Types of quantum field thories
The target space spectrum of the string sigma-model contains beyond the massless particles of the effective supergravity theory an infinite tower of massive excitations, of ever higher spin. There are, however, certain limits in which all these masses become negligible to a reference energy scale, notably for compactifications on anti de Sitter spaces of small radius. In this limit the string spectrum looks like a an infinite collection of massless spinning particles for ever higher spin. Due to their common orgin in the string, these share intricate relations among each other, which are described by what Vasiliev termed higher spin gauge theory.
Original articles include
Reviews and lecture notes include
Further developments include for instance
Chern-Simons theory for higher spin fields is discussed in
M P Blencowe, A consistent interacting massless higher-spin field theory in Classical and quantum gravity, volume 6 no 4 (1998)
E. S. Fradkin, V. Ya. Linetsky, a Superconformal Theory of Massless Higher Spin Fields in D=2+1 (web)
Johan Engquist, Olaf Hohm, Higher-spin Chern-Simons theories in odd dimensions (arXiv:0705.3714)
We list references that discuss the relation of higher spin gauge theory to the AdS/CFT correspondence.
Simone Giombi, Xi Yin, Higher Spin Gauge Theory and Holography: The Three-Point Functions (arXiv:0912.3462)
Simone Giombi, Xi Yin, Higher Spins in AdS and Twistorial Holography (arXiv:1004.3736)