A class of theories that attempt to explain all existing particles (including force carriers) as vibrational modes of extended objects, such as the 1-dimensional fundamental string. PLEASE DO NOT USE THIS TAG for non-relativistic material strings, such as, e.g., a guitar string.

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71 views

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 ...
7
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1answer
166 views

Relations between diffeomorphism symmetry theories and invariant $SU(N), N \rightarrow \infty$ theories

Is it possible to have, an exhaustive panorama (as much as possible), about the relations between theories having a diffeomorphism symmetry, and theories having a $SU(N), N\rightarrow\infty$ ...
1
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0answers
16 views

Explanation of two slit experiment [duplicate]

Whilst going through 'a brief history of time' ,I faced difficulty in understanding the two slit experiment. How can individual electrons cause fringes?
1
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0answers
25 views

Is there any known dynamical process to obtain supertubes?

I'm looking for a dynamical process to produce supertubes. For example, microstates of the D1-D5 black hole system can be understood as supertubes. See, for example, ...
1
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0answers
17 views

Ask help for calculation from Veneziano amplitude to expansion at small $s$? [closed]

The Veneziano amplitude \begin{eqnarray} A_{ven}(s,t)={\Gamma(-\alpha_0-\alpha^\prime s)\Gamma(-\alpha_0-\alpha^\prime t)\over \Gamma(-2\alpha_0-\alpha^\prime (s+t))}, \end{eqnarray} as claimed in ...
1
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1answer
124 views

Why are string theorist so indifferent to the gauge structure of gravity? [closed]

Gravity shares many of the characteristics of Yang-Mills gauge theory. For example, the affine connection plays the similar role as the gauge potential in gauge theory, the Riemann tensor plays the ...
2
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1answer
701 views
0
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0answers
25 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 ...
5
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1answer
202 views

Mass of a superstring between two branes?

A open bosonic string between two parallel branes seems to obey formulae such as $M^2 = \big((n + {\theta_i - \theta_j \over 2 \pi}) {R' \over \alpha'}\big)^2 + {N-1 \over \alpha'} $ So that the ...
0
votes
1answer
29 views

Boundary Conditions For Strings? [closed]

There seems to be two main boundary conditions for Strings. 1. Neumann Condition: Ends of Strings are free to move up or down. 2. Dirichlet Condition: Ends of Strings are fixed. What other ...
1
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0answers
30 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 $a$?
1
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1answer
50 views

Derivation Of The Equation Of Motion Of String from Polyakov action

I'm stuck at a step in the derivation of the equations of motions of a string using the Polyakov action. In Polchinski's textbook in String Theory , Page 14 ; Equation ( 1.2.25 ) , Varying the ...
3
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1answer
67 views

Wilson Loop in AdS/CFT

In AdS/CFT correspondence one can compare results in $\mathcal{N}=4$ SYM with string theory type IIB in $AdS_5 \times S^5$. One of the observables that it's possible to get non-perturbative results is ...
3
votes
1answer
67 views

S-duality of Einstein-Maxwell-Dilaton theory

Consider theory with action $$S = \int d^D x \sqrt{-g} (R - \frac{1}{2} \partial_\mu \phi \partial^\mu \phi - \frac{1}{2k!} e^{a \phi} F^2 _{[k]} ) $$ where $\phi$ is dilaton and $F_{[k]}$ is ...
1
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1answer
64 views

About Planck tension in strings theory as stated in “The Elegant Universe”

In the book "The Elegant Universe" by Brian B. Greene, on chapter 6 it is stated that there's the so called "Planck tension" in string theory, and it is given a value of $10^{39}$ tons. This value is ...
6
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1answer
168 views

How does higher spin theory evade Weinberg's and the Coleman-Mandula no-go theorem?

Recently I heard some seminar on higher spin gauge theory, and got some interest. I know there are some no-go theorems in quantum field theories: Weinberg: Massless higher spin amplitudes are ...
0
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0answers
54 views

Correlation functions in a zero dimensional QFT?

I would like to ask about correlation functions in a 0-dimensional matrix model QFT. What information do these correlators give? I know only of correlators between two different spatial positions.
4
votes
1answer
280 views

Virasoro operators commutation relations [closed]

For the commutation relation in quantising the bosonic string $$\left[L_n,L_{m}\right]=(n-m)L_{n+m}+\frac{D}{12}n(n^2-1)\delta_{n+m,0}$$ we can then calculate this for $m=-n$ in between the vacuum ...
4
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0answers
55 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 ...
3
votes
1answer
92 views

BRST quantization (Green, Schwarz, Witten)

In Green, Schwarz, Witten Volume 1, section 3.2, BRST quantization is introduced in a general way. A Lie algebra $G$ is defined with elements $$ [K_i,K_j] = f_{ij}{}^k K_k \tag{3.2.1}$$ where ...
3
votes
3answers
776 views

Question on Conformal Field Theory

Since every question has to be asked in a seperate topic, I'm asking a question refering to the following topic: Beginners questions concerning Conformal Field Theory In particular I'm referring to ...
25
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4answers
2k views

What is your simplest explanation of the string theory?

How would you explain string theory to non physicists such as myself? I'm specially interested on how plausible is it and what is needed to successfully prove it?
1
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1answer
258 views

Why does Weyl invariance imply a traceless energy-momentum tensor?

I've begun to self-study String Theory from Polchinski and Becker, Becker and Schwarz. I don't see why the fact that the Polyakov action is invariant under Weyl transformations is related to the ...
1
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1answer
73 views

Why do people care about Mathieu groups and related things? (Something about monstrous moonshine)

Before I begin, let me say I don't know anything about what I am asking. This morning for somewhat random reasons I decided to google moonshine and related things. As it were I discovered my ignorance ...
0
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1answer
45 views

STU-model for Black holes

In string theory in the realm of black holes, what does the acronym STU stands for when we talk about the STU model?
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0answers
15 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. ...
2
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0answers
29 views

Blackhole microstate counting

It's widely belived that p-branes and Dp-branes are the same objects in string theory. P-branes are charged solutions of type IIB supergravity that have the topology of a black hole, one would expect ...
1
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0answers
96 views

What is the justification for continuing to model space-time as a manifold in string theory?

Background The question I have arises from taking seriously the idea that, in a physical theory, one should first define all physical quantities via (thought) experiment. Justification and ...
1
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1answer
41 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 ...
3
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0answers
54 views

Physical meaning of the Morse functions? [closed]

What is the physical correspondence of the Morse functions in a physical system? Currently I am studying Mirror symmetry but I can not get a physical intuition out of it.
1
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0answers
82 views

What is the status of Lorentz Invariance in String Theory ? Is it global or local?

The questions is simple, what is the status of lorentz invariance in string theory ? Is it global or is it only local ? The proof of absence of anomalies assumes lorentz invariance. However, I believe ...
0
votes
1answer
50 views

Energy density of a 1D string?

As I understand there is a problem in physics where point-like massive (or charged, etc.) particles would have infinite mass/energy (or charge, etc.) density. I'm curious how in the context of String ...
1
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0answers
25 views

Manifold corners and M theory

I am currently trying to understand a paper by Hisham Sati on manifold corners and M theory. The background is that M theory admits manifolds with corners. One of the results in the paper is that the ...
0
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0answers
49 views

About the non-locality of gravitational energy 2

Gravitational energy is non-local which is essentially because of the equivalence principle. The equivalence principle says that you can always transform your frame so that you feel like in a ...
2
votes
0answers
63 views

What is the “single equation” in string theory that's an inch long? [duplicate]

Michio Kaku, famous theoretical physicist claims to be one of the founders of string field theory and to have contributed a equation that's "no bigger than your thumb" that ties general relativity and ...
2
votes
1answer
67 views

Problems with covariant action of the superstring

I was reading Kiritsis notes (http://arxiv.org/abs/hep-th/9709062), at page 105/106 (equation 10.1), where he has a covariant action of the superstring including the gravitino. I have problems showing ...
2
votes
1answer
174 views

How much QFT do I need to get started on String Theory? [closed]

I want to get started learning String Theory (most likely from David Tong's lecture notes) and I would like to know which topics I need to know from QFT. In particular, if I were to follow Peskin, ...
1
vote
0answers
57 views

Can anyone explain the Matrix version of M-Theory?

I am trying to understand "Matrix-Theory" (the version of M-Theory which describes the theory in the infinite momentum frame). I tried to read Susskinds original paper on it but it doesn't make any ...
0
votes
0answers
41 views

Can the KLT low-energy limit relations be obtained without string theory?

The KLT (Kawai-Lewellen-Tye) relations roughly say that -at the tree level- closed string amplitudes equal open string amplitudes squared and in the low-energy limit this becomes a "Gravity = Gauge ...
3
votes
0answers
43 views

Direction about future [closed]

I am finishing high school this year and i want to be a theoretical physicist. My academic result in mathematics is not good throughout last 5 years. But physics is my dream. I want to overcome every ...
0
votes
1answer
198 views

Why doesn't gravity fit into quantum theory?

Before you read, I want to point out that I probably don't know nearly as much as you guys about quantum theory, even though I love learning about it, so I would prefer explanations in relatively ...
-1
votes
1answer
137 views

What does the finding of gravitational waves mean for M Theory? [duplicate]

I was wondering if the finding of gravitational waves proves M theory. I know at Fermi Lab scientists were looking for gravitons in distant places in our universe so that they can prove string theory. ...
1
vote
1answer
71 views

“Dictionary” between QFTs in D and D-1 dimensions?

Consider the Einstein field equations. Suppose, for instance, that the RHS, the stress-energy tensor, is uniquely determined by the electromagnetic field. Now, if we imagine a quantized version of ...
1
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1answer
59 views

How does this quantisation relation come about?

I'm currently doing a course in string theory and in the lecture notes it is stated: $$ [x^-, p^+]~=~-i \tag{1}$$ I am fine with this. However, after trying (and failing) a question, I looked at ...
5
votes
1answer
75 views

Interplay between the cosmological constant and “microscopic” properties of string vacua

As far as I understand, string phenomenology is usually concerned with compactifications of string theory, M-theory or F-theory in which the uncompactified dimensions form a 4-dimensional Minkowski ...
0
votes
0answers
35 views

Does flat-land really exist?

In a paper "Out of the White Hole: A Holographic Origin for the Big Bang." The authors talk about the possibility that our 4D(3+1) universe could of emerged from a 5D(4+1) Schwarzschild black hole. ...
8
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2answers
740 views

Advanced topics in string theory

I'm looking for texts about topics in string theory that are "advanced" in the sense that they go beyond perturbative string theory. Specifically I'm interested in String field theory (including ...
4
votes
3answers
128 views

String models of particle physics

What general features of particle physics are derived/replicated by constructing string models of particle models? How do such models address the fixing of free parameters like the masses and the ...
1
vote
2answers
93 views

In a 2D CFT of a free boson $X$, is $X$ a primary field?

A primary field $\mathcal{O}(w,\bar{w})$ with weight $(h,\bar{h})$ is defined by having the following OPEs with the stress tensor: ...
2
votes
0answers
62 views

Correlation function for ghosts in 2D CFT

In Di Fracenso, page 117, it is explained that the correlation function for two primary fields $\phi_1,\phi_2$ of weights $h_1,h_2$ is constrained to be of the form ...