How higher-spin gravity surpasses the spin two barrier: no-go theorems versus yes-go examples
Jul, 2010Citations per year
Abstract: (arXiv)
Aiming at non-experts, we explain the key mechanisms of higher-spin extensions of ordinary gravity. We first overview various no-go theorems for low-energy scattering of massless particles in flat spacetime. In doing so we dress a dictionary between the S-matrix and the Lagrangian approaches, exhibiting their relative advantages and weaknesses, after which we high-light potential loop-holes for non-trivial massless dynamics. We then review positive yes-go results for non-abelian cubic higher-derivative vertices in constantly curved backgrounds. Finally we outline how higher-spin symmetry can be reconciled with the equivalence principle in the presence of a cosmological constant leading to the Fradkin--Vasiliev vertices and Vasiliev's higher-spin gravity with its double perturbative expansion (in terms of numbers of fields and derivatives).Note:
- LaTeX, 50 pages, minor changes, many refs added; version accepted for publication in Reviews of Modern Physics
- particle: massless
- spin: 2
- derivative: high
- gravitation
- equivalence principle
- scattering
- S-matrix
- coupling: minimal
- invariance: gauge
- field theory: conformal
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