Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options answers only not deleted user 121

Mathematical methods in classical mechanics, classical and quantum field theory, quantum mechanics, statistical mechanics, condensed matter, nuclear and atomic physics.

20 votes

Theoretical physics: Why not just $\mathbb{R}^4$?

I can answer your literal question. Not everyone studies exotic $\mathbb{R}^4$, because the universe of mathematical and theoretical physics is a big one with many interesting ideas, and there's no r …
S. Carnahan's user avatar
  • 45.7k
9 votes
Accepted

Why are operads so closely connected to mathematical physics?

I'm not a mathematical physicist, so parts of this may be wrong. In quantum field theory, one encounters operators that are supported at points in spacetime, or at least are very local. For example …
S. Carnahan's user avatar
  • 45.7k
9 votes

Where does a math person go to learn quantum mechanics?

I disagree (though not particularly strongly) with the comments claiming that you should learn classical mechanics first. You don't need much physics background to learn to do basic calculations with …
9 votes

Physicists misuse the term "Kac Moody algebra". Does that bring problems?

I can't address all uses by all physicists, but in many contexts, they consider only representations at a fixed level that admit a well-behaved energy grading. That is, sometimes an energy grading is …
S. Carnahan's user avatar
  • 45.7k
8 votes
Accepted

What are braided vertex algebras?

For the case of vector spaces graded by an abelian group (with braiding determined by an abelian 3-cocycle following Joyal-Street), this was done by Dong and Lepowsky in their 1993 book "Generalized V …
S. Carnahan's user avatar
  • 45.7k
7 votes
Accepted

The use of Schur's lemma for Lie algebras in physics (CFT)

Let $\mathfrak{g}$ be a complex Lie algebra with a distinguished nonzero central element $x$, and let $V$ be an irreducible representation of $\mathfrak{g}$. The usual proof of Schur's lemma can be a …
S. Carnahan's user avatar
  • 45.7k
6 votes
Accepted

One particle irreducible Feynman diagrams

Section 5 of Borcherds, Barnard, Lectures on Quantum Field Theory is a discussion of the 0-dimensional spacetime case, which gives finite dimensional integrals.
S. Carnahan's user avatar
  • 45.7k
5 votes
Accepted

When two vertex (operator) algebras can be patched-up to a full CFT on a genus 0 surface?

If your VOA $V$ is not rational, then it is quite unlikely that its category of representations is a modular tensor category. That is, you can safely conclude that Theorem 3 contains an unstated assu …
S. Carnahan's user avatar
  • 45.7k
5 votes
Accepted

On $e^{\pi\sqrt{4\cdot163}}$ and unusual connections

I'm not an expert on black holes, but I can give you a couple pointers. From work of Bekenstein and Hawking in the 1970s, we are pretty sure that macroscopic black holes in our 3+1 dimensional univer …
S. Carnahan's user avatar
  • 45.7k
5 votes

Phase transitions between Category Theories

In general, we expect field theories to be described by some higher categorical structures, where bulk models are assigned objects (also called 0-morphisms), domain walls are assigned morphisms (also …
S. Carnahan's user avatar
  • 45.7k
5 votes
Accepted

Manifolds whose isometry group is Pati-Salam?

$S^3 \times S^5$ has isometry group $SO_4(\mathbb{R}) \times SO_6(\mathbb{R})$, which has $SU(2) \times SU(2) \times SU(4)$ as a four-fold cover. Since it appears that you aren't worrying too much ab …
S. Carnahan's user avatar
  • 45.7k
4 votes

decomposition of Hilbert space into tensor product $L^2([0,\tfrac{1}{2}]) \otimes L^2([\tfra...

I think the suggested example is not a good fit for illustrating a tensor product decomposition, because $L^2$ functions on an interval are most naturally identified with states of a single particle i …
S. Carnahan's user avatar
  • 45.7k
4 votes
Accepted

Morphisms of supermanifolds

The ring of functions on your supermanifold is $C^\infty(\mathbb{R}) \otimes \mathbb{C}[a,b]$, where $a$ and $b$ are odd. The even part is then $C^\infty(\mathbb{R}) \oplus C^\infty(\mathbb{R})ab$, w …
S. Carnahan's user avatar
  • 45.7k
4 votes

question about notation

The notation $*/\!/G$ refers to the topological groupoid with a single object, whose morphisms are described by the compact Lie group $G$. The double slash in this context means groupoid quotient, an …
S. Carnahan's user avatar
  • 45.7k
4 votes
Accepted

Relationship between irreducible representations of the Schur covering group and elements of...

The answer to your question is Yes. Consider your covering group $C$ as a central extension: $$1 \to N \to C \to G \to 1$$ and suppose it is given by a 2-cocycle $\alpha \in H^2(G, N)$. Then for any …
S. Carnahan's user avatar
  • 45.7k

15 30 50 per page