Breaking an Abelian gauge symmetry near a black hole horizon
Steven S. Gubser
TL;DR
The paper investigates whether a charged scalar can condense near the horizon of an AdS4 black hole, spontaneously breaking the U(1) gauge symmetry and signaling holographic superconductivity. It analyzes the RN-AdS4 background and searches for marginally stable, non-backreacting perturbations of the scalar; when the effective mass $m_eff^2 = m^2 + g^{tt} q^2 Phi^2$ becomes negative outside the horizon for large charge $q$ and suitable $m^2$, a near-horizon condensate can form. The results show marginal modes on parameter-space surfaces, with a tower of such modes in AdS4 that disappear in the flat-space limit, indicating the essential role of AdS boundary conditions. The work provides a simple, renormalizable gravity-based mechanism for horizon superconductivity and motivates future holographic studies of transport, vortices, and dual boundary theories.
Abstract
I argue that coupling the Abelian Higgs model to gravity plus a negative cosmological constant leads to black holes which spontaneously break the gauge invariance via a charged scalar condensate slightly outside their horizon. This suggests that black holes can superconduct.
