Talk:Universality class
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 | The content of Ising critical exponents was merged into Universality class on 19 June 2025. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. For the discussion at that location, see its talk page. |
Mean field symmetries entry
editI think that the mean field row of the first table can be clarified somewhat. While mean field theory gives the same exponents for many symmetries, it actually doesn't give the same exponents for all symmetries, as is currently incorrectly implied in the table. As an example, the cubic term in the percolation field theory will change the beta exponent to 1 instead of 1/2 in the usual Landau mean field theory. — Preceding unsigned comment added by 2600:4040:A318:5200:99F1:6237:A79A:EF8 (talk) 18:51, 10 August 2025 (UTC)
Symmetries
editthe column "symmetries" of the table has to be rethought. Logically, this column has to refer to the symmetries of the scale-invariant fixed point, not to the symmetries of some particular representative of the universality class (i.e. of the lattice model). The symmetries of the fixed point are larger. So the part "symmetry of the interaction" has to be removed. I would keep just the internal symmetry of the fixed point in this column. All listed universality classes are rotationally and translationally invariant (and also conformally invariant).
PhysicsAboveAll (talk) 09:02, 27 March 2020 (UTC)
undirected percolation
edit"this dimension is 2d for the Ising model, or for undirected percolation, but 1d for undirected percolation"
This sentence appears contradictory. Lewis Goudy (talk) 22:34, 23 October 2017 (UTC)
update
editI think since the conformal bootstrap, some of the exponents (like 3d ising) are known more accurately? — Preceding unsigned comment added by 82.17.71.110 (talk) 18:22, 3 April 2019 (UTC)
Merged material from Ising critical exponents
editThe article Ising critical exponents was put up for deletion, with an eventual consensus against deleting it, but not solid agreement as to what to do beyond that. In order to reduce the number of distinct articles on overlapping topics in this subject area and curtail the fragmentation of the material, I have boldly merged the text of Ising critical exponents into a dedicated section of this article. Now, we can define the notation in one unified place, and we have only one article to fix up, instead of two. (I'd be inclined to split the equilibrium universality classes in the table apart from the dynamic ones like directed percolation, for example.) Stepwise Continuous Dysfunction (talk) 19:53, 19 June 2025 (UTC)
- Is it still possible to access the history and Talk page of Ising critical exponents? Sylvain Ribault (talk) 11:28, 23 June 2025 (UTC)
- Yes: here (talk page) and here (history). In fact the page "Ising critical exponents" has been deleted: it is now a redirection. Malparti (talk) 17:24, 23 June 2025 (UTC)