Normal forms of elliptic automorphic Lie algebras and Landau-Lifshitz type of equations (2412.20482v1)

Abstract: We present normal forms of elliptic automorphic Lie algebras with symmetry group $D_2$, the dihedral group of order 4, which appear prominently in the context of Landau-Lifshitz type of equations. The normal forms are established through the construction of certain intertwining maps, which are formulated in terms of theta functions. Furthermore, we realise the Wahlquist- Estabrook prolongation algebra of the Landau-Lifshitz equation in terms of an automorphic Lie algebra on a complex torus with one orbit of punctures, and show that it is isomorphic to an $\mathfrak{sl}(2,\mathbb{C})$-current algebra. Finally, we show that a Lie algebra introduced by Uglov and the well-known hidden symmetry algebra of Holod are isomorphic to an elliptic $\mathfrak{sl}(2,\mathbb{C})$-current algebra.