A class of theories that attempt to explain all existing particles (including force carriers) as vibrational modes of one-dimensional objects.
1
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1answer
16 views
Path Integral Quantization Bosonic String Theory
I was reading through my notes on the path integral quantization of bosonic string theory when a general question about path integral quantization arised to me.
The widely used intuitive explanation ...
0
votes
1answer
39 views
Entropy of Black Hole
What is the relation between the entropy of rotating and non rotating Black hole?
Which one's entropy is greater?
3
votes
1answer
48 views
Proof of S-duality between Type IIB, IIB and Type HO, I string theories
About every source on string theory I've read which do mention S-duality state that:
$$\begin{array}{l}
\operatorname S:\operatorname{IIB} \leftrightarrow \operatorname{IIB}\\
\operatorname ...
-5
votes
0answers
81 views
Criticism of String Theory by other string theorists [closed]
*EDIT: Due to policy I will edit this into a question:
Do you know any string theorist that have criticized string theory and if so please could you give me references? thanks.
End of EDIT. ...
4
votes
1answer
64 views
T-Duality between Type HE String theory and Type HO string theory
My question is regarding T-Duality between the 2 Type H string theories.
I know that the Type II String theories are T-dual to each other because T-Duality changes the sign of the Gamma Matrix so
...
3
votes
1answer
46 views
Question on Type HO/HE string theory
The Heterotic string state is a tensoring of the bosonic string left-moving state and the Type II string right-moving state. Therefore, I expect the spectrum to be:
$$\begin{array}{*{20}{c}}
\hline
...
0
votes
0answers
83 views
How can it be seen that ST unifies GR and QM as the quantum gravity scale is not directly accessible
I am a newbie to superstring theories, but I came into this question:
so superstring theories purport to unify general relativity and quantum theory.
However, there is yet no definitive way to test ...
5
votes
2answers
136 views
How can string theory work without supersymmetry?
This question is inspired from reading Mitchell Porter's nice answer here to a question asking why supersymmetry should be expected naturally. Among other things, he explains that since weak scale ...
2
votes
2answers
76 views
Question on the Hagedorn tower in Type I string theory
In a previous question (Mass spectrum of Type I string theory), I had asked about the mass spectrum of Type I string theory. I got a response saying that it is a Hagedorn tower. However, my source ...
2
votes
1answer
69 views
Flavour diagonal SUSY breaking
Because there is a single Yukawa matrix for the SM leptons, the lepton mass and flavour states can be aligned, by diagonalization, even if the Yukawa matrix had off-diagonal elements.
SUSY breaking, ...
3
votes
1answer
56 views
Gauging discrete symmetries
I read somewhere what performing an orbifolding (i.e. imposing a discrete symmetry on what would otherwise be a compactification torus) is equivalent to "gauging the discrete symmetry". Can anybody ...
2
votes
0answers
50 views
About deriving the multi-trace index in terms of the single-trace index
This question is in reference to this paper
Combining their equations 5.2, 5.3, 5.6 and 5.7 one seems to be looking at the integral/partition function,
$Z(x) = \prod_{n=1}^{n =\infty}\left [ \int ...
2
votes
0answers
50 views
Mass spectrum of Type I string theory
I understand that the massless fields of the Type I string theory are the described by:
[\begin{array}{*{20}{c}}
{{\rm{Sector}}}&{{\rm{Massless fields}}}\\
{{\rm{R - R}}}&{{C_0}}\\
{{\rm{NS - ...
3
votes
1answer
66 views
Spectra of the Type II String theories
The spectrum of the Type II string theory (both IIA and IIB) is given by:
\begin{array}{*{20}{c}}
\hline
& {{\text{Sector}}}& & {{\text{Spectrum}}}& & {{\text{Massless Fields}}} ...
9
votes
1answer
264 views
How do I find constraints on the Nambu-Goto Action?
Let $X^\mu (t,\sigma ^1,\ldots ,\sigma ^p)$ be a $p$-brane in space-time and let $g$ be the metric on $X^\mu$ induced from the ambient space-time metric. Then, the Nambu-Goto action on $X^\mu$ is ...
2
votes
0answers
40 views
Construction of the supergravity side explicitly in gauge/gravity dualities
Although the motivation of this question comes from the AdS/CFT correspondence, it actually is related to a more general principle of gauge/gravity duality. We know from Maldacena's conjecture that a ...
3
votes
0answers
96 views
Holonomy twisting
There is Witten's topological twist of standard SUSY QFTs with enough SUSY into Witten-type TQFTs. What is a holonomy twist?
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 ...
1
vote
2answers
150 views
Where does quantum mechanics come from? [closed]
Where does quantum mechanics come from?
If string theory is proved to be the correct quantum theory of gravity but it failed to explain where quantum mechanics came from can we still consider it a ...
2
votes
0answers
28 views
Is there a critical order of the Abelian gauge theory in (2+1)D
In (2+1)D spacetime, it is known that the $U(1)$ gauge theory is always confined (according to Polyakov), while the $\mathbb{Z}_2$ gauge theory can support a deconfined phase. Now consider a generic ...
2
votes
0answers
26 views
``integrated vertex operators" in 1-loop open/closed bosonic string amplitude
This question is in reference to the first ~15 minutes of this String Theory lecture by Prof.Shiraz Minwalla,
http://theory.tifr.res.in/Videos/strings28_24sep08.mp4
Can one give a reference ...
1
vote
0answers
39 views
A three string tree diagram evaluated in CFT is different from string field theory evaluation
Hi Guys generally when you evaluate the 3 open string tachyon tree level amplitude in CFT, you do a conformal transformation mapping the worldsheet to the upper half of the complex plane and the ...
5
votes
1answer
60 views
AdS/RCFT examples?
RCFT's (rational conformal field theories) in two dimension are very well-studied, but it seems that there is no any gravity dual of such theories has been found. Is there example of the holographic ...
2
votes
0answers
50 views
Standard Quantum Mechanics representation as a constrained 2 + 1 space-time (membrane) theory?
Could a particular Standard Quantum Mechanics representation be a constrained 2 + 1 space-time theory (membrane theory) ?
(i) This question is motivated by a possible (approximative) analogy with ...
-3
votes
0answers
43 views
What is string tension in quark confinement? [closed]
What is string tension?
is it real or just an idea?
What is, its amount?
i've heard that string tension increase $a_s$, why?
3
votes
1answer
93 views
Supersymmetry and non-compact $R$-symmetry group?
The $R$-symmetry for $N$ supercharges is $U(N)$. Is it possible to generalize $R$-symmetry [let's take $U(4)$) to be something like $U(2,2)$ (maybe analogous to Wick rotation of $SO(3,1)$ to ...
2
votes
1answer
54 views
Question about charge conservation at vertices of web diagram
My question is about web diagram in paper of Aganagic et al.
How to get the $\alpha-\beta$ line rather than $-\alpha+\beta$ line of rightmost diagram of fig.3?
More precisely, how to show the charge ...
4
votes
2answers
240 views
Fundamental equation(s) of string theory?
I often hear about string theory and its complicated mathematical structure as a physical theory, but I can't say that I've ever actually seen any of the related math. In general, I'm curious as to ...
5
votes
0answers
238 views
Can the laws of quantum mechanics be derived from a more fundamental theory? [closed]
String theory takes quantum mechanics for granted and tries to make it compatible with gravity but if it turns out to be a theory of everything then shouldn't it in principle explain why our world is ...
2
votes
1answer
90 views
Energy Functional
I am a graduate student in pure mathematics, during my study on Ricci Flow I faced some functional known as energy functional. For example Einstein-Hilbert functional is called an energy functional, ...
7
votes
1answer
163 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 ...
3
votes
3answers
305 views
What does this “Witten's Dog” Feynman diagram in Futurama episode mean? [closed]
In an old episode ("Mars University") of Futurama which is a TV show, a character named Professor Farnsworth was trying to lecture "Superdupersymmetric String Theory" and "Witten's Dog" to some ...
-5
votes
0answers
60 views
Consequences of Third Postulate of Special Relativity [closed]
Consequences of SR arise from two postulates.
know as this abstract states:
"relativistic action is limited to planck's constant", and maybe we've to consider it as the possible third postulate of ...
3
votes
1answer
118 views
Why does in string theory the amount of supersymmetry have to be $\cal{N} \leq 2 $?
Why is this, that in string theory the maximum amount of supersymmetry is $\cal{N} = 2$, whereas in supergravity one can have up to $\cal{N} = 8$ ?
3
votes
0answers
66 views
What is kappa symmetry?
On page 180 David McMohan explains that to obtain a (spacetime) supersymmetric action for a GS superstring one has to add to the bosonic part
$$
S_B = -\frac{1}{2\pi}\int d^2 \sigma ...
5
votes
1answer
106 views
Vector and Spinor Representation in Ramond-Neveu-Schwarz Superstring Theory
I am learning Ramnond-Neveu-Schwarz Superstring theory (RNS theory). I often find the following notation, especially in the closed string spectrum etc.:
$$\mathbf{8}_s,\mathbf{8}_v $$
And it is ...
6
votes
0answers
94 views
Is it believed that all UV completions have “Maldacena duals”?
I have heard occasional rumors that effective field theories have gravity duals. For example, I've been told that UV momentum cutoffs in N=4 SYM become finite radii in AdS. I've heard speculations ...
1
vote
2answers
312 views
Are the $10^{500}$ different string theories being whittled down?
An example of a test: Ask each variant whether its estimate of the electron mass lies within $\pm\,x\%$ of the known value. This surely can't take long per theory. Although $10^{500}$ is huge, ...
2
votes
1answer
94 views
Symmetries in Wilsonian RG (2)
This question is related to the paper http://arxiv.org/abs/1204.5221 and is a continuation of the previous question Symmetries in Wilsonian RG
In the liked paper why do the equalities in equation ...
9
votes
0answers
213 views
Derivation of KLT relations
The KLT relations (Kawai, Lewellen, Tye) relate a closed string amplitude to a product of open ones. While I get the physics behind this I don't really understand the derivation in the original paper ...
1
vote
1answer
70 views
Can the fuzzball conjecture be applied to microscopically explain the entropy of a region beyond the gravitational observer horizon?
In this article discussing this and related papers, it is explained among other things, how the neighborhood of an observer's worldline can be approximated by a region of Minkowsky spacetime.
If I ...
1
vote
0answers
44 views
Divergent sum in lightcone quantization of bosonic string theory
I had the following question regarding lightcone quantization of bosonic strings - The normal ordering requirement of quantization gives us this infinite sum $\sum_{n=1}^\infty n$. This is regularized ...
4
votes
1answer
84 views
Virasoro TT OPE in Polchinski's book
I'm trying to understand eq. 2.2.11 in Polchinski's first book.
He's computing
$$:\partial X^\mu(z)\partial X_\mu(z): :\partial' X^\nu(z')\partial' X_\nu(z'):$$
Now, I understand why this ...
1
vote
0answers
20 views
S-Wave for minimally coupled scalar field
This question is in reference to the paper here (Equation 3).The extremal 3-brane metic in $D=10$ can be written as:
\begin{equation*}
ds^2 = A^{-1/2}(-dt^2 +dx_1^2 +dx^2+ dx^3) + A^{1/2}(dr^2 +r^2 ...
5
votes
2answers
99 views
How to understand worldsheet fermion as a section?
I am reading Witten's paper on topological string, and I found some mathematical notation is hard to understand for me.
Consider the nonlinear sigma model in 2 dimensions governed by maps
$\Phi : ...
0
votes
0answers
105 views
Does String Theory explain spin?
The state of a particle will generally change if you rotate it. The details of how the state changes under an infinitesimal rotation are contained in the angular momentum operator J. This operator can ...
3
votes
1answer
126 views
What are the conserved charges related to the Virasoro generators?
I have just learned from reconsidering my demystified book, that when conformally maping the worldsheet of a closed string to the complex plain by using the transformation $z = e^{\tau + i\sigma}$ ...
0
votes
1answer
111 views
Strings and QFT: particles moving backward in time?
New question: In string theory and QFT, do particles travel back in time? Not related to antimatter: Do they travel back and forth in time in reality or are these just interpretations of mathematical ...
3
votes
0answers
50 views
Does the ensemble of effective Lagrangians in the String theory landscape mostly include gauge theories?
String theory false vacua can be described by effective Lagrangians at low energy. Is there generally a correspondence between these effective Lagrangians and SU(N) gauge theories? Or do the effective ...
5
votes
1answer
77 views
About Vanishing of BRST commutator in path integral
In Witten's paper Topological Quantum Field Theory, about formula (3.2), the property $<\{Q,\mathcal{O}\}>=0$ depends on the assertion that $Z_{\varepsilon}(\mathcal{O})= \int \mathcal{D}X ...
