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  • Open Access

Yang-Baxter sigma model from twistor space

Meer Ashwinkumar1,* and Jitendra Pal2,†

  • *Contact author: meer.ashwinkumar@unibe.ch
  • †Contact author: jeetupal007@gmail.com

Phys. Rev. D 114, 046008 – Published 10 August, 2026

DOI: https://doi.org/10.1103/99hb-q8bd

Abstract

We derive a novel two-field four-dimensional integrable field theory (IFT) from 6D holomorphic Chern-Simons theory on twistor space. The four-dimensional IFT depends on a skew-symmetric linear operator acting on a Lie algebra, and when this operator is specialized to a solution of the modified classical Yang-Baxter equation, the IFT develops a semilocal symmetry associated with this solution. The resulting 4D analog of the Yang-Baxter sigma model is related by symmetry reduction to the well-known 2D Yang-Baxter sigma model. An important implication that we find is the embedding of the equations of motion of the 2D Yang-Baxter sigma model in the anti-self-dual Yang-Mills equations. The 6D Chern-Simons theory on twistor space can alternatively be symmetry reduced to a 4D Chern-Simons theory configuration with disorder surface defects. The latter realizes the Yang-Baxter sigma model, implying a “diamond” for the Yang-Baxter sigma model obtained from twistor space. We also show that the homogeneous 2D Yang-Baxter sigma model can be derived from a limit of our setup.

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