Talk:Gell-Mann matrices

I have two suggestions:

Firstly, the statement that there are three independent copies of SU(2) is not correct. Since x, y and lambda_3 are linear combinations of one another, the three subalgebras are not independent.

Secondly, at some points in the article there is confusion as to whether we are talking about a Lie Group or a Lie Algebra. The Gell-Mann matrices are a basis for the Lie Algebra, so we should refer to there being three L(SU(2)) subalgebras, where L(SU(2)) is the Lie Algebra of SU(2). We could use the more standard Fraktur script to represent this.

Speedlemur (talk) 13:39, 17 April 2015 (UTC)[reply]

Construction site reorganization

It appears User:75.139.254.117 is planning to reorganize the article, by providing here more context to those unfamiliar with Lie algebra representations, presumably refugees from QCD. However, it would be better to actually provide the improvements incrementally himself, rather than littering the article with templates instructing the passer-by to provide filler, and spooking the reeder seeking facts. In particular, the plea for clarification to a perfectly concise instruction for the structure constants vanishing, unless they fit into the class explicitly constructed, and the reason why is completely unwarranted, and was removed, as it was all but guaranteed to confuse the reader. Cuzkatzimhut (talk) 23:48, 10 January 2017 (UTC)[reply]

In any case, it would be redundant and disorienting to reduplicate the more complete, and sensible!, coverage of Clebsch–Gordan coefficients for SU(3). There is a real danger of converting a concise "resource" article of quick reference into a confused and turgid appendix of a bad High Energy Theory text, of which there are so many that confused readers thereof end up here. It is also important to keep things mathematically sound. Please discuss first.Cuzkatzimhut (talk) 00:04, 11 January 2017 (UTC)[reply]

I addressed the latest spate of gratuitous huh? templates , hopefully to the OP's satisfaction. It really would be best for him to first voice his concerns here, rather than splattering templates on the page and thereby inviting confusion rather than allaying it. This is a short article reminding the student of the basic properties of a highly specialized and arbitrary, albeit supremely intuitive and useful basis, but it cannot possibly provide a Lie algebra tutorial to somebody unfamiliar with them (L-As). Most good texts in HEP, including the refs, cover the basics, but poor Murray's matrices cannot possibly raise a reader to full L-A competence. Sylvester's nonions might be better for that purpose. Cuzkatzimhut (talk) 14:31, 12 January 2017 (UTC)[reply]

The standard argument about the nonvanishing structure constants is what undergraduates learn upon introduction to SU(3), namely that since

{\frac {-i}{2}}\mathrm {tr} ([\lambda _{m},\lambda _{j}]\lambda _{k})=f_{mjk}

,

transposition of the argument of the trace yields a minus sign from the commutator, so requiring an odd number of antisymmetric λs if f is not to equal to minus itself. Cuzkatzimhut (talk) 17:58, 12 January 2017 (UTC)[reply]

Gluon modelling via SU(3)

Unfortunately, I have nowhere near the level of understanding to complete it myself, but I think the article could benefit from some additional exposition on its role in generating SU(3), and through this, its role in the Lie group U(1)×SU(2)×SU(3) used in the Standard Model (per Lie group#Examples with a specific number of dimensions and Special unitary group#n = 3). — Sasuke Sarutobi (talk) 13:13, 13 January 2017 (UTC)[reply]

Pardon I fail to understand your comment: Both of these issues are dealt with in the appropriate pages, and notably the Special unitary group#n = 3 you refer to. Why do you want improvements/explications of these articles here? In particular, in that very link, the generation of the group is worked out explicitly: you get the complete, explicit closed formula of the general SU(3) element in the triplet representation. What exactly, are you proposing? Copying that material here to spare the reader a mouse click? Re: HEP and gluons, so QCD, again, why would anyone come here, rather than go there, for this information? Why would G-M matrices need to know about the weak isospin and hypercharge groups, which, by the very construction, know nothing about them? This sounds odd. This ex-stub is a narrow tabulation of basics for G-M matrices and their properties, for quick reference, not a tutorial on Lie Algebras or particle physics gauge theories. Can you be more explicit about what you propose? Cuzkatzimhut (talk) 15:44, 13 January 2017 (UTC)[reply]

Adduced more technical Clebsch–Gordan coefficients for SU(3) link, but, again, this is not a tutorial for the layman--could try Wikiversity for that. Cuzkatzimhut (talk) 17:29, 22 November 2017 (UTC)[reply]

Typo in the matrix definition

Factors g_i/2 are mentioned in the first section but don't appear anywhere.