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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17 views

String theory uncertainty limit? [duplicate]

Is there an uncertainty limit, constant (if there is a practically viable numerical constant) or not, to string theory? If so, could you explain what it means, the assumptions it has to hold to be ...
2
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2answers
59 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 ...
2
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0answers
43 views

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

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 ...
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0answers
17 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 ...
1
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0answers
46 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 ...
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0answers
22 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 ...
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0answers
37 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 ...
2
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0answers
37 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^{-}, ...
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2answers
74 views

Does String Theory Predict more than Four Forces?

String theory literature tells us that ST predicts the four forces: weak, strong, EM, and gravity. What it fails to tell us is if that's all the forces it predicts. Might there be a fifth force that ...
2
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2answers
45 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 ...
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3answers
56 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 ...
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0answers
31 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 ...
1
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1answer
48 views

Closed strings = open ones attached to a D0-brane?

I decided recently (to try) to learn String Theory, however from the beginning some newbie questions came up, which haven't given me a break. For this reason, I decided to ask some of them. I'd prefer ...
2
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2answers
34 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: ...
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1answer
31 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
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1answer
44 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}\, ...
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0answers
64 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
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1answer
70 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 ...
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0answers
43 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} = ...
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1answer
62 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 ...
3
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1answer
42 views

Dirac operator partial integration

When you have an action with bosonic $X$ and fermionic $\psi$ (Majorana) fields and perform a SUSY transformation $\epsilon$ (the constant, infinitesimal parameter of transformation, a real, ...
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0answers
44 views

Regarding Randall Sundrum model

In Randall Sundrum model 2, that is the one with non compact fifth dimension, there is only one brane, which is the Planck brane. The TeV brane is removed by taking the radius of the fifth dimension ...
3
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0answers
64 views

Non-abelian bosonization

Reading this review about non-abelian bosonization, Non-abelian bosonization by I.Karmazin, I stumbled about two questions Below equation 6, I don't get the final point in the statement about the ...
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1answer
49 views

Simple question [closed]

How much of this can you understand and which videos or simplified ways would you suggest for me to understand more? http://www.youtube.com/watch?v=2rjbtsX7twc I understood about... 3%... I ...
5
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1answer
56 views

Questions on D branes and their role in the AdS/CFT correspondence

I'm a beginner in learning the AdS/CFT correspondence, and I come across two problems that I hope an answer will be given here. D branes in string theory are usually introduced through the T-duality ...
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0answers
53 views

Is Functional Analysis used at all in String Theory? [closed]

Is functional analysis used at all in string theory? (and if so, how?)
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1answer
71 views

Can the strings in string theory be thought of as troughs in a field?

I figure that string theory is a new breed of QFT which looks at fields in terms of a network of strings and also incorporates gravity into its module, however my question is that since elementary ...
0
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1answer
55 views

breitenlohner freedman stability condition

I am looking for a simple way to derive the breitenlohner-freedman bound. Actually I can't understand why we have stability above the BF bound and instability below the BF bound,while both have ...
0
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1answer
120 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 ...
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0answers
28 views

How does lattice field theory relate to string theory?

The former is sort of a "mapping" technique with the goal of making quantum fields computable, while the latter wants to act as an underlying system of it. (as far as I know) What is their relation to ...
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1answer
103 views

Why do we believe in a “force” driven universe? [closed]

Why do we not believe in the potential for a "unified force field" universe, to the exclusion of the belief in the potential for a mechanical, gear driven universe, if the correct shape for the gear ...
2
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1answer
34 views

A paradoxical equation in RNS string fermionic part

It is well known for RNS string, $i.e.$, worldsheet supersymmetry formalism, the open string NS sector has worldsheet fermion expansion: \begin{equation} \psi^{\mu}_{\pm} = \frac{1}{\sqrt 2} \sum_{r ...
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0answers
20 views

how to specify eigenfunctions(eigentensors) of Lichnerowicz operator?

Lichnerowicz operator is an operator which acts on transverse trace-free symmetric tensors. If this statement is correct, my question is that any transverse trace-free symmetric tensor is an ...
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0answers
38 views

Massive gauge string sigma model action

I want to know how to insert massive gauges in string sigma model action. For massless fields it is possible by integrating the U(1) field over the string worldsheet, but in the case of massive gauge ...
1
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1answer
70 views

OPE of fermionic field bosonization in string theory, in Polchinski 10.3.12

In Polchinski's String Theory Vol. 2, equations 10.3.12 are $$e^{iH(z)}e^{-iH(-z)}~=~\frac{1}{2z}+i\partial H(0)+2zT_B^H(0)+O(z^2)\tag{10.3.12a}$$ ...
1
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1answer
76 views

Is it possible to make superpartner of Standard Model live in Mirror World?

In the ordinary Supersymmetry (SUSY), the superpartner of SM live in SM world (matter world). Then we introduce mirror world with mirror particle live there. I would like to make a new concept that ...
10
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2answers
128 views

Why do fermions come in generations, but not bosons?

Why does the $1/2$ spin of fundamental fermions (electrons, quarks, and neutrinos) split them into three variants that differ only in mass, while the integer spins of massless fundamental bosons (e.g. ...
2
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1answer
128 views

Physics in torus, cylinder, Klein bottle and mobius strip

In string theory, or supersymmetric gauge theory, they often calculate the partition function on specific Riemann surfaces, such as torus, cylinder, Klein bottle, Mobius strip. Refer to the ...
2
votes
1answer
54 views

D-brane book-keeping and non-abelianity

In Becker's book String Theory and M-Theory in the chapter about T-duality and D-brane (Chapter 6) the following comment is made The Chan–Paton factors associate $N$ degrees of freedom with each ...
9
votes
1answer
106 views

Confusion about two definitions of anomalies

As I am currently studying for an exam about quantum field theory and string theory, I got confused about the notion of "anomalies" and how they are actually defined. Similar questions have already ...
5
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1answer
116 views

What produces String tension in Strings theory?

In (classical) physics, tension describes the pulling force exerted by each end of a string, which is a one-dimensional continuous object, At the atomic level, tension is produced when atoms or ...
2
votes
0answers
51 views

Open string 4-tachyon amplitude for cylinder/annulus topology in bosonic string theory

One knows the formula for the open string $4$-tachyon amplitude for the disk topology in the bosonic string theory : it is proportional to the $s \leftrightarrow t \leftrightarrow u$ symmetrisation ...
0
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0answers
80 views

Gauge invariance in arXiv:1406.1804

I am reading the paper arXiv:1406.1804. I don't show that the invariance of the connection under the gauge transformation (2.48), I have written an email to the authors about this question. However, ...
2
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0answers
84 views

What is the future of complexity theory in black-hole physics and string theory? [closed]

I found the recent work by Hayden and Harlow and Susskind very fascinating. I have also heard talks by Scott Aaronson about this emerging connection. In particular this idea of understanding ...
-1
votes
1answer
91 views

Why & What extra dimensions in M-theory?

I am not into String or M theory. Recently I am again reminded that M-theory "requires extra dimensions" beyond the usual string theories, beyond the usual space-time dimensions. To me, dimensions ...
3
votes
1answer
58 views

What is the difference between D branes, M branes, and NS branes?

I know that D$p$ branes are branes with $p$ spatial dimension with satisfying Dirichlet boundary condition. I want to confirm the following things. First, I heard the D-branes are massive, and these ...
2
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1answer
140 views

Higgs branch and Coulomb branch

I heard that the distinguish between Higgs branch and Coulomb branch is the limit of some parameters. (If i remember correctly, something like FI parameters. ) Here i want to know what is FI ...
1
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0answers
69 views

Beta function of the non-linear sigma model

In chapter 7.1.1. inTong's notes about String Theory could someone sketch how can I show the statements that he nmakes around eq. 7.5 That the addition of the counterterm can be absorbed by ...
4
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0answers
62 views

Relation of Betti numbers to Veneziano's scattering amplitude?

I came across Veneziano's famous formula for the scattering amplitude for four tachyons written as $$A(s,t)= \sum_{n \geq0} \frac{(-1)^n}{n-1 + ...
1
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1answer
80 views

What is the general theory that describes the interactions between strings?

What is the general theory that describes the interactions between strings? I mean the basic object in the theory is (closed) string and they have interactions among them. The string theory, as I ...