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9 votes
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What are double groups mathematically?

As far as I can tell, a double group is a double cover of a group. Specifically, if $G \subset \operatorname{SO}(n)$ is a group acting by rotations of $n$-dimensional space, its double group is the ...
Theo Johnson-Freyd's user avatar
8 votes
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Is the Gödel universe Wick rotatable?

$\DeclareMathOperator\SL{SL}$Clearly, as Robert Bryant indicates, it is Wick-rotatable to a different Lorentzian space. However, it is also Wick-rotatable to a Riemannian space, albeit negative ...
Sigbjørn Hervik's user avatar
3 votes
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7-sphere x 4-sphere manifold and its physical significance

I suppose that you don't really mean for both spaces to be spheres, so I will interpret your question about the (4,7) split. The context here is eleven-dimensional supergravity and the studies of ...
José Figueroa-O'Farrill's user avatar
4 votes

Why computing $n$-point correlations?

Now, suppose I am not interested in QFT (in the sense that I don't want to quantize a classical field) but, instead, I want to study many body quantum mechanics. Tough luck! :-) These are ...
Igor Khavkine's user avatar
2 votes

Why computing $n$-point correlations?

The $n$-point functions for $n\ge 3$ are required if you are interested in how your system responds to an external probe $\phi$ (e.g. an electromagnetic field). You have to couple this to your system ...
gmvh's user avatar
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4 votes

Why computing $n$-point correlations?

In physics, you certainly want to do more than just find the energy eigenvalues that you get from the 2-point functions. You also want to evaluate matrix elements of operators in the corresponding ...
Michael Engelhardt's user avatar
6 votes

Why computing $n$-point correlations?

Quite generally, three-point (and higher order) correlators are used to reveal the non-Gaussian (read: nonclassical) character of the fields, see for example Experimental characterization of a quantum ...
Carlo Beenakker's user avatar
2 votes

Reference for rigorous interacting many-body quantum mechanics

I believe all of these topics and more are also covered in Dereziński, Jan; Gérard, Christian, Mathematics of quantization and quantum fields, Cambridge Monographs on Mathematical Physics. Cambridge: ...
Igor Khavkine's user avatar
4 votes

Reference for rigorous interacting many-body quantum mechanics

A textbook that covers much ground in a mathematically rigorous way is Mathematical Methods of Many-Body Quantum Field Theory by Detlef Lehmann (2004). This book offers a comprehensive, ...
Carlo Beenakker's user avatar
8 votes

Is the Gödel universe Wick rotatable?

I may be misreading the sources that you list for the definition of Wick-rotatable, but, I believe that the following construction does fit that definition: According to the Wikipedia page that the ...
Robert Bryant's user avatar

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