Effective field theory for a heavy Higgs boson: A manifestly gauge-invariant approach

For large values of the Higgs boson mass the low energy structure of the gauged linear a model in the spontaneously broken phase can adequately be described by an effective held theory. In this work. we present a manifestly gauge-invariant technique to explicitly evaluate the corresponding effective Lagrangian from the underlying theory. In order to demonstrate the application of this functional method, the effective field theory of the Abelian Higgs model is thoroughly analyzed. We stress that this technique does not rely on any particular property of the Abelian case. The application to the non-Abelian theory is outlined.