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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Action formalism of braneworld gravity and effective field equation on the brane

Is it possible to derive the effective gravitational field equation on the brane by simply varying the action? Context: The popular way to derive that equation is by starting from Einstein's field ...
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3D manifestation of a higher dimensional object

The starting points of this theorical exploration are the following. I do believe we exist in a universe where 10 (or 11) dimensions do exist, but the ones beyond 3 spatial + 1 time are compactified. ...
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Understanding 4D Gauge Fields in Compactified String Theory

Question: I have a conceptual question regarding $4$-dimensional compactifications in string theory. For example, if we consider flat $10$-dimensional space with D$6$-branes, we obtain $7$-dimensional ...
Nathanael Noir's user avatar
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Wilson lines with Chan-Paton factors in string theory

In the context of compactifying the open string with Chan-Paton factors, Polchinski (Volume I Section 8.6) considers a toy example with a point particle of charge $q$ which has the action $$ S = \int ...
Adrien Martina's user avatar
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Why and how we study different limits in quantum gravity?

While I'm reading an article, I get confused by why and how we study different limits in quantum limit. In this paper, the author introduced four limits in D0-brane quantum mechanics: the DKPS (...
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References for closed string collisions on finite number of fixed type mutually intersecting orbifolds with D-branes at the orbifold singularities

I don't know if this topic is studied at all but I'm looking for good references for closed string collisions on a finite number of fixed type mutually intersecting football orbifolds with D-branes at ...
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Why do spherical M2 branes have no net charge?

In the paper Invasion of the Giant Gravitons from Anti de Sitter Space, the authors claim that We are interested in the dynamics of a relativistic spherical membrane moving in $S^4$. The membrane has ...
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References for Hanany-Witten setups

What are some good, possibly modern, references for Hanany-Witten brane setups? I know the one of Giveon and Kutasov: Brane Dynamics and Gauge Theories, but I would like to have some more since this ...
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Open bosonic string with boundary conditions representing D-branes

(This is the first part of Polchinski's problem 1.6, here it my attempt). I have the following boundary conditions on the $X^{25}$ component being $X^{25}(\tau,0) = 0$ and $X^{25}(\tau,l) = y$ for ...
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Non-abelian Chern-Simons forms and Wess-Zumino action

Is there any closed analytic relationship between the Wess-Zumino action and the (non-abelian) Chern-Simons forms for arbitrary spacetime dimensions that appear in brane theories?
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What are Bubbling Geometries?

I know that Wilson loops in certain higher rank representations are dual to Bubbling Geometries. Also, certain local operators are dual to this kind of solutions. But (independently from holography), ...
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Must open string endpoints lie on a D-brane?

In the second edition of professor Zwiebach's book "A First Course in String Theory", on page 331, on the 3rd line of section 15.1, it says "In the presence of a D-brane, the endpoints ...
Lifetime Beginner's user avatar
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Can open Strings interact and lead to a String which is not fixed to a Brane?

Would it be possible that two open Strings interacted with each other and could they theoretically then leave their Brane?
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What is the mass dimension of scattering amplitudes in string and membrane theories?

It's all in the title: I am interested in the mass dimension (in natural units) of scattering amplitudes in string and membrane theories. For particles in $d=4$, it seems to be $$[ \mathcal{A}^{(n)} ] ...
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Are branes topological defects? How else could they be physical?

As far as I understand, the branes of brane cosmology are lower-dimensional "sub-manifolds" of some space. It was hard to imagine for me how such structure could exist and be physical. But ...
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Could the universe be a topological defect in a higher space?

I am a mathematician with an undergrad understanding of physics. I recently learned of topological defects in quantum fields. It is an intriguing idea that there could be regions in our universe that, ...
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Integrating out the 5th dimension in AdS/CFT

My main understanding of AdS/CFT is through the idea that the partition functions on the boundary and bulk are equivalent when expressed in terms of source fields $J_0$. On the boundary $J_0$ is a ...
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D-Brane charge (IIB string theory)

Can someone please give a detailed explanation of what the D-brane charge is? In particle physics and gauge theory, The charge of a particle can be obtained by taking the integral of a closed surface ...
htr's user avatar
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What are 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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Explanation of Hierarchy Problem in Kaluza-Klein String Scenarios

During the last few days I have been interested in the gravitational hierarchy problem and the different explanations for it/solutions to it. Among the most "concrete" (insofar as anything ...
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Can a brane contain different Calabi-Yau compactifications in various areas?

In Brian Greene's book The Hidden Reality he discusses the string landscape, and the possibility of it leading to a multiverse. In short, a universe with 3 large dimensions such as ours would contain ...
cosmicpawn's user avatar
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What is the dimension of an Instanton?

My thought process about this question was this: A point particle couples to a $p=1$-Form field and is itself $p-1=0$-dimensional. A string couples to a $p=2$-Form field an is $p-1=1$ dimensional. An ...
David's user avatar
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Jump in Extrinsic Curvature

In the thin shell formalism, the components of the surface stress-energy tensor are found using the next equation: \begin{equation} S^{a}_{\, \, \, b} = const\left([K^{a}_{\, \, \, b}] - \delta^{a}_{\,...
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What sort of entity do strings convert into when embedded in spacetime? or What do strings represent?

I hope someone can help with this question with some open mind. I know there has been close questions, but I have read them and they do not target the same spot I do. In the worldline formalism of QFT,...
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What is BPS state?

I am preparing a presentation about black holes thermodynamics in string theory. Both in polchinski and in many famous articles there is a discussion about BPS and I am not able to understand why it ...
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Multivariate beta function and supermembranes [closed]

Similarly to the beta function being related to superstrings, is there any good reason to relate the multivariate beta function: $$B (\alpha_1,\alpha_2,\ldots\alpha_n) = B (\alpha_1+1,\alpha_2,\ldots\...
riemannium's user avatar
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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-...
htr's user avatar
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1 answer
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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 ...
tomdodd4598's user avatar
3 votes
1 answer
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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 ...
tomdodd4598's user avatar
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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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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 ...
Dr. phy's user avatar
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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 ...
ShoutOutAndCalculate's user avatar
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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 ...
dennis's user avatar
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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\...
johnnydines's user avatar
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1 answer
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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 ...
Gerald's user avatar
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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 ...
Mauro Giliberti's user avatar
4 votes
1 answer
172 views

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 $a \in \{0,\dots,p\}$ ...
horropie's user avatar
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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 ...
ShoutOutAndCalculate's user avatar
4 votes
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190 views

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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1 answer
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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 ...
Nathanael Noir's user avatar
8 votes
1 answer
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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?
Арман Гаспарян's user avatar
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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?
Арман Гаспарян's user avatar
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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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