added pointer to:

- Edward Witten,
*Some Milestones in the Study of Confinement*, talk at*Prospects in Theoretical Physics 2023: Understanding Confinement*, IAS (2023) [web, YT]

with this quote:

]]>26:26: “by now it’s clear [Lucini & Teper 2001] that lattice gauge theory, at least for the glueball sector, has made it clear that the $1/N$-expansion is a good approximation to the real world, especially if you include a leading correction to the large $N$ limit. Now unfortunately this is best established in the glueball sector, which is not very accessible experimentally.”

28:56: “but the $1/N$ expansion doesn’t explain everything. In fact, it’s not hard to find phenomena in meson physics where the $1/N$-expansion does

notwork well.”36:15: “I suspect the $1/N$-expansion works reasonably well for many aspects of baryons. However, as for mesons, it is easy to point to things that won’t work well for baryons. In particular, among other things, I don’t think the $1/N$ expansion will be successful for nuclei as opposed to individual nucleons.”

37:12: “I don’ t think the phenomenological models used by nuclear physicists would have any success at of if the large N limit was a good description of nuclei.”

added pointer to today’s:

- Yosuke Imamura,
*Finite-$N$ superconformal index via the AdS/CFT correspondence*(arXiv:2108.12090)

added pointer to

- Masayasu Harada, Shinya Matsuzaki, and Koichi Yamawaki,
*Implications of holographic QCD in chiral perturbation theory with hidden local symmetry*, Phys. Rev. D 74, 076004 (2006) (doi:10.1103/PhysRevD.74.076004)

added this pointer:

- David Jorrin, Nicolas Kovensky, Martin Schvellinger,
*Towards $1/N$ corrections to deep inelastic scattering from the gauge/gravity duality*, JHEP 04 (2016) 113 (arXiv:1601.01627)

added this pointer on 1/N corrections in 2d QCD:

- Itzhak Bars,
*QCD and Strings in 2D*(arXiv:hep-th/9312018)

That would be fun if M-theory could help out with the four-colour problem!

]]>I wonder if Bar-Natan didn’t know that the double line construction he uses so effectively is earlier due to ’t Hooft, or if he intentionally chose to never cite him. Seems a curious omission.

]]>Thanks, excellent. So let’s add that to all related entries:

On the logical equivalence between the four-colour theorem and a statement about transition from the small N limit to the large N limit for Lie algebra weight systems on Jacobi diagrams via the ’t Hooft double line construction:

- Dror Bar-Natan,
*Lie Algebras and the Four Color Theorem*, Combinatorica 17-1(1997) 43–52 (arXiv:q-alg/9606016, doi:10.1007/BF01196130)

I was just reminded of John Baez years ago describing Bar-Natan’s paper on the four-color problem and the relation between $SU(2)$ and $SU(n)$ gauge theory. Bar-Natan’s paper is here.

]]>now some minimum in place.

]]>Starting something. Not done yet, but need to save.

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