# Tagged Questions

String theory is an research framework in particle physics that attempts to reconcile quantum mechanics and general relativity.

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### String Theory: What to do?

This is going to be a relatively broad/open-ended question, so I apologize before hand if it is the wrong place to ask this. Anyways, I'm currently a 3rd year undergraduate starting to more seriously ...
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### Algebraic Geometry in String Theory?

I'm currently studying String Theory and hope to do research in this area. I have now reached a point where even with a background in Mathematics instead of Physics, I have no clue what's going on ...
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### Complex and Kähler-manifolds

I was woundering if anyone knows any good references about Kähler and complex manifolds? I'm studying supergravity theories and for the simpelest N=1 supergravity we'll get these. Now in the course-...
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### CFT's vs Vertex Operator Algebras

I am trying to clear my ideas about the relation between a Conformal Field Theory (CFT) and a Vertex Operator Algebra (VOA). For me a CFT based on a (complex) vector space $H$ is a projective monoidal ...
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### Solving numerically the equation of motion of D7 brane perturbation

I want to solve this equation $$\partial_{\rho}^{2}\phi+\frac{3}{\rho}\partial_{\rho}\phi+\left(\frac{M^{2}}{(1+\rho^{2})^{2}}-\frac{l(l+2)}{\rho^{2}}\right)\phi=0$$ numerically. I know that ...
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### Trace identities for $\text{SO}(n)$

The Green-Schwarz mechanism in Type I string theory involves certain identities relating traces in the vector and adjoint representations of $\text{SO}(n)$ of dimension $n$ and $n(n - 1)/2$ ...
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### (Soft Question) How active an area of research is Non-Commutative Geometry? [closed]

I am currently an undergraduate, but I am considering applying for a phd in algebraic geometry or a related field. I am quite interested in the link between non-commutative geometry and theoretical ...
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### Why are there cubics in a Calabi-Yau manifold?

I heard from a recent talk that the "number of $n$-degree curves" in a Calabi-Yau manifold is an invariant of the space. But what does that mean? (Specifically I would like to ask the following.) ...
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### What is a good gentle introduction to the Virasoro algebra and its application in theoretical physics?

I am looking for an as gentle and pedagogical as possible introduction that explains the Virasoro algebra and its applications in theoretical physics; finally I am interested in its application in ...
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### Physical interpretation of categorical structures related to Dirichlet Branes

In Dirichlet Branes and Mirror Symmetry by Aspinwall et al, section 5.9 discusses various questions that remain open. In particular they say: "There are many constructions from homological ...
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### Status of a question from Freeman Dyson's 1972 article

In a famous article, Freeman Dyson mentions an interesting relationship between the $\tau$ functions of number theory and the dimensions of finite-dimensional simple Lie algebras (section 2). He ...
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### rigorous treatment of infinitesimal reparametrizations

my first post :) I am asking this directed to mathematicians or mathematical physicists since I don't like the usual physics approach. Reading some string theory books I always find that the ...
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### Semi-infinite forms?

I am reading Vafa's paper 'Topological Mirros and Quantum Strings'(arXiv:hep-th/9111017). In this paper, the author says the Hilbert Space of a fermionic string theory corresponds to the space of semi-...
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### Weyl transformation of geodesic distance

Consider a Riemannian manifold $M$ with a metric $g$. For two points $x,y \in M$ the geodesic distance $d(x,y)$ is defined in the usual way. I would like to know if there is a formula expressing how ...
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### Are $T^2/Z_2$ orbifolds just ironed spheres?

(Note that this question is migrated from the physics SE... I apologize for the imprecise language) The only $Z_2$ symmetries I can think of the torus are reflection on plane, whose quotient should ...
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### Chandrasekhar history [closed]

I have misplaced an article by Chandrasekhar from the mid 90's in which he drew an analogy between himself and his neat desk and a co-laborer 'down the hall' who was more chaotic with managing his ...
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### String probability (with conditional prob and combinations)

I'm having trouble with the questions below, all relating to string probability. I'll write the problem and then provide my work for my (incorrect) answer. Please help me figure out what I did wrong. ...
Consider the Thue-Morse string. Suppose it has $n$ elements. My question is: how many different substrings(or subsequence) in this string. Actually I'm interest in bound of this value. Is it smth ...