A generalization of Born-Infeld non-linear vacuum electrodynamics involvingaxion and dilaton fields is constructed with couplings dictated byelectromagnetic duality and SL(2,R) symmetries in the weak field limit. Besidesthe Newtonian gravitational constant the model contains a single fundamentalcoupling parameter b0. In the absence of axion and dilaton interactions itreduces, in the limit as b0 tends to infinity, to Maxwell's linear vacuumtheory while for finite b0 it reduces to the original Born-Infeld model. Thespherically symmetric static sector of the theory is explored in a backgroundMinkowski spacetime where numerical evidence suggests the existence ofaxion-dilaton bound states possessing confined electric flux.
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