On Symmetry Enhancement in the psu(1,1|2) Sector of N=4 SYM

Understand

Strong evidence indicates that the spectrum of planar anomalous dimensions of N=4 super Yang-Mills theory is given asymptotically by Bethe equations.

• A curious observation is that the Bethe equations for the psu(1,1|2) subsector lead to very large degeneracies of 2^M multiplets, which apparently do not follow from conventional integrable structures.
• In this article, we explain such degeneracies by constructing suitable conserved nonlocal generators acting on the spin chain.
• We propose that they generate a subalgebra of the loop algebra for the su(2) automorphism of psu(1,1|2).