Small instantons in weakly-gauged holographic models

Tony Gherghetta, Alex Pomarol

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Small instantons can play an important role in Yang-Mills theories whose gauge couplings are sizeable at small distances. An interesting class of theories where this could occur is in weakly-gauged holographic models (dual to Yang-Mills theories interacting with strongly-coupled CFTs), since gauge couplings are indeed enhanced towards the UV boundary of the 5D AdS space. However, contrary to expectations, we show that small instantons in these non-asymptotically-free models are highly suppressed and ineffective. This is due to the conservation of topological charge that forbids instantons to be localized near the UV boundary. Despite this fact we find non-trivial UV localized instanton-anti-instanton solutions of the Yang-Mills equations where the topological charges annihilate in the AdS bulk. These analytic solutions arise from a 5D conformal transformation of the uplifted 4D instanton. Our analysis therefore reveals unexpected nonperturbative configurations of Yang-Mills theories when they interact with strongly-coupled CFTs.

Original languageEnglish (US)
Article number136
JournalJournal of High Energy Physics
Issue number11
StatePublished - Nov 2021

Bibliographical note

Publisher Copyright:
© 2021, The Author(s).


  • AdS-CFT Correspondence
  • Field Theories in Higher Dimensions
  • Gauge-gravity correspondence
  • Solitons Monopoles and Instantons


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