Seven Dimensional Octonionic Yang-Mills Instanton and its Extension to an Heterotic String Soliton

Abstract

We construct an octonionic instanton solution to the seven dimensional Yang-Mills theory based on the exceptional gauge group $G_2$ which is the automorphism group of the division algebra of octonions. This octonionic instanton has an extension to a solitonic two-brane solution of the low energy effective theory of the heterotic string that preserves two of the sixteen supersymmetries and hence corresponds to $N=1$ space-time supersymmetry in the (2+1) dimensions transverse to the seven dimensions where the Yang-Mills instanton is defined.

7 pages, Latex document. This is the final version that appeared in Phys. Lett. B that includes an extra paragraph about the physical properties of the octonionic two-brane. We have also put an addendum regarding some related references that were brought to our attention recently