# Higher-spin operators in CFT
## Higher-spin conserved currents
It was shown in [[2015# by Hartman, Jain, and Kundu]] that a CFT cannot have a finite number of higher-spin conserved currents. Their method was to study the [[0619 Lightcone OPE|Lorentzian OPE]] and show that the dominant operator exchange near the lightcone must have spin $\le 2$.
## Single-trace higher-spin operators
A [[0122 Holographic CFT|holographic CFT]] should have a large gap to higher-spin single-trace operators.
## Refs
- proof of no (finitely many) higher-spin conserved currents in CFT
- [[2011#Maldacena, Zhiboedov]]: 3d
- [[2013#Boulanger, Ponomarev, Skvortsov, Taronna]]: higher than 3d; using higher-spin algebras
- [[2015#Alba, Diab]]: higher than 3d
- [[2015#Hartman, Jain, Kundu]]: any dimension
- $\mathcal{W}_N$ symmetry
- [[2017#Afkhami-Jeddi, Colville, Hartman, Maloney, Perlmutter]]: a lower bound on the dimension of any non-vacuum higher-spin primary state, which is linear in the [[0033 Central charge|central charge]]
- using chaos bound
- [[2016#Perlmutter]]
## Related
- [[0122 Holographic CFT]]