Abelian instantons and monopole scattering

Csaba Csáki, Rotem Ovadia*, Ofri Telem, John Terning, Shimon Yankielowicz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

It is usually assumed that 4D instantons can only arise in non-Abelian theories. In this paper we re-examine this conventional wisdom by explicitly constructing instantons in an Abelian gauge theory: QED4 with Nf flavors of Dirac fermions, in the background of a Dirac monopole. This is the low-energy effective field theory for fermions interacting with a ’t Hooft-Polyakov monopole, in the limit where the monopole is infinitely heavy (hence pointlike) and static. This theory, whose non-topological sectors were studied by Rubakov and Callan, has a far richer structure than previously explored. We show how to calculate the topological instanton number, demonstrate the existence of ’t Hooft zero modes localized around such instantons, and show how instantons in the path integral provide the underlying mechanism for the Callan-Rubakov process: monopole-catalyzed baryon decay with a cross section that saturates the unitarity bound. Our computation relies on correctly identifying the relevant 2D EFT for monopole catalysis as Axial QED2 in an effective AdS2 metric.

Original languageEstonian
Article number165
JournalJournal of High Energy Physics
Volume2024
Issue number11
DOIs
StatePublished - Nov 2024

Keywords

  • Effective Field Theories
  • Field Theories in Lower Dimensions
  • Nonperturbative Effects
  • Solitons Monopoles and Instantons

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