24/07/06 07:00:18.79 4dqNnAH/.net
In the previous lecture we constructed a k = 1 SU(2) instanton on S
4
and in fact saw that it belongs
to a five-parameter family of such instantons. This is not an accident and in this lecture we will see
that there is a moduli space of instantons, which is a disjoint union of a countable number of finitedimensional connected subspaces labelled by the instanton number. To a first approximation, the
moduli space is the quotient of the space of (anti)self-dual connection modulo gauge transformations.
However this space turns out to be singular in general and in order to guarantee a smooth quotient we
will have either to restrict ourselves to irreducible connections, or else quotient by a (cofinite) subgroup
of gauge transformations.