A class of theories that attempt to explain all existing particles (including force carriers) as vibrational modes of one-dimensional objects.
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1answer
144 views
Are string theories gauge theories?
The wikipedia page for String Theory lists SO(32) and E8×E8 as group symmetries of some of the string theory types, and the page on E8 says:
E8×E8 is the gauge group of one of the two types of ...
5
votes
1answer
120 views
Correlators in String Theory (Green Schwarz Witten)
I'm reading about correlators in string theory for amplitude computations. More specifically formulae 7.1.53 and 7.1.54 in Green Schwarz Witten. I don't see how they can be derived.
E.g. 7.1.53 is
...
1
vote
0answers
73 views
Explicit evaluation of a radially ordered product
I am trying to understand the application of the operator product expansion to calculate the radially ordered product in the complex plain of $T_{zz}(z)\partial_w X^{\rho}(w)$ which should result in
...
1
vote
1answer
108 views
About higher spin gauge theory
I'm going to listen to a talk about Vasiliev's higher spin gauge theory. Before that I want to know more about the background.This is an introduction. Could anybody give a more detailed introduction ...
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0answers
53 views
It's time, but not as we know it [closed]
What time is it?
My watch has stopped...
I am inside a photon bubble and watches do not work here.
What does this mean? This post does not meet our quality standards.
What is a quality standard?
What ...
2
votes
1answer
158 views
From Freshman Mechanics to String Theory: A Comprehensive Textbook Sequence in Physics [duplicate]
If a student with no background in physics and an understanding of only single variable calculus wanted to learn string theory, what sequence of textbooks would most succinctly, clearly, and ...
8
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0answers
121 views
Compactifying on a circle and the exchange of R and NS sectors
I've noticed a general phenomenon in compactifying on a circle where if you start with, say, an NS field, then the KK fields with an index along the circle will be in the R sector, and those without ...
4
votes
2answers
194 views
The string Poisson bracket
Where does the factor $\frac{1}{T}$ ($T$ is the string tension) in this Poisson bracket come from?
$$ \{X^{\mu}(\tau,\sigma),\dot{X}^{\nu}(\tau,\sigma')\} ~=~ ...
7
votes
1answer
153 views
topological twisting by introducing bosonized operator
In this paper http://arxiv.org/abs/hep-th/9309140 on page 125, the authors claim that one can twist the $N=2$ theory by introducing a term in the action
$\frac{1}{2}\int R \phi$,
where $\phi$ is the ...
4
votes
1answer
155 views
Trick for deriving the stress tensor in any theory
In D. Tong's notes on string theory (http://www.damtp.cam.ac.uk/user/tong/string/four.pdf) section 4.1.1 he explains a trick for deriving the stress-energy tensor which arises from translations in the ...
2
votes
0answers
83 views
Our Universe in collision with another one
This question is related to the possibility that there are many other universes in the UNIVERSE,the multiverse, that were created during collisions between membranes, according to string theories. The ...
3
votes
2answers
168 views
Can string theory be used to solve basic quantum problems?
When I studied physics I was shown that special relativity would become Newton's laws at low speeds. Similarly, quantum mechanics could also be shown to be Newtonian at large quantum numbers.
My ...
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0answers
79 views
What are the implications if Supersting theory is discredited? [duplicate]
Please forgive my ignorance, I am not a student of physics in any capacity, therefor my understanding of string theory is extremely limited to say the least. Based on the recent lack of evidence in ...
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votes
2answers
160 views
Imaginary time and string theory
Is imaginary time an extra dimension?
In other words, are time and imaginary time considered two separate dimensions?
If so, does imaginary time appear (as a separate dimension) in string theory (thus ...
2
votes
1answer
174 views
Polyakov action: difference induced metric and dynamical metric
The Polyakov action is given by:
$$
S_p ~=~ -\frac{T}{2}\int d^2\sigma \sqrt{-g}g^{\alpha\beta}\partial_{\alpha}X^{\mu}\partial_{\beta}X^{\nu}\eta_{\mu\nu} ~=~ -\frac{T}{2}\int d^2\sigma ...
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0answers
101 views
Has hep-th/0312070 forgotten to fix $s_{0} = 1/2$ for the fermionic states in the second table on page 52?
Link to the original paper: The Gauge/String Correspondence Towards Realistic Gauge Theories (arXiv paper)
On page 52 we see that, for a theory of Dp-branes placed at an orbifold (orbifold = ...
2
votes
3answers
272 views
Could all strings be one single string which weaves the fabric of the universe?
This question popped out of another discussion, about if the photon needs a receiver to exist. Can a photon get emitted without a receiver? A universe containing only one electron was hypothetically ...
2
votes
1answer
111 views
Number of strings in elementary particles
I've seen many articles about the string theory and have a very simple question : I'd like to know how many Strings are in a quark or an electron?
10
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1answer
387 views
Why one-dimensional strings, but not higher-dimensional shells/membranes?
One way that I've seen to sort-of motivate string theory is to 'generalize' the relativistic point particle action, resulting in the Nambu-Goto action. However, once you see how to make this ...
5
votes
2answers
120 views
Quantization of strings on a curved backgrond
usually when people want to quantize the string on flat background, they will try to find the the OPE of embeddings (by solving a green function in a 2D space) and use them to find the energy-momentum ...
3
votes
1answer
220 views
Deriving the reduced Green's functions in Polchinski's volume 1
In equation 6.2.7, Polchinski defines his reduced Green's functions $G'$ on the 2-manifold to satisfy the equation,
$$ \frac{-1}{2\pi \alpha '}\nabla ^2 G'(\sigma_1, \sigma_2) = ...
3
votes
0answers
206 views
Mathematics and Physics prerequisites for mirror symmetry [closed]
I am a physics undergrad interested in Mathematical Physics. I am more interested in the mathematical side of things, and interested to solve problems in mathematics using Physics. My current ...
2
votes
1answer
91 views
Strings on a curved spacetime
Suppose we are interested in in string on a specific metric G, is it necessary to include a Dilaton field on back ground in order to preserve the Weyl invariance? suppose the spacetime is not empty, ...
6
votes
2answers
1k views
What is the current status of string theory (2013)?
I've seen a bunch of articles talking about how new findings from the LHC seem to disprove (super)string theory and/or supersymmetry, or at least force physicists to reformulate them and change ...
2
votes
1answer
205 views
What happens to string theory if spacetime is doomed?
What is expected to happen with string theory, if physics is reformulated according the lines hinted at by the twistor-uprising business discussed in this question and its answers for example and ...
1
vote
0answers
144 views
Starting string theory studies in grad school
How is it possible for a grad student to do research in any modern area of string theory like AdS/CFT or ABJM if they need to start grad school by having to learn QFT from scratch?
Is there a ...
1
vote
1answer
89 views
Learning more about String theory [duplicate]
I know the concept behind String Theory. But I was wondering if anyone knows of a good place to start learning more about the theoretical physics behind it? Maybe a book someone can recommend to me! I ...
5
votes
1answer
254 views
In what limit does string theory reproduce general relativity?
In quantum mechanical systems which have classical counterparts, we can typically recover classical mechanics by letting $\hbar \rightarrow 0$. Is recovering Einstein's field equations (conceptually) ...
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votes
0answers
38 views
How does quantum jitter “fix” the masses of strings?
So the masses of strings should be huge because of the high energy levels. Which means, in other words, the strings are vibrating with enough energy to have large masses as point particles. But ...
3
votes
1answer
173 views
The theory of strings stretching between intersecting D-branes
I am trying to understand various aspects of intersecting D-branes in terms of the gauge theories on the worldvolume of the D-branes. One thing I'd like to understand is the worldvolume action for ...
4
votes
0answers
58 views
Dimensional transmutation in Gross-Neveu vs others
Firstly I don't know how generic is dimensional transmutation and if it has any general model independent definition.
Is dimensional transmutation in Gross-Neveau somehow fundamentally different ...
1
vote
1answer
106 views
Topology for physicists [duplicate]
Which are the best introductory books for topology, algebraic geometry, manifolds etc, needed for string theory?
1
vote
0answers
59 views
What's the significance between a closed and open string? And how do strings interact with one another?
I'm somewhat familiar with standard model physics but completely clueless about string theory.
If a string is a vibrating strand of energy, then what is the significance of a closed loop of string? ...
4
votes
1answer
158 views
Defining a CFT using beta-functions
Won't it be correct to define a CFT as a QFT such that the beta-function of all the couplings vanish?
But couldn't it be possible that the beta-function of a dimensionful coupling vanishes but it ...
4
votes
0answers
45 views
Animating the Bosonic String
I am interested in studying the classical solutions to the Bosonic string in flat 3+1 dim. spacetime by having them rendered a moving picture on a computer. This is partly for fun, and partly to ...
2
votes
1answer
905 views
Unified field theory in layman's terms
I watched some videos on the unified field theory, specifically interviews with Michio Kaku and John Hagelin, and want to learn a bit more about it. I looked up the theory of everything, string theory ...
6
votes
1answer
179 views
Gravity duals to Navier Stokes and interpretation of non linear contributions
I have been reading the paper The Incompressible Non-Relativistic Navier-Stokes Equation from Gravity. In it they state,
"An instability, if it occurs, must necessarily break a symmetry ...
...
7
votes
0answers
351 views
About defining “baryons” and “mesons”
I want to understand the proof of the claims (of the construction as well as of its uniqueness) of gauge singlet states given around equation 2.13 (page 10) of this paper.
Also does the listing of ...
2
votes
1answer
70 views
Who first provided a string realization of dual resonance models?
After the $N$-particle generalization of the Veneziano amplitude was written down and studied, who was the first (or who were among the first) to realize that the amplitudes could be understood in ...
5
votes
0answers
113 views
Are QFT solitons expected to represent standard model particles? Or strings?
Is work on solitons in QFT's focused on finding solutions that could represent the fundamental particles of the Standard Model, or is the work focused on finding particles Beyond The Standard Model? ...
12
votes
0answers
202 views
Anomalous target space diffeomorphisms for one-loop world-line integrals
The Schwinger effect can be calculated in the world-line formalism by coupling the particle to the target space potential $A$.
My question relates to how this calculation might extend to computing ...
3
votes
0answers
253 views
What are the mathematical prerequisites to understand this paper? [closed]
What are the mathematical prerequisites to understand this paper?
Blumenhagen et al. Four-dimensional String Compactifications with D-Branes, Orientifolds and Fluxes. Phys. Rept. 445 no. 1-6, pp. ...
3
votes
1answer
97 views
Why does unbroken supersymmetry imply the absence of tachyons?
Just a quick question, same as in the title. I'm trying to understand stable D-branes.
5
votes
0answers
92 views
Master Field Large N limit
I would like to ask a question about the so-called ''Master Field''. As far as I understand, this represents a classical configuration in the large n limit (saddle point solution) but there is no ...
3
votes
0answers
54 views
Expectation of 2-form field $B_{MN}$ in string theory
In the context of string theory, in particular when we're dealing with a low energy effective action, if we have an effective action of the form:
$$S_{eff} \sim S^{(0)} + \alpha S^{(1)} + (\alpha)^2 ...
3
votes
0answers
109 views
Course advice for someone interested in strings and mathematical physics [closed]
I'll be doing Introductory General Relativity and Graduate Quantum Mechanics II next semester. I still need to choose 2 (or maybe 3, but I don't want to overload too much) from the following:
...
4
votes
1answer
88 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 ...
3
votes
0answers
124 views
Inclusion of information about external particles to calculate scattering amplitudes
In this (schematic) equation to calculate the scattering amplitude A by integrating over all possible world sheets and lifetimes of the bound states
$$ A = \int\limits_{\rm{life time}} d\tau ...
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votes
0answers
106 views
P-adic Numbers and Eternal Inflation
In October(??) 2011, Leonard Susskind gave a talk and with few other people wrote papers about p-adic numbers and measure problems in cosmology, see e.g. arXiv:1110.0496. Has there been any recent ...
1
vote
2answers
186 views
How exactly do superstrings reduce the number of dimensions in bosonic string theory from 26 to 10 and remove the tachyons?
In bosonic string theory, to obtain the photon as the first excited state, the ground state must have a negative mass (tachyon). By applying $1 + 2 + 3 + \cdots = -1/12$, it can be shown (in a ...
