Questions tagged [branes]

A (p-)brane is a dynamically evolving physical object that generalizes the notion of a point particle to (p) higher dimensions. A point particle can be viewed as a brane of dimension zero, a string as a brane of dimension one, and a membrane (sheet) as a brane of dimension two. Do not use for particles or strings, however, unless in comparative juxtapositions.

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Value of $\omega_{BD}$ of Brans-Dicke and String theory

In a context of Brans-Dicke framework, I am working on an article and there is a part of it that I can't get to understand. Here this part : We remember that the string theory predicts a low energy ...
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D-brane wrapping around A-cycle and B-cycle

I have heard people use the terminology D-brane wrapping around A-cycle and B-cycle when talking about compactifications on a torus. What do A-cycle, and B-cycle means here, and how it's related to T-...
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Dynamical compactification under confinement mechanisms

I've been wondering about semi-euclidean shapes as a stable fixed point of dynamical forces of particles in higher dimensions among themselves without appealing to tightly wound extra dimensions For ...
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Are magnetic charges compulsory in string theory?

In this penultimate lecture of a series given by Freddy Cachazo, the differential forms corresponding to the massless excitations in the Ramond–Ramond sector signal the existence of p-branes sourcing ...
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Branes in Closed Bosonic String Theory

I've seen in these lectures by Freddy Cachazo that type II-A/B superstring theory has to contain D-branes and open strings non-perturbatively, even though it appears to only contain closed strings in ...
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Are gravitons actually lost to the bulk?

In the brane world version of superstring/m-theory, the weakness of gravity compared to the other fundamental forces can be explained by gravitons not being confined to being able to travel in the ...
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The scale of extra dimensions

I wonder how in this Paper (page : 6) the scale of extra dimensions have been assumed or calculated The authors study a Generalized (n+1)-d Randall-Sundrum Model, in the beginning of page 6 they ...
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How to know the scale of an extra dimension in units of length?

I’m studying a model with an extra fifth dimension with a scale factor $b(t)$ . The modified Friedmann-like equations are: $$ \left[ {\left( {\frac{{\dot a}}{a}} \right)^2 + \left( {\frac{{\dot a}}{a}...
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Calculating the size of extra dimensions from the scale factor

Any help to understand how the authors of this paper Fine Tuning Problem of the Cosmological Constant in a Generalized Randall-Sundrum Model calculted this size of the extra dimension Equ. (3.8) from ...
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The dimensions of the universe and the scale factor

How to get the universe’s volume from the universe’s scale factor? Taking into account that the scale factor is dimensionless and the volume has dimensions of $cm^3$ or $m^3$ ? In this paper for ...
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Can D-brane vibrate and generate more allowed boundary conditions?

Previously the D-branes were said to be fixed hyperplane or a boundary where a string could end. The commonly known boundary conditions were Dirichlet Brane and the Neumann Brane and the superposition ...
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Mode expansion for $p$-branes

In the quantization of $p$-branes, for $p>1$ what is the mode expansion? What I am after, more specifically, is: what is the configuration around which the expansion is made? For example, for the ...
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Dirichlet/Neumann conditions for the quantized string

Background In textbooks (e.g. see around page 14 of [1]), string theory is introduced classically with the Polyakov action: $$S_P = \int d\tau d\sigma L :=-T \int d\tau d\sigma \sqrt{-h} h^{\alpha\...
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Is it impossible to describe all particles using only 3-branes? [duplicate]

Pardon my terminology, I might be using the words wrong. I watched Susskind string theory course, where he explained the attempt to describe particles using vibrating strings instead of point ...
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Do branes in M-theory form closed structures or do they have an edge?

In M-theory, besides strings, branes play their role. Strings can be attached to them, for example when a number of branes in a stack rotate around a common axis and the strings between them get ...
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Is there an hamiltonian formulation of $D_p$-brane theory?

I'm aware that the dynamics of $D_p$-branes can be studied using the DBI action: $$S_{DBI}=-T_p\int d^{p+1}\xi\sqrt{-\det(g_{\alpha\beta})}$$ (with external fields set to zero). I'd like to know ...
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Does QFT Imply Strings the Same Way that String Theory Implies Branes?

It is part of every introductory course on string theory (e.g. Tong) that the open bosonic string in $D = 26$ dimensions with Neumann-Neumann boundary conditions for directions $a \in \{0,\dots,p\}$ ...
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Must the interaction of the $D$-brane be done through the closed or the open strings?

The interaction of the D brane was through the closed or open strings. However, as a distinct object, why the D brane could not have some sort of interaction themselves? i.e. an incident energy when ...
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Chan-Paton factors for branes in string theory

In open string theory, we can have additional degrees of freedom residing at the string endpoints, in addition to strings propagating. Therefore we can add a new degree of freedom, known as a Chan-...
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Is the black brane picture valid only at small string coupling?

As far as I am aware there are two pictures of branes: for $g_SN\gg1$: branes as solitonic solutions to the field equations of supergravity (i.e. black branes) for $g_SN\ll1$: branes as fundamental ...
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The basics of domain walls

Could someone example the basics of domain walls (string theory) and what their properties are? I've looked around but I can't find much.
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Confusion about the definition of negative angles between two D-branes

I have a conceptual question regarding a paper I am reading. More precisely, the first appendix starting on page 29. In this paper, schematically, the classical oriented open strings get quantised ...
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Open strings and branes

In string theory, open strings are attached to branes. What does "attached" mean? Do they just interact with the branes, or are they related to them in some other way?
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D0, D1, D2... DN branes consist of D0 branes?

In BFSS Matrix theory, D0-branes connect the ends of open strings. Do other D-branes (D1, D2... DN) consist of D0-branes?
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Partially closed bosonic strings and freely moving D-branes

For closed bosonic strings, the embedding coordinates must satisfy $$X^\mu(\tau,\sigma+2\pi)=X^\mu(\tau,\sigma)$$ for $\mu=0,1,\dots,D-1$. On the other hand, for open N-N bosonic strings, the ...
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D-branes mechanics and D-branes field theory

Following those two questions: The different frameworks around the point particle (for $p=0$), The different frameworks around the string (for $p=1$), I was wondering if the discussion could ...
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Parallel Dp-branes and force

While studying basic Dp-brane dynamics from A. Giveon & D. Kutasov reference, on page 24 they state the following Since Dp-branes are BPS saturated objects, parallel branes do not exert forces on ...
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Brane fluctuations via $S$-duality

Caveat lector: I'm a mathematician trying to learn physics so I apologize if my questions are very vague or trivial. I'm currently studying Maldacena's Black Holes in String Theory (https://arxiv.org/...
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Question about Kaluza-Klein excitations

In Randall Sundrum (RS) model-type 1 : A Large Mass Hierarchy from a Small Extra Dimension, it’s mentioned that: This result contrasts sharply with the scenario of large extra dimensions for solving ...
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Gauge invariance / charge conservation on string ending on brane

Consider a fundamental string charged under the Kalb-Ramond 2-form $B$ and ending on a D5-brane. Charge conservation implies the existence of a 1-form gauge field $A$ with field strength $F$ living on ...
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Mathematical prerequisites for M-theory [duplicate]

I am interested in learning M-theory; however I have no Idea as to what mathematics is required for it. Are the prerequisites the same as string theory? Is there more mathematical knowledge needed for ...
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Amount of SUSY preseved by branes

Consider 10d superstring theory, a D5 brane extended in the 012789 directions, and an NS5 brane extended in the 012345 directions. I have read that this configuration preserves 1/4 of the ...
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What is "bulk" in brane cosmology?

The central idea of brane cosmology is that the visible, three-dimensional universe is restricted to a brane inside a higher-dimensional space, called the "bulk". What is "bulk"? ...
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Why open strings must all end on same D brane?

Consider 10-d open string theory with a D9 brane (i.e. an open string), and $X^9$ compactified on a circle. T-dualising, we find a D8 brane. Why is it that the endpoints of all open strings in this ...
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The volume of infinitly large extra dimension

What I understand is that, according to the string theory our universe is a membrane parallel to several other membranes or (universes). These parallel universes are separated by the bulk or extra ...
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Branes with any number $n$ of dimensions and their relation to the laws of physics?

I had a few questions about this paper by Nima Arkani-Hamed, Georgi Dvali and Savas Dimopoulos (https://arxiv.org/abs/hep-th/9907209) which is closely related to the concept of branes (https://en....
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Constraints on non-compactified extra dimensions

I'm reading this paper An introduction to extra dimensions and string phenomenology Which according to it, in string theory the 4-dimensional Plank scale is related to the Planck scale of ...
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The Hubble parameter of Randall-Sundrum model

It’s mentioned in this paper On the cosmological constant problem and brane-world geometry that the Hubble parameter of the Randall-Sundram model is given by: $$ H^2 = \frac{8\pi}{3m_{pl}^2} \rho + \...
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Area element with worldsheet metric in Polyakov action

I became confused while reading this article for the following reason: For $p=1$ we have strings such that the Nambu-Goto action is proportional to the area of the worldsheet embedded by the maps $X^\...
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Event horizon around branes

I'm wondering if a brane is a massive topological defect, does it have an event horizon? Is it related to the effect capuring matter fields on the brane? Thanks for the answers
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The M2 brane of M theory creates the Type IIA string and D2; the M5 brane creates the D4 and NS5. What are the other objects grouped with the D0?

Type IIA string theory is related to M theory with the 10th spatial dimension compactified on a circle.  The origin of the F1 string, D2 brane, D4 brane and NS5 branes is simple: they come from the M2 ...
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Are "Selective Extra Dimensions" possible?

The large extra dimensions model also known as the ADD model proposes that the six hidden dimensions implied by string theory are not rolled up to the Planck length and some (or all) of them are ...
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CFTs describing branes

In this paper section 3, the author describes how a $U(N) \;\mathcal{N}=4$ SYM theory can be coupled to 2 boundary 3D CFTs. Then the boundary CFT would describe the low-energy physics of $N$ semi-...
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How can one modify the Nambu-Goto action to include the longitudinal degrees of motion?

The Nambu-Goto action is given by $$ S = -\frac{T_0}{c} \int_{-\infty}^{+\infty} d\tau \int_{0}^{\sigma} d\sigma \sqrt{ \Bigg(\frac{\partial X^\mu}{\partial \tau} \frac{\partial X_\mu}{\partial \...
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What is an End of The World (ETW) brane?

In literature I have found this terminology several times and I would like to see if there is a definition of the 'end of the world' brane. This paper is the closest thing I could find to a definition....
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Deriving einbein action from Polyakov $p$-brane action

In this paper the author derives a "Polyakov style" $p$-brane action which is given by \begin{equation} S_{p}=-\frac{T_{p}}{2} \int d^{p+1} \xi \sqrt{-g}\left(g^{A B} h_{A B}-(p-1)\right) \...
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Supergravity 3-form $C$ fields from 2d string worldsheets

In supergravity, there are 3-form fields known as C fields. However, according to string theory, the fundamental degrees of freedoms are from string worldsheets (so at most they are fundamentally 2d). ...
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Chiral zero modes in type IIB matrix model

I have seen many articles in which the authors consider various modifications of IKKT matrix model (non-perturbative regularization of type IIB string theory) such as (Orbifolds, fuzzy spheres, ...
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$D0$ brane and open string bound state radiating a closed string

I had this quite vague picture in my head of how a bound state of two $D0$ branes and an open string might "radiate" a closed string when the open string forms a cusp. I know the idea is ...
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Physical origin of coisotropic branes

The paper "Remarks on A-branes, Mirror Symmetry, and the Fukaya category" develops the possibility of A-model open strings ending on a coisotropic submanifold equipped with a holomorphic ...

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