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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1answer
109 views

Is it worth reading The Elegant Universe? [closed]

noob question here. I'm interested in reading The Elegant Universe by Brian Greene, but I've read some reviews that say the science has been discredited. I'm a total layman, has the science been ...
4
votes
1answer
101 views

Theories that predict the number of space-time dimensions

My impression in that most theories assume three spatial dimensions and one temporal dimension, though could in principle be formulated in others numbers of dimensions without inconsistencies. I know, ...
0
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0answers
52 views

Algebraic number theory and physics [duplicate]

I would like to ask if there are any aspects of algebraic number theory related to physics (for example in string theory or Moonshine etc). I am thinking of attending a course on algebraic number ...
3
votes
0answers
156 views

Vertex insertions as functionals

In lecture notes on string theory by David Tong (available for free here http://www.damtp.cam.ac.uk/user/tong/string.html) a brief explanation of the vertex operator for tachyon is given. The main ...
1
vote
1answer
97 views

AdS/CFT in global coordinates (as opposed to Poincare coordinates)

When the usual derivation for AdS/CFT is given for the most famous example of Type IIB string theory on $AdS_5 \times S^5$, the AdS space is clearly seen as the near horizon geometry of a stack of D3 ...
3
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3answers
713 views

Are quantum mechanics and general relativity predictions of string theory, or were they built into the theory from the start?

Are quantum mechanics and general relativity predictions of string theory, or were they built into the theory from the start? If the former, why aren't tests of GR and QM considered simultaneous tests ...
4
votes
1answer
95 views

(Euclideanized) QFT on $S^d$ vs $S^{d-1}\times S^1$

Broadly I would like to understand what is the difference in the physical interpretation of a (Euclideanized) QFT which is on space-time $S^d$ and which is on a space-time $S^{d-1}\times S^1$. In ...
1
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2answers
161 views

Why does AdS/CFT with non-zero temperature correspond to a black hole in the bulk?

Is there a good intuitive explanation on why AdS/CFT with non-zero temperature corresponds to a black hole in the bulk? And what is the role of temperature and chemical potential in this black hole?
2
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0answers
177 views

Coulomb Branch vs. Higgs Branch (and the connection with D-branes, AdS/CFT)

I am confused about the difference between the Coulomb and Higgs branches of the moduli space of supersymmetric gauge theories. It's easy to find a definition for $D=4$, $\mathcal{N}=2$ supersymmetric ...
4
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0answers
40 views

Where can I find a video on Liouville Non-Critical String Path Integral?

Would anybody know of a video lecture course in which Polyakov's non-critical string path integral $$Z = \int D [\psi(\xi)]\, \, \exp \left\{ \frac{D-26}{48 ...
6
votes
0answers
125 views

Questions regarding $D=4 $ ${\cal N}=4$ supersymmetric Yang-Mills

I have some questions regarding the $D=4 $ ${\cal N}=4$ super-Yang-Mills theory (the one with a really long action which can be acquired by compactifying the 10-dimensional ${\cal N}=1$ theory). I ...
0
votes
1answer
64 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
vote
1answer
68 views

Generalized spin connection and dreibein in higher spin gravity

I am studying 3D higher spin gravity and I would like to know the mathematical and physical meaning of generalized spin connection and generalized dreibein that appear in this theory. It is well known ...
4
votes
2answers
82 views

Definition of Duality (opposed to Symmetry)

I'm learning basic string theory right now and we came across T-duality which was presented as a symmetry of the formula for the mass of a string in the context of compactification. There was a remark ...
0
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0answers
29 views

Modular S matrix in 2D rational conformal field theory

The modular $S$ matrix in 2D CFT is defined by $$ \chi_a(-\frac{1}{\tau})=S_{ab} \chi_b(\tau). $$ Can $S$ depend on the modular parameter $\tau$?
0
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0answers
15 views

how to measure the wave emitted from some particles after input sine wave into the particle

which waves can be input into the particle? is it sine wave? is the wave emitted from the particle after input wave into the particle different? if want to measure the output wave, how to use math ...
0
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1answer
52 views

Are end points of an open bosonic strings orthogonal to D-branes?

I'm apologizing for such simple question, I just started to learn string theory. If one end of an open bosonic string is attached to a Dp-brane it means that in directions normal to the brane ...
0
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0answers
32 views

What's the string size cutoff?

The instantaneous string size is infinite Susskind say that the string's instantaneous size is infinite. its peak-to-mean amplitude and distance between endpoints is the harmonic series. it's ...
1
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1answer
32 views

In Rational Gaussian Model, why must $R^2$ be rational?

I am reading Fusion Rules and Modular Transformations in 2D Conformal Field Theory and Verlinde talks about the rational gaussian model. The simplest class of RCFT's are the rational gaussian ...
1
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1answer
99 views

What is the motivation behind the GSO projection in superstring theory?

I do agree that the GSO "works", making the number of degrees of freedom match on the bosonic and fermionic side and that it sweeps away the problematic tachyon. However it is very artificial, it ...
3
votes
1answer
9k views

Is this pseudo science or real: code found in superstring [closed]

Article in question: http://humansarefree.com/2013/01/science-strange-computer-code.html Problem: no credible looking or sounding site has anything on it. Only bunch of youtube videos. And some ...
1
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1answer
80 views

Representations of subalgebra in the super virasoro algebra

In the Virasoro algebra, which is generated by $L_n$, one has the obvious subalgebra spanned by $L_{-1}$ ,$L_{1}$ and $L_{0}$ which is isomorphic to the Lie algebra $\mathfrak{sl}(2,\mathbb{R})$. The ...
2
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0answers
79 views

Stack presentations and massive non-conformal theories

In the paper, Cluster Decomposition, T-duality, and Gerby CFT’s , by Hellerman, Henriques, Pantev and Sharpe, in the introduction it says: "Briefly, the idea is that nearly every stack has a ...
4
votes
1answer
114 views

String Theory: Why should(n't) the string snap?

My question is related to a comment in the margin of the popularising site The Official String Theory Web Site. There are two basic types of string theories: those with closed string loops that ...
4
votes
1answer
92 views

Fifth force in string theory [closed]

I can't seem to get a clear description of what the "fifth force" in string theory is. What is the fifth force in string theory? What does it do? What mediates it?
2
votes
1answer
109 views

Can a fuzzball collapse into a singularity?

I've been reading Kip Thorne's Black Holes and Time Warps and got curious about extreme states of degenerate matter; a little research reveals that since the book was written quark and preon ...
2
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0answers
75 views

Is time depending on the observer in string theory?

I heard that in the theory of relativity the time of an action is depending on the observer. But in string theory, is the time also depending on the observer? Are strings acting according to the ...
1
vote
0answers
30 views

String Theory Landscape [duplicate]

I have seen multiple times that physicists used a formula to find the number of vacua in string theory, What formula was used to calculate the number of vacua in string theory? How did they arrive at ...
2
votes
2answers
104 views

Can string theory get rid of randomness in quantum processes?

I am not a physicist, but I am very much into popular science, especially string theory. I would like to know if it is conceivable that string theory might be able to get rid of the randomness ...
3
votes
0answers
143 views

Euler-Lagrange equation (equation of motion) solution with hairy Lagrangian [closed]

I'm going through Zwiebach Chapter 6 on relativistic strings to try to solve a similar problem. I got all the way to my equation of motion \begin{eqnarray*} \delta S & = & [ p' \delta ...
-3
votes
2answers
656 views

Since when were Loop Quantum Gravity (LQG) and Einstein-Cartan (EC) theories experimentally proven?

Can this template at Wikipedia be true? It seems to suggest that Einstein-Cartan theory, Gauge theory gravity, Teleparalleism and Euclidean Quantum Gravity are fully compatible with observation! It ...
5
votes
2answers
245 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?
1
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0answers
61 views

Why does String Theory seem to have a split following? [closed]

I'm an undergrad, and haven't moved very far into my courses in Physics. As I look around the internet and books to gain information about string theory, it seems to me there is a much more heated ...
0
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0answers
24 views

String theory online resources [duplicate]

I am a calculus 3 student (just starting multivariable calculus) and going to start out with linear algebra. I also am pretty knowledgable on classical mechanics (such as the Lagrangian, Hamiltonian ...
2
votes
2answers
75 views

Holographic principle and string theory are related in some way or completely independent?

Are the Holographic principle and string theory related in some way or are completely independent? Everything is happening in a surface and our three-dimensionality is an illusion of our ...
0
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0answers
49 views

SUSY condition on string theory

In each string theory, there is some condition so called SUSY condition. I want to know susy condition for Type I, Type II, and Heterotic string. Can anyone give some brief explanation about ...
3
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0answers
51 views

Spin of an operator in supersymmetric theories

How exactly is the spin of an operator in the context of a supersymmetric theory defined? For example, in page 25 of [1], $\mathcal{N} = 2$ supersymmetry is defined to have operators $J, G^{+}, G^{-}, ...
1
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3answers
124 views

How do you define a “universe” (in the context of multiverse)?

How do you define a universe (in the context of multiverse)? The traditional definition of universe is something like "The Universe is all of spacetime and everything that exists therein". But in ...
0
votes
0answers
34 views

Can String Theory ever be proven? [duplicate]

While learning more about String Theory, I learned that its opponents in the scientific world oppose the theory because it cannot be proven by experiment. I'm not sure if this is true, but that's why ...
2
votes
2answers
41 views

String Excited States / Spectrum

I am working through David Tong's lecture notes on string theory. The bit I am stuck on is page 41/42 in Chapter 2. The PDF file is here. In 2.3.2 "The First Excited States" on page 41/42, he says: ...
2
votes
1answer
74 views

The spin and weight of a primary field in CFT

A primary field in Conformal Field Theory transforms as $$\phi (z,\bar{z}) =\left(\frac{dz}{dz'} \right)^h \left(\frac{d\bar{z}}{d\bar{z}'} \right)^\bar{h}\phi (z',\bar{z}') $$ under a conformal ...
3
votes
1answer
69 views

The contribution to the one loop beta function for the WZW model

When the Wess-Zumino-Witten model $$S_{WZW}=\frac{k}{4\pi}\int d^2 z \, \, \mathrm{Tr}[\partial u \bar{\partial}u^{-1} ]+ \frac{k}{12\pi}\int d^3 \sigma \epsilon^{ijk}\, ...
2
votes
0answers
97 views

BRST quantization of point particle

Suppose we have Lie algebra $\mathfrak{g}$ with basis $t_a$ with a representation $$ t_a \mapsto K_a: V \to V. $$ Denote by $c^a$ the dual basis. Chevalley differential is defined as $$ Q = c^i K_i - ...
2
votes
0answers
74 views

Expectation of 2-form field $B_{MN}$ in string theory

In the context of string theory, in particular when we are dealing with a low energy effective action, if we have an effective action of the form, $$S_{\mathrm{eff}} \sim S^{(0)} + \alpha S^{(1)} + ...
2
votes
1answer
84 views

Why do derivatives act on vector fields on a worldsheet?

The covariant derivative of a vector $A^{\mu}$ at a point $x$ is defined as $$D_z A^{\mu}=\partial_zA^{\mu}+\Gamma^{\mu}_{\rho\sigma}(x)\partial_{z}x^{\rho}A^{\sigma}$$ where Greek symbols are ...
-1
votes
1answer
173 views

Explanation for the minus sign in $\Omega_3$ in the Kappa symmetry of the Green - Schwarz formalism for F1 strings

Just so that there can be more higher - level physics questions here, let me post this question + answer. Also because I'm a bit sad that there are almost no questions on the Green-Schwarz ...
5
votes
1answer
1k views

Some questions on Conformal Field Theory, Current algebras and the Sugawara construction

Since I don't know how to add another question to an already existing topic, I'm opening a new thread. However I'm referring to: Beginners questions concerning Conformal Field Theory As noted, a ...
0
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0answers
52 views

Background field expansion in normal coordinates

Background field expansion following form $Y= X+\pi$ where $X$ is my background field and $\pi$ is the fluctuation. From the Normal coordinates we have the expansion of $\pi^{\mu} = ...
0
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1answer
271 views

Do we exist in multiple dimensions?

I have heard that there are 12 spatial dimensions. Does this mean that this many are possible, or that 12 dimensions actually exist? If the latter, then do the same things that exist in 3 dimensions ...
1
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1answer
69 views

What are the two dimensions of relativity that are added to string theory?

Based on the Ramanujam's modular functions, somehow these magic numbers 10 and 26 spacetime dimensions appear in string theory. The dimensions can be viewed as 8 + 2 and 24 + 2. The number 2 is added ...