Questions tagged [string-theory]
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.
2,825 questions
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When was the Regge trajectories first proven with $J\sim M^2$?
In Regge's original papers in 1959 and 1960, the function between spin and energy was shown, however, the inequality was proven for a bound of $\frac{1}{\sqrt{E}}\sim \frac{1}{M}$, which is also what'...
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Question on basic strings in curved spaces
Recently when studying strings on curved spaces I arrived at a question that I wasn't able to answer myself. In the particular setup I'm using, I'm considering the Polyakov action $$S = - \frac{T}{2}\...
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SUSY QM as point-particle limit of Superstrings
There is a pretty clear resemblance between the Lagrangians for SUSY QM (1-dim susy sigma model) and various superstring theories (2-dim susy sigma models). Again intuitively, one should expect the ...
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Global conformal gauge
I'm reading the Blumenhagen-Lust-Theisen book on string theory. On page 18, They want to discuss whether a global conformal flat metric can exist, namely $$ h_{\alpha\beta}=e^{2\phi}\eta_{\alpha\beta} ...
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Inner automorphism in $G$-WZW model
In the context of $G$-WZW model, the claim is that inner twist of a $G$-valued field, $g(\sigma, \tau) : \Sigma\rightarrow G$, can be absorbed into a trivial field redefinition. Suppose that the twist ...
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What is the relationship between $g_s$ and $\alpha'$?
On page 300 in the book "string theory and M-theory" by M. Becker-Becker-Schwarz, the author mentions "we have described in previous chapters that how various superstring theories ...
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Magnetic dual of M2 branes and M5 branes?
Why do we say: the M2 branes and M branes are magnetic dual?
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Field redefinition to absorb counter term
Consider the following string action $$S = \frac{1}{4\pi\alpha'} \int d^2\xi \bigg[\alpha'\eta_{\mu\nu}\partial_\alpha Y^\mu\partial^\alpha Y^\nu - \frac{(\alpha')^2}{3}R_{\mu\alpha\nu\beta}(X_0) Y^\...
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String theory suppose world-sheet is globally conformally flat?
It is known that every 2-dimensinal Lorentzian manifold is conformally flat and in general it's not globally conformally flat. (Here, globally conformally flat means there are a global coordinates ...
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String theory without coordinates
I'm sorry but I'm not good at English. If you find any sentence or word doesn't make sense, please comment. Is there any string theory's book or review reference that doesn't use coordinate-depending ...
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Dine-Seiberg moduli
The Dine-Seiberg problem requires $\lim _{\Phi \to \infty } V(\Phi )=0$ where $V$ is the scalar superpotential. And in type IIB SUGRA, your moduli are essentially the axiodilaton, Kahler moduli and ...
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How much do we know about Yukawa couplings?
Wikipedia says that "The Yukawa coupling for any given fermion in the Standard Model is an input to the theory. The ultimate reason for these couplings is not known: it would be something that a ...
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1answer
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Does string theory predict the list of elementary particles?
Does string theory predict the list of elementary particles? I mean that like the Schrödinger equation predicts a discrete list of possible energies for THE electron of hydrogen atom, some equation of ...
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Where does the string theory’s exponentially damped propagator come from?
I was reading Quantum Gravity and Quantum Cosmology (edited by Gianluca Calcagni, Lefteris Papantonopoulos, George Siopsis, and Nikos Tsamis, p. 6), and I came across this interesting statement about ...
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1answer
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Supercurrent from supersymmetric
In the book "Superstring Theory" by Green-Schwarz-Witten on page 189 (vulume 1) the author give the formula for the supercurrent (by Neother method) as $$J_{\alpha}=\frac{1}{2}\rho^{\beta}\...
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