A class of theories that attempt to explain all existing particles (including force carriers) as vibrational modes of one-dimensional objects.
7
votes
3answers
547 views
Covariant Quantisation and the Time Operator in String Theory
Covariant quantisation in string theory is accomplished by giving the commutator relations
$[X^\mu(\sigma,\tau),P^\nu(\sigma',\tau)] =
i \eta^{\mu\nu} \delta(\sigma - \sigma')$.
Although ...
7
votes
1answer
153 views
Starting examples of Maldacena duality
I would like to know of what are the simplest/starting/basic examples that a student can work through to learn (and to convince oneself!) that AdS/CFT really works? I would like to know of the basic ...
7
votes
0answers
352 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 ...
7
votes
0answers
86 views
gauss-bonnet gravity constraints from string theory
recently there has been advances in observational constraints of gravity theories that contains scalars coupled to the gauss-bonnet topological term:
http://arxiv.org/abs/0704.0175
...
7
votes
0answers
53 views
Quantum statistics of branes
Quantum statistics of particles (bosons, fermions, anyons) arises due to the possible topologies of curves in D-dimensional spacetime winding around each other
What happens if we replace particles by ...
7
votes
1answer
606 views
String theory and trace anomaly in semiclassical gravity?
what does string theory have to say about the trace anomaly in the expectation value of the stress energy tensor of massless quantum fields on a curved background and its interpretation as the ...
6
votes
3answers
257 views
References on the non-compositeness of the known elementary particles
What paper(s) or theory(s) describe or prove that the elementary particles that we have determined today cannot be made up of smaller more fundamental particles?
6
votes
2answers
274 views
How relevant is LHC to quantum gravity?
Premise: the LHC is obviously mapping unseen territory in high energies, and therefore it's always possible to imagine far out results.
Excluding completely unexpected outcomes - is the LHC ...
6
votes
1answer
188 views
Was the universe a black hole at the beginning?
Big bang cosmology, as far as I understand it, says that the universe was super hot and super dense and super small. It looks like that all the current matter, seen and unseen, were compressed to ...
6
votes
1answer
633 views
Where does the $10^{500}$ estimate for the number of stringy vacua come from?
This number is thrown around a lot so I'd like to understand its origin. I know that it counts compactifications of string theories on (not only) Calabi-Yau manifolds and probably also some other ...
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 ...
6
votes
2answers
261 views
Is there stringy Morse theory?
This question is pretty vague and open. I'm just curious if anyone has considered this.
Morse theory has a nice physical formulation: a Morse function can be thought of as a potential, so the ...
6
votes
2answers
177 views
Why is a stack of N D-branes equivalent to an extremal black brane?
A stack of N D-branes can have open strings ending on them. There is a U(N) brane gauge field, and r adjoint Higgs fields, with r equal to the number of transverse spatial dimensions. The eigenvalues ...
6
votes
2answers
390 views
Introduction to string theory
I am in the last year of MSc. and would like to read string theory. I have the Zwiebach Book, but along with it what other advanced book can be followed, which can be a complimentary to Zwiebach. I ...
6
votes
1answer
47 views
“gauge fixed world-sheet action”
My question is in reference to the action in equation 4.130 of Becker, Becker and Schwartz.
It reads as,
$S_{matter}= \frac{1}{2\pi}\int (2\partial X^\mu \bar{\partial}X_\mu + \frac{1}{2}\psi^\mu ...
6
votes
2answers
218 views
Does the lack of modular nuclearity in string theory mean anything?
Nuclearity is a postulate in algebraic quantum field theory (AQFT). Basically, it says thermal states at any temperature always have a thermodynamic limit with extensive quantities. This is violated ...
6
votes
1answer
282 views
Chern-Simons Theory in 3D
For the CS theory on a three manifold $M$ with a gauge group $G$, it is said that the gauge field $A$ is a connection on the trivial bundle over $M$. Why the bundle should be trivial? I know that ...
6
votes
1answer
200 views
Reference for the ${\cal N}=3$ Chern-Simons Lagrangian at general $N_c$, $N_f$
I was wondering if someone could give me a reference where someone has explicitly written the Lagrangian for ${\cal N}=3$ $SU(N_c)$ Chern-Simons theory coupled to $N_f$ fundamental hypermultiplets.
...
6
votes
1answer
74 views
Scherk-Schwarz and other compactifications?
I have been thinking about various types of compactifications and have been wondering if I have been understanding them, and how they all fit together, correctly.
From my understanding, if we want ...
6
votes
1answer
43 views
Why is there no double counting of $s$- and $t$-channels in string theory?
In string theory for the four particle tree diagram exchange, why is there some mysterious crossing duality between the $s$- and $t$- and $u$-channels? Why isn't there a double counting in the Feynman ...
6
votes
1answer
178 views
Can long strings always snap?
In quantum chromodynamics, long flux tubes will always snap because a quark-antiquark pair gets created from the vacuum, and hadronization results with a quark attached to each new end.
In string ...
6
votes
1answer
201 views
Does string theory provide a physical regulator for Standard Model divergencies?
In other question, Ron Maimon says that he thinks string theory is the physical regulator. I did not know that string theory regularize divergencies.
So, Q1: How does string theory regularize the ...
6
votes
1answer
140 views
Uniqueness of the 5 string theories
This question combines several sub-questions, the common theme being: why the known 5 string theories are unique?
Firstly, regarding heterotic theory. I understand the only allowed gauge groups are ...
6
votes
1answer
191 views
Why aren't D-branes and strings independent degrees of freedom?
A condensate of open strings with both ends attached to the same D-brane can be equivalent to a displacement of the D-brane with no open string condensate.
A solution to the D-brane Born-Infeld ...
6
votes
1answer
599 views
How does the holographic principle imply nonlocality?
For example in the discussions here and here there are comments by Ron Maimon:
Your complaint about locality would be more serious if holography
didn't show the way--- the CFT in AdS/CFT ...
6
votes
1answer
112 views
Who added $\frac{3}{2} \partial^2 c$ to the virasoro BRST current (and why)?
I've been looking at the literature on quantizing the bosonic string, and I noticed that there was a change made in the definition of the BRST current around 1992. However, I haven't found any ...
6
votes
1answer
49 views
References for phase-transitions in supersymmetric field theory
Apart from other reasons, recently my interest in this area got piqued when I heard an awesome lecture by Seiberg on the idea of meta-stable-supersymmetry-breaking.
I am looking for references on ...
6
votes
1answer
55 views
Poisson structure on moduli space of CFTs
The moduli space of CFTs with central charge 26 forms the classical phase space of bosonic string theory, in some sense. Similarily the moduli space of SCFTs with central charge 10 forms the classical ...
6
votes
1answer
275 views
Why does string theory (in case it is true ) have NO divergencies?
Why is string theory in 10 or 26 dimension not divergent? Due to the high number of spacetime dimension (10 or 26) it should have a lot of UV divergencies of the form $ \int k^{n}dk $ and gravity ...
6
votes
1answer
469 views
Geometric/Visual Interpretation of Virasoro Algebra
I've been trying to gain some intuition about Virasoro Algebras, but have failed so far.
The Mathematical Definition seems to be clear (as found in http://en.wikipedia.org/wiki/Virasoro_algebra). I ...
6
votes
3answers
501 views
Bosonic M-theory and moonshine gravity
Last month I asked about a 27-dimensional origin of the heterotic string. Now I'm looking at Witten's "Three-dimensional gravity revisited", where he proposes that pure gravity on AdS3 is dual to the ...
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 ...
...
6
votes
1answer
146 views
If a fundamental theory exibits e.g. a mirror symmetry, in what sense it the underlying geometry real?
Are the more recently discovered symmetries in string theory such that the theories based on mirroring geometries are absolutely the same from an observable point of view?
I have mirror symmetry ...
6
votes
1answer
408 views
What's with Mandelstam's argument that only linear regge trajectories are stable?
While thinking about how to answer a "describe string theory" question, I remembered an old argument of Stanley Mandelstam's that linear Regge trajectories implies stability. I never fully understood ...
6
votes
1answer
413 views
Do we need a quantum deformation of the diffeomorphism group in string theory?
Let me justify my question before I go on. In string theory, gravitons are strings extended over space. Longitudinal gravitons are pure gauge modes of the diffeomorphism group. However, in string ...
6
votes
1answer
249 views
Graviton Emission from D-Branes
I'm working through Polchinski's book on string theory, and I ran into something that I don't think I understand. I'm hoping that someone who knows this stuff can help me out.
Before calculating the ...
6
votes
1answer
80 views
Critical dimension in quantization of p-branes
So I have what might be a fairly basic question, but my understanding that in the quantization of the the string, or the 1-brane, there are conditions on the number of spacetime dimensions to ensure ...
6
votes
1answer
102 views
Disappearance of moduli for condensate of open strings
Consider a Dp-brane. Compactify $d$ spatial dimensions over a torus $T^d$. Suppose $d\geqslant p$, and that the Dp-brane is completely wrapped around the compactified dimensions.
Look at the open ...
6
votes
1answer
248 views
Mathematical concept of supersymmetry
I wish to study supersymmetry in field theory(sometime in december). However, I am quite not sure what is needed for its study. In supersymmetry, I just want to get the mathematical idea, such as its ...
6
votes
1answer
267 views
About the definition/motivation/properties of the twisted chiral superfield in ${\cal N}=2$ theories in $1+1$ dimensions
The following is in the context of the ${\cal N}=2$ supersymmetry in $1+1$ dimensions - which is probably generically constructed as a reduction from the ${\cal N}=1$ case in $3+1$ dimensions.
In ...
6
votes
1answer
86 views
random matrix ensembles from BMN model
My friends working on Thermalization of Black Holes explained solutions to their matrix-valued differential equations (from numerical implementation of the Berenstein-Maldacena-Nastase matrix model) ...
6
votes
2answers
576 views
Why is the string theory graviton spin-2?
In string theory, the first excited level of the bosonic string can be decomposed into irreducible representations of the transverse rotation group, SO(D-2). We then claim that the symmetric traceless ...
6
votes
2answers
306 views
Lagrangians combining terms with 1 and 2 derivatives
How are field theory Langrangians treated when some terms have 2 derivatives but others have only 1? Because the number of derivatives in a Lagrangian term is more easily even than odd, the ...
6
votes
2answers
376 views
Classifying all possible BPS configurations in string theory
Is there a classification of all possible BPS configurations in string theory? It has to include Calabi-Yau orbifolds, intersecting D-branes, coincident D-branes, etc. . To simplify matters, take the ...
6
votes
0answers
92 views
Is it believed that all UV completions have “Maldacena duals”?
I have heard occasional rumors that effective field theories have gravity duals. For example, I've been told that UV momentum cutoffs in N=4 SYM become finite radii in AdS. I've heard speculations ...
6
votes
0answers
46 views
Pohlmeyer reduction of string theory for flat and AdS spaces
The definition of Pohlmeyer invariants in flat-space (as per eq-2.16 in Urs Schreiber's DDF and Pohlmeyer invariants of (super)string) is the following:
$ Z^{\mu_1...\mu_N} (\mathcal{P}) = ...
6
votes
0answers
48 views
String landscape in different dimensions
For D = 11 large (uncompactified) spacetime dimensions, the only "string theory" vacuum is M-theory
For D = 10, there are 5 vacua. Or maybe it's more correct to say 4, since type I is S-dual to ...
6
votes
0answers
425 views
Why is there a deep mysterious relation between string theory and number theory, elliptic curves, $E_8$ and the Monster group? [closed]
Why is there a deep mysterious relation between string theory and number theory (Langlands program), elliptic curves, modular functions, the exceptional group $E_8$, and the Monster group as in ...
5
votes
4answers
515 views
Does string theory tells us anything concrete about black hole decay?
EDIT: I edited the question to reflect Moshe's objections. Please, look at it again.
It's apparently a black hole time around here so I decided to ask a question of my own.
After a few generic ...
5
votes
1answer
42 views
Are there stable string theory vacua with non-minimal cosmological constant?
Naive reasoning suggests that a string theory vacuum with cosmological constant Lambda1 is always unstable as long as there is a string theory vacuum with cosmological constant Lambda2 < Lambda1 ...
