Speaker
Description
We consider an Abelian gauge field in $(d+1)$-dimensional anti-de Sitter space (AdS). The gauge symmetry is Higgsed by a bulk scalar with symmetry breaking triggered from an ultraviolet brane that regulates the AdS boundary. We show that the bulk mass of the Higgs field controls whether the $d$-dimensional spectrum of the gauge field is a continuum, gapped continuum, or a discretuum. When the Higgs field has no bulk mass, the dual conformal field theory (CFT) has a non-conserved $U(1)$ current whose anomalous dimension is proportional to the square of the Higgs vacuum expectation value. Studying the theory around this point, we introduce a WKB approximation to compute the gauge field boundary action and find that the anomalous dimension of the $U(1)$ current runs logarithmically with energy.
As an application, we present a holographic model of a continuum dark photon in AdS$_5$. The mixing with the visible photon is computed exactly via dressing. We present a method for extrapolating existing dark photon bounds to a continuum dark photon.
