Branching rule on winding subalgebras of affine Kac-Moody algebras

In this paper, by using the Lakshmibai-Seshadri paths, we give the branching rule for representations of affine Kac-Moody algebras to their winding subalgebras. As a corollary, we can describe branching multiplicities in the language of paths. An analog of Steinberg’s formula for branching multiplicities is also given.