# Tagged Questions

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### How many orientifold planes does one need?

According to the book ''String Theory in a Nutshell'' by Elias Kiritsis (page 204, linked here), the tension of an $Op$-plane is $$T_{Op} = -2^{p-4}T_{Dp}$$ With this picture, one gets -- for type ...
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### For intersecting branes, are we allowed to compactify on a torus such that one of the branes becomes dense in it? What is the result?

The story of how to get chiral fermions in the low-energy effective theory of a string theory with intersecting branes goes something like this: At the point of intersection of two branes, a direct ...
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In the string theory book by Ibanez and Uranga (click here for the Google books excerpt), the four-dimensional multi-center Taub-NUT metric is written as $$ds^2 = \frac{V(\textbf{x})}{4}d\textbf{x}^2 ... 0answers 16 views ### Query about Ramond-Ramond fluxes associated with a Dp-brane A paragraph in the string theory book by Ibanez and Uranga (String Theory and Particle Physics by Luis Ibáñez and Angel Uranga) has confused me. According to the book (for a screenshot of the ... 1answer 81 views ### What, exactly, is a “delta function p-form” as used in the theory of branes? In string theory, when dealing with branes, the following happens: We rewrite a worldvolume action S = \int_{\Sigma_{p+1}} \omega^{(p+1)} of a D_p-brane as an integral over the whole \mathbb{R}^{... 1answer 38 views ### Enhanced D-Brane Gauge Symmetry and the string decoupling limit Consider a system of N_C Dp-branes (in Type IIA or Type IIB string theory, depending on whether p is even or odd). In the Les Houches lectures on supersymmetric gauge theories by Berman and ... 0answers 57 views ### Flux with or without sources I want to check whether my understanding about flux is correct. So let me consider a d-dimensional spacetime manifold M and a (p+2)-form flux (or field strength) F. Then there are two ... 1answer 42 views ### Confusion about supergravity multiplet I have a bit of confusion with the following consideration. Generally, to impose some BPS condition (i.e. to check if some multiplet preserves some SUSY charges) one imposes to zero the SUSY ... 1answer 49 views ### What kind of fields can couple naturally to a p-form gauge fields in a Lagrangian? Ordinary U(1) gauge fields can naturally couple to classical fields such as spin-1/2 fields via the Dirac Lagrangian, or to complex spin-0 fields via the obvious covariant derivative coupling, ... 1answer 113 views ### How can Big Bang happen without time? I had recently watched a video and he says big bang could have happen by the slow collision rather than a fast collision. But I know that there was no time before the big bang and fast and slow are ... 0answers 37 views ### Which supersymmetry principles make the axio-dilaton field in F-theory holomorphic? I am following the lecture notes on F-theory by T. Weigand . On page 7 he states that when considering F-theory as the strong coupling limit of type IIB orientifolds with D-branes, the axio-dilaton ... 1answer 39 views ### Type II Superstring and Open String I would like to trow away some confusion I'm accumulating. Usually when superstrings are introducted (see for example Wikipedia) one says: Type I is a theory of open and closed strings, while Type ... 1answer 59 views ### D-branes conserving only half of the supersymmetries Concerning D-branes as BPS states from T-duality. In D-Branes by Johnson (and other sources) I find the following statement (p.196): "Only the total [supersymmetric] charge of Q_a+\tilde{Q}_a of ... 1answer 54 views ### Membrane Theory I'm not a physicist or educated mathematician, so please excuse me if my question is scientifically rudimentary. It concerns Membrane Theory. If all open strings are attached to the surface of the D ... 1answer 70 views ### What makes the strings (or p-branes) that occur in string theory vibrate? A normal spring (for example in my ballpoint) is made of particles that interact with each other wich makes the string vibrate with a frequency that depends on the material (the particles). Now a ... 0answers 32 views ### D4 branes ending on NS5 branes (Witten's construction): query about harmonic functions This query stems from Witten's paper, ''Solutions of Four-Dimensional Field Theories via M Theory'' (hep-th/9703166). Specifically, consider Type IIA string theory, and suppose one has a stack of NS5 ... 0answers 31 views ### Superstring mass between 2 D-branes The mass of a superstring between 2 parallel D-branes of dimension p and q is$$m^2=(N−a)+(y/2π)^2$$But what is the value of the normal ordering constant a? 0answers 61 views ### Higgs mechanism on a brane- application to a 2d superconductor In usual three-dimensional superconductors the would-be Goldstone mode is eaten up by the electromagnetic gauge field via the standard Higgs mechanism. I am thinking now about a problem of a two-... 0answers 41 views ### Could a 3+1 space be embedded in a 4+1 space and retain its 3+1 characteristics? [closed] I'm confused because I can conceptualize this embedding scenario in two seemingly incompatible ways. Which of the following scenarios are possible?: 1) 4+1 space automatically enforces 4 dimensions ... 0answers 17 views ### C.o.m. position and total momentum of open DD string I'm trying to calculate c.o.m. position q_\text{DD}^\mu and total momentum p_\text{DD}^\mu of the open string with Dirichlet boudnary conditions on both ends. Something is going very wrong though. ... 1answer 42 views ### Non-perturbative Brane effects In Johnson's Book about D-branes he gets the Tension of a D brane:$$\tau_p = \frac{\sqrt{\pi}}{16 \kappa_0 g_s}(4\pi^2\alpha')^{(11-p)/2} By performing a string amplitude calculation and ...
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Do we have an extension of the AdS/CFT correspondence for rotating branes? Are the rotating branes, the supergravity analog of the Kerr Black Holes in General Relativity? What are the most successful ...
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### What is known about the physics of Planckbrane (another brane) in Randall–Sundrum model?

Randall–Sundrum model imagines that our universe is a five-dimensional anti-de Sitter space and the elementary particles except for the graviton are localized on a (3 + 1)-dimensional brane or branes. ...
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### Does Type IIB string theory feature D(-1) and D9 branes?

I'm slightly confused as to how one deduces the D-brane content of a string theory by studying the p-form fields in the effective field theory. In type IIB supergravity one has: The Kalb-Ramond 2-...
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### What are the difference between a black holes and a black branes? [closed]

I want to know the fundamental difference between a black hole and a black brane? What is the planar limit?
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### Brane interactions?

In particle physics, in QFT's, interactions come from the interaction piece in the Lagrangian (action). In string theory, waiting for a complete formulation of SFT, we have to add "by hand" ...
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### What is the relationship between a brane, a manifold, and a space?

I've read many ways to define manifold; one way is to define it as a type of mathematical space (a type of topological space to be exact). All of the definitions that I've seen for brane, on the ...
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### What exactly is a fundamental string as opposed to a D-string?

What exactly is a "fundamental string" in string theory? For bosonic string theory we have the bosonic string inside a 26-dimensional target space. Introducing supersymmetry, we have the ...
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### What's between the branes?

So I'm doing my best to explain M Theory to some friends... Mind you, I'm no expert... When we finally got past the obstacle of more than three dimensions... which can be difficult for folks who aren'...
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### Is M-Theory and 11D Supergravity the same thing?

Is M-Theory and 11D Supergravity the same thing? Reading Hawking, he uses 11D Supergravity and M-Theory interchangeably. http://www.hawking.org.uk/quantum-cosmology-m-theory-and-the-anthropic-...
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### What would happen if two branes collided and stuck together?

There is a theory that the universe began when two "branes" bumped each other, creating the energy that sparked the beginning of our universe. What if instead of separating, they actually stuck, ...
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### Galileons and the brane origins of their Galilean invariance

I've been reading through a paper on Galileons by K. Hinterbichler et al. in which they discuss the brane origin of their Galilean invariance (starting on page 9) http://arxiv.org/abs/1008.1305 The ...
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### DBI action with Weyl Invariance

The DBI action, given by $S_{Dp}=-T_p\int d^{p+1}\xi e^{-\phi(\xi)}\sqrt{-\textrm{det}\left(G_{ab}(\xi)+B_{ab}(\xi)+2\pi{\alpha}'F_{ab}(\xi)\right)}$ is diff and Poincaré invariant. I want to ...
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### In M theory, what size are the branes/D branes?

In string theory strings are around Planck length, but how big are the D branes in M theory? Can we see them with the LHC?
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### Bulk action - Can a brane velocity be defined?

a) If a brane action in a bulk is defined, in that case, that a brane is modelwise moving through a bulk, how is this ratio defined? Is this a regular "velocity" in that meaning, that space is being ...
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### In M theory, can a fundamental open string attach to a M5 brane?

I only saw a couple of pages online that showed this so i guess I'll ask on here, can fundamental open 1 string end on an M5 brane?
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### In M Theory, what does the M5 brane look like?

In M theory, the fundamental 1 strings are made out of the compactification of an M2 brane. In String Theory: Volume 2, Superstring Theory and Beyond By Joseph Polchinski Pg. 204 He states that ...
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### In M-theory, are strings created by membranes?

In M-theory there are 2- and 5-branes, but where are the one-dimensional strings which are responsible for all the particles? Can 5-branes turn into 1-dimensional strings due to compactification?
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### Sources that explain strings between two branes, where one brane ends on the other

I can't seem to find a source that explains what happens when there are strings between one brane and another brane, where one brane ends on the other brane. For example, consider a D3-brane ending on ...
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### M-theory and Mathematics [closed]

If the framework of M-theory is the right path for a unification of gravity with quantum mechanics, is it obligatory to believe that, at a certain level, reality is not just easily describable by ...
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### Concerning topology of BPS states of the M5-brane

My question is about the M5-brane in M-theory. I would like to know whether the BPS states of the M5-brane worldvolume theory (especially the 1/2 BPS and 1/4 BPS ones) are independent of the topology ...
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### Fayet-Iliopolous Parameters from Separation of NS5-branes in $(x_{7}, x_{8}, x_{9})$: An ambiguity as to which gauge group the FI parameter belongs

hep-th/9611230v3, page 12 explains how, for a configuration of D3s along $(x_{1}, x_{2}, x_{6})$, and NS5's along $(x_{1}, x_{2}, x_{3}, x_{4}, x_{5})$, the Fayet-Iliopolous D-term coefficient $\zeta$ ...
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### Connection between the M5 brane and (2, 0) superconformal field theory

I have read that the worldvolume theory of the M5 brane is a $(2, 0)$ superconformal field theory (SCFT). But I have also learnt from talks that the $(2, 0)$ theory lacks a Lagrangian description. ...
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### Type I string theory on $K3 \times \mathbb T^2/\mathbb Z_2$ and the K3 orbifold limit

Consider Type IIB string theory with 4 O7-planes and 32 D7-branes on $K3 \times \mathbb T^2/\mathbb Z_2$. The K3 induces D3-charge on their world-volumes which can be cancelled by the introduction of ...
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### D-brane tension of type I D9-branes after T-duality

Type I contains branes with a brane tension which is $\frac{1}{\sqrt 2}$ times that of type II branes. The reason is that, e.g., in the computation of the D9-D9 amplitude the open string is unoriented....
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### Creation of a miniature universe?

I am not referring to the experiment being conducted at Lancaster University involving liquid helium and a magnetic field to build a marble sized representation of the early cosmos. My question is: ...
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### In string theory, are strings really just one dimensional? [duplicate]

Is it possible that they are 3 dimensional? Or what if they are 10 dimensional? Is it allowed that they are more than just one dimensional?
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### Why should the modes of the linearized metric perturbation be “wavefunctions” of gravitons (in the Randall-Sundrum model)?

In "An Alternative to Compactification" by Randall and Sundrum, they discuss the localization of "graviton modes" around the Planck brane in the Randall-Sundrum model where we have a compact fifth ...