The bundle of pure spinors
The worldsheet theory has spinor ghosts and .
Because, as we explained, they are in some sense infinitesimal objects,
we should tell them to live in some nontrivial bundle over space-time. The transition functions of that bundle
should respect the pure spinor constraints
. This means that the
transition functions should belong to:
|
We will formulate the sigma-model so that the target space is , but there is a gauge symmetry projecting .
This is how the sigma-model for is constructed. The target space is
, but with the gauge symmetry .