The su(2|3) dynamic spin chain

The complete one-loop, planar dilatation operator of the N = 4 superconformal gauge theory was recently derived and shown to be integrable. Here, we present further compelling evidence for a generalisation of this integrable structure to higher orders of the coupling constant. For that we consider the su(2\3) subsector and investigate the restrictions imposed on the spin chain Hamiltonian by the symmetry algebra. This allows us to uniquely fix the energy shifts up to the three-loop level and thus prove the correctness of a conjecture in hep-th/0303060. A novel aspect of this spin chain model is that the higher-loop Hamiltonian, as for N = 4 SYM in general, does not preserve the number of spin sites. Yet this dynamic spin chain appears to be integrable. (C) 2004 Elsevier B.V. All rights reserved.