Talk:Skyrmion

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Wrong concept[edit]

"where SU(N)L and SU(N)R are the left and right parts of the SU(N) matrix"

There is no such thing as left and right part of an SU(N) matrix. The group in question is a direct product and the left and right parts refer to the subgroups of the direct product isomorphic to the two SU(N) factors. The origin of this is the approximate flavor chiral symmetry present in the quark model. — Preceding unsigned comment added by Moribana (talk • contribs) 16:35, 21 January 2014 (UTC)[reply]

Yep. See comment below. The left and right parts refer to the two inequivalent but still isomorphic fundamental representations of the Lie algebra. Why there are two, and why they are inequivalent but isomorphic is a topic from the representation theory of Lie algebras, and that is a rather deep and complex topic on it's own. So technically, the original wording was fine: there actually are two parts. It was just a bit poorly stated. 67.198.37.17 (talk) 03:47, 5 July 2017 (UTC)[reply]

Ungrammatical sentence[edit]

The second sentence ("It arises ... the diagonal subgroup") is ungrammatical and therefore uninterpretable. A full sentence could end grammatically after "(the structure group)", but then there is a dangling part that has no discernible grammatical relationship with the rest. --LambiamTalk 07:11, 25 August 2006 (UTC)[reply]

No kidding, does anyone know enough about the topic to discern what is trying to be said?Millertime246 (talk) 22:15, 29 October 2011 (UTC)[reply]
Its the diagonal vector subgroup of the chiral group. (as opposed to the axial vector subgroup). I don't understand what the problem is. 67.198.37.17 (talk) 03:49, 5 July 2017 (UTC)[reply]
Oh. I see the confusion. There are two inequivalent but isomorphic fundamental representations of the Lie algebra. They are charge-conjugate to each other. Getting into the representation theory of Lie groups is a bottomless pit. But, to keep it short, in physics, these two are used to represent particles and anti-particles (e.g. that's why there are three quarks in QCD: they are the roots of the root system for SU(3).) The Littlewood-Richardson coefficients (aka Clebsch-Gordon coefficients, when its su(2)) tell you how to combine different representations; here, they are used to combine left and right into a vector current (the rho meson), and an axial vector current. Articulating all of this "common knowledge" is way beyond the scope of this article. Unfortunately, this "common knowledge" is also exactly what pretty much everyone doesn't quite get, and I don't know what to do about that. 67.198.37.17 (talk) 05:44, 5 July 2017 (UTC)[reply]

graphene references[edit]

See many papers on skyrmions in graphene, from the past decade: http://arxiv.org/pdf/1202.6047.pdf . Also needs a link to Tony Skyrme. – SJ + 19:59, 21 September 2012 (UTC)[reply]

Still Hypothetical?[edit]

There appears to be substantial research going on and from the writeups I've read, they're not sounding very hypothetical. They're sounding pretty real. This article from Nature, for example: http://www.nature.com/news/twisted-magnetic-fields-tie-information-in-a-knot-1.13530 70.182.96.10 (talk) 13:02, 9 August 2013 (UTC)[reply]

Seems pretty conclusive now. "Realization of Ground State Artificial Skyrmion Lattices at Room Temperature". Nature Communications. 6: 8462. 8 October 2015. doi:10.1038/ncomms9462. {{cite journal}}: Cite uses deprecated parameter |authors= (help); Unknown parameter |laysource= ignored (help)

LeadSongDog come howl! 16:34, 8 October 2015 (UTC)[reply]

The magnetic skyrmions might no longer be hypothetical. The nuclear skyrmions are, and might continue to be, because we know that QCD is a better model for the nucleon. However, mathematicians and physicists both are making slow progress towards demonstrating that low-energy QCD might in fact be the skyrme model. This article is trying to cover multiple topics at once. 67.198.37.17 (talk) 03:53, 5 July 2017 (UTC)[reply]

Demonstrated experimentally, see "Synthetic electromagnetic knot in a three-dimensional skyrmion."[1] Dsmatthews (talk) 22:42, 4 March 2018 (UTC)[reply]

Lee, Wonjae; Gheorghe, Andrei H.; et al. (2 March 2018). "Synthetic electromagnetic knot in a three-dimensional skyrmion". Science Advances. 4 (3): eaao3820. doi:10.1126/sciadv.aao3820.

[2]

A picture could really help this article[edit]

References

  1. ^ DOI: 10.1126/sciadv.aao3820
  2. ^ Lee, Wonjae; Gheorghe, Andrei H.; et al. (2 March 2018). "Synthetic electromagnetic knot in a three-dimensional skyrmion". Science Advances. 4 (3): eaao3820. doi:10.1126/sciadv.aao3820.

"Hollowed-out skyrmion"?[edit]

Is there a layperson's explanation (whatever that means here) of the term "hollowed-out" skyrmion? Jimw338 (talk) 17:32, 12 November 2019 (UTC)[reply]

Conserved current is not Noether[edit]

The winding number is a topological current, it is not related to a continuous symmetry, so it is not a Noether current for the chiral symmetry.

Meron[edit]

A meron is a a second-order half-skyrmion https://scitechdaily.com/second-order-optical-merons-or-light-pretending-to-be-a-ferromagnet/ Maybe worth to mention. --Ernsts (talk) 15:21, 2 March 2021 (UTC)[reply]

Etymology[edit]

There really needs to be something explaining where the name comes from. Without that it feels like turboencabulator language to me. Hellbus (talk) 01:28, 26 April 2021 (UTC)[reply]

Really? Something like: from [Tony ]Skyrm[e]+[ferm]ion ?

It would be nice to know who coined the term. It's a bit mysterious Found it - OED (OED Online, Oxford University Press, March 2021, accessed 26 April 2021) points to an article on 'chiral solitons and current algebra' by Namik K.Pak and Hsiung Chia Tze that appeared in 1979 in Annals of Physics vol 117, p 174

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