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.

learn more… | top users | synonyms (7)

0
votes
0answers
52 views

Constructing dual gravity theory from general CFT

AdS/CFT is a little over my head at the moment, particularly the AdS side but I'll ask anyway. Has there been any work done on starting with a mathematically rigorous conformal field theory defined ...
4
votes
0answers
41 views

Will the new LHC data falsify some theories? [closed]

There are plenty of extensions of the Standard Model, that all agree until the energy scales that have already been explored, but will differ at the new energy range of 14 TeV. This means the data ...
0
votes
0answers
20 views

Do cosmic strings or global monopoles interact with magnetic field?

Does anyone know any phenomenon that shows the interaction between cosmic strings or global monopoles with magnetic field? I looked for that in Vilenkin and Shellard's book but, as I'm not a ...
3
votes
3answers
518 views

How to imagine higher dimensions?

In the link below Carl Sagan described about higher dimension: http://www.youtube.com/watch?v=UnURElCzGc0 and here's a description of Brian Greene: http://www.youtube.com/watch?v=v95WjxpMIQg Carl ...
6
votes
2answers
299 views

Seiberg-Witten theory and Superconductivity

There seems to have some (deep) relation between Seiberg-Witten theory and superconductivity. e.g. this Witten paper. Q: Could someone introduce the relations between the twos both physically in ...
7
votes
1answer
170 views

Cluster decomposition in string theory

Do amplitudes and correlation functions in string theory satisfy the cluster decomposition principle? Note added: Even without local observables such as correlation functions, one can define the ...
1
vote
1answer
43 views

Singleton representations of $SO(2, d)$?

What is meant by "singleton" representations of $SO(2, d)$ and 'small representations' in Witten's paper, Anti de Sitter Space and Holography?
0
votes
0answers
45 views

From String Frame to Einstein Frame for 10D supergravity

This question is related to but not answered in the post String frame and Einstein frame for a Dp-brane, so it should be treated as a separate question. Beginning with the gravity action $$S = ...
0
votes
1answer
37 views

Low-energy “effective measure” from superstrings?

There is obviously a gap in my knowledge of the origin of effective actions in string theory. As far as I understand it, the strategy is straightforward (at least in principle): Write down the ...
2
votes
0answers
34 views

Meaning of the Coulomb and Higgs branch for non-Lagrangian theories?

What is the meaning of the Coulomb and Higgs branch for non-Lagrangian theories like the $T_N$ theories that arise as 5-brane webs and correspond to CY 3-folds in M-theory? This is related to an older ...
2
votes
0answers
33 views

What physical effects cause materialization of a system of particles for a short time?

It is well-known from physics that a photon with enough energy creates a pair of particles: one electron and one positron. This pair of particles can only exist for a short time. This process is ...
1
vote
1answer
56 views

Curvature of Weyl-rescaled metric from curvature of original metric

I'm trying to go from the low-energy effective action in the string-frame to the corresponding action in the Einstein frame. The action in the string frame has the form $$S = \frac{1}{(2\pi)^7 ...
1
vote
2answers
94 views

What does the “T” stand for in T-duality?

First of all, I am not a physicist. I'm a graduate math student and recently I came across the concept of T-duality. Actually I'm studying generalized complex geometry, which according to this paper ...
4
votes
2answers
123 views

$D$-brane and 5th dimensions

While I was looking up the 5th dimension of the Randall-Sandram model, I have wondered whether Kaluza Klein theory can be applied to the $D$-brane or $p$-brane. Can the $D$-brane and $p$-brane ...
1
vote
1answer
138 views

Calculus of variations and string theory

In Polchinski's String theory book, Vol 1., in chapter 1, p. 18, he is deriving the Lagrangian in the light cone gauge (that's not necessary to know in order to answer this question), and he gets ...
9
votes
1answer
159 views

What are the implications for the AdS/Cft program if AdS is unstable?

To my understanding recent progress in the study of the non linear stability of AdS spacetime suggest that $AdS$ might be unstable. If this is true, what are the physical and mathematical ...
0
votes
1answer
66 views

Polyakov equation in the strings theory

In the equation of Polyakov there wouldn't be in our universe 10 or 11 dimensions but more (26) because it is referred to the bosonic theory. Are there any connections between this equation and the ...
1
vote
1answer
40 views

Why is the torus important for compactification in string theory? (aka much ado about the torus)

Why is the torus important in string theory and supergravity? To be specific, why does one care about something like compactification of Type IIB or IIA supergravity on a torus $T^5$, as opposed to ...
1
vote
1answer
39 views

Basic question about curved and flat indices, and the Dirac matrices on $S^5$

In discussing the Kaluza-Klein formalism for Type IIB Supergravity on $S^5$, or the AdS5xS5 compactification, one requires Killing spinors on $S^5$. I read that the Dirac matrices on $S^5$ satisfy ...
0
votes
1answer
87 views

Why is the universe 3D if the holographic principle says it's encoded in a its surface?

The way I understand the holographic principle is that everything in a 3D space can be thought of as living on the 2D boundary of that space. If that is the case, why does everything in the universe ...
2
votes
1answer
56 views

What does it mean to “uplift” a supergravity solution to higher dimensions?

What does it mean to "uplift" a supergravity solution to higher dimensions? This is a common term used in the literature but I cannot understand it. A very common example is "uplifting d-dimensional ...
3
votes
2answers
97 views

Idea behind Compactified Boson

On p. 167 of his Conformal Field Theory, Di Francesco introduces "Compactified Boson". He says: The invariance of the free-boson Lagrangian [...] with respect to translations $\varphi(x) ...
5
votes
2answers
120 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 ...
1
vote
0answers
30 views

The low dimensional end of the brane scan

Common wisdom says that only the top dimensional part of the brane scan of Green-Schwarz super p-brane sigma models is quantum consistent (the critical strings and the M-branes). But by the results in ...
0
votes
3answers
2k views

Relation between quarks and strings

In string theory(s), are quarks just individual strings, or are they made of multiple strings? Are the heavier quarks made of heavier or longer strings? Are there red, blue, and green strings ...
1
vote
1answer
147 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 $$e^{iH(z)}e^{-iH(-z)}~=~\frac{1}{2z}+i\partial H(0)+2zT_B^H(0)+O(z^2)\tag{10.3.12a}$$ ...
6
votes
2answers
826 views

On black holes, Hawking radiation and gravitational atoms

Over the past hour or so I've been following one of my standard physics-based, wanders-through-the-internet. Specifically, I began by reviewing some details of dark energy theory but soon found myself ...
1
vote
0answers
62 views

How does the sum of natural numbers arise in the derivation of critical string dimensions?

In the standard treatment of bosonic string theory the “heuristic” argument for the critical dimension goes as follows (see Ref. 1-4). Upon quantization the mass-squared operator becomes normal ...
3
votes
1answer
70 views

Type IIB string theory is chiral. Do there exist non-chiral II SUGRA theories?

Type IIB string theory is chiral. Do there exist non-chiral $\mathcal{N}=2$ II SUGRA theories? The answer is apparently yes. Additionally how do we understand the fact that Type IIB SUGRA is chiral ...
3
votes
1answer
66 views

What is meant by the following divergent formula?

I have encountered the following formula a couple of times (in different physics contexts which I do not have a good understanding of) $$\int_{0}^\infty \frac{dt}{t}e^{-tx}=-\log x$$ Formally one ...
7
votes
1answer
2k 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 ...
8
votes
1answer
432 views

Mathematically rather than physically speaking, is there something “special” about 10 (or 11) dimensions?

As I understand it, string theory (incorporating bosons and fermions) "works" in $9+1=10$ spacetime dimensions. In the context of dual resonance theory, I've read descriptions of why that is ...
5
votes
1answer
375 views

Divergence theorem in complex coordinates

This question is related to Stokes' theorem in complex coordinates (CFT) but, I still don't understand :( Namely how to prove the divergence theorem in complex coordinate in Eq (2.1.9) in ...
1
vote
0answers
20 views

How do we use the Killing spinors to determine the resulting supersymmetry conserved?

How do we exactly use the Killing spinors to determine the resulting supersymmetry conserved? Is there some nice "toy" example you could provide me with to see this and convince my self? And is there ...
2
votes
1answer
41 views

Decomposition of the gravitino into helicity $\pm \frac{3}{2}$ and $\pm \frac{1}{2}$ components

I'm reading this book on string theory. When they decompose two dimensional gravitino (formula 7.16) $$ \chi_\alpha = \frac{1}{2}\rho^\beta \rho_\alpha \chi_\beta + \frac{1}{2}\rho_\alpha \rho^\gamma ...
1
vote
0answers
24 views

What is the significance of self-duality and anti self-duality in supergravity?

So I see the terms "self-dual" and "anti self-dual" appear routinely in supergravity/string thery, e.g. the fact that Type IIB supergravity contains a real self-dual rank-5 antisymmetric tensor ...
1
vote
1answer
81 views

D branes Ns brane and p-branes

It is now a common knowledge that "D-p branes are equivalent to p-branes" due to Polchinski's work. Note that D-p branes are objects in string theory and p-branes are objects in blackhole theory. So ...
4
votes
3answers
489 views

Does the need for renormalization in QFT vanish once you use a more fundamental theory (e.g., string theory)?

It is often explained that renormalization arises in QFT because QFT is a low-energy effective theory that needs to be replaced by a more fundamental theory at higher energies/smaller distances. While ...
3
votes
2answers
196 views

Why M-theory has only M2 and M5 branes?

Why M-theory has only M2 and M5 branes? In string theory, depending on the type one considers, you get all kind of D-branes. What is so special in M-theory that only allows 2 and 5 branes?
1
vote
0answers
40 views

Fermion counting operator for open superstring

In Barton Zwiebach's A First Course in String Theory, in section 14.4, there's a fermion counting operator $(-1)^F$ which is supposed to give you $+1$ if the state is bosonic, or $-1$ if the state is ...
1
vote
0answers
18 views

Correlation functions on $S^2$ (from OPE singularities)

Consider a closed string scattering (worldsheet topology $S^2$ sphere). Given that the OPE: $i \partial X^\mu(z) e^{ik X(w)} \sim \frac{k^\mu}{z - w} e^{ik X (w)} + ... \ \ , \ \ i \partial X^\mu (z) ...
1
vote
1answer
42 views

How can extra (non-curled up) dimensions be hidden from us?

Wikipedia says: If extra dimensions exist, they must be hidden from us by some physical mechanism. One well-studied possibility is that the extra dimensions may be "curled up" at such tiny ...
2
votes
1answer
90 views

Compactified extra dimensions and symmetry

It's my understanding that M-Theory necessitates 11 space-time dimensions (10 spatial dimensions plus 1 time dimension) in order work mathematically. This appears to jar with reality, which only ...
0
votes
0answers
39 views

The limited Computing Capabilities of Space, Increased quantized info leads to time-dilation?

Are there any approaches to Special and General Relativity using space as a computing medium? With space having a maximum computing capability and time dilation as lag? Could this idea describe the ...
0
votes
0answers
32 views

SUSY preserved by an extended D-brane

There's a nice way to prove that for an extended D-brane half of SUSY is preserved, from perturbative string argument with SUSY Ward identities and the doubling trick (at least, at tree-level and ...
1
vote
0answers
28 views

Tadpole-free condition

Tadpole-free is a very important condition for perturbative string theory (which is equivalent to the theory to be expanded around the "right" vacuum). For simplicity, let's consider closed string ...
3
votes
1answer
119 views

States in light cone string theory

Currently I'm trying to understand string theory in the light cone quantization. I just have had a look into Polchinski (Vol. 1, Introduction to the bosonic string), because – as far as I could see – ...
3
votes
0answers
34 views

What information do quiver gauge diagrams provide?

I am struggling to understand what the information one can extract by looking a quiver diagram for a quiver gauge theory is. I understand what quivers are but I cannot get some physical intuition and ...
7
votes
2answers
1k views

Dirac, Weyl and Majorana Spinors

To get to the point - what's the defining differences between them? Alas, my current understanding of a spinor is limited. All I know is that they are used to describe fermions (?), but I'm not sure ...
0
votes
0answers
22 views

T-Duality for closed bosonic string: what is the difference between a graviphoton and a B-vector?

Consider the closed bosonic string in 26 dimensions, of which one physical dimension, say $X^{24}$ is compactified into a circle of radius $R$. The lowest lying massless states are the graviton, the ...