Fractional instantons and bions in the O(N) model with twisted boundary conditions

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Abstract

Abstract: Recently, multiple fractional instanton configurations with zero instanton charge, called bions, have been revealed to play important roles in quantum field theories on compactified spacetime. In two dimensions, fractional instantons and bions have been extensively studied in the ℂP<sup>N−1</sup> model and the Grassmann sigma model on ℝ<sup>1</sup> × S<sup>1</sup> with the ℤ<inf>N</inf> symmetric twisted boundary condition. Fractional instantons in these models are domain walls with a localized U(1) modulus twisted half along their world volume. In this paper, we classify fractional instantons and bions in the O(N) nonlinear sigma model on ℝ<sup>N−2</sup> × S<sup>1</sup> with more general twisted boundary conditions in which arbitrary number of fields change sign. We find that fractional instantons have more general composite structures, that is, a global vortex with an Ising spin (or a half-lump vortex), a half sine-Gordon kink on a domain wall, or a half lump on a “space-filling brane” in the O(3) model (ℂP<sup>1</sup> model) on ℝ<sup>1</sup> × S<sup>1</sup>, and a global monopole with an Ising spin (or a half-Skyrmion monopole), a half sine-Gordon kink on a global vortex, a half lump on a domain wall, or a half Skyrmion on a “space-filling brane” in the O(4) model (principal chiral model or Skyrme model) on ℝ<sup>2</sup> × S<sup>1</sup>. We also construct bion configurations in these models.

Original languageEnglish
Article number108
Pages (from-to)1-38
Number of pages38
JournalJournal of High Energy Physics
Volume2015
Issue number3
DOIs
Publication statusPublished - 2015 Mar 1

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instantons
boundary conditions
domain wall
vortices
monopoles
composite structures
configurations

Keywords

  • Sigma Models
  • Solitons Monopoles and Instantons

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

Fractional instantons and bions in the O(N) model with twisted boundary conditions. / Nitta, Muneto.

In: Journal of High Energy Physics, Vol. 2015, No. 3, 108, 01.03.2015, p. 1-38.

Research output: Contribution to journalArticle

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