Affine Lie algebras, string junctions and 7-branes

We consider the realization of affine ADE Lie algebras as string junctions on mutually non-local 7-branes in Type 1113 string theory. The existence of the affine algebra is signaled by the presence of the imaginary root junction δ, which is realized as a string encircling the 7-brane configuration. The level k of an affine representation partially constrains the asymptotic (p, q) charges of string junctions departing the configuration. The junction intersection form reproduces the full affine inner product, plus terms in the asymptotic charges.