Double field theory
Double field theory in theoretical physics refers to formalisms that capture the T-duality property of string theory as a manifest symmetry of a field theory. == Background == In double field theory, the T-duality transformation of exchanging momentum and winding modes of closed strings on toroidal backgrounds translates to a generalized coordinate transformation on a doubled spacetime, where one set of its coordinates is dual to momentum modes and the second set of coordinates is interpreted as dual to winding modes of the closed string.