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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49 views

Hypermultiplet as BPS particles

In the third paragraph of page 7 of the paper arxiv:1112.3984 it mentions that we form a basis out of hypermultiplets on the charge lattice $\Gamma$. My questions are: In what sense do we form such ...
4
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0answers
56 views

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 ...
1
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1answer
59 views

How does the holographic principle apply to the $n$ dimensional space of String Theory?

The holographic principle is a property of string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a ...
0
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1answer
95 views

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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1answer
117 views

Can someone explain about M-theory? [closed]

Can someone explain about M-theory? I am very new to M-theory and string theory. I am very through with classical physics and little bits of quantum mechanics. Will you be able to explain why ...
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0answers
18 views

Toroidal compactification and number of susy

In case of Tordial compactification, reference states page 13, A.Font et al, Introduction to string compactification, it does not reduce the number of real supercharges. I wonder why this happens. ...
1
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0answers
66 views

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 $\zeta$ ...
4
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0answers
194 views

Has Sen quantized superstring fields?

Today I saw a paper by Ashoke Sen titled "BV Master Action for Heterotic and Type II String Field Theories". Is it really the "quantization" of superstring fields for the first time? What can be its ...
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2answers
145 views

Quantum computers for string theory? [closed]

I read something about that locating our space in the multitude of multidimensional spaces of M-theory (and so identifying particular particles which we can measure with particular strings) is a too ...
1
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0answers
56 views

How can the stress tensor components of a worldsheet CFT in general background be (anti)-holomorphic?

In all textbooks/lecture notes on string theory (e.g. Polchinski, page 43 at the bottom) it is proven that, as the stress tensor is traceless and conserved, $T^a_a=\partial^a T_{ab}=0$, we have ...
6
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3answers
432 views

Problems book recommendation on supersymmetry, supergravity and superstring theory

I'm learning supersymmetry, supergravity and superstring. I want some problems books to have some idea in this area. Is there this kind of books? Or are there some papers that have many solved model?
2
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1answer
229 views

What causes gravity in M-Theory?

New and updated, because people were misunderstanding what I meant! General relativity describes gravity as the result of....(very roughly) spacetime curvature Newtonian gravity describes gravity as ...
1
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1answer
126 views

Global symmetries in type IIB string theory vs type IIB supergravity

In the AdS/CFT correspondence I know that the mapping of global symmetries involves also the S duality that in the field theory side is $SL(2,Z)$. In Type IIB supegravity this duality is $SL(2,R)$. I ...
2
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0answers
76 views

QFT background needed for AdS/CFT integrability [closed]

Apologies if this type of question isn't permitted. I'm very interested in integrability in the context of AdS/CFT. I'm starting my Masters soon in a very GATIS-involved institute and would like to ...
1
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0answers
37 views

Holography with wave functionals rather than partition functions

Roughly speaking Gubser-Klebanov-Polyakov Witten's (GKPW) prescription in the context of holography tells us partition function of CFT is "equal" to that of the gravity theory in one higher dimension ...
2
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1answer
186 views

Proper way to quantize the string in the light-cone gauge

In many books like Polchinski and Green-Schwarz-Witten the light cone quantization is carried out in a fast way. They just use the virasoro constraint in the light-cone gauge to get the ligh-cone ...
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0answers
48 views

Effect of orbifolding on form ields

A paper by Lalak et al, entitled "Soliton Solutions of M-theory on an orbifold", considers the brane solutions of 11 dimensional supergravity on a space of the form $R^{10} \times S^1/\mathbb{Z}_2$. ...
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0answers
61 views

Gravity dual of N free scalars in 2D

I have a very basic (and might be very naive) question. What should be the dual gravity description of $N$ (with $N>>1$) free scalars in two dimensions? I was wondering whether it would be ...
0
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0answers
60 views

Has string theory predicted any experimently verified results? [duplicate]

I'm just getting into string theory and I'm wondering if it has made any unique predictions that have been verified by experiment?
1
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1answer
90 views

Calabi Yau Motivation

I have just begin to study Calabi Yau compactification. Looking in many book I found that, if we start with a critical superstring theory in $D=10$, we are in search of a compact $D=6$ Calabi Yau ...
6
votes
2answers
319 views

Is there some no-go theorem for $D=9$ Kaluza Klein QCD+EM?

While QCD is a typical product of AdS/CFT and some other research trends in extra dimensions, I have never found in the literature an example producing the non-chiral part of the standard model, ...
10
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2answers
10k views

Fundamental equation(s) of string theory?

I often hear about string theory and its complicated mathematical structure as a physical theory, but I can't say that I've ever actually seen any of the related math. In general, I'm curious as to ...
0
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0answers
57 views

Can string theory and the Penrose interpretation coexist?

Is it possible for string theory to coexist with the Penrose interpretation of quantum mechanics? Does string theory require the many worlds interpretation?
2
votes
1answer
285 views

What is a ghost number?

I am currently studying CFT chapter of Becker,Becker,Schwarz and am trying to understand what the ghost number is in BRST Quantization. From what I gather BRST Quantization is used to add an extra ...
0
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0answers
48 views

How much do we know about Quantum Gravity at energies larger than Planck energy?

What kind of predictions do current approaches to quantum gravity (superstrings/M-theory, loop quantum gravity,...) make at energies LARGER than Planck scale? Or is that a meaningless question? Does ...
12
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2answers
948 views

Why can the Euler beta function be interpreted as a scattering amplitude?

The Wikipedia article on the Veneziano Amplitude claims that the Euler beta function can be interpretted as a scattering amplitude. Why is this? In another word, when the Euler beta function is ...
5
votes
1answer
119 views

Where do $X_0^{-d}$ and $G'_r$ come from in Polchinski Eq. (6.2.13)?

I have a question about deriving Eq. (6.2.13) in Polchinski's string theory book volume I. It is claimed that Now consider the path integral with a product of tachyon vertex operators, ...
2
votes
0answers
82 views

Problem with OPE (from Polchinski) [closed]

I was reading Polchinski, Vol. 2 pag 12, while I found (10.3.12a): $$ e^{iH(z)}e^{-iH(z)}=\frac{1}{2z} + i\partial H(0) + 2zT^H_B(0) + O(z^2).\tag{10.3.12a} $$ Now I tried to do the OPE, what I ...
3
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0answers
48 views

Superstring NS tachyon vertex operator

After reading some confusing chapter of various string theory book I'm trying to construct the Tachyon vertex operator for superstring theory. I know that this is removed after GSO projection, but for ...
2
votes
0answers
37 views

Correlator $bc$ system [closed]

I have da doubt with bc system. Polchinski says (2.5.10) $$ b(z)b(0)~=~O(z). \tag{2.5.10} $$ I tried to compute the correlation function With eom, using eq (2.5.6b) by Polchinki, removing the ...
1
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1answer
105 views

Polchinski Equation (10.4.7) [closed]

I'm having a problem to interpret eq. (10.4.7) in Polchinski: $$ \gamma(z)\delta(\gamma(0)) = O(z), \qquad \beta(z)\delta(\gamma(0)) = O(z^{-1}). $$ What does he mean by $\delta$? He tries to ...
4
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0answers
78 views

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. ...
6
votes
3answers
973 views

Does string theory and preons exclude each other?

Does string theory contradict the theory of preons, especially the Harari-Shupe one?
3
votes
1answer
167 views

How is a string in string theory different from a harmonic oscillator or a point?

I am reading String Theory and M-Theory: A Modern Introduction by Becker, Becker and Schwartz. I've tried to read this book before but not succeeded because I didn't know enough math or physics. This ...
1
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0answers
43 views

Quantum corrections to holographic entanglement entropy

I was looking at this paper by Faulkner-Lewkowycz-Maldacena. They give a very interesting proposal of calculating one loop (i.e, 1/N) correction to EE from computing the EE between the bulk regions. ...
3
votes
0answers
43 views

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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0answers
37 views

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 ...
1
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1answer
144 views

Conformal blocks in 2D CFTs

I have studied conformal field theories in two dimensions and I understand the basic idea behind conformal blocks too. But I never completely realized what they are when it comes to computing them. ...
0
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3answers
4k views

Relation between quarks and strings

In string theory, are quarks just individual strings, or are they made of multiple strings? Are the heavier quarks made of heavier or longer strings? Are there red, blue, and green strings ...
4
votes
0answers
78 views

Target Space Lorentz Invariance vs. World Sheet Weyl Invariance

The Polyakov action, $S\sim \int d^2\sigma\sqrt{\gamma}\, \gamma_{ab}\partial^a X^\mu \partial ^b X_\mu$, has the well known classical symmetries of world sheet diffeomorphism invariance, world ...
2
votes
2answers
443 views

Black hole entropy

Bekenstein and Hawking derived the expression for black hole entropy as, $$ S_{BH}={c^3 A\over 4 G \hbar}. $$ We know from the hindsight that entropy has statistical interpretation. It is a measure ...
2
votes
1answer
61 views

What is the definition of the duality group $E_{7(7)}$?

What is the definition of the duality group $E_{7(7)}$ that appears in ${\cal N}=8$ Supergravity and what are the basics properties? Moreover what is the relation with the Lie Algebra $E_7$? ...
3
votes
1answer
115 views

Maldacena's decoupling argument

I am a bit confused about Maldacena's original decoupling argument. There are two different low energy (i.e, $\alpha^\prime \to 0$) descriptions of the stack of D3-branes: $\mathcal{N}=4$ SYM and ...
3
votes
1answer
112 views

D-branes in type II string theory

D-branes, as I currently understand them, are submanifolds of spacetime on which open strings can end with Dirichlet boundary conditions. On the other hand, type II string theory is a theory of ...
1
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1answer
91 views

Dimensional reduction of SUSY theories

I know that if one reduces 10 dimensional $\mathcal{N}=1$ SYM theory to 4 dimensions one gets $\mathcal{N}=4$ SYM. There are other examples also. I have two related questions regarding this fact. ...
4
votes
2answers
144 views

Where and how is the entropy of a black hole stored?

Where and how is the entropy of a black hole stored? Is it around the horizon? Most of the entanglement entropy across the event horizon lies within Planck distances of it and are short lived. Is ...
2
votes
0answers
74 views

Amplitude for a string to propagate from one point to another

In Zwiebach’s book sections 12.6 and 12.7 interesting aspects of the wave function of the string are discussed. In order to introduce my question first recall what happens with the relativistic ...
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1answer
105 views

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?
2
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2answers
248 views

Mathematics needed for string theory [duplicate]

I'm interested in cutting edge string theory studied by research physicist. I'm wonder what mathematics is needed and how far am I in terms of mathematics background needed and how much more ...
3
votes
2answers
87 views

How can one calculate the central term of the conformal field theory algebra (and show it's really the virasoro algebra)?

So I'm following Szabo's book "An Introduction to String Theory and D-brane Dynamics (2nd ed, 2011); still on the canonical treatment in chapter 3. After doing a mode expansion, we get (up to a ...