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The Sakai-Sugimoto soliton

Bolognesi, S.; Sutcliffe, P.M.

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S. Bolognesi


The Sakai-Sugimoto model is the preeminent example of a string theory de- scription of holographic QCD, in which baryons correspond to topological solitons in the bulk. Here we investigate the validity of various approximations of the Sakai-Sugimoto soliton that are used widely to study the properties of holographic baryons. These ap- proximations include the flat space self-dual instanton, a linear expansion in terms of eigenfunctions in the holographic direction and an asymptotic power series at large radius. These different approaches have produced contradictory results in the literature regarding properties of the baryon, such as relations for the electromagnetic form factors. Here we determine the regions of validity of these various approximations and show how to relate different approximations in contiguous regions of applicability. This analysis clarifies the source of the contradictory results in the literature and resolves some outstanding issues, including the use of the flat space self-dual instanton, the detailed properties of the asymp- totic soliton tail, and the role of the UV cutoff introduced in previous investigations. A consequence of our analysis is the discovery of a new large scale, that grows logarithmically with the ’t Hooft coupling, at which the soliton fields enter a nonlinear regime. Finally, we provide the first numerical computation of the Sakai-Sugimoto soliton and demonstrate that the numerical results support our analysis.


Bolognesi, S., & Sutcliffe, P. (2014). The Sakai-Sugimoto soliton. Journal of High Energy Physics, 2014(1), Article 78.

Journal Article Type Article
Acceptance Date Dec 23, 2013
Online Publication Date Jan 16, 2014
Publication Date Jan 16, 2014
Deposit Date Jan 29, 2014
Publicly Available Date Feb 4, 2014
Journal Journal of High Energy Physics
Print ISSN 1126-6708
Publisher Scuola Internazionale Superiore di Studi Avanzati (SISSA)
Peer Reviewed Peer Reviewed
Volume 2014
Issue 1
Article Number 78
Keywords Solitons Monopoles and Instantons, AdS-CFT Correspondence.


Published Journal Article (798 Kb)

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Copyright Statement
This article is distributed under the terms of the Creative Commons
Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in
any medium, provided the original author(s) and source are credited.

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