In this thesis we investigate classical integrability of the string worldsheet on different super-gravity backgrounds. We focus in particular on the class of half-supersymmetric AdS7 solutions of Massive Type IIA supergravity, that are thought to be the near-horizon limit of a D6-D8-NS5 Hanany-Witten brane set-up, and are dual to six-dimensional conformal field theories with N = (1, 0) supersymmetry. We use both analytical and numerical methods to show the (bosonic sector of the) string worldsheet is non-integrable on most of these backgrounds. The backgrounds on which the string is integrable are an infinite massless solution (corresponding to an infinite constant quiver), and a background corresponding to an infinite linear quiver theory.In addition we find that the (bosonic sector of the) string is integrable on a background that we call AdS7 × (S3)λ. For this background we show that it corresponds to a 6d SCFT with an infinitely long quiver with an infinite number of flavour groups, all proportional to the colour groups. We study this particular supergravity background in detail, and suggest it corresponds to the large-N limit of the dual SCFT in the limit where the Chern-Simons level k goes to infinity.This integrable AdS7 × (S3)λ background can be obtained as the λ-deformation of AdS7×S3. In this context we study integrable deformations of supergravity backgrounds in the last part of this thesis, in particular non-Abelian T-duality. We present another back-ground on which the string is integrable by performing two non-Abelian T-dualities on two three-spheres inside the AdS5×S5 solution and study the resulting background.
Correlators of large N fermionic Chern-Simons vector models