higherspin

Higherspin is a term used in theoretical physics to describe the study of higher-spin fields and the gauge theories that aim to describe them. It encompasses the examination of quantum fields with spin values greater than the familiar lower-spin particles, such as spin-0, spin-1/2, spin-1, and spin-2, and the mathematical structures needed to formulate their dynamics.

In the standard framework, massless fields of spin s require gauge invariance. For symmetric, totally-tract tensor fields of rank s, the Fronsdal equations provide a generalization of familiar equations like Maxwell’s and linearized gravity. The higher-spin program seeks consistent descriptions of these fields, including their linear and nonlinear interactions, across spacetime backgrounds.

Constructing interacting higher-spin theories faces significant obstacles. Several no-go theorems show obstructions to local, interacting massless higher-spin fields in flat spacetime. A productive line of research bypasses these restrictions by working in anti-de Sitter space and invoking extended gauge symmetries, leading to nonlinear frameworks such as Vasiliev’s higher-spin gravity, which includes an infinite spectrum of massless fields of all spins.

In the context of holography, higher-spin theories in AdS have been explored as potential duals to certain conformal field theories, offering insights into quantum gravity and emergent spacetime. Despite theoretical interest, there is currently no experimental evidence for elementary higher-spin gauge fields, and the field remains primarily a domain of mathematical and theoretical investigation. See also higher-spin theory, Fronsdal equation, Vasiliev equations, and AdS/CFT.