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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1answer
73 views

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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77 views

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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42 views

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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54 views

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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Branes without Fayet-Iliopoulos term

Often D-brane effective actions are given as (let's take D3-branes) $$ S=-T\int d^4x \sqrt{-det(g_{mn}+2\pi\alpha'F_{mn})}. $$ After expansion in $2\pi\alpha'$ there is a constant Fayet-Iliopoulos ...
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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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Magnetic and electric “Coulomb-like” forces for p-branes in D-dimensions

For a point particle, the magnetic and electrical forces read: $$F_e=qE=\dfrac{KQq}{r^2}$$ $$F_m=qv\times B$$ with B given. What are the equivalent expressions for the electric and magnetic forces of ...
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30 views

A generalized Veneziano formula for p-branes?

The rise of string theory as a theory of quantum gravity is in debt to G. Veneziano and his formula for the string scattering in terms of Euler beta function. Could a generalization of that formula, ...
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19 views

Superstrings and supermembranes withouth the maximal spin constraint

Can supermembranes exist in higher dimensional superspaces if we admit higher spin fields?
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79 views

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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687 views

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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52 views

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 ...
2
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1answer
101 views

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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1answer
75 views

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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109 views

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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45 views

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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94 views

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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83 views

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
117 views

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
54 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
83 views

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
129 views

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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2answers
226 views

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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1answer
54 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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1answer
91 views

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
286 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 ...
6
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1answer
163 views

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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1answer
119 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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58 views

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 ...
3
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1answer
95 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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69 views

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
83 views

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
143 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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2answers
125 views

Would black holes be present in all dimensions? [closed]

I'm watching a video about string theory, in which the fact that gravity is weaker than the other forces is explained in that gravitons aren't bound to our universe directly, and can flow across ...
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1answer
151 views

Understanding string theory branes

I've been looking into string theory, and I understand the $D1$ strings, but I find the concept of branes confusing. Are they just $D2$ strings? Or are they woven constructs made out of many $D1$ ...
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80 views

Are M branes fundamental?

In M theory, are M branes fundamental or are they made of something else? Are they made up of fields? Say for instance the M2 brane is not fundamental, wouldn't that mean that the string is not ...
4
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1answer
152 views

Klebanov-Witten and Conifold equation

I'm a bit confused by some that is understood in the following papers: 1 and 2. I understood that there is a GLSM with fields $A_i,B_i$ with $i=1,2$ whose moduli space is the conifold described with ...
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66 views

Can fractional D-branes be described in F-theory?

In Type IIB string theory, there can exist fractional D-branes at singularities. Additionally, F-theory is in some sense an alternative description of Type IIB string theory. So there should be an F-...
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1answer
64 views

Spinning particle lagrangians [closed]

What is the most general relativistic and non-relativistic lagrangian describing a spinning object in the following cases? Classical point particles. "Classical" point super-particles.
2
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1answer
345 views

M branes/D branes are solitons?

I'm really confused. In M theory/String theory, the fundamental objects are M/D branes. However, branes by defintion are just solitons. Solitons are just waves that maintain there shape. So if a ...
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1answer
104 views

Can the D3 brane be described by M theory?

M theory has only 2 fundamental objects, the M2 and M5 brane. These can describe a variety of different branes. However, is there any description on how M theory describes D3 branes?