roughly independent, with a characteristic distribution which is peaked around 0 and in which integers with fewer divisors are mildly suppressed. As an application, the number of models containing a gauge group SU(3) x SU(2) x U(1) or SU(4) x SU(2) x SU(2) and 3 generations of appropriate types of chiral matter is estimated to be order O(10), in accord with previous explicit constructions. As another application of the methods developed in the paper, we construct a new pair of 3-generation SU(4) x SU(2) x SU(2) Pati-Salam models using intersecting branes. We conclude with a description of how this analysis can be generalized to a broader class of Calabi-Yau orientifolds, and a discussion of how the numbers of IBM's are related to numbers of stabilized vacua.
The landscape of intersecting brane models
Douglas, Michael R.; Taylor, Washington
2007-01-01
We develop tools for analyzing the space of intersecting brane models. We apply these tools to a particular T6/Bbb Z22 orientifold which has been used for model building. We prove that there are a finite number of intersecting brane models on this orientifold which satisfy the Diophantine equations coming from supersymmetry. We give estimates for numbers of models with specific gauge groups, which we confirm numerically. We analyze the distributions and correlations of intersection numbers which characterize the numbers of generations of chiral fermions, and show that intersection numbers are roughly independent, with a characteristic distribution which is peaked around 0 and in which integers with fewer divisors are mildly suppressed. As an application, the number of models containing a gauge group SU(3) × SU(2) × U(1) or SU(4) × SU(2) × SU(2) and 3 generations of appropriate types of chiral matter is estimated to be order Script O(10), in accord with previous explicit constructions. As another application of the methods developed in the paper, we construct a new pair of 3-generation SU(4) × SU(2) × SU(2) Pati-Salam models using intersecting branes. We conclude with a description of how this analysis can be generalized to a broader class of Calabi-Yau orientifolds, and a discussion of how the numbers of IBM's are related to numbers of stabilized vacua.
Brane model with two asymptotic regions
Lubo, Musongela
2005-02-01
Some brane models rely on a generalization of the Melvin magnetic universe including a complex scalar field among the sources. We argue that the geometric interpretation of Kip. S. Thorne of this geometry restricts the kind of potential a complex scalar field can display to keep the same asymptotic behavior. While a finite energy is not obtained for a Mexican hat potential in this interpretation, this is the case for a potential displaying a broken phase and an unbroken one. We use for technical simplicity and illustrative purposes an ad hoc potential which however shares some features with those obtained in some supergravity models. We construct a sixth dimensional cylindrically symmetric solution which has two asymptotic regions: the Melvin-like metric on one side and a flat space displaying a conical singularity on the other. The causal structure of the configuration is discussed. Unfortunately, gravity is not localized on the brane.
A Brane model with two asymptotic regions
Lubo, M
2004-01-01
Some brane models rely on a generalization of the Melvin magnetic universe including a complex scalar field among the sources. We argue that the geometric interpretation of Kip.S.Thorne of this geometry restricts the kind of potential a complex scalar field can display to keep the same asymptotic behavior. While a finite energy is not obtained for a Mexican hat potential in this interpretation, this is the case for a potential displaying a broken phase and an unbroken one. We use for technical simplicity and illustrative purposes an ad hoc potential which however shares some features with those obtained in some supergravity models. We construct a sixth dimensional cylindrically symmetric solution which has two asymptotic regions: the Melvin-like metric on one side and a flat space displaying a conical singularity on the other. The causal structure of the configuration is discussed. Unfortunately, gravity is not localized on the brane.
Brane model with two asymptotic regions
Some brane models rely on a generalization of the Melvin magnetic universe including a complex scalar field among the sources. We argue that the geometric interpretation of Kip. S. Thorne of this geometry restricts the kind of potential a complex scalar field can display to keep the same asymptotic behavior. While a finite energy is not obtained for a Mexican hat potential in this interpretation, this is the case for a potential displaying a broken phase and an unbroken one. We use for technical simplicity and illustrative purposes an ad hoc potential which however shares some features with those obtained in some supergravity models. We construct a sixth dimensional cylindrically symmetric solution which has two asymptotic regions: the Melvin-like metric on one side and a flat space displaying a conical singularity on the other. The causal structure of the configuration is discussed. Unfortunately, gravity is not localized on the brane
Causal Structure and Gravitational Waves in Brane World Cosmology
Ichiki, Kiyotomo; Nakamura, Kouji
2003-01-01
The causal structure of the flat brane universe of RSII type is re-investigated to clarify the boundary conditions for stochastic gravitational waves. In terms of the Gaussian normal coordinate of the brane, a singularity of the equation for gravitational waves appears in the bulk. We show that this singularity corresponds to the ``seam singularity'' which is a singular subspace on the brane universe. Based upon the causal structure, we discuss the boundary conditions for gravitational waves ...
Brane world cosmologies with varying speed of light
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)
Modular symmetry in magnetized/intersecting D-brane models
Kobayashi, Tatsuo; Uemura, Shohei
2016-01-01
We study the modular symmetry in four-dimensional low-energy effective field theory, which is derived from type IIB magnetized D-brane models and type IIA intersecting D-brane models. We analyze modular symmetric behaviors of perturbative terms and non-perturbative terms induced by D-brane instanton effects. Anomalies are also investigated and such an analysis on anomalies suggests corrections in effective field theory.
Gravitational collapse due to dark matter and dark energy in the brane world scenario
Nath, Soma; Chakraborty, Subenoy; Debnath, Ujjal
2005-01-01
Gravitational collapse of FRW brane world embedded in a conformaly flat bulk is considered for matter cloud consists of dark matter and dark energy with equation of state $p=\\epsilon \\rho$ $(\\epsilon
Discussion on some characteristics of the Charged Brane-world Black holes
Kalam, M; Ghosh, A; Raychaudhuri, B
2008-01-01
Several physical natures of charged brane-world black holes have been investigated. At first, time-like and null geodesics of the charged brane-world black holes are presented. We also analyze all the possible motions by plotting the effective potentials for various parameters for circular and radial geodesics. Secondly, we investigate the motion of test particles in the gravitational field of charged brane-world black holes using Hamilton-Jacobi (H-J) formalism. We have considered charged and uncharged test particles and examine its behavior both in static and non-static cases. Thirdly, thermodynamics of the charged brane-world black holes are studied. Finally, it has been also shown that there is no phenomenon of superradiance for an incident massless scalar field for this black hole.
Holography and trace anomaly: What is the fate of (brane-world) black holes?
The holographic principle relates (classical) gravitational waves in the bulk to quantum fluctuations and the Weyl anomaly of a conformal field theory on the boundary (the brane). One can thus argue that linear perturbations in the bulk of static black holes located on the brane be related to the Hawking flux and that (brane-world) black holes are therefore unstable. We try to gain some information on such instability from established knowledge of the Hawking radiation on the brane. In this context, the well-known trace anomaly is used as a measure of both the validity of the holographic picture and of the instability for several proposed static brane metrics. In light of the above analysis, we finally consider a time-dependent metric as the (approximate) representation of the late stage of evaporating black holes which is characterized by decreasing Hawking temperature, in qualitative agreement with what is required by energy conservation
Generalised second law of thermodynamics for interacting dark energy in the DGP brane world
Dutta, Jibitesh; Chakraborty, Subenoy
2010-01-01
In this paper, we investigate the validity of the generalized second law of thermodynamics (GSLT) in the DGP brane world when universe is filled with interacting two fluid system: one in the form of cold dark matter and other is holographic dark energy. The boundary of the universe is assumed to be enclosed by the dynamical apparent horizon or the event horizon. The universe is chosen to be homogeneous and isotropic FRW model and the validity of the first law has been assumed here.
Newton law in brane-world scenario with 4d induced gravity: singular quantum mechanical approach
From the viewpoint of the singular quantum mechanics the effect of the energy-dependent coupling constant for δ-function potential is examined. The energy-dependence of the coupling constant naturally generates the time-derivative in the boundary condition of the Euclidean propagator. This is explicitly confirmed by making use of the simple 1d model. The result is applied to the linearized gravity fluctuation equation for the brane-world scenario with 4d induced gravity. Our approach generates 5d Newton potential at a certain intermediate range of distance between two test massive sources. For other range of distance 4d Newton potential is recovered
Brane-world black holes and the scale of gravity
Alberghi, G L; Micu, O; Orlandi, A
2011-01-01
A particle in four dimensions should behave like a classical black hole if the horizon radius is larger than the Compton wavelength or, equivalently, if its degeneracy (measured by entropy in units of the Planck scale) is large. For spherically symmetric black holes in 4 + d dimensions, both arguments again lead to a mass threshold MC and degeneracy scale Mdeg of the order of the fundamental scale of gravity MG. In the brane-world, deviations from the Schwarzschild metric induced by bulk effects alter the horizon radius and effective four-dimensional Euclidean action in such a way that MC \\simeq Mdeg might be either larger or smaller than MG. This opens up the possibility that black holes exist with a mass smaller than MG and might be produced at the LHC even if M>10 TeV, whereas effects due to bulk graviton exchanges remain undetectable because suppressed by inverse powers of MG. Conversely, even if black holes are not found at the LHC, it is still possible that MC>MG and MG \\simeq 1TeV.
Brane-world stars with a solid crust and vacuum exterior
Ovalle, Jorge; Gergely, László Á.; Casadio, Roberto
2015-02-01
The minimal geometric deformation approach is employed to show the existence of brane-world stellar distributions with a vacuum Schwarzschild exterior, thus without energy leaking from the exterior of the brane-world star into the extra dimension. The interior satisfies all the elementary criteria of physical acceptability for a stellar solution, namely, it is regular at the origin, the pressure and density are positive and decrease monotonically with increasing radius, and all energy conditions are fulfilled. A very thin solid crust with negative radial pressure separates the interior from the exterior, having a thickness Δ inversely proportional to both the brane tension σ and the radius R of the star, i.e. {{Δ }-1}˜ Rσ . This brane-world star with Schwarzschild exterior would appear only thermally radiating to a distant observer and be fully compatible with the stringent constraints imposed on stellar parameters by observations of gravitational lensing, orbital evolutions or properties of accretion disks.
Conductivity bounds in probe brane models
Ikeda, Tatsuhiko N; Nakai, Yuichiro
2016-01-01
We discuss upper and lower bounds on the electrical conductivity of finite temperature strongly coupled quantum field theories, holographically dual to probe brane models, within linear response. In a probe limit where disorder is introduced entirely through an inhomogeneous background charge density, we find simple lower and upper bounds on the electrical conductivity in arbitrary dimensions. In field theories in two spatial dimensions, we show that both bounds persist even when disorder is included in the bulk metric. We discuss the challenges with finding sharp lower bounds on conductivity in three or more spatial dimensions when the metric is inhomogeneous.
Study of branes with variable tension
Aros, Rodrigo
2016-01-01
In this work we study a brane world model with variable tension which gives rise to four dimensional cosmologies. The brane worlds obtained correspond to E\\"{o}tv\\"{o}s branes whose (internal) geometry can be casted as either a four dimensional (A)dS$_{4}$ or a standard radiation period cosmology. The matter dominated period is discussed as well.
Split supersymmetry in brane models
Ignatios Antoniadis
2006-11-01
Type-I string theory in the presence of internal magnetic fields provides a concrete realization of split supersymmetry. To lowest order, gauginos are massless while squarks and sleptons are superheavy. For weak magnetic fields, the correct Standard Model spectrum guarantees gauge coupling unification with sin2 W = 3/8 at the com-pactification scale of GUT ≃ 2 × 1016 GeV. I discuss mechanisms for generating gaugino and higgsino masses at the TeV scale, as well as generalizations to models with split extended supersymmetry in the gauge sector.
De Sitter brane-world, localization of gravity, and the cosmological constant
Cosmological models with a de Sitter 3-brane embedded in a 5-dimensional de Sitter spacetime (dS5) give rise to a finite 4D Planck mass similar to that in Randall-Sundrum (RS) brane-world models in anti-de Sitter 5-dimensional spacetime(AdS5). Yet, there arise a few important differences as compared to the results with a flat 3-brane or 4D Minkowski spacetime. For example, the mass reduction formula (MRF) MPl2=M(5)3lAdS as well as the relationship MPl2=MPl(4+n)n+2Ln (with L being the average size or the radius of the n extra dimensions) expected in models of product-space (or Kaluza-Klein) compactifications get modified in cosmological backgrounds. In an expanding universe, a physically relevant MRF encodes information upon the 4-dimensional Hubble expansion parameter, in addition to the length and mass parameters L, MPl, and MPl(4+n). If a bulk cosmological constant is present in the solution, then the reduction formula is further modified. With these new insights, we show that the localization of a massless 4D graviton as well as the mass hierarchy between MPl and MPl(4+n) can be explained in cosmological brane-world models. A notable advantage of having a 5D de Sitter bulk is that in this case the zero-mass wave function is normalizable, which is not necessarily the case if the bulk spacetime is anti-de Sitter. In spacetime dimensions D≥7, however, the bulk cosmological constant Λb can take either sign (Λb0). The D=6 case is rather inconclusive, in which case Λb may be introduced together with 2-form gauge field (or flux). We obtain some interesting classical gravity solutions that compactify higher-dimensional spacetime to produce a Robertson-Walker universe with de Sitter-type expansion plus one extra noncompact direction. We also show that such models can admit both an effective 4-dimensional Newton constant that remains finite and a normalizable zero-mode graviton wave function.
Generic junction conditions in brane-world scenarios
Battye, R. A.; Carter, B.
2001-01-01
We present the generic junction conditions obeyed by a co-dimension one brane in an arbitrary background spacetime. As well as the usual Darmois-Israel junction conditions which relate the discontinuity in the extrinsic curvature to the to the energy-momentum tensor of matter which is localized to the brane, we point out that another condition must also be obeyed. This condition, which is the analogous to Newton's second law for a point particle, is trivially satisfied when $Z_2$ symmetry is ...
Cosmological Perturbations in Brane World - Brane view v.s. Bulk view -
Soda, J; Soda, Jiro; Koyama, Kazuya
2003-01-01
First, we will study the cosmological perturbations from the brane point of view. It turns out that two types of the extra data are necessary to know the evolution of the system. To fix these data, the analysis of the bulk is needed. So, we have solved equations of motion for the bulk gravity and determined the extra data. We would like to stress that, both analysis take complementary roles to achieve this goal.
Li, L X
2005-01-01
In this Letter we show that the vacuum polarization of quantum fields in an anti-de Sitter space naturally gives rise to a small but nonzero cosmological constant in a brane world living in it. To explain the extremely small ratio of mass density in the cosmological constant to the Planck mass density in our universe (\\approx 10^{-123}) as suggested by cosmological observations, all we need is a four-dimensional brane world (our universe) living in a five-dimensional anti-de Sitter space with a curvature radius r_0 \\sim 10^{-3}cm and a fundamental Planck energy M_P \\sim 10^9 GeV, and a scalar field with a mass m \\sim r_0^{-1}\\sim 10^{-2}eV. Probing gravity down to a scale \\sim 10^{-3}cm, which is attainable in the near future, will provide a test of the model.
Noncommutative brane-world (Anti) de Sitter vacua and extra dimensions
We investigate a curved brane-world, inspired by a noncommutative D3-brane, in a type IIB string theory. We obtain, an axially symmetric and a spherically symmetric (anti) de Sitter black holes in 4D. The event horizons of these black holes possess a constant curvature and may be seen to be governed by different topologies. The extremal geometries are explored, using the noncommutative scaling in the theory, to reassure the attractor behavior at the black hole event horizon. The emerging two dimensional, semi-classical, black hole is analyzed to provide evidence for the extra dimensions in a curved brane-world. It is argued that the gauge nonlinearity in the theory may be redefined by a potential in a moduli space. As a result, D = 11 and D = 12 dimensional geometries may be obtained at the stable extrema of the potential
Brane brick models, toric Calabi-Yau 4-folds and 2d (0,2) quivers
Franco, Sebastián; Lee, Sangmin; Seong, Rak-Kyeong
2016-02-01
We introduce brane brick models, a novel type of Type IIA brane configurations consisting of D4-branes ending on an NS5-brane. Brane brick models are T-dual to D1-branes over singular toric Calabi-Yau 4-folds. They fully encode the infinite class of 2 d (generically) {N}=(0,2) gauge theories on the worldvolume of the D1-branes and streamline their connection to the probed geometries. For this purpose, we also introduce new combinatorial procedures for deriving the Calabi-Yau associated to a given gauge theory and vice versa.
Brane Brick Models, Toric Calabi-Yau 4-Folds and 2d (0,2) Quivers
Franco, Sebastian; Seong, Rak-Kyeong
2015-01-01
We introduce brane brick models, a novel type of Type IIA brane configurations consisting of D4-branes ending on an NS5-brane. Brane brick models are T-dual to D1-branes over singular toric Calabi-Yau 4-folds. They fully encode the infinite class of 2d (generically) N=(0,2) gauge theories on the worldvolume of the D1-branes and streamline their connection to the probed geometries. For this purpose, we also introduce new combinatorial procedures for deriving the Calabi-Yau associated to a given gauge theory and vice versa.
Cosmological constraints on parameters of one-brane models with extra dimension
Iofa, Mikhail Z
2009-01-01
We study some aspects of cosmologies in 5D models with one infinite extra dimension. Matter is confined to the brane, gravity extends to the bulk. Models with positive and negative tension of the brane are considered. Cosmological evolution of the 4D world is described by warped solutions of the generalized Friedmann equation. Cosmological solutions on the brane are obtained with the input of the present-time observational cosmological parameters. We estimate the age of the Universe and abundance of ${}^4 He$ produced in primordial nucleosynthesis in different models. Using these estimates we find constraints on dimensionless combinations of the 5D gravitational scale, scale of the warp factor and coupling at the 4D curvature term in the action.
Flavor structure in D-brane models: Majorana neutrino masses
Hamada, Yuta; Uemura, Shohei
2014-01-01
We study the flavor structure in intersecting D-brane models. We study anomalies of the discrete flavor symmetries. We analyze the Majorana neutrino masses, which can be generated by D-brane instanton effects. It is found that a certain pattern of mass matrix is obtained and the cyclic permutation symmetry remains unbroken. As a result, trimaximal mixing matrix can be realized if Dirac neutrino mass and charged lepton mass matrices are diagonal.
Gravity, Stability and Energy Conservation on the Randall-Sundrum Brane-World
Sasaki, Misao; Shiromizu, Tetsuya; Maeda, Kei-ichi
1999-01-01
We carefully investigate the gravitational perturbation of the Randall-Sundrum (RS) single brane-world solution [hep-th/9906064], based on a covariant curvature tensor formalism recently developed by us. Using this curvature formalism, it is known that the `electric' part of the 5-dimensional Weyl tensor, denoted by $E_{\\mu\
Strings and brane world scenarios in financial market data
Richard Pincak
2013-05-01
Full Text Available 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. 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 possible utilizations of the string theory approach in financial market are slight.
Casimir force for a scalar field in a single brane world
Vacuum force is an interesting low energy test for brane worlds due to its dependence on field's modes and its role in submillimeter gravity experiments. In this contribution we obtain the scalar field vacuum force between two parallel plates lying in the brane of a Randall-Sundrum scenario extended by p compact dimensions (RSII-p). We obtain the force using the Green's function technique and we compare our results with the ones obtained by using the zeta function regularization method. As a result we obtain agreement in the expression for the force independently of the method used, thus we solve a previous discrepancy between the two approaches.
Noncommutative brane-world, (Anti) de Sitter vacua and extra dimensions
Kar, Supriya
2006-01-01
We investigate a curved brane-world, inspired by a noncommutative D3-brane, in a type IIB string theory. We obtain, an axially symmetric and a spherically symmetric, (anti) de Sitter black holes in 4D. The event horizons of these black holes possess a constant curvature and may be seen to be governed by different topologies. The extremal geometries are explored, using the noncommutative scaling in the theory, to reassure the attractor behavior at the black hole event horizon. The emerging two...
Brane-world stars with a solid crust and vacuum exterior
The minimal geometric deformation approach is employed to show the existence of brane-world stellar distributions with a vacuum Schwarzschild exterior, thus without energy leaking from the exterior of the brane-world star into the extra dimension. The interior satisfies all the elementary criteria of physical acceptability for a stellar solution, namely, it is regular at the origin, the pressure and density are positive and decrease monotonically with increasing radius, and all energy conditions are fulfilled. A very thin solid crust with negative radial pressure separates the interior from the exterior, having a thickness Δ inversely proportional to both the brane tension σ and the radius R of the star, i.e. Δ−1∼Rσ. This brane-world star with Schwarzschild exterior would appear only thermally radiating to a distant observer and be fully compatible with the stringent constraints imposed on stellar parameters by observations of gravitational lensing, orbital evolutions or properties of accretion disks. (paper)
Towards an Explicit Model of D-brane Inflation
Baumann, Daniel; Klebanov, Igor R; McAllister, Liam
2007-01-01
We present a detailed analysis of an explicit model of warped D-brane inflation, incorporating the effects of moduli stabilization. We consider the potential for D3-brane motion in a warped conifold background that includes fluxes and holomorphically-embedded D7-branes involved in moduli stabilization. Although the D7-branes significantly modify the inflaton potential, they do not correct the quadratic term in the potential, and hence do not cause a uniform change in the slow-roll parameter eta. Nevertheless, we present a simple example based on the Kuperstein embedding of D7-branes, z_1=constant, in which the potential can be fine-tuned to be sufficiently flat for inflation. To derive this result, it is essential to incorporate the fact that the compactification volume changes slightly as the D3-brane moves. We stress that the compactification geometry dictates certain relationships among the parameters in the inflaton Lagrangian, and these microscopic constraints impose severe restrictions on the space of p...
On Factorization Constraints for Branes in the H3+ Model
Adorf, Hendrik; Flohr, Michael
We comment on the brane solutions for the boundary H3+ model that have been proposed so far and point out that they should be distinguished according to the patterns regular/irregular and discrete/continuous. In the literature, mostly irregular branes have been studied, while results on the regular ones are rare. For all types of branes, there are questions about how a second factorization constraint in the form of a b-2/2-shift equation can be derived. Here, we assume analyticity of the boundary two-point function, which means that the Cardy-Lewellen constraints remain unweakened. This enables us to derive unambiguously the desired b-2/2-shift equations. They serve as important additional consistency conditions. For some regular branes, we also derive 1/2-shift equations that were not known previously. Case by case, we discuss possible solutions to the enlarged system of constraints. We find that the well-known irregular continuous AdS2 branes are consistent with our new factorization constraint. Furthermore, we establish the existence of a new type of brane: the shift equations in a certain regular discrete case possess a nontrivial solution that we write down explicitly. All other types are found to be inconsistent when using our second constraint. We discuss these results in view of the Hosomichi-Ribault proposal and some of our earlier results on the derivation of b-2/2-shift equations.
Spontaneous Symmetry Breaking in General Relativity. Brane World Concept
Meierovich, Boris E
2009-01-01
Gravitational properties of a hedge-hog type topological defect in two extra dimensions are considered in General Relativity employing a vector as the order parameter. The developed macroscopic theory of phase transitions with spontaneous symmetry breaking is applied to the analysis of possible "thick" brane structures. The previous considerations were done using the order parameter in the form of a multiplet in a target space of scalar fields. The difference of these two approaches is analyzed and demonstrated in detail. There are two different symmetries of regular solutions of Einstein equations for a hedgehog type vector order parameter. Both solutions are analyzed in parallel analytically and numerically. Regular configurations in cases of vector order parameter have one more free parameter in comparison with the scalar multiplet solutions. It is shown that the existence of a negative cosmological constant is sufficient for the spontaneous symmetry breaking of the initially plain bulk. Regular configurat...
Evolution of gravitational waves in the high-energy regime of brane-world cosmology
Hiramatsu, T; Taruya, A; Hiramatsu, Takashi; Koyama, Kazuya; Taruya, Atsushi
2004-01-01
We discuss the cosmological evolution of gravitational waves (GWs) after inflation in a brane-world cosmology embedded in five-dimensional anti-de Sitter (AdS_5) bulk spacetime. In a brane-world scenario, the evolution of GWs is affected by the non-standard cosmological expansion and the excitation of the Kaluza-Klein modes (KK-modes), which are significant in the high-energy regime of the universe. We numerically solve the wave equation of GWs in the Poincare coordinates of the AdS_5 spacetime. Using a plausible initial condition from inflation, we find that, while the behavior of GWs in the bulk is sensitive to the transition time from inflation to the radiation dominated epoch, the amplitude of GWs on the brane is insensitive to this time if the transition occurs early enough before horizon re-entry. As a result, the amplitude of GWs is suppressed by the excitation of KK-modes which escape from the brane into the bulk, and the effect may compensate the enhancement of the GWs by the non-standard cosmologica...
T-branes as branes within branes
Collinucci, Andres
2014-01-01
Bound states of 7-branes known as 'T-branes' have properties that defy usual geometric intuition. For instance, the gauge group of n coincident branes may not be U(n). Also, charged matter may not show up at the intersection between two branes, but might be localized at some unexpected curve, or even at a point. By analyzing T-branes of perturbative type IIB string theory in the tachyon condensation picture we gain the following insights: In a large class of models, the tachyon can be diagonalized even though the worldvolume Higgs cannot. In those cases, we see the structure of these bound states more manifestly, thereby drastically simplifying analysis of gauge groups and spectra. Whenever the tachyon is not diagonalizable, matter localizes at unexpected loci, and we find that there is a lower-dimensional brane bound to the 7-brane.
D 3 -Brane Model Building and the Supertrace Rule
Bena, Iosif; Graña, Mariana; Kuperstein, Stanislav; Ntokos, Praxitelis; Petrini, Michela
2016-04-01
A common way to obtain standard-model-like Lagrangians in string theory is to place D 3 -branes inside flux compactifications. The bosonic and fermionic masses and couplings of the resulting gauge theory are determined by the ten-dimensional metric and the fluxes, respectively, and the breaking of supersymmetry is soft. However, not any soft-supersymmetry-breaking Lagrangian can be obtained this way since the string theory equations of motion impose certain relations between the soft couplings. We show that for D 3 -branes in background fluxes, these relations imply that the sums of the squares of the boson and of the fermion masses are equal and that, furthermore, one- and two-loop quantum corrections do not spoil this equality. This makes the use of D 3 -branes for constructing computationally controllable models for physics beyond the standard model problematic.
D3-Brane Model Building and the Supertrace Rule.
Bena, Iosif; Graña, Mariana; Kuperstein, Stanislav; Ntokos, Praxitelis; Petrini, Michela
2016-04-01
A common way to obtain standard-model-like Lagrangians in string theory is to place D3-branes inside flux compactifications. The bosonic and fermionic masses and couplings of the resulting gauge theory are determined by the ten-dimensional metric and the fluxes, respectively, and the breaking of supersymmetry is soft. However, not any soft-supersymmetry-breaking Lagrangian can be obtained this way since the string theory equations of motion impose certain relations between the soft couplings. We show that for D3-branes in background fluxes, these relations imply that the sums of the squares of the boson and of the fermion masses are equal and that, furthermore, one- and two-loop quantum corrections do not spoil this equality. This makes the use of D3-branes for constructing computationally controllable models for physics beyond the standard model problematic. PMID:27104696
Black Holes in the Presence of Cosmological Constant and Large N Brane World
Luo, M; Luo, Mingxing; Zheng, Sibo
2006-01-01
Analytic form has been obtained for four-dimensional black holes with a minimal Hawking temperature in a theory with cosmological constant, dilaton and gauge fields. In general dimensions, black hole solutions are shown to exist and their asymptotic behaviors are obtained. In theories of ten dimension, N coincident D3-branes as the boundary of an $AdS_5$ space are constructed by embedding black D3-branes, with a five-dimensional compactified space of negligible size if N is large, which provide natural realizations of the Randall-Sundrum scenario. For this $AdS_{5}$ background, the cosmological constant is a higher order perturbation and its effect on the spectra of standard model fields on the branes can be calculated.
Decompactifications and massless D-branes in hybrid models
Aspinwall, Paul S.; Ronen Plesser, M.
2010-07-01
A method of determining the mass spectrum of BPS D-branes in any phase limit of a gauged linear sigma model is introduced. A ring associated to monodromy is defined and one considers K-theory to be a module over this ring. A simple but interesting class of hybrid models with Landau-Ginzburg fibres over {mathbb{P}^n} are analyzed using special Kähler geometry and D-brane probes. In some cases the hybrid limit is an infinite distance in moduli space and corresponds to a decompactification. In other cases the hybrid limit isat a finite distance and acquires massless D-branes. An example studied appears to correspond to a novel theory of supergravity with an SU(2) gauge symmetry where the gauge and gravitational couplings are necessarily tied to each other.
Phenomenological Lagrangians, gauge models and branes
Zheltukhin, A. A.
2016-01-01
Phenomenological Lagrangians for physical systems with spontaneously broken symmetries are reformulated in terms of gauge field theory. Description of the Dirac $p$-branes in terms of the Yang-Mills-Cartan gauge multiplets interacting with gravity, is proved to be equivalent to their description as a closed dynamical system with the symmetry $ISO(1,D-1)$ spontaneously broken to $ISO(1,p)\\times SO(D-p-1)$.
On Factorization Constraints for Branes in the H3+ Model
Adorf, Hendrik
2008-01-01
We comment on the brane solutions for the boundary H3+ model that have been proposed so far and point out that they should be distinguished according to the patterns regular/irregular and discrete/continuous. In the literature, mostly irregular branes have been studied, while results on the regular ones are rare. For all types of branes, there are questions about how a second factorization constraint in the form of a b^{-2}/2-shift equation can be derived. Here, we assume analyticity of the boundary two point function, which means that the Cardy-Lewellen constraints remain unweakened. This enables us to derive unambiguously the desired b^{-2}/2-shift equations. They serve as important additional consistency conditions. For some regular branes, we also derive 1/2-shift equations that were not known previously. Case by case, we discuss possible solutions to the enlarged system of constraints. We find that the well-known irregular continuous AdS_2 branes are consistent with our new factorization constraint. Furt...
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
Classical Tests of General Relativity: Brane-World Sun from Minimal Geometric Deformation
Casadio, Roberto; Ovalle, Jorge; da Rocha, Roldao
2015-01-01
We consider a solution of the effective four-dimensional brane-world equations, obtained from the General Relativistic Schwarzschild metric via the principle of Minimal Geometric Deformation, and investigate the corresponding signatures stemming from the possible existence of a warped extra dimension. In particular, we derive bounds on an extra-dimensional parameter, closely related with the fundamental gravitational length, from the experimental results of the classical tests of General Rela...
Fluid/gravity correspondence and the CFM brane-world solutions
Casadio, Roberto; Cavalcanti, Rogerio T.; da Rocha, Roldao
2016-01-01
We consider the lower bound for the shear viscosity-to-entropy 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-Newtonia...
Classical tests of general relativity: Brane-world Sun from minimal geometric deformation
Casadio, R.; Ovalle, J.; da Rocha, Roldão
2015-05-01
We consider a solution of the effective four-dimensional brane-world equations, obtained from the general relativistic Schwarzschild metric via the principle of minimal geometric deformation, and investigate the corresponding signatures stemming from the possible existence of a warped extra-dimension. In particular, we derive bounds on an extra-dimensional parameter, closely related with the fundamental gravitational length, from the experimental results of the classical tests of general relativity in the Solar system.
Classical Tests of General Relativity: Brane-World Sun from Minimal Geometric Deformation
Casadio, Roberto; da Rocha, Roldao
2015-01-01
We consider a solution of the effective four-dimensional brane-world equations, obtained from the General Relativistic Schwarzschild metric via the principle of Minimal Geometric Deformation, and investigate the corresponding signatures stemming from the possible existence of a warped extra dimension. In particular, we derive bounds on an extra-dimensional parameter, closely related with the fundamental gravitational length, from the experimental results of the classical tests of General Relativity in the Solar system.
Comments on SUSY inflation models on the brane
Lee, Lu-Yun; Lin, Chia-Min
2009-01-01
In this paper we consider a class of inflation models on the brane where the dominant part of the inflaton scalar potential does not depend on the inflaton field value during inflation. In particular, we consider supernatural inflation, its hilltop version, A-term inflation, and supersymmetric (SUSY) D- and F-term hybrid inflation on the brane. We show that the parameter space can be broadened, the inflation scale generally can be lowered, and still possible to have the spectral index $n_s=0.96$.
Cosmological evolution in a two-brane warped geometry model
Kumar, Sumit; SenGupta, Soumitra
2014-01-01
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 into 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.
Frolov, Valeri P
2010-01-01
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/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/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 ...
Aspects of scalar field dynamics in Gauss-Bonnet brane worlds
The Einstein-Gauss-Bonnet equations projected from the bulk to brane lead to a complicated Friedmann equation which simplifies to H2∼ρq in the asymptotic regimes. The Randall-Sundrum (RS) scenario corresponds to q=2 whereas q=2/3 and q=1 give rise to high-energy Gauss-Bonnet (GB) regime and the standard general relativity (GR), respectively. Amazingly, while evolving from RS regime to high-energy GB limit, one passes through a GR-like region which has important implications for brane world inflation. For tachyon GB inflation with potentials V(φ)∼φp investigated in this paper, the scalar to tensor ratio of perturbations R is maximum around the RS region and is generally suppressed in the high-energy regime for the positive values of p. The ratio is very low for p>0 at all energy scales relative to GB inflation with ordinary scalar field. The models based upon tachyon inflation with polynomial type of potentials with generic positive values of p turn out to be in the 1σ observational contour bound at all energy scales varying from GR to high-energy GB limit. The spectral index nS improves for the lower values of p and approaches its scale invariant limit for p=-2 in the high-energy GB regime. The ratio R also remains small for large negative values of p, however, difference arises for models close to scale invariance limit. In this case, the tensor to scale ratio is large in the GB regime whereas it is suppressed in the intermediate region between RS and GB. Within the framework of patch cosmologies governed by H2∼ρq, the behavior of ordinary scalar field near cosmological singularity and the nature of scaling solutions are distinguished for the values of q1. The tachyon dynamics, on the other hand, exhibits stable scaling solutions for all q if the adiabatic index of barotropic fluid γ<1
Gauged linear sigma model for exotic five-brane
We study an N=(4,4) supersymmetric gauged linear sigma model which gives rise to the nonlinear sigma model for multi-centered KK-monopoles. We find a new T-duality transformation of the model even in the presence of F-terms. Performing T-duality, we find the gauged linear sigma model whose IR limit describes the exotic 522-brane with B-field
Black Diamonds at Brane Junctions
Chamblin, Andrew; Csaki, Csaba; Erlich, Joshua; Timothy J. Hollowood
2000-01-01
We discuss the properties of black holes in brane-world scenarios where our universe is viewed as a four-dimensional sub-manifold of some higher-dimensional spacetime. We consider in detail such a model where four-dimensional spacetime lies at the junction of several domain walls in a higher dimensional anti-de Sitter spacetime. In this model there may be any number p of infinitely large extra dimensions transverse to the brane-world. We present an exact solution describing a black p-brane wh...
Gauge Fields, Fermions and Mass Gaps in 6D Brane Worlds
Parameswaran, S L; Salvio, A
2006-01-01
We study fluctuations about axisymmetric warped brane solutions in 6D minimal gauged supergravity. Much of our analysis is general and could be applied to other scenarios. We focus on bulk sectors that could give rise to Standard Model gauge fields and charged matter. We reduce the dynamics to Schroedinger type equations plus physical boundary conditions, and obtain exact solutions for the Kaluza-Klein wave functions and discrete mass spectra. The power-law warping, as opposed to exponential in 5D, means that zero mode wave functions can be peaked on negative tension branes, but only at the price of localizing the whole Kaluza-Klein tower there. However, remarkably, the codimension two defects allow the Kaluza-Klein mass gap to remain finite even in the infinite volume limit. In principle, not only gravity, but Standard Model fields could `feel' the extent of large extra dimensions, and still be described by an effective 4D theory.
D-brane scattering and annihilation
D'Amico, Guido; Kleban, Matthew; Schillo, Marjorie
2014-01-01
We study the dynamics of parallel brane-brane and brane-antibrane scattering in string theory in flat spacetime, focusing on the pair production of open strings that stretch between the branes. We are particularly interested in the case of scattering at small impact parameter $b < l_s$, where there is a tachyon in the spectrum when a brane and an antibrane approach within a string length. Our conclusion is that despite the tachyon, branes and antibranes can pass through each other with only a very small probability of annihilating, so long as $g_s$ is small and the relative velocity $v$ is neither too small nor too close to 1. Our analysis is relevant also to the case of charged open string production in world-volume electric fields, and we make use of this T-dual scenario in our analysis. We briefly discuss the application of our results to a stringy model of inflation involving moving branes.
On brane-world black holes and short scale physics
There is evidence that trans-Planckian physics does not affect the Hawking radiation in four dimensions and, consequently, deviations from the linear dispersion relation (for massless particles) at very high energies cannot be revealed using four-dimensional black holes. We study this issue in the context of models with extra-spatial dimensions and show that small black holes that could be produced in accelerators might also provide a chance of testing the high energy regime where non-linear dispersion relations are generally expected
Fluid/gravity correspondence and the CFM brane-world solutions
Casadio, Roberto; da Rocha, Roldao
2016-01-01
We consider the lower bound for the shear viscosity-to-entropy 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 of the CFM metrics. This lends further support to the physical relevance of the viscosity-to-entropy ratio lower bound and fluid/gravity correspondence overall.
Possibility of catastrophic black hole growth in the warped brane-world scenario at the LHC
In this paper, we present the results of our analysis of the growth and decay of black holes possibly produced at the Large Hadron Collider, based on our previous study of black holes in the context of the warped brane-world scenario. The black hole mass accretion and decay is obtained as a function of time, and the maximum black hole mass are obtained as a function of a critical mass parameter. The latter occurs in our expression for the luminosity and is related to the size of extra-dimensional corrections to Newton's law. Based on this analysis, we argue against the possibility of catastrophic black hole growth at the LHC.
Warped Higgsless Models with IR-Brane Kinetic Terms
Davoudiasl, H; Lillie, Benjamin Huntington; Rizzo, T G
2004-01-01
We examine a warped Higgsless $SU(2)_L\\times SU(2)_R\\times U(1)_{B-L}$ model in 5--$d$ with IR(TeV)--brane kinetic terms. It is shown that adding a brane term for the $U(1)_{B-L}$ gauge field does not affect the scale ($\\sim 2-3$ TeV) where perturbative unitarity in $W_L^+ W_L^- \\to W_L^+ W_L^-$ is violated. This term could, however, enhance the agreement of the model with the precision electroweak data. In contrast, the inclusion of a kinetic term corresponding to the $SU(2)_D$ custodial symmetry of the theory delays the unitarity violation in $W_L^\\pm$ scattering to energy scales of $\\sim 6-7$ TeV for a significant fraction of the parameter space. This is about a factor of 4 improvement compared to the corresponding scale of unitarity violation in the Standard Model without a Higgs. We also show that null searches for extra gauge bosons at the Tevatron and for contact interactions at LEP II place non-trivial bounds on the size of the IR-brane terms.
Semi-doubled Sigma Models for Five-branes
Kimura, Tetsuji
2015-01-01
We study two-dimensional ${\\cal N}=(2,2)$ gauge theory and its dualized system in terms of complex (linear) superfields and their alternatives. Although this technique itself is not new, we can obtain a new model, the so-called "semi-doubled" GLSM. Similar to doubled sigma model, this involves both the original and dual degrees of freedom simultaneously, whilst the latter only contribute to the system via topological interactions. Applying this to the ${\\cal N}=(4,4)$ GLSM for H-monopoles, i.e., smeared NS5-branes, we obtain its T-dualized systems in quite an easy way. As a bonus, we also obtain the semi-doubled GLSM for an exotic $5^3_2$-brane whose background is locally nongeometric. In the low energy limit, we construct the semi-doubled NLSM which also generates the conventional string worldsheet sigma models. In the case of the NLSM for $5^3_2$-brane, however, we find that the Dirac monopole equation does not make sense any more because the physical information is absorbed into the divergent part via the ...
Time-like geodesic structure of a spherically symmetric black hole in the brane-world
Zhou Sheng; Chen Ju-Hua; Wang Yong-Jiu
2011-01-01
Recently Malihe Heydari-Fard obtained a spherically symmetric exterior black hole solution in the brane-world scenario,which can be used to explain the galaxy rotation curves without postulating dark matter.By analysing the particle effective potential,we have investigated the time-like geodesic structure of the spherically symmetric black hole in the brane-world.We mainly take account of how the cosmological constant α and the stellar pressure β affect the time-like geodesic structure of the black hole.We find that the radial particle falls to the singularity from a finite distance or plunges into the singularity,depending on its initial conditions.But the non-radial time-like geodesic structure is more complex than the radial case.We find that the particle moves on the bound orbit or stable (unstable) circle orbit or plunges into the singularity,or reflects to infinity,depending on its energy and initial conditions.By comparing the particle effective potential curves for different values of the stellar pressure β and the cosmological constant α,we find that the stellar pressure parameter β does not affect the time-like geodesic structure of the black hole,but the cosmological constant α has an impact on its time-like geodesic structure.
Time-like geodesic structure of a spherically symmetric black hole in the brane-world
Recently Malihe Heydari-Fard obtained a spherically symmetric exterior black hole solution in the brane-world scenario, which can be used to explain the galaxy rotation curves without postulating dark matter. By analysing the particle effective potential, we have investigated the time-like geodesic structure of the spherically symmetric black hole in the brane-world. We mainly take account of how the cosmological constant α and the stellar pressure β affect the time-like geodesic structure of the black hole. We find that the radial particle falls to the singularity from a finite distance or plunges into the singularity, depending on its initial conditions. But the non-radial time-like geodesic structure is more complex than the radial case. We find that the particle moves on the bound orbit or stable (unstable) circle orbit or plunges into the singularity, or reflects to infinity, depending on its energy and initial conditions. By comparing the particle effective potential curves for different values of the stellar pressure β and the cosmological constant α, we find that the stellar pressure parameter β does not affect the time-like geodesic structure of the black hole, but the cosmological constant α has an impact on its time-like geodesic structure. (general)
Farakos, K.; Koutsoumbas, G.; Pasipoularides, P.
2007-01-01
Brane world models with a non-minimally coupled bulk scalar field have been studied recently. In this paper we consider metric fluctuations around an arbitrary gravity-scalar background solution, and we show that the corresponding spectrum includes a localized zero mode which strongly depends on the profile of the background scalar field. For a special class of solutions, with a warp factor of the RS form, we solve the linearized Einstein equations, for a point-like mass source on the brane, ...
Brane world corrections to the scalar vacuum force in the Randall-Sundrum II-p scenario
Vacuum force is an interesting low energy test for brane worlds due to its dependence on field's modes and its role in submillimeter gravity experiments. In this work, we generalize a previous model example: the scalar field vacuum force between two parallel plates lying in the brane of a Randall-Sundrum scenario extended by p compact dimensions (RSII-p). Upon use of Green's function technique, for the massless scalar field, the 4D force is obtained from a zero mode while leading order corrections due to the noncompact dimension turn out attractive and depend on the separation between plates as l-(6+p). For the massive scalar field, a quasilocalized mode yields the 4D force with attractive corrections behaving like l-(10+p). Corrections are negligible with respect to 4D force for anti-de Sitter (AdS(5+p)) radius much less than ∼10-6 m. In the massless case we also determined, numerically, the corrections due to compact dimensions. To avoid conflict with experimental data we get R≤0.4 μm, 0.3 μm for the cases p=1, 2, respectively. Although the p=0 case is not physically viable due to the different behavior in regard to localization for the massless scalar and electromagnetic fields it yields a useful comparison between the dimensional regularization and Green's function techniques as we describe in the discussion.
Cosmological constraints for a two brane-world system with single equation of state
Perez, Juan L; Urena-Lopez, L Arturo; 10.1063/1.3647549
2012-01-01
We present the study of two 3-brane system embedded in a 5-dimensional space-time in which the fifth dimension is compactified on a $S^{1}/Z_{2}$ orbifold. Assuming isotropic, homogeneous, and static branes, it can be shown that the dynamics of one brane is dominated by the other one when the metric coefficients have a particular form. We study the resulting cosmologies when one brane is dominated by a given single-fluid component.
Black diamonds at brane junctions
Chamblin, Andrew; Csáki, Csaba; Erlich, Joshua; Hollowood, Timothy J.
2000-08-01
We discuss the properties of black holes in brane-world scenarios where our Universe is viewed as a four-dimensional sub-manifold of some higher-dimensional spacetime. We consider in detail such a model where four-dimensional spacetime lies at the junction of several domain walls in a higher dimensional anti-de Sitter spacetime. In this model there may be any number p of infinitely large extra dimensions transverse to the brane-world. We present an exact solution describing a black p-brane which will induce on the brane-world the Schwarzschild solution. This exact solution is unstable to the Gregory-Laflamme instability, whereby long-wavelength perturbations cause the extended horizon to fragment. We therefore argue that at late times a non-rotating uncharged black hole in the brane-world is described by a deformed event horizon in p+4 dimensions which will induce, to good approximation, the Schwarzschild solution in the four-dimensional brane world. When p=2, this deformed horizon resembles a black diamond and more generally for p>2, a polyhedron.
Black diamonds at brane junctions
We discuss the properties of black holes in brane-world scenarios where our Universe is viewed as a four-dimensional sub-manifold of some higher-dimensional spacetime. We consider in detail such a model where four-dimensional spacetime lies at the junction of several domain walls in a higher dimensional anti-de Sitter spacetime. In this model there may be any number p of infinitely large extra dimensions transverse to the brane-world. We present an exact solution describing a black p-brane which will induce on the brane-world the Schwarzschild solution. This exact solution is unstable to the Gregory-Laflamme instability, whereby long-wavelength perturbations cause the extended horizon to fragment. We therefore argue that at late times a non-rotating uncharged black hole in the brane-world is described by a deformed event horizon in p+4 dimensions which will induce, to good approximation, the Schwarzschild solution in the four-dimensional brane world. When p=2, this deformed horizon resembles a black diamond and more generally for p>2, a polyhedron. (c) 2000 The American Physical Society
Free-field representation of permutation branes in Gepner models
We consider a free-field realization of Gepner models based on the free-field realization of N = 2 superconformal minimal models. Using this realization, we analyze the A/B-type boundary conditions starting from the ansatz with the left-moving and right-moving free-field degrees of freedom glued at the boundary by an arbitrary constant matrix. We show that the only boundary conditions consistent with the singular vector structure of unitary minimal model representations are given by permutation matrices, thereby yielding an explicit free-field construction of the permutation branes of Recknagel
Gravity localization on hybrid branes
Veras, D. F. S.; Cruz, W. T.; Maluf, R. V.; Almeida, C. A. S.
2016-03-01
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.
Equation-of-state formalism for dark energy models on the brane and the future of brane universes
Astashenok, Artyom V.; Yurov, Artyom V. [Baltic Federal University of I. Kant, Department of Theoretical Physics, Kaliningrad (Russian Federation); Elizalde, Emilio [Facultat de Ciencies, Consejo Superior de Investigaciones Cientificas, ICE/CSIC and IEEC Campus UAB, Bellaterra, Barcelona (Spain); Odintsov, Sergei D. [Facultat de Ciencies, Consejo Superior de Investigaciones Cientificas, ICE/CSIC and IEEC Campus UAB, Bellaterra, Barcelona (Spain); Institucio Catalana de Recerca i Estudis Avancats (ICREA), Barcelona (Spain)
2012-12-15
Brane dark energy cosmologies, leading to various possible evolutions of our universe, are investigated. The discussion shows that while all these models can be made arbitrarily close to the standard {Lambda}CDM cosmology at present, their future evolutions can be very different, even diverge with time in a number of ways. This includes asymptotic de-Sitter evolution, Little Rip with dissolution of bound structures, and various possible singularities, as the Big Rip, a sudden future singularity (Type II), and Type III and Type IV cases. Specifically, some interesting effects coming from the brane tension are investigated. It is shown, in particular, that the Little Rip occurs faster on the brane model than in usual FRW cosmology. In the asymptotic de-Sitter regime the influence of the brane tension leads to a deviation of the value of the effective cosmological constant from that corresponding to ordinary dark energy. As a consequence, the value of the inertial force from the accelerating expansion can greatly exceed the corresponding inertial force in ordinary cosmological models. (orig.)
Thick brane models in generalized theories of gravity
This work deals with thick braneworld models, in an environment where the Ricci scalar is changed to accommodate the addition of two extra terms, one depending on the Ricci scalar itself, and the other, which takes into account the trace of the energy–momentum tensor of the scalar field that sources the braneworld scenario. We suppose that the scalar field engenders standard kinematics, and we show explicitly that the gravity sector of this new braneworld scenario is linearly stable. We illustrate the general results investigating two distinct models, focusing on how the brane profile is changed in the modified theories
Non-Perturbative Effects in Matrix Models and D-branes
Alexandrov, Sergei Yu.; Kazakov, Vladimir A.; Kutasov, David
2003-01-01
The large order growth of string perturbation theory in $c\\le 1$ conformal field theory coupled to world sheet gravity implies the presence of $O(e^{-{1\\over g_s}})$ non-perturbative effects, whose leading behavior can be calculated in the matrix model approach. Recently it was proposed that the same effects should be reproduced by studying certain localized D-branes in Liouville Field Theory, which were constructed by A. and Al. Zamolodchikov. We discuss this correspondence in a number of di...
Brane-world and loop cosmology from a gravity–matter coupling perspective
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
Newton law in DGP brane-world with semi-infinite extra dimension
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
Configurational entropy in $f(R,T)$ brane models
Correa, R A C
2015-01-01
In this work we investigate generalized theories of gravity in the so-called configurational entropy (CE) context. We show, by means of this information-theoretical measure, that a stricter bound on the parameter of $f(R,T)$ brane models arises from the CE. We find that these bounds are characterized by a valley region in the CE profile, where the entropy is minimal. We argue that the CE measure can open a new role and an important additional approach to select parameters in modified theories of gravitation.
Configurational entropy in f(R,T) brane models
Correa, R.A.C. [Universidade Federal do ABC, CCNH, Santo Andre, Sao Paulo (Brazil); Moraes, P.H.R.S. [ITA, Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, Sao Paulo (Brazil)
2016-02-15
In this work we investigate generalized theories of gravity in the so-called configurational entropy (CE) context. We show, by means of this information-theoretical measure, that a stricter bound on the parameter of f(R, T) brane models arises from the CE. We find that these bounds are characterized by a valley region in the CE profile, where the entropy is minimal. We argue that the CE measure can play a new role and might be an important additional approach to selecting parameters in modified theories of gravitation. (orig.)
Cosmological evolution in a two-brane warped geometry model
Kumar, Sumit, E-mail: sumit@ctp-jamia.res.in [Center For Theoretical Physics, Jamia Millia Islamia, New Delhi 110025 (India); Sen, Anjan A., E-mail: aasen@jmi.ac.in [Center For Theoretical Physics, Jamia Millia Islamia, New Delhi 110025 (India); SenGupta, Soumitra, E-mail: tpssg@iacs.res.in [Department of Theoretical Physics, Indian Association for the Cultivation of Science, Kolkata 700032 (India)
2015-07-30
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.
Cosmological evolution in a two-brane warped geometry model
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.
Brane structure and metastable graviton in five-dimensional model with (non)canonical scalar field
Zhong, Yuan; Zhao, Zhen-Hua
2014-01-01
The appearance of inner brane structure is an interesting issue in domain wall {brane model}. Because such structure usually leads to quasilocalized modes of various kinds of bulk fields. In this paper, we construct a domain wall brane model by using a scalar field $\\phi$, which couples to its kinetic term. The inner brane structure emerges as the scalar-kinetic coupling increases. With such brane structure, we show that it is possible to obtain gravity resonant modes in both tensor and scalar sectors. The number of the resonant modes depends on the vacuum expectation value of $\\phi$ and the form of scalar-kinetic coupling. The correspondence between our model and the canonical one is also discussed. The noncanonical and canonical background scalar fields are connected by an integral equation, while the warp factor remains the same. Via this correspondence, the canonical and noncanonical models share the same linear perturbation spectrum. So the gravity resonances {obtained} in the noncanonical frame can also...
Semiclassical description of D-branes in the SL(2)/U(1) gauged WZW model
In this paper we examine some semiclassical features of D-branes in the SL(2)/U(1) gauged WZW model and determine the small fluctuation spectra for one class of branes. We compare our results with expectations from the CFT side
Sigma-model Solutions and Intersecting p-Branes Related to Lie Algebras
Grebeniuk, M. A.; Ivashchuk, V. D.
1998-01-01
A family of Majumdar-Papapetrou type solutions in sigma-model of p-brane origin is obtained for all direct sums of finite-dimensional simple Lie algebras. Several examples of p-brane dyonic configurations in D=10 (IIA) and D=11 supergravities corresponding to the Lie algebra sl(3,C) are considered.
Massive modes in magnetized brane models
Hamada, Yuta
2012-01-01
We study higher dimensional models with magnetic fluxes, which can be derived from superstring theory. We study mass spectrum and wavefunctions of massless and massive modes for spinor, scalar and vector fields. We compute the 3-point couplings and higher order couplings among massless modes and massive modes in 4D low-energy effective field theory. These couplings have non-trivial behaviors, because wavefunctions of massless and massive modes are non-trivial.
Geometry of the Savvidy model for branes
Campuzano, C.; Capovilla, R.; Cervantes, A.; Rojas, E.
2012-02-01
We report on preliminary results about the geometrical properties of a generalized Savvidy action for relativistic extended objects [1]. The action is proportional to the worldvolume integral of the square root of the square of the mean extrinsic curvature. It can be seen as a generalization to extended objects of the model linear in the first Frenet-Serret curvature for a relativistic particle. The Hamiltonian formulation is considered using the Ostrogradski approach for higher derivative theories. We show that there are first-and second-class constraints. A geometrical analysis of the constraints is described, as the ensuing counting of the physical degrees of freedom of the theory.
On D-branes from gauged linear sigma models
We study both A-type and B-type D-branes in the gauged linear sigma model by considering worldsheets with boundary. The boundary conditions on the matter and vector multiplet fields are first considered in the large-volume phase/non-linear sigma model limit of the corresponding Calabi-Yau manifold, where we find that we need to add a contact term on the boundary. These considerations enable to us to derive the boundary conditions in the full gauged linear sigma model, including the addition of the appropriate boundary contact terms, such that these boundary conditions have the correct non-linear sigma model limit. Most of the analysis is for the case of Calabi-Yau manifolds with one Kaehler modulus (including those corresponding to hypersurfaces in weighted projective space), though we comment on possible generalisations
D-Brane Probes in the Matrix Model
Ferrari, Frank
2013-01-01
Recently, a new approach to large N gauge theories, based on a generalization of the concept of D-brane probes to any gauge field theory, was proposed. In the present note, we compute the probe action in the one matrix model with a quartic potential. This allows to illustrate several non-trivial aspects of the construction in an exactly solvable set-up. One of our main goal is to test the bare bubble approximation. The approximate free energy found in this approximation, which can be derived from a back-of-an-envelope calculation, matches the exact result for all values of the 't Hooft coupling with a surprising accuracy. Another goal is to illustrate the remarkable properties of the equivariant partial gauge-fixing procedure, which is at the heart of the formalism. For this we use a general xi-gauge to compute the brane action. The action depends on xi in a very non-trivial way, yet we show explicitly that its critical value does not and coincide with twice the free energy, as required by general consistency...
D-brane probes in the matrix model
Recently, a new approach to large N gauge theories, based on a generalization of the concept of D-brane probes to any gauge field theory, was proposed. In the present note, we compute the probe action in the one matrix model with a quartic potential. This allows to illustrate several non-trivial aspects of the construction in an exactly solvable set-up. One of our main goal is to test the bare bubble approximation. The approximate free energy found in this approximation, which can be derived from a back-of-an-envelope calculation, matches the exact result for all values of the 't Hooft coupling with a surprising accuracy. Another goal is to illustrate the remarkable properties of the equivariant partial gauge-fixing procedure, which is at the heart of the formalism. For this we use a general ξ-gauge to compute the brane action. The action depends on ξ in a very non-trivial way, yet we show explicitly that its critical value does not and coincides with twice the free energy, as required by general consistency. This is made possible by a phenomenon of ghost condensation and the spontaneous breaking of the equivariant BRST symmetry
D-brane probes in the matrix model
Ferrari, Frank
2014-03-01
Recently, a new approach to large N gauge theories, based on a generalization of the concept of D-brane probes to any gauge field theory, was proposed. In the present note, we compute the probe action in the one matrix model with a quartic potential. This allows to illustrate several non-trivial aspects of the construction in an exactly solvable set-up. One of our main goal is to test the bare bubble approximation. The approximate free energy found in this approximation, which can be derived from a back-of-an-envelope calculation, matches the exact result for all values of the 't Hooft coupling with a surprising accuracy. Another goal is to illustrate the remarkable properties of the equivariant partial gauge-fixing procedure, which is at the heart of the formalism. For this we use a general ξ-gauge to compute the brane action. The action depends on ξ in a very non-trivial way, yet we show explicitly that its critical value does not and coincides with twice the free energy, as required by general consistency. This is made possible by a phenomenon of ghost condensation and the spontaneous breaking of the equivariant BRST symmetry.
Branes in the GL(1 vertical stroke 1) WZNW-Model
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.)
Branes in the GL(1 vertical stroke 1) WZNW-Model
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.)
Gravity localization on hybrid branes
Veras, D F S; Maluf, R V; Almeida, C A S
2015-01-01
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 behaviour 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 are 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 behaviour 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 ...
D-branes, topological defects in string theory on which string endpoints can live, may give new insight into the understanding of the cosmological evolution of the Universe at early epochs. We analyze the dynamics of D-branes in curved backgrounds and discuss the parameter space of M-theory as a function of the coupling constant and of the curvature of the Universe. We show that D-branes may be efficiently produced by gravitational effects. Furthermore, in curved space-times the transverse fluctuations of the D-branes develop a tachyonic mode and when the fluctuations grow larger than the horizon the branes become tensionless and break up. This signals a transition to a new regime. We discuss the implications of our findings for the singularity problem present in string cosmology, suggesting the existence of a limiting value for the curvature which is in agreement with the value suggested by the cosmological version of the holography principle. We also comment on possible implications for the so-called brane world scenario, where the Standard Model gauge and matter fields live inside some branes while gravitons live in the bulk
Chiral symmetry breaking in lattice QED model with fermion brane
Shintani, E
2012-01-01
We propose a novel approach of spontaneous chiral symmetry breaking at near zero temperature in 4 dimensional QED model with 3+1 dimensional fermion brane using Hybrid Monte Carlo simulation. We consider an anisotropic QED coupling in non-compact QED action with the manifest gauge invariant interaction and fermi-velocity which is less than speed of light. This model allows for the scaling study at low temperature and strong coupling region with reduced computational cost. We compute the chiral condensate and its susceptibility with different coupling constant, velocity parameter and flavor number, and therefore obtain a compatible behavior with gap equation in broken phase. We also discuss about the comparison of Graphene model.
Black Diamonds at Brane Junctions
Chamblin, A; Erlich, J; Hollowood, Timothy J; Chamblin, Andrew; Csaki, Csaba; Erlich, Joshua; Hollowood, Timothy J.
2000-01-01
We discuss the properties of black holes in brane-world scenarios where ouruniverse is viewed as a four-dimensional sub-manifold of somehigher-dimensional spacetime. We consider in detail such a model wherefour-dimensional spacetime lies at the junction of several domain walls in ahigher dimensional anti-de Sitter spacetime. In this model there may be anynumber p of infinitely large extra dimensions transverse to the brane-world. Wepresent an exact solution describing a black p-brane which will induce on thebrane-world the Schwarzschild solution. This exact solution is unstable to theGregory-Laflamme instability, whereby long-wavelength perturbations cause theextended horizon to fragment. We therefore argue that at late times anon-rotating uncharged black hole in the brane-world is described by a deformedevent horizon in p+4 dimensions which will induce, to good approximation, theSchwarzschild solution in the four-dimensional brane world. When p=2, thisdeformed horizon resembles a black diamond and more gener...
Standard Model-like D-brane models and gauge couplings
Hamada, Yuta; Uemura, Shohei
2014-01-01
We systematically search intersecting D-brane models, which just realize the Standard Model chiral matter contents and gauge symmetry. We construct new classes of non-supersymmetric Standard Model-like models. We also study gauge coupling constants of these models. The tree level gauge coupling is a function of compactification moduli, string scale, string coupling and winding number of D-branes. By tuning them, we examine whether the models can explain the experimental values of gauge couplings. As a result, we find that the string scale should be greater than $10^{14-15}$GeV if the compactification scale and the string scale are the same order.
D-brane Solitons in Supersymmetric Sigma-Models
Gauntlett, J P; Tong, D; Townsend, P K; Gauntlett, Jerome P.; Portugues, Rubén; Tong, David; Townsend, Paul K.
2001-01-01
Massive D=4 N=2 supersymmetric sigma models typically admit domain wall (Q-kink) solutions and string (Q-lump) solutions, both preserving 1/2 supersymmetry. We exhibit a new static 1/4 supersymmetric `kink-lump' solution in which a string ends on a wall, and show that it has an effective realization as a BIon of the D=4 super DBI-action. It is also shown to have a time-dependent Q-kink-lump generalization which reduces to the Q-lump in a limit corresponding to infinite BI magnetic field. All these 1/4 supersymmetric sigma-model solitons are shown to be realized in M-theory as calibrated, or `Q-calibrated', M5-branes in an M-monopole background.
Non-perturbative effects in matrix models and D-branes
The large order growth of string perturbation theory in c ≤ 1 conformal field theory coupled to world sheet gravity implies the presence of O(e-circumflex{-{1/gs}}) non-perturbative effects, whose leading behavior can be calculated in the matrix model approach. Recently it was proposed that the same effects should be reproduced by studying certain localized D-branes in Liouville Field Theory, which were constructed by A. and Al. Zamolodchikov. We discuss this correspondence in a number of different cases: unitary minimal models coupled to Liouville, where we compare the continuum analysis to the matrix model results of Eynard and Zinn-Justin, and compact c = 1 CFT coupled to Liouville in the presence of a condensate of winding modes, where we derive the matrix model prediction and compare it to Liouville theory. In both cases we find agreement between the two approaches. The c = 1 analysis also leads to predictions about properties of D-branes localized in the vicinity of the tip of the cigar in SL(2)/U(1) CFT with c = 26. (author)
Non-Perturbative Effects in Matrix Models and D-branes
Alexandrov, S Yu; Kutasov, D; Alexandrov, Sergei Yu.; Kazakov, Vladimir A.; Kutasov, David
2003-01-01
The large order growth of string perturbation theory in $cle 1$ conformal field theory coupled to world sheet gravity implies the presence of $O(e^{-{1over g_s}})$ non-perturbative effects, whose leading behavior can be calculated in the matrix model approach. E. Martinec recently proposed that the same effects should be reproduced by studying certain localized D-branes in Liouville Field Theory, which were constructed by A. and Al. Zamolodchikov. We discuss this correspondence in a number of different cases: unitary minimal models coupled to Liouville, where we compare the continuum analysis to the matrix model results of Eynard and Zinn-Justin, and compact c=1 CFT coupled to Liouville in the presence of a condensate of winding modes, where we derive the matrix model prediction and compare it to Liouville theory. In both cases we find agreement between the two approaches. The c=1 analysis also leads to predictions about properties of D-branes localized in the vicinity of the tip of the cigar in SL(2)/U(1) CF...
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.
Gravitating global monopoles in extra dimensions and the brane world concept
Bronnikov, K A
2005-01-01
Multidimensional configurations with Minkowski external space-time and a spherical global monopole in extra dimensions are discussed in the context of the brane world concept. The monopole is formed with a hedgehog-like set of scalar fields \\phi^i with a symmetry-breaking potential V depending on the magnitude \\phi^2 = \\phi^i \\phi^i. All possible kinds of globally regular configurations are singled out without specifying the shape of V(\\phi). These variants are governed by the maximum value \\phi_m of the scalar field, characterizing the energy scale of symmetry breaking. If \\phi_m < \\phi_cr (where \\phi_cr is a critical value of \\phi related to the multidimensional Planck scale), the monopole reaches infinite radii while in the ``strong field regime'', when \\phi_m\\geq \\phi_cr, the monopole may end with a cylinder of finite radius or possess two regular centers. The warp factors of monopoles with both infinite and finite radii may either exponentially grow or tend to finite constant values far from the cente...
New observational limits on dark radiation in brane-world cosmology
Sasankan, Nishanth; Mathews, Grant J; Kusakabe, Motohiko
2016-01-01
A dark radiation term arises as a correction to the energy momentum tensor in the simplest five-dimensional RS-II brane-world cosmology. In this paper we revisit the constraints on dark radiation based upon the newest results for light-element nuclear reaction rates, observed light-element abundances and the power spectrum of the Cosmic Microwave Background (CMB). Adding the effect of dark radiation during big bang nucleosynthesis alters the Friedmann expansion rate causing the nuclear reactions to freeze out at a different temperature. This changes the final light element abundances at the end of BBN. Its influence on the CMB is to change the effective expansion rate at the surface of last scattering. We find that the BBN constraint reduces the the allowed range for dark radiation to between -12.1% and +6.2% of the photon background. Combining this result with fits to the CMB power spectrum constraint, the range decreases to -6.0% to +6.2%. Thus, we find, that the ratio of dark radiation to the background to...
Super Lie n-algebra extensions, higher WZW models, and super p-branes with tensor multiplet fields
Fiorenza, Domenico; Schreiber, Urs
2013-01-01
We formalize higher dimensional and higher gauge WZW-type sigma-model local prequantum field theory, and discuss its rationalized/perturbative description in (super-)Lie n-algebra homotopy theory (the true home of the "FDA"-language used in the supergravity literature). We show generally how the intersection laws for such higher WZW-type sigma-model branes (open brane ending on background brane) are encoded precisely in (super-) L-infinity-extension theory and how the resulting "extended (super-)spacetimes" formalize spacetimes containing sigma model brane condensates. As an application we prove in Lie n-algebra homotopy theory that the complete super p-brane spectrum of superstring/M-theory is realized this way, including the pure sigma-model branes (the "old brane scan") but also the branes with tensor multiplet worldvolume fields, notably the D-branes and the M5-brane. For instance the degree-0 piece of the higher symmetry algebra of 11-dimensional spacetime with an M2-brane condensate turns out to be the ...
D7-brane dynamics and thermalization in the Kuperstein-Sonnenschein model
Kaviani, Dariush
2016-01-01
We study the temperature of rotating probe D7-branes, dual to the temperature of flavored quarks, in the Kuperstein--Sonnenschein holographic model including the effects of spontaneous breakdown of the conformal and chiral flavor symmetry. The model embeds probe D7-branes into the Klebanov-Witten gravity dual of conformal gauge theory, with the embedding parameter, given by the minimal radial extension of the probe, setting the IR scale of conformal and chiral flavor symmetry breakdown. We show that when the minimal extension is positive definite and additional spin is turned on, the induced world volume metrics on the probe admit thermal horizons and Hawking temperatures despite the absence of black holes in the bulk. We find the scale and behavior of the temperature in flavored quarks are determined notably by the IR scale of symmetry breaking, and by the strength and sort of external fields. We also derive the energy--stress tensor of the rotating probe and study its backreaction and energy dissipation. We...
Revolving D-branes and spontaneous gauge-symmetry breaking
Iso, Satoshi; Kitazawa, Noriaki
2015-12-01
We propose a new mechanism of spontaneous gauge-symmetry breaking in the world-volume theory of revolving D-branes around a fixed point of orbifolds. In this paper, we consider a simple model of the T^6/Z_3 orbifold on which we put D3-branes, D7-branes, and their anti-branes. The configuration breaks supersymmetry, but the Ramond-Ramond tadpole cancellation conditions are satisfied. A set of three D3-branes at an orbifold fixed point can separate from the point, but, when they move perpendicular to the anti-D7-branes put on the fixed point, they are pulled back due to an attractive interaction between the D3- and anti-D7-branes. In order to stabilize the separation of the D3-branes at nonzero distance, we consider revolution of the D3-branes around the fixed point. Then the gauge symmetry on the D3-branes is spontaneously broken, and the rank of the gauge group is reduced. The distance can be set at will by appropriately choosing the angular momentum of the revolving D3-branes, which should be determined by the initial condition of the cosmological evolution of the D-brane configurations. The distance corresponds to the vacuum expectation values of brane moduli fields in the world-volume theory and, if it is written as M/M_s^2 in terms of the string scale M_s, the scale of gauge-symmetry breaking is given by M. Angular momentum conservation of revolving D3-branes assures the stability of the scale M against M_s.
Revolving D-branes and spontaneous gauge-symmetry breaking
We propose a new mechanism of spontaneous gauge-symmetry breaking in the world-volume theory of revolving D-branes around a fixed point of orbifolds. In this paper, we consider a simple model of the T6/Z3 orbifold on which we put D3-branes, D7-branes, and their anti-branes. The configuration breaks supersymmetry, but the Ramond–Ramond tadpole cancellation conditions are satisfied. A set of three D3-branes at an orbifold fixed point can separate from the point, but, when they move perpendicular to the anti-D7-branes put on the fixed point, they are pulled back due to an attractive interaction between the D3- and anti-D7-branes. In order to stabilize the separation of the D3-branes at nonzero distance, we consider revolution of the D3-branes around the fixed point. Then the gauge symmetry on the D3-branes is spontaneously broken, and the rank of the gauge group is reduced. The distance can be set at will by appropriately choosing the angular momentum of the revolving D3-branes, which should be determined by the initial condition of the cosmological evolution of the D-brane configurations. The distance corresponds to the vacuum expectation values of brane moduli fields in the world-volume theory and, if it is written as M/Ms2 in terms of the string scale Ms, the scale of gauge-symmetry breaking is given by M. Angular momentum conservation of revolving D3-branes assures the stability of the scale M against Ms
Revolving D-branes and Spontaneous Gauge Symmetry Breaking
Iso, Satoshi
2015-01-01
We propose a new mechanism of spontaneous gauge symmetry breaking in the world-volume theory of revolving D-branes around a fixed point of orbifolds. In this paper, we consider a simple model of the T6/Z3 orbifold on which we put D3-branes, D7-branes and their anti-branes. The configuration breaks supersymmetry, but the R-R tadpole cancellation conditions are satisfied. A set of three D3-branes at an orbifold fixed point can separate from the point, but when they move perpendicular to the anti-D7-branes put on the fixed point, they are forced to be pulled back due to an attractive interaction between the D3 and anti-D7 branes. In order to stabilize the separation of the D3-branes at nonzero distance, we consider revolution of the D3-branes around the fixed point. Then the gauge symmetry on D3-branes is spontaneously broken, and the rank of the gauge group is reduced. The distance can be set at our will by appropriately choosing the angular momentum of the revolving D3-branes, which should be determined by the...
The structure of f(R)-brane model
Xu, Zeng-Guang; Yu, Hao [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China); Zhong, Yuan [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China); Universitat Autonoma de Barcelona, IFAE, Barcelona (Spain); Liu, Yu-Xiao [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China); Lanzhou University, Key Laboratory for Magnetism and Magnetic Materials of the MoE, Lanzhou (China)
2015-08-15
Recently, a family of interesting analytical brane solutions were found in f(R) gravity with f(R) = R + αR{sup 2} in Bazeia et al. (Phys Lett B 729:127 2014). In these solutions, the inner brane structure can be turned on by tuning the value of the parameter α. In this paper, we investigate how the parameter α affects the localization and the quasilocalization of the tensorial gravitons around these solutions. It is found that, in a range of α, despite the brane having an inner structure, there is no graviton resonance. However, in some other regions of the parameter space, although the brane has no internal structure, the effective potential for the graviton Kaluza-Klein (KK) modes has a singular structure, and there exist a series of graviton resonant modes. The contribution of the massive graviton KK modes to Newton's law of gravity is discussed briefly. (orig.)
D-brane scattering in IIB string theory and IIB matrix model
We consider two Dirichlet p-branes with lower dimensional brane charges and their scattering. We first calculate the cylinder amplitude of the open string with suitable boundary conditions. We compare this result with that in the 11B matrix model. We find agreement between them in the long distance, low velocity, or large field limit. We also find a way to investigate more general boundary conditions for the open string
N=(4,4) Gauged Linear Sigma Models for Defect Five-branes
Kimura, Tetsuji
2015-01-01
We study two-dimensional ${\\cal N}=(4,4)$ gauged linear sigma model (GLSM). Its low energy effective theory is a nonlinear sigma model whose target space gives rise to a configuration of five-branes in string theory. In this article we focus on sigma models for NS5-branes, KK5-branes and an exotic $5^2_2$-brane. In particular, we carefully analyze the GLSM for an exotic $5^2_2$-brane whose background configuration is multi-valued. The exotic $5^2_2$-brane is a concrete example of nongeometric configuration in string theory. We find that the exotic feature originates from the string winding coordinate in a very clear way. In order to complete this analysis, we propose a duality transformation formula which converts an ${\\cal N}=(2,2)$ chiral superfield in F-term to a twisted chiral superfield coupled to an unconstrained complex superfield. This article is a short review based on arXiv:1304.4061 in collaboration with Shin Sasaki.
Holographic dark energy in braneworld models with moving branes and the w = −1 crossing
We apply the bulk holographic dark energy in general 5D two-brane models. We extract the Friedmann equation on the physical brane and we show that in the general moving-brane case the effective 4D holographic dark energy behaves as a quintom for a large parameter-space area of a simple solution subclass. We find that wΛ was larger than −1 in the past while its present value is wΛ0≈−1.05, and the phantom bound wΛ = −1 was crossed at zp≈0.41, a result in agreement with observations. Such a behavior arises naturally, without the inclusion of special fields or potential terms, but a fine-tuning between the 4D Planck mass and the brane tension has to be imposed
No Swiss-cheese universe on the brane
We study the possibility of brane-world generalization of the Einstein-Straus Swiss-cheese cosmological model. We find that the modifications induced by the brane-world scenario are excessively restrictive. At a first glance only the motion of the boundary is modified and the fluid in the exterior region is allowed to have pressure. The general relativistic Einstein-Straus model emerges in the low density limit. However by imposing that the central mass in the Schwarzschild voids is constant, a combination of the junction conditions and modified cosmological evolution leads to the conclusion that the brane is flat. Thus no generic Swiss-cheese universe can exist on the brane. The conclusion is not altered by the introduction of a cosmological constant in the FLRW regions. This shows that although allowed in the low density limit, the Einstein-Straus universe cannot emerge from cosmological evolution in the brane-world scenario
Standard model-like D-brane models and gauge couplings
Hamada, Yuta [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Kobayashi, Tatsuo [Department of Physics, Hokkaido University, Sapporo 060-0810 (Japan); Uemura, Shohei, E-mail: uemura@gauge.scphys.kyoto-u.ac.jp [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)
2015-08-15
We systematically search intersecting D-brane models, which just realize the Standard Model chiral matter contents and gauge symmetry. We construct new classes of non-supersymmetric Standard Model-like models. We also study the gauge coupling constants of these models. The tree level gauge coupling is a function of the compactification moduli, the string scale, the string coupling and the winding numbers of D-branes. By tuning them, we examine whether the models can explain the experimental values of gauge couplings. As a result, we find that the string scale should be greater than 10{sup 14–15} GeV if the compactification scale and the string scale are of the same order.
Standard model-like D-brane models and gauge couplings
Hamada, Yuta; Kobayashi, Tatsuo; Uemura, Shohei
2015-08-01
We systematically search intersecting D-brane models, which just realize the Standard Model chiral matter contents and gauge symmetry. We construct new classes of non-supersymmetric Standard Model-like models. We also study the gauge coupling constants of these models. The tree level gauge coupling is a function of the compactification moduli, the string scale, the string coupling and the winding numbers of D-branes. By tuning them, we examine whether the models can explain the experimental values of gauge couplings. As a result, we find that the string scale should be greater than 1014-15 GeV if the compactification scale and the string scale are of the same order.
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.)
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.)