K.S. Stelle, «Horava-Witten origin of Salam-Sezgin: supergravity and boundaries in 7 & 6 dimensions»
The Salam-Sezgin model of D=6 supergravity provides a pathway towards interesting gauge groups and couplings after reduction further down to D=4. But the origin of this model from a string/M-theory perspective has remained obscure. In this talk, the problem will be addressed using a D=7 Horava-Witten construction, with particular attention to the type of bulk-boundary couplings required and the necessary classical noninvariances needed to compensate for quantum gauge and supersymmetry anomalies.