Breaking E8 to SO(16) in M-theory and F-theory Original Research Article

M-theory on an 11-dimensional manifold with a boundary must have E8 gauge groups at each boundary in order to cancel anomalies. The type IA supergravity must have SO(16) gauge group at each boundary in order to be a consistent theory. The latter action can be obtained from the former one via dimensional reduction. Here we make use of the current algebra of the open membrane which couples to the former action to explain why the gauge group E8 breaks down to SO(16) in going from M-theory to type IA supergravity. We also use the same current algebra to explain why F-theory has an E8 × E8 gauge group in its strong coupling limit while it has an SO(16) × SO(16) gauge group in its weak coupling limit.