Pohlmeyer invariants are expressible in terms of DDF invariants
arXiv:math-ph/0404007
Abstract
It is shown that the Pohlmeyer invariants of the classical bosonic string are a proper subset of the classical DDF invariants. This makes the quantization of the Pohlmeyer invariants particularly transparent and allows to generalize them to the superstring.
3 pp, references to papers by Isaev and Borodulin added, where essentially the same results as discussed here are reported