Solving for Root Subgroup Coordinates: The SU(2) Case

Previously we showed that a loop in a simply connected compact Lie group K has a unique triangular factorization if and only if the loop has a unique root subgroup factorization (relative to a choice of a reduced sequence of simple reflections in the affine Weyl group). In this paper we show that in the K=SU(2) case, root subgroup coordinates are rational functions (with positive denominators) of the triangular factorization coordinates. We conjecture that in general they are algebraic functions.