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.

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1answer
40 views

Why does product of Moduli and Diff x Weyl Variation vanish?

According to equation 5.2.5 in Polchinski :- $$\int d^2 \sigma~ \delta^{'}g_{ab} \times [-2(P_1 \delta \sigma)_{ab} +(2\delta w - \Delta \cdot \delta \sigma)g^{ab}]=0$$ The assumption here is that " ...
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0answers
60 views

Polchinski equation 4.3.16

I am trying to obtain the polchinski's equation 4.3.16 which is following $ Q_B^2 = \frac{1}{2}\{ Q_B, Q_B \} = -\frac{1}{2}g^{K}_{IJ}g^{M}_{KL}c^Ic^Jc^L b_M =0$ Where $ Q_B = C^I(G_I^m ...
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2answers
46 views

Are string theories extra dimensions required to be “higher” than the four we know of? [on hold]

Does the mathematics of string theory require extra dimensions to be "higher" than our own? Is it possible that extra dimensions are lower that that the four we currently know? Could our four be ...
1
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1answer
101 views

About solitons, what is the difference between kinks and vortices?

I am reading papers about solitons for my small reports, and i could not understand its physical meaning in detail. I know soliton is solitary wave which behaves like particle. And many text they ...
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0answers
21 views

diff-invariant, regulator, cutoff integral on string theory

The diff-invariant distance between $z'$ and $z$ is (for short distances) $e^{w(z)}|z'-z|$, so a diff-invaraint cutoff would be at $|z'-z|=\epsilon e^{-w(z)}$. Then $$ \int ...
2
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1answer
95 views

What comes after string theory/M-theory?

Classical mechanics is a good approximation to special relativity, which is a good approximation to general relativity etc. I have heard that if string theory/M-theory is right, then it is not just an ...
1
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1answer
60 views

Instantons as a -1 dimensional object

I don't know much about Instantons, and looking through the Wiki page it seems like one must have a lot of knowledge about QFT to understand them. However recently I've encountered a statement (which ...
3
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2answers
104 views

What experiment would prove string theory?

The conceptual model of multidimensional vibrating strings provides an incredibly rich and diverse "language" that almost certainly is encompassing all of known physics as a singular point somewhere ...
1
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1answer
38 views

why is it important to find stability of supergravity solutions? [closed]

I want to know about the importance of the stability, generally,why is stability important in super-gravity? and why do we like these solutions?
2
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0answers
43 views

M-Theory and computer simulation

I have a question. Is it possible to perform computer simulations based on the M-Theory? I was looking for such simulators or source codes but I have not found anything. However, M-theory must have ...
2
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4answers
226 views

Is our universe an emulation?

I was watching one of Neil Degrasse Tyson talks and there was a scientist (can't recall his name sorry) who was talking about a recent discovery: "Doubly-even self-dual linear binary ...
11
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2answers
507 views

Why can the Euler beta function be interpreted as a scattering amplitude?

The Wikipedia article on the Veneziano Amplitude claims that the Euler beta function can be interpretted as a scattering amplitude. Why is this? In another word, when the Euler beta function is ...
6
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1answer
123 views

What does this question about entanglement and classical geometry mean?

Below is the question from Andy Strominger's presentation at the String 2014 conference. The question was asked by credible physicist Ashoke Sen as an important question. "What is the precise ...
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0answers
194 views

What is the meaning of this String Theory Equation from CERN? [closed]

I have recently visited CERN, and in the Globe they showed an equation from string theory. My knowledge about it goes only as far as 'The elegant universe', so no mathematics, but i would say that ...
2
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1answer
48 views

The equivalence of two worlds related by T-duality

T-duality in string theory relates a world containing open and closed strings with a D$p$-brane with a compact dimension with radius $R$ with a dual world with a D$(p-1)$-brane with a radius ...
3
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1answer
85 views

What is the logic of regarding perturbative renormalizability is not a fundamental requirement?

I read a statement in Becker and Becker's String Theory and M-Theory page 2. After pointing out the non-renormalizablity of GR by the dimension of gravitational constant, it is said: Some ...
2
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1answer
35 views

Deriving conserved currents by promoting parameter

I currently reading Tong's text on String Theory. In Chapter 4.1.1 he alludes to a technique to derive conserved currents Recall that we can usually derive conserved currents by promoting the ...
1
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1answer
44 views

How can one calculate the central term of the conformal field theory algebra (and show it's really the virasoro algebra)?

So I'm following Szabo's book "An Introduction to String Theory and D-brane Dynamics (2nd ed, 2011); still on the canonical treatment in chapter 3. After doing a mode expansion, we get (up to a ...
7
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0answers
112 views

What is the state-of-the-art on spacelike singularities in string theory?

What lessons do we have from string theory regarding the fate of singularities in general relativity? What happens to black hole singularities? What happens to cosmological singularities? Which ...
6
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0answers
94 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 ...
1
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1answer
75 views

Infinite number of universes? Black holes are guilty? [closed]

I was thinking, if the space is infinite, what if there are infinite number of spaces, inside our universe? I mean, everyone knows that black holes exist, but nobody knows what happens when you get ...
7
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1answer
422 views

Why does tachyon arise in bosonic string theory?

I am looking for precise mathematical and physical reasons which cause the presence of tachyon in bosonic string theory(specially closed bosonic string theory). Has it to do with the specific form of ...
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0answers
33 views

What is string theory? [duplicate]

What is string theory? By that I mean: Why has the theory, as I have heard, postulated multiple dimensions outside our reach, and How does its mathematical proof account for this?
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2answers
52 views

Is any one compact dimension for one particle the same as for another particle?

In the 3+1 dimensions of everyday life and GR particles can share the same extended dimensions. Probably all particles share the same 3+1 dimensions. In string theory compact dimensions seem to be ...
2
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1answer
40 views

relating spinor and fundamental representation for $E_8$

While proving a very important relation which is satisfied both by $SO(32)$ AND $E_8$, which makes it possible to factorize the anomaly into two parts. The relation is ...
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7answers
3k views

What are the strings in string theory made of?

This is a follow-up to an intriguing question last year about tension in string theory. What are the strings in string theory composed of? I am serious. Strings made of matter are complex objects ...
2
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1answer
197 views

Can the compactified dimensions of M-Theory/String Theory become uncurled?

Is it possible for the curled dimensions described in superstring theories to become uncurled and open up. I have read that the big bang could have been the uncurling over 3 dimensions through ...
1
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0answers
41 views

“Dictionnary” between QFTs in D and D-1 dimensions?

Considering Einstein equations, suppose, for instance, that the RHS, the stress-energy tensor, is uniquely due to the electromagnetic field. Now, if we imagine a quantized version of these Einstein ...
2
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0answers
20 views

Stability of D-Branes and Coupling to Fields

I've been brushing up on my string theory using Becker, Becker, Schwarz (p. 208 in particular). They state that some D-branes can couple to R-R fields from closed string excitations. They then go on ...
1
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1answer
32 views

Long string model of black hole

I wonder if anyone can advise me literature about "long string model" of black hole. I've tried Google, and of course arXiv.org. Still I couldn't find anything about this theme. I would be also very ...
5
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1answer
295 views

What does it mean to renormalize an effective field theory?

This is in reference to slide 19 of this talk "As always in Effective Field Theory, the theory becomes predictive when there are more observables than parameters" Can one explain what this exactly ...
1
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0answers
14 views

Are O-planes not dynamical?

In Polchinski's book "String theory", he is saying "Unlike the case of D-branes, there are no string modes tied to the orientifold plane to represent fluctuations in its shape. Our heuristic argument ...
17
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1answer
1k views

Why is there a deep mysterious relation between string theory and number theory, elliptic curves, $E_8$ and the Monster group?

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 ...
6
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1answer
118 views

geometric quantization of the moduli space of abelian Chern-Simons theory

I wish to understand the statement in this paper more precisely: (1). Any 3d Topological quantum field theories(TQFT) associates an inner-product vector space $H_{\Sigma}$ to a Riemann surface ...
7
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3answers
574 views

The Chern-Simons/WZW correspondence

Can someone tell me a reference which proves this? - as to how does the bulk partition function of Chern-Simons' theory get completely determined by the WZW theory (its conformal blocks) on its ...
0
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0answers
40 views

Compactification and off-diagonal terms of the metric tensor

In standard 3+1 dimensional spacetime, the metric tensor is of order 4 and had ten independent coefficients, hence there are 6 terms off the diagonal in the corresponding $4\times 4$ real symmetric ...
3
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1answer
51 views

Traces in different representation

I am actually working with Green-Schwarz anomaly cancellation mechanism in which I have came across a strange formula which relates trace in the adjoint representation (Tr) to trace in fundamental ...
2
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0answers
66 views

Open problems in string theory [closed]

I'm thinking of applying to do a PhD in String Theory. I'm gradually learning more about the subject through external reading, but still most papers are impenetrable. Could anyone give me a ...
1
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0answers
94 views

I want to decompose a tensor product using Littlewood-Richardson rule, How do I find the component of this in each irreducible space?

Let me set up the notation I am using. $(abc,de)$ denotes the standard Young tableau where the first row is $abc$ and the second row is $de$. Each young tableau corresponds to the young symmetriser, ...
6
votes
1answer
276 views

Energy-momentum tensor of Bosonic Ghost Action in String Theory

When quantizing bosonic string theory by means of the path integral, one inverts the Faddeev-Popov determinant by going to Grassmann variables, yielding: $$ S_{\mathrm{ghosts}} = ...
0
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1answer
52 views

About Shor's error correcting algorithm

In this paper, http://arxiv.org/abs/1301.4504 in equation 4.1 in what sense are the two states a "9-qubit state"? I did not understand this counting. Can someone explain what are the different $X_i$ ...
-2
votes
1answer
49 views

Resonant Frequency & Opera Singers [closed]

Would it be possible under math of strings to note the frequency of each string vibrations? And in doing so, in hand with using the technique opera singers use to shatter glass with their voice, would ...
0
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0answers
180 views

Colliding bubbles in hyperspace

Assuming the following A universe is the surface from a bubble in hyperspace. Inside a bubble there is nothing, only the surface represents a universe. The size of the bubble is time. Dark matter is ...
3
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0answers
65 views

Values of Spacetime Dimension and Virasoro Generator Ambiguity in Bosonic String Theory

I have already asked a similar question but I was suggested to split the questions so I do that now. In the book by Green, Schwarz and Witten spurious states are introduced to find values for the ...
3
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2answers
526 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 ...
2
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0answers
37 views

Existence and Uniqueness of spurious states in Bosonic String Theory

Green, Schwarz and Witten introduce so called spurious states $\phi$, that fulfill $$ (L_0 -a )\phi = 0\quad \text{and} \quad (\phi,\psi)=0 \text{ for all physical states }\psi $$ where the $L_n$ are ...
3
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0answers
35 views

Structure of Hilbert Space in Bosonic String Theory

My question is about the canonical quantization of free bosonic string theory as described by Green, Schwarz & Witten. There they use spurious states to calculate a value for the ambiguity ...
2
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0answers
30 views

What is the X(t) dependence of the ends of stretched Nambu-Goto string?

I'd like to have an expression for the velocity of an end of an open string being contracted due to it's tension. Not that of transverse oscillations, which seems to be the velocity of light, but ...
3
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0answers
31 views

A question on the Bousso-Polchinski paper

In this famous paper by Bousso and Polchinski, Quantization of Four-form Fluxes and Dynamical Neutralization of the Cosmological Constant an example in M-theory compactification is given in section ...
1
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1answer
83 views

String Theory and Fourier Analysis [closed]

Me and my friend, both many years from learning string theory, had a recent debate about it anyway. He said he already partially discounts it because after learning waves, he believes any function, ...