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
296 views

What if microstates increase proportional to universe volume? [closed]

I am probably a delusional crank with a lot of crazy, overly speculative conjectures. If I am not delusional, than at the very least I've been ahead of the curve, the last 40 or so years. I was a ...
1
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0answers
90 views

Some questions about flavour and R-symmetry in $2+1$ ${\cal N}=3$ theory

I have heard this fact that for ${\cal N}=3$ theories in $2+1$ with $N_f$ ${\cal N}=3$ matter fields the flavour symmetry group is $USp(N_f)$, $U(N_f)$ or $SO(2N_f)$ depending on whether the gauge ...
4
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5answers
743 views

Regarding string theory: how to refute the argument “if it cannot be tested experimentally then it is not science”? [duplicate]

Possible Duplicate: What differs string theory from philosophy or religion? I find a lot of people disbelieve in string theory, saying that since it cannot be tested experimentally then it ...
6
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2answers
625 views

Does String theory say that spacetime is not fundamental but should be considered an emergent phenomenon?

Does String theory say that spacetime is not fundamental but should be considered an emergent phenomenon? If so, can quantum mechanics describe the universe at high energies where there is no ...
4
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1answer
567 views

Wilson loops and gauge invariant operators (Part 2)

These questions are sort of a continuation of this previous question. I would like to know of the proof/reference to the fact that in a pure gauge theory Wilson loops are all the possible gauge ...
11
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4answers
4k views

Is spacetime discrete or continuous?

Is the spacetime continuous or discrete? Or better, is the 4-dimensional spacetime of general-relativity discrete or continuous? What if we consider additional dimensions like string theory ...
2
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2answers
179 views

Are the only observables in string theory the S-matrix?

Is the S-matrix the only observable in string theory? What about time varying spacetime backgrounds, or thermal states then?
2
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1answer
113 views

Hypothetical very massive particles

I'm looking for a table or compilation of hypothetical very massive ($m\gtrsim 1$ TeV) particles and their expected masses (or bounds on them or relation with other scales). All I know is (please, ...
2
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1answer
292 views

Pedagogic reference for calculation of 2-loop anomalous dimension (supersymmetric)

I want to know of pedagogic references which teach how to compute anomalous dimensions (..wave-function renormalization..) at lets say 2-loops. I guess there might be specialized techniques for ...
5
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0answers
150 views

Dual Resonance Model: Fermions

I am going through Ramond's 1971 paper Dual Theory for Free Fermions Phys Rev D3 10, 2415 where he first attempts to introduce fermions into the conventional dual resonance model. I get the 'gist' of ...
1
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2answers
152 views

What is unification, unified interactions, or dualities between interactions?

Scientists succeeded in unifying EM with the weak force, then with the strong force to achieve the standard model. They then studied supersymmetry and GUTs that showed improved gauge coupling ...
6
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0answers
99 views

R charge of the chiral multiplet in $2+1$ dimensions

These are two examples that I am puzzled by, One can see in this paper on page 16 that for ${\cal N} =2$ theory on $2+1$ the R-charge of the $\phi$ and the $\psi$ is determined to be $\frac{1}{2}$ ...
3
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1answer
211 views

Why do strings split in string theory?

In string theory, we are told strings can split and merge if the string coupling is nonzero, even while the worldsheet action remains Nambu-Goto or Polyakov plus a topological term. However, a ...
10
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3answers
2k 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 ...
2
votes
1answer
458 views

Wilson loops and gauge invariant operators (Part 1)

I guess the Hilbert space of the theory is precisely the space of all gauge invariant operators (mod equations of motion..as pointed out in the answers) Is it possible that in a gauge theory the ...
5
votes
1answer
351 views

Taking the continuum limit of $U(N)$ gauge theories

I would like to draw your attention to appendix $C$ on page 38 of this paper. The equation $C.2$ there seems to be evaluating the sum $\sum_R \chi _R (U^m)$ in equation 3.16 of this paper. I ...
2
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1answer
199 views

Why doesn't the anthropic principle select for N=2 SUSY compactifications with an exactly zero cosmological constant?

The party line of the anthropic camp goes something like this. There are at least $10^{500}$ flux compactifications breaking SUSY out there with all sorts of values for the cosmological constant. Life ...
1
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2answers
473 views

Laws of gravity for a universe that only consists of two objects?

So, we know that when two objects of normal matter get away from each other, the gravitational pull they feel from each other, decreases. I wanted to see how that would work. And in my ...
3
votes
1answer
179 views

How could we experience multiverse through cosmic background radiation?

I'm reading a book about string theory, and it tells me in the future it could be possible to detect existence of other bubble universes through cosmic background radiation. Is this true? What could ...
1
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1answer
139 views

Superspace Uncertainty Principle

Do the "operator for translations in superspace" and the "position in superspace operator" follow an uncertainty principle? How "real" is superspace? Aside from being weird (and possibly just a ...
25
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11answers
6k views

Discreteness and Determinism in Superstrings?

So Gerard 't Hooft has a brand new paper (thanks to Mitchell Porter for making me aware of it) so this is somewhat of a expansion to the question I posed on this site a month or so ago regarding 't ...
1
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1answer
1k views

What's next after Higgs Boson discovery? [duplicate]

Possible Duplicate: Practical matter of the Higgs-Mechanism As everybody knows that the Higgs Boson was discovered on July 4th,2012, I am so curious about it. What are the possible ...
2
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3answers
3k views

Why does string theory require 9 dimensions of space and one dimension of time?

String theorists say that there are many more dimensions out there, but they are too small to be detected. However, I do not understand why there are ten dimensions and not just any other number? ...
1
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2answers
391 views

What Observations could undeniably support string theory?

What experiments could provide observable "stringy" effects. All valid experiments are acceptable (also theoretical experiments).
5
votes
1answer
234 views

About 2+1 dimensional superconformal algebra

I would like to get some help in interpreting the main equation of the superconformal algebra (in $2+1$ dimenions) as stated in equation 3.27 on page 18 of this paper. I am familiar with supersymmetry ...
5
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1answer
3k views

How would the discovery of Higgs Boson affect superstring theories?

As we probably all know, a new particle similar to Higgs Boson has been discovered. If this turns out to be true, standard model will get a boost (as the discovered mass almost equals to the ...
3
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1answer
297 views

Twistor notation in space-time (Part 1)

This is sort of a continuation of this and this previous discussions. In the first of my links one sees the surjective isometry between real or complex $(1,3)$ signature Minkowski space and the real ...
1
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2answers
505 views

M-theory no lagrangian?

Is there any formulated lagrangian (density) for M-theory? If not, why is there no lagrangian? If not, is this related to many vacua existing? Thnx.
3
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1answer
322 views

Causality in String Theory

For a point particle we have light cone: String Theory- with it's extended body concepts- however will not admit a light cone such as this. In particular the most problematic causal issue would be ...
6
votes
1answer
521 views

Bosonic Tachyon Condensation?

The tachyonic string mode in perturbative bosonic string theory indicates that the "vacuum", flat Minkowski $\mathbb{R}^{25,1}$, is not really a vacuum. What is conjectured about tachyon condensation ...
4
votes
1answer
279 views

What does AdS/CFT have to say about quantum gravity in our world?

The Ads side of the AdS/CFT correspondence is a model of quantum gravity in 5 dimensional antidesitter space. What can it say about quantum gravity in our 4-spacetime dimensions? Or is it just a toy ...
1
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1answer
178 views

1-Dimensional Sigma Models

I'm currently interested in 1-dimensional (linear) Sigma Models. In the theory of 2-Dimensional GLSM, the fields can be viewed as an embedding of the worldsheet in some target Manifold of higher ...
8
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3answers
1k views

What is the physical significance of the dilaton in string theory?

Strings always have a dilaton in their spectrum. Its a scalar field (so presumably no spin), and so far a hypothetical particle. What is its physical significance?
7
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2answers
659 views

Is string length in string theory quantized?

Is there a minimal string length (maybe the Planck length), and is it quantized? Do strings have a 0-dimensional (ie point) cross-section?
4
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5answers
2k views

What differs string theory from philosophy or religion? [duplicate]

Possible Duplicate: What experiment would disprove string theory? A hypothesis without hard evidence sounds very much like philosophy or religion to me. All of them tries to establish a ...
2
votes
2answers
242 views

What exactly are right movers and left movers in string theory?

In string theory , What exactly are right movers and left movers ?Are they waves propagating along the string to the right and to the left respectively ? Can some-one please show me how to derive in ...
2
votes
2answers
349 views

Has the use of the holographic principle of string theory in condensed matter physics silenced the skeptics? [closed]

It seems to me that the use of string theory in calculations of strongly-interacting matter in condensed matter physics is an example of the theory being on the right track. And then there's the ...
6
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4answers
514 views

Is String Theory a Field Theory?

Is String Theory a Field or Quantum Mechanical Theory of the String rather than a Particle? I should know this having studied this for a term, but we jumped into the deep end, without really ...
4
votes
2answers
1k views

How does String Theory predict Gravity? [duplicate]

Firstly, General Relativity states that Spacetime is dynamic and is consonant with the distribution of matter/energy. How does String Theory predict gravity, when it is background dependent, that is ...
5
votes
0answers
203 views

The ${\cal N} = 3$ Chern-Simons matter lagrangian

This question is sort of a continuation of this previous question of mine. I would like to know of some further details about the Lagrangian discussed in this paper in equation 2.8 (page 7) and in ...
7
votes
1answer
217 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 ...
0
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1answer
107 views

Entropy, Mass and Brane gravity

Does string theory state as vibrational entropy increases, mass increases? Related: What is a D-brane? Reference: Cambridge Relativity
3
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0answers
166 views

Some more questions on conformal spinors of $SO(n,2)$

This is somewhat of a continuation of my previous question. I had stated there that a conformal spinor ($V$) of $SO(n,2)$ can be created by taking a direct sum of two $SO(n-1,1)$ spinors $Q$ and $S$ ...
6
votes
1answer
167 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 ...
3
votes
0answers
86 views

Relating the deformation of Calabi-Yau metrics and the conformal quantum field theories

(v2) As I read e.g. in this question, the nice holonomy group features of Calabi-Yau manifolds are valuable regarding supersymmetry (I suspect because it's a symmetry involving the target manifold, ...
5
votes
2answers
790 views

The multiverse of eternal inflation

I don't have a clear picture of what is "by definition" the multiverse appearing in the models of eternal inflation. A long time ago I heard that it is a quantum state, but in the cosmology books I ...
0
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0answers
75 views

Does quantum field theory accept gravitational wave?

Does quantum field theory accept gravitational wave? As quantum field theory is flat spacetime theory, I wonder whether gravitational wave would be true. Does contemporary string theory variants ...
-4
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1answer
1k views

Total Number of Dimensions in the Universe? [duplicate]

I have often heard that there are more than 4 (3 space and 1 time) dimensions of spacetime. What are the theories that say so, and how many does each predict? Has any experimental evidence been ...
3
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1answer
208 views

Lorentz spinors of $SO(n,1)$ and conformal spinors of $SO(n,2)$

It would be great if someone can give me a reference (short enough!) which explains the (spinor) representation theory of the groups $SO(n,1)$ and $SO(n,2)$. I have searched through a few standard ...
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votes
1answer
591 views

What do scientists believe about existence in dimensions? [closed]

I couldn't really think of a suitable question title, I'm not sure if it's completely related or not. But this is as far as I know (well, I thought it all up last night and it seemed extremely ...