Witt type Realizations of 2-D Cayley-Klein Algebras with non-zero curvatures
Arindam Chakraborty
TL;DR
<3-5 sentence high-level summary> This paper develops Witt-type vector-field realizations of 2-D Cayley-Klein algebras with non-zero curvatures by constructing 2×2 matrix generators from bi-orthogonal systems and then expressing the corresponding Lie algebra actions as differential operators via Jacobi elliptic functions. It shows how the elliptic modulus, tied to bi-orthogonality, controls these realizations and demonstrates how modular transformations extend the constructions to arbitrary moduli, including cases with modulus k′ and general |λ|. The work presents multiple concrete realizations using elliptic, reciprocal, and modular-transformation-based methods, discusses an intrinsic Casimir operator to address representation-dependence of invariants, and analyzes limiting behavior where elliptic functions reduce to trigonometric or hyperbolic forms in some cases. Together, these results connect CK geometries with elliptic-function-based representations, offering a framework potentially extensible to higher dimensions.
Abstract
The article presents various Witt type vector field realizations of 2-D Cayley-Klein algebras with non-vanishing curvatures. The expressions of the vector fields involve Jacobi elliptic functions whose moduli are directly related to the parameters that appear in the corresponding matrix representation obtained from a bi-orthogonal set of vectors. First, the realizations are obtained with the values of the moduli lying in the unit interval (0, 1). The parameter of biorthogonality plays a crucial role in this context. Later, with the help of modular transformation, realizations involving arbitrary moduli have been obtained.
