Effective field theory for a three-brane universe

A general effective field theory formalism is presented which describes the low-energy dynamics of a 3-brane universe. In this scenario an arbitrary four-dimensional particle theory, such as the standard model, is constrained to live on the world volume of a (3+1)-dimensional hypersurface, or ``3-brane,'' which in turn fluctuates in a higher-dimensional, gravitating spacetime. The inclusion of chiral fermions on the 3-brane is given careful treatment. The power counting needed to renormalize quantum amplitudes of the effective theory is also discussed. The effective theory has a finite domain of validity, restricting it to processes at low enough energies that the internal structure of the 3-brane cannot be resolved.