Tachyons in a slice of AdS

TL;DR

This paper explores the stability conditions of scalar fields in AdS space, clarifying the role of tachyons and brane actions in Randall-Sundrum models, with implications for CFT interpretations and stability limits.

Contribution

It clarifies the stability bounds and the role of brane actions in Randall-Sundrum models, connecting bulk tachyons to boundary CFT phenomena.

Findings

Stability of AdS allows negative mass squared scalar fields within bounds.

In compactified AdS, brane actions are necessary to prevent instabilities.

The instability disappears in the infinite space limit, with a CFT interpretation as radiative symmetry breaking.

Abstract

Stability of AdS space allows scalar fields to have negative mass squared as long as the Breitenlohner-Freedman bound is satisfied. In a compactification of AdS instead, to avoid instabilities, a tachyonic bulk mass must be supplemented by appropriate brane actions. In this paper we clarify the meaning of the lower bound in the Randall-Sundrum scenario with two branes and explain how the instability disappears in the infinite space limit. A CFT interpretation is also given as radiative symmetry breaking.