Gauge Invariances and Phases of Massive Higher Spins in (A)dS

TL;DR

This paper explores the phase structure of massive higher-spin fields in (A)dS spaces, revealing gauge invariances, unitarity conditions, and the unique effects of non-zero cosmological constant on their properties.

Contribution

It introduces a detailed phase diagram of massive higher-spin fields in (A)dS, identifying gauge invariances and unitarity regions influenced by the cosmological constant.

Findings

Identification of phases separated by partially massless gauge lines

Norms of states flip across gauge lines, affecting unitarity

Unitarity depends on the ordering of gauge lines in the phase diagram

Abstract

The (m^2,\Lambda) plane of spin s>1 massive fields in (A)dS backgrounds is shown to consist of separate phases, divided by lines of novel ``partially massless'' gauge theories that successively remove helicities, starting from the lowest, 0 or +/-(1/2). The norms of the excluded states flip as the gauge lines are crossed and only the region containing the massive Minkowski theory is unitary. The partially massless gauge theories are unitary or not, depending on the ordering of the gauge lines. This ``level splitting'' of massless Minkowski gauge theories is specific to non-zero \Lambda.