# 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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### 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. Kurasov 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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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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### Detecting space-filling $D$-Branes in string theory

I am currently studying Zweibach's "A First Course in String Theory" CH:9 and I have managed to understand mode expansion in the light-cone gauge, at the classical level. Right before ...
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### Are there consistent theories of GR where our Universe is embedded in higher dimensional space?

In GR we have a metric space given by the metric $g^{\mu\nu}(x)$. This allows us to deetermine the curvature $R^{\mu\nu}$ at each point in space-time. This curved 4D manifold is not required to be ...
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### $T$-duality in effective gauge theories of a $D(p+1)$-brane

I am considering a $D(p+1)$-brane in a space $\mathbb R^{1,p}\times S_R^1$ where $S_R^1$ is the circle of radius $R$. I am assuming low energies $ER\ll1$, so that only the massless spectrum of the ...
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### Transformation of the string coefficient under T-duality

I am trying to study an effective string theory valid in the low energy limit $ER<<1$. The effective action corresponds to a $D(p+1)$-brane in $R^{1,p}\times S^1$ and it is given by S_{D(p+1)} ...
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### Casimir Effect and parallel $D$-Branes

In the well-known setup for the calculation of the Casimir effect, we take 2 perfectly reflecting plates, impose the appropriate boundary conditions on the relevant fields (scalar, vector, etc.) and ...
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### Rolled-up dimensions vs surfaces in a higher dimensional space

All the accounts of dimensions higher than 4 seem to talk about them being 'rolled up'. Is this different to being confined to a 4D surface that exists in a higher dimensional space?
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### Why are these open string oscillation modes identified with spin 1 particles on the brane?

On page 55 of David Tong's String Theory lecture notes, during the discussion of the first excited states of open strings, two classes of states are identified, both of which are massless. The first ...
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### Do the fields in string theory only live on the world line of the string?

Say for instance we have a $D0$ brane, and this $D0$ brane is charged under the KK field. Does the strength of the KK field only exist on the worldline of the $D0$ brane? Same goes for strings: do the ...
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### Macroscopic dimension of a brane

I'm reading Witten's Solutions Of Four-Dimensional Field Theories Via M Theory, where it is discussed a configuration of threebranes stretched between fivebranes. My questions are: how can I ...
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### Motion open string

In the introduction book of Zwiebach, he mentions in chapter 6 that the endpoints of an open string move with the speed of light. First, I assume he means in the longitudinal direction. But then, ...
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This question concerns the boundary conditions that A-branes solve. Consider the following problem: Suppose that an A-brane wraps a submanifold $Y$ of $X$. Let $\mathcal{L} \rightarrow Y$ be a rank ...