  Any N=2 superconformal gauge theory (including N=4 SYM) contains a set of
local operators made only out of fields in the N=2 vector multiplet that is
closed under renormalization to all loops, namely the SU(2,1|2) sector. For
planar N=4 SYM the spectrum of local operators can be obtained by mapping the
problem to an integrable model (a spin chain in perturbation theory), in
principle for any value of the coupling constant. We present a diagrammatic
argument that for any planar N=2 superconformal gauge theory the SU(2,1|2)
Hamiltonian acting on infinite spin chains is identical to all loops to that of
N=4 SYM, up to a redefinition of the coupling constant. Thus, this sector is
integrable and anomalous dimensions can be, in principle, read off from the N=4
ones up to this redefinition.
