All Questions
Tagged with heterotic-string or string-theory
2,861 questions
3
votes
1
answer
134
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Riemann 2-manifold volume form: complex vs real
Question 1: is it always possible to write the metric in that form? Is it sufficient the local conformally-flat form to obtain the volume?
Question 2: Is the volume form in (4.1) well-defined? Going ...
- 129
1
vote
0
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85
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Can a universe with only one spatial dimension and one time dimension still produce complex physical behaviour? [closed]
Can a universe with only one spatial dimension and one time dimension still have meaningful physics? For example, can quantum fields in 1+1 dimensions produce effects similar to higher dimensions, or ...
- 19
1
vote
0
answers
64
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Worldsheet ADM Formalism & Hamiltonian Path Integral
Consider the following bosonic NS-NS sector of closed string worldsheet action, having the following spacetime fields - metric tensor $G_{\mu\nu}(x)$ Kalb-Ramond Field $B_{\mu\nu}(x)$ and scalar ...
0
votes
0
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71
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EOM of Nambu-Goto in second fundamental form
I am computing the EOM of the Nambu-Goto action $$S[X] = -T\int d^2 \sigma \sqrt{-\det{(\partial_a X^\mu \partial_b X_\mu)}}$$ and I want to write this in a specific form using the second fundamental ...
- 688
3
votes
1
answer
121
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D-branes, string field theory, and Chern-Simons
Reading the book$^{\dagger}$ Chern-Simons Theory, Matrix Models, and Topological Strings by Marcos Marino, I'm trying to understand the argument in 7.3.2: here are my main questions which can also be ...
- 592
1
vote
0
answers
84
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How to calculus the corresponding operators of bosonic beta-gamma ghost systems? [closed]
In Polchinski's book, it states that the corresponding operators of $|1\rangle, |-1\rangle$ are $\delta(\beta),\delta(\gamma)$, and suggests that it can be shown by path integral. I'm a little ...
- 19
2
votes
1
answer
133
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Structure constants of quantum cohomology of (partial and complete) flag varieties [closed]
I have an extremely efficient way to compute the structure constants of the quantum cohomology rings of partial flag varieties (which are modeled by quantum (parabolic) Schubert polynomials, the three-...
- 173
4
votes
2
answers
199
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Integrals in Euclidean plane with complexified coordinates?
Calculations are carried out in Euclidean plane with complexified coordinates $z,\bar{z}$ as we do in CFT. I need to derive the following:
$$\int{\frac{d^2 z_1}{(z-z_1)(\bar{z_1}-\bar{w})}}=\pi\ln{|z-...
- 523
0
votes
0
answers
171
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Why are strings in string theory considered as elementary?
I was reading "The classical theory of fields" by Landau & Lifshitz and, in the beginning of the third chapter of the 4th edition, they explain that the existence of a rigid body is ...
- 139
3
votes
1
answer
187
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How does string theory handle non-renormalizability of QED in $d>4$?
Quantum electrodynamics is non-renormalizable in more than four dimensions (see Peskin & Schroeder, chapter 10). This would seem to put it on similar footing as gravity for $d>4$ in the sense ...
- 3,352
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123
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Why is the string worldsheet theory a CFT?
Why do we say that the (gauge-fixed) worldsheet theory in string theory is a conformal field theory (CFT)? Where exactly does this conformal invariance come from? Is it simply because, after gauge ...
- 135
0
votes
1
answer
127
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Why conformal gauge?
In the path integral of the bosonic string, we fix the gauge by setting the metric $ h $ to a reference metric $ \hat{h} $. A common choice is the conformal gauge:
\begin{equation}
h_{\alpha \beta} \...
- 135
13
votes
2
answers
2k
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Is it true that string theory is definitively wrong on account of it being a theory of an anti de Sitter space?
I'd like to preface this by mentioning that I come from an experimental astrophysics background, and am woefully ignorant of string theory. I apologize if I ask something particularly ignorant or ...
- 349
2
votes
0
answers
137
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Wick contraction in CFT
I am reading Tong's lecture notes on CFT and I can't reproduce a result at pag. 82
$$T(z):e^{ikX(w)}:=-\frac{\alpha'^{2}k^{2}}{4}\frac{:e^{ikX(w)}:}{(z-w)^{2}}+ik\frac{:∂X(z)e^{ikX(w)}:}{z-w}+...\tag{...
- 783
0
votes
1
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147
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Chan-Paton factors and gauge symmetries?
In Ammon and Erdmenger's book on AdS/CFT there is a short discussion on Chan-Paton factors. They state in chapter 4
Although the Chan–Paton factors are global symmetries of the worldsheet action, the ...
- 688