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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35 views

‘t Hooft loops, yang mills, and “free energy”

When reading through the N=4 SYM s-duality literature, one will encounter some interesting properties i.e. twists (on boundary conditions), non-trivial electric and magnetic fluxes, the so called “...
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Path integral for fermion on circle

I am trying to understand talk by Edward Witten Nonsupersymmetric D-Branes and the Kitaev Fermion Chain. More concretely, I wanna to understand this slide: If I try to calculate such path integral I ...
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Conformal symmetry extension for super p-branes?

Conformal symmetry plays a vital role in string and superstring theories. Why can not we generalize conformal symmetry to objects of greater dimensions as branes? Where are we with this puzzle in 2020?...
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How does the $D$-brane geometry influence the gauge symmetries?

I am trying to understand why the $D$-brane structure of a string theory matters for string phenomenology. From what I understood from Wikipedia, the $D$-brane structure determines the gauge ...
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Why is de Sitter spacetime a better model of our universe than brane world models?

Why is it assumed that we live in a de Sitter space-time? Besides the de Sitter Lambda Cold Dark Matter model, there are Anti de Sitter brane world models, which also generates Friedmann equations ...
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Branes ending on branes

From Polchinski book, I know that a one-dimensional brane can end on a higher dimensional brane. However, I was wondering if an even more generic picture could be developed, where a $(p+1)$-...
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D7-brane in Type IIB and axio-dilaton

In the context of Type IIB string theory with one D7-brane we have the following situation. The axio-dilaton complex scalar is defined by $\tau:= C_0+i e^{-\phi}$ where $C_0$ is the axion and $\phi$ ...
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Could dark matter actually be matter which resides in a different spatial dimension? [closed]

I have at best a rudimentary understanding of the math in this side of physics, so bear with me. I am also aware of this question, but it was asked and answered 4 years ago and I don't want to ...
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Why D-brane can be attached to NS5 branes?

What is NS5 brane? Is it possible (in analogy with D-brane) understand appearance of NS5 brane in perturbative string spectrum? Why D-brane can be attached to NS5 branes?
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1answer
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How I can get the numerical factor in the relation between string coupling and YM coupling?

I'm trying to understand some references about Wilson loops being used to test AdS/CFT. Some of them are Nadav Drukker, David J. Gross: An Exact Prediction of N=4 SUSYM Theory for String Theory ...
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99 views

Weak Solutions to the Einstein Equation across a Junction

Consider the principle part, i.e., the part which contains the highest derivatives of the metric (which is the $2^{nd}$ derivative) is $$\mathcal{P}\{R_{ab}\}=\frac{1}{2}g^{cd}\left(\partial_{a}\...
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Extended objects, bundle description and transformations

In the hope of trying to come up with a clear mental picture for what a transformation is in physics, I encounter some difficulties due to the variety of objects that appear in physics. While no ...
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How does a Lagrangian with delta potential transform to a Hamiltonian?

Suppose the Lagrangian was given as: $$L = \frac{1}{2}\int_{-\infty}^{\infty} \underbrace{\left(\dot{A(}z)^2-A(z)^2\right)+\left(\dot{Q(}z)^2\delta(z)-Q(z)^2\delta(z)\right)+2\dot{Q(}z)\cdot A(z) \...
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Is Randall-Sundrum model background independent?

Randall-Sundrum model (https://en.wikipedia.org/wiki/Randall%E2%80%93Sundrum_model) is related on string theory. String theory can be background independent (https://en.wikipedia.org/wiki/...
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Tachyon mode in Brane-Antibrane system (Type II)

Lets First start with coincident $D3$ brane- $D3$ Brane system. Superstring stretch between these two contain a Tachyon mode But GSO projection removes this. For open string, $D$ branes serve just as ...
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Why are Goldstone bosons associated to translation symmetry breaking corresponding to the coordinates transverse to the D-brane?

In some lecture notes, in the presence of a Dp-brane, translational symmetry is broken in the direction transverse to the brane. However, they identify the coordinates, $$\Phi^a,\quad a=p+1,\cdots,D-1$...
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In M-Theory are membranes excited states of a field? [duplicate]

Are M2 and M5 membranes in M-Theory excited states of some underlying field, or are they fundamental? In what sense are membranes solitonic? In the reference question, someone made a comment that had ...
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What is the relation between a $D_2$-brane and an $M2$-brane?

I am only familiar with the concept of a $D_2$-brane from a first course in String theory. I would like to learn, at least on a conceptual level, what an $M2$-brane is and what is its relation to the $...
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Differentiating D3 brane worldvolume theories with NS5 brane and NS5 antibrane boundary conditions

In 'Supersymmetric Boundary Conditions in N=4 Super Yang-Mills Theory', Gaiotto and Witten derive boundary conditions for the worldvolume theory of the D3 brane. In particular the boundary conditions (...
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What does a closed 3-brane look like?

A closed 2-brane looks like a donut, or in scientific terms, a torus. This is a three-dimensional object. I came across this diagram in a book, "The Little Book of String Theory". A torus is a three-...
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Why does only gravity leak into extra non-compact dimensions?

This article K. Pardo, et. al., Limits on the number of spacetime dimensions from GW170817, Journal of Cosmology and Astroparticle Physics, Vol. 2018, 2018. which was published recently in JCAP ...
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World-volume (higher) gauge theory on D-branes

It is well known that if one constructs ordinary WZW type sigma model for string action, it is possible whenever they find a cocycle in appropriate Chevalley-Eilenberg algebra. If I understand it ...
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What are the known ways to model baryons in string theory?

As I understand, string theory models baryons by including a so called "baryon vertex". Is this right? It seems that baryon vertex's are usually D/M branes. Is that always the case?
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Wrapped M2 brane gauge field coupling?

An M2 brane is coupled to the C3 field of SUGRA. And as you all know, a wrapped M2 brane gives us the fundamental string. My question is, does the wrapped M2 brane (fundamental string) still couple ...
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1answer
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How does magnetic charge in string theory arise?

In string theory, all of the standard model charges (electric, color, and weak hypercharge) arise from Kaluza Klein theory and through the interactions between strings and branes. But little is said ...
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Have string theory and brane cosmology the same landscape?

Has any of these hypothetical theories a "higher" number of possible universes or has string theory landscape the same type of possible universes than brane cosmology?
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Derivation of Born-Infeld (BI) for D-brane

I am trying to reproduce derivation of the Born-Infeld (BI) action for D-branes as it is presented in R.J. Szabo, BUSSTEPP Lectures on String Theory, arXiv:hep-th/0207142. In particular, I don't ...
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About ghost D-branes and wrong statistics

I'm currently reading this article, which is about Ghost D-branes in string theory. The authors define these objects as something that cancels the effects of an ordinary D-brane. However, there is ...
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D-brane worldvolume actions: Where are the Fermions?

I am studying D$p$-brane polarization (Myer's effect https://arxiv.org/abs/hep-th/9910053) and brane-flux annihilation (KPV mechanism, https://arxiv.org/abs/hep-th/0112197). There is little to no ...
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Anomalous curvature coupling corrections for $Dp$-branes worldvolume actions

The Chern-Simons term of an (abelian brane) is commonly written as $$ \sim\int_{\mathcal M_{p+1}}\sum_iC_{i}[e^{2\pi\alpha'F+B}], $$ where $C_i$ is the background Ramond-Ramond $i$-form, $F$ is the ...
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How to understand the non-abelian DBI action?

I'm reading chapter 7 in "String Theory and M-theory, A Modern Introduction" by Becker, Becker and Schwarz. It says that the understanding of the square root of the determinant is to compute the ...
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Fuzzy sphere of polarized D0 branes, non-abelian worldvolume action regime validity

I am studying Myer's paper "Dielectric Branes" (https://arxiv.org/abs/hep-th/9910053v2), where it is shown that a stack of D0 branes polarizes into a spherical D0-D2 bound state. The stack of $N$ D0 ...
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1answer
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Chern-Simons action for non-abelian brane worldvolume and Tsetlyn's symmetric trace prescription

I am trying to reproduce the results of the (famous) Myer's paper "Dielectric Branes" https://arxiv.org/abs/hep-th/9910053. I am struggling a bit to obtain the numerical factors in the equations. When ...
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1answer
87 views

DBI action expansion for non-abelian brane worldvolume

I am trying to reproduce the results of the (famous) Myer's paper "Dielectric Branes" https://arxiv.org/abs/hep-th/9910053. In eq (33), when he expands the determinant factor for a flat-space ...
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2answers
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Can we have bubbles of the tenth dimension in our universe?

If the gap between the branes in the Big Bounce theory is the 10th dimension, and branes have wrinkles as they collide, can our universe have 'bubbles' in the 10th dimension? This is in reference to ...
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Questions about BPS D-branes

For the purposes of this question, I imagine I want to restrict attention to M-theory compactified on $X \times S^{1}$, Type IIA or IIB compactified on $X$, or the A/B topological sigma models on with ...
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1answer
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Why does Kaluza-Klein theory or the Randall-Sundrum model propose only one extra dimension?

Reading popular accounts on string theory, I have the impression that the number of extra dimensions of string theory is not an ad hoc postulate; it's uniquely determined by mathematical consistency. ...
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Very basic question on AdS/CFT

I was going through the introductory material by Horatiu in Ads-CFT. It says that $N+1$ D-branes are split into $N$ D-Branes and a probe D-Brane. The Wilson loop is located on the probe D-brane, which ...
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What's the physics on the boundary of a D-brane?

First of all, I'm not sure if a D-brane can have a boundary? Naively, I can imagine under certain background potential(from NS B field or RR field), at the "D-brane boundary," the open strings could ...
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56 views

P-branes (extended objects) with multime time-like dimensions

Why M-theory/supestring theory restrict itself to one time-like (internal!) dimension (excepting F and S-theory)? After all a brane with $X^\mu(\sigma,\tau$) can be extended in principle to $X^\mu(\...
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Light branes and swampland/landscape

Following a talk by Cumrum Vafa, I understood that light branes are important as he quoted the formula: $$m\sim \exp(-\alpha M/M_P)$$ and then, he stated that light massive particles AND extended ...
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1answer
396 views

How does 11D Supergravity relate to M-Theory?

I know Type IIA/B, Type I, HO, & HE are related through the T and S Dualities. However, how does SUGRA factor in here? What exactly is 11D SUGRA’s significance in M-Theory? Some seem to suggest ...
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Black p-branes vs. fundamental branes

After the duality revolution, we learned about the important role of both, black p-branes and p-branes. However, sometimes their fundamental definition is confused in the literature. I mean the ...
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141 views

Are the possible universes in brane cosmology embedded in string theory landscape?

String theory has a landscape of possible universes. Brane cosmology is related to string theory because it needs extra dimensions, but are the possible different universes of brane cosmology ...
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Strings ending on moving D-brane

If a fundamental string is hanging from a D-brane (with one end fixed on it) along radial direction and there is another D-brane which comes and attach to the string. What happens when the second ...
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1answer
105 views

How do parallel branes remain parallel?

In Maldacena paper he writes: We start with type IIB string theory with string coupling g, which will remain fixed. Consider N parallel D3 branes separated by some distances which we denote by r. ...
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Can branes obstruct complex structure deformations in string theory?

In compactifications of string theory, to preserve supersymmetry often branes need to wrap subspaces that are specified by holomorphic equations in the compactification space $X$. Additionally there ...
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Physical point of view of D-branes

I am new in string theory and recently I came up to the D-branes. I have understood all the mathematics and the technical definitions, that is, they are the (p+1)-dimensional objects upon which open ...
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2answers
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What is the magnitude of a D-brane?

According to this the average size of a string should be somewhere near the length scale of quantum gravity, called the Planck length, which is about $10^{-33}$ As far as I understand string ...
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2answers
169 views

Physics of D-branes

I was following the question What is a D-brane? and I want to ask further: Does each open string have its own D-brane or pair of branes? Do elementary particles arise from oscillation of strings onto ...

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