Branes in extended spacetime

We propose a novel approach to the brane worldvolume theory based on the geometry of extended field theories; double field theory and exceptional field theory. We demonstrate the effectiveness of this approach by showing that one can reproduce the conventional bosonic string/membrane actions, and the M5-brane action in the weak field approximation. At a glance, the proposed 5-brane action without approximation looks different from the known M5-brane actions, but it is consistent with the known non-linear self-duality relation, and it may provide a new formulation of a single M5-brane action. Actions for exotic branes are also discussed.