Gauge-independent Higgs mechanism and the implications for quark confinement

We propose a gauge-invariant description for the Higgs mechanism by which a gauge boson acquires the mass. We do not need to assume spontaneous breakdown of gauge symmetry signaled by a non-vanishing vacuum expectation value of the scalar field. In fact, we give a manifestly gauge-invariant description of the Higgs mechanism in the operator level, which does not rely on spontaneous symmetry breaking. For concreteness, we discuss the gauge-Higgs models with U(1) and S U(2) gauge groups explicitly. This enables us to discuss the confinement-Higgs complementarity from a new perspective. (author)