  We consider "gauge invariant" operators in Sym^N T^4, the symmetric product
orbifold of N copies of the 2d supersymmetric sigma model with T^4 target. We
discuss a spin chain representation for single-cycle operators and study their
two point functions at large N. We perform systematic calculations at the
orbifold point ("tree level"), where non-trivial mixing is already present, and
some sample calculations to first order in the blow-up mode of the orbifold
("one loop").
