A polynomial first-order action for the Dirichlet 3-brane

A new first-order action for type IIB Dirichlet 3-brane is proposed. Its form is inspired by the superfield equations of motion obtained recently from the generalized action principle. The action involves auxiliary symmetric spin tensor fields. It seems promising for a reformulation of the generalized action in a structure most adequate for investigating the extrinsic geometry of the super-3-brane, but also for further studies of string dualities.