Covert Symmetry Breaking

TL;DR

This paper investigates a novel form of spontaneous symmetry breaking that occurs at fourth order in the effective field theory, revealed through a simple scalar QED model with boundary conditions, with implications for braneworld scenarios.

Contribution

It introduces the concept of covert symmetry breaking manifesting at quartic order in lower-dimensional effective theories derived from higher-dimensional models.

Findings

Symmetry breaking appears only at fourth order in the effective action.

The model exhibits Maxwellian dynamics with unusual symmetry breaking in interaction terms.

Implications are discussed for gravitational braneworld scenarios.

Abstract

Reduction from a higher-dimensional to a lower-dimensional field theory can display special features when the zero-level ground state has nontrivial dependence on the reduction coordinates. In particular, a delayed `covert' form of spontaneous symmetry breaking can occur, revealing itself only at fourth order in the lower-dimensional effective field theory action. This phenomenon is explored in a simple model of $(d+1)$-dimensional scalar QED with one dimension restricted to an interval with Dirichlet/Robin boundary conditions on opposing ends. This produces an effective $d$-dimensional theory with Maxwellian dynamics at the free theory level, but with unusual symmetry breaking appearing in the quartic vector-scalar interaction terms. This simple model is chosen to illuminate the mechanism of effects which are also noted in gravitational braneworld scenarios.