A class of theories that attempt to explain all existing particles (including force carriers) as vibrational modes of one-dimensional objects.
9
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0answers
212 views
Derivation of KLT relations
The KLT relations (Kawai, Lewellen, Tye) relate a closed string amplitude to a product of open ones. While I get the physics behind this I don't really understand the derivation in the original paper ...
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3answers
626 views
Giant string in space
I saw an interview with Ed Witten, where he said one way to confirm string-theory is to observe a giant string floating in space, left over from the Big-Bang.
How does one observe such a string, does ...
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8answers
2k views
What are cosmological “firewalls”?
Reading the funny title of this talk, Black Holes and Firewalls, just made me LOL because I have no idea what it is about but a lively imagination :-P (Sorry Raphael Bousso but the title is just too ...
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3answers
48 views
Does the complex 3-sphere have a complex structure modulus?
This question has a flavor which is more mathematical than physical, however it is about a mathematical physics article and I suspect my misunderstanding occurs because the precise mathematical ...
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2answers
2k views
Higgs boson and string theory
Assuming Higgs is found at 125 GeV.Is there any direct or indirect consequence on string theory ? Will it be a blow to string theory or models employing string theory ?
...
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1answer
494 views
Is String Theory formulated in flat or curved spacetime?
String Theory is formulated in 10 or 11 (or 26?) dimensions where it is assumed that all of the space dimensions except for 3 (large) space dimensions and 1 time dimension are a compact manifold with ...
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2answers
395 views
What is the physical interpretation of the S-matrix in QFT?
A few closely related questions regarding the physical interpretation of the S-matrix in QFT: I am interested in both heuristic and mathematically precise answers.
Given a quantum field theory when ...
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1answer
294 views
What are some significant contributions of string theory to other fields of physics?
What are some contributions that string theory has made to other branches of physics/science (other than research in string theory)?
I'm looking for specifics, for example mentioning what string ...
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3answers
290 views
Question about associative 3-cycles on G2 manifolds
Let $X$ be a manifold with $G_2$ holonomy and $\Phi$ be the fundamental associative 3-form on $X$. Let $*\Phi$ be the dual co-associative 4-form on $X$. Now consider a particular associative 3-cycle ...
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1answer
262 views
Quivers in String Theory
Why do a physicist, particularly a string theorist care about Quivers ?
Essentially what I'm interested to know is the origin of quivers in string theory and why studying quivers is a natural thing ...
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1answer
93 views
AdS/CFT at D = 3
AdS/CFT at D = 3 (on the AdS side) seems to have some special issues which I bundled into a single question
The CFT is 2D hence it has an infinite-dimensional group of symmetries (locally). The ...
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5answers
573 views
How does the string worldsheet affect the space-time in which they live?
I don't understand much about string theory and never really got much further past the Nambu-Goto action and very basic supersymmetry (SUSY) lectures in my undergraduate courses, but the only thing ...
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2answers
319 views
Heterotic string as worldvolume theory of two coincident 9-branes in 27 dimensions?
The heterotic string is a combination of right-moving excitations from a D=10 superstring and left-moving excitations from a D=26 bosonic string, with the left-movers behaving as if the extra 16 ...
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1answer
377 views
Does the renormalization group apply to string theory?
Can we implement a scale dependent cutoff Λ to string theory? Can we perform a renormalization group analysis of string theory consistently?
8
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1answer
173 views
Derivation of the basic equation for Witten diagrams
I could understand the derivation of the "bulk-to-boundary" propagators ($K$) for scalar fields in $AdS$ but the iterative definition of the "bulk-to-bulk" propagators is not clear to me.
On is ...
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votes
1answer
642 views
Dual conformal symmetry and spin networks in ABJM
In this question, I would love to hear some independent opinions on an issue I asked Juan Maldacena, Nathan Berkovits, Dan Jafferis, and others, but all the physicists may be missing something. The ...
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1answer
841 views
What is a D-brane?
I know that in string theory, D-branes are objects on which open strings are attached with Dirichlet boundary conditions. But what exactly is a brane? Are they equally fundamental objects like string? ...
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votes
1answer
85 views
“finite” QFTs and short-distance singularities and vanishing beta functions
I am not sure that I can frame this question coherently enough - it springs from various things in QFT that I have recently been thinking and reading about. May be these thoughts are mis-directed but ...
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1answer
442 views
The measure problem in the anthropic principle
The anthropic principle is based upon Bayesian reasoning applied to the ensemble of universes, or parts thereof, conditioned upon the existence of conscious observers. That still leaves us with the ...
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2answers
357 views
Is eternal inflation and the multiverse compatible with causal patch complementarity?
The argument for eternal inflation is we have some patch of metastable vacuum with positive cosmological constant, and so it expands exponentially a la de Sitter. Most of the patch decays to something ...
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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 ...
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0answers
48 views
Super Lie-infinity algebra of closed superstring field theory?
Bosonic closed string field theory is famously governed by a Lie n-algebra for $n = \infty$ whose $k$-ary bracket is given by the genus-0 (k+1)-point function in the BRST complex of the string.
One ...
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0answers
120 views
Intuitive sketch of the correspondence of a string theory to its limiting quantum field theory
I'm looking for an intuitive sketch of how one shows the correspondence of string theory to a certain QFT. My best guess is that one calculates the scattering amplitudes in the string theory as a ...
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0answers
36 views
Minimal strings and topological strings
In http://arxiv.org/abs/hep-th/0206255 Dijkgraaf and Vafa showed that the closed string partition function of the topological B-model on a Calabi-Yau of the form $uv-H(x,y)=0$ coincides with the free ...
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8answers
1k views
What future technologies does particle physics and string theory promise? [closed]
What practical application can we expect from particle physics a century or two from now? What use can we make of quark-gluon plasmas or strange quarks? How can we harness W- and Z-bosons or the Higgs ...
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2answers
200 views
Advice on doing physics under the umbrella of mathematics and the converse
In the current scenario of research in QFT and string theory (and related mathematical topics), which of the following would an undergraduate student, like me, be advised to do and why if s/he is ...
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4answers
1k views
Can Loop Quantum Gravity connect in any way with string theory?
The one difficulty I see with LQG is that it requires an enormous number of degrees of freedom, e.g. these spin variables in the net. This is in contrast to stringy holographic theory where the ...
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votes
7answers
1k views
Why are extra dimensions necessary?
Some theories have more than 4 dimensions of spacetime. But we only observe 4 spacetime dimensions in the real world, cf. e.g. this Phys.SE post.
Why are the theories (e.g. string theory) that ...
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votes
3answers
892 views
PhD Research Areas in String Theory
I'm thinking of applying to do a PhD in String Theory, starting in September 2013. I'm gradually learning more about the subject through external reading, but still most papers are impenetrable! Could ...
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3answers
211 views
Is the “Great Attractor” an indicator of the “Multiverse”?
I have heard a bit about the Great Attractor (the gravitational anomaly that seems to be "sweeping" our universe in one direction). Someone (and forgive me, I do not recall the specifics) has ...
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votes
2answers
179 views
Particles mass determined by SO(D-2) vs SO(D-1)
I've recently come across this statement that massless particles arise from $SO(D-2)$ symetry and massive particles from $SO(D-1)$.
I would have guessed that it would be the exact opposite way, but ...
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votes
1answer
49 views
Why isn't there heterotic holographic QCD?
I think the question speaks for itself... Top-down holographic QCD, like Sakai-Sugimoto, always involves the Type II string. There are one or two papers on hQCD using the Type 0 string. But I can't ...
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votes
2answers
264 views
Interesting topics to research in mathematical physics for undergraduates
I'm planning on getting into research in mathematical physics and was wondering about interesting topics I can get into and possibly make some progress on.
I'm particularity fond of abstract algebra ...
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3answers
98 views
String-theoretic significance of extended CFT
Extended TQFT and CFT have been puzzling me for while. While I understand the mathematical motivation behind them, I don't quite understand the physical meaning. In particular, it's not clear to me to ...
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votes
2answers
555 views
What does second quantization mean in the context of string theory?
String field theory (in which string theory undergoes "second quantization") seems to reside in the backwaters of discussions of string theory. What does second quantization mean in the context of a ...
7
votes
1answer
292 views
D-brane Lagrangian?
As I understand it from the threads I read, D-branes are viewed as somewhat secondary to strings: If I know what all the open strings do, then I know what the D-branes do as well. But if the D-brane ...
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votes
1answer
837 views
Electric charge in string theory
The mass of an elementary particle in string theory is related with the way the string vibrates. The more frantically a string vibrates the more energy it posses and hence the more massive it is. My ...
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votes
4answers
1k views
Number of dimensions in string theory and possible link with number theory
This question has led me to ask somewhat a more specific question. I have read somewhere about a coincidence. Numbers of the form $8k + 2$ appears to be relevant for string theory. For k = 0 one gets ...
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votes
1answer
132 views
String theory - OPE and primary operators
First, a disclaimer: I am new to Physics SE, and I am primarily a mathematician, not a physicist. I apologise in advance for the possibly poor quality of the question, any and thank you for your ...
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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 ...
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votes
2answers
141 views
Embedding of $F(4)$ in $OSp(8|4)$?
Is the superconformal algebra in five dimensions, $F(4)$, a subalgebra of the (maximal) six-dimensional superconformal algebra $OSp(8|4)$?
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votes
1answer
44 views
Matrix geometry for F-strings
A stack of N D-branes has the strange property that the traverse D-brane coordinates are matrix-valued. When the matrices commute, they can be interpreted as ordinary coordinates for N ...
7
votes
1answer
264 views
How do ideas of leading singularities and Grassmanian help in curing infrared divergences when calculating N=4 scattering amplitudes?
Broadly speaking how do ideas of leading singularities and Grassmanian help in curing infrared divergences when calculating N=4 scattering amplitudes? My understanding is that one gets infra red ...
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votes
2answers
628 views
Do traversable wormholes exist as solutions to string theory?
There has been some heated debate as to whether the laws of physics allow for traversable wormholes. Some physicists claim we require exotic matter to construct wormholes, but then others counter the ...
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votes
1answer
110 views
Is the LEP B meson asymmetry evidence for higher dimensions and/or string theory?
According to this blog, new standard model calculations have changed the 3 sigma B meson forward and backward production asymmetry observed at LEP into two anomolies:
A 2.5 sigma B meson production ...
7
votes
1answer
25 views
Low-energy gluodynamics as a string
Does anyone know of a (most likely heuristic) derivation of the use of the string sigma model action to model the soft gluonic interactions between color charges? I'm familiar with the classic ...
7
votes
1answer
176 views
Statistics and macrolocality in string theory
Take two identical closed strings, both tracing out exactly the same path in space. These two strings are coincident everywhere. Call this state I.
Take a single closed string following exactly the ...
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votes
1answer
194 views
Clarification on “central charge equals number of degrees of freedom”
It's often stated that the central charge c of a CFT counts the degrees of freedom: it adds up when stacking different fields, decreases as you integrate out UV dof from one fixed point to another, ...
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votes
1answer
154 views
does AdS/CFT implies that there is an CFT in physical horizons?
so my rough understanding is that the AdS/CFT duality is some sort of isomorphism between an N dimensional gravitational theory and a N-1 dimensional conformal field theory on the boundary.
The ...
7
votes
1answer
178 views
What happens when two D-branes annihilate?
What happens when two D-branes annihilate? Do we get a radiation of strings?
Thanks in advance
