Higher-Spin Fields in Braneworlds

TL;DR

This paper explores the behavior, localization, and interactions of higher-spin fields in braneworld models, analyzing boundary conditions, zero modes, and holographic dualities in AdS_5 contexts.

Contribution

It introduces boundary conditions for higher-spin fermions, proposes a gauge-invariant action with non-minimal couplings, and discusses holographic duals of higher-spin theories in AdS_5.

Findings

Zero modes exist only for spin-one fields without boundary couplings.

Boundary couplings enable zero modes for all bosons, regardless of spin.

Chiral zero modes can be generated for fermions through specific boundary conditions.

Abstract

The dynamics of higher-spin fields in braneworlds is discussed. In particular, we study fermionic and bosonic higher-spin fields in AdS_5 and their localization on branes. We find that four-dimensional zero modes exist only for spin-one fields, if there are no couplings to the boundaries. If boundary couplings are allowed, as in the case of the bulk graviton, all bosons acquire a zero mode irrespective of their spin. We show that there are boundary conditions for fermions, which generate chiral zero modes in the four-dimensional spectrum. We also propose a gauge invariant on-shell action with cubic interactions by adding non-minimal couplings, which depend on the Weyl tensor. In addition, consistent couplings between higher-spin fields and matter on the brane are presented. Finally, in the AdS/CFT correspondence, where bulk 5D theories on AdS are related to 4D CFTs, we explicitly discuss the holographic picture of higher-spin theories in AdS_5 with and without boundaries.