Codimension two souls and cancellation phenomena

For each m≥0m≥0 we find an open (4m+9)(4m+9)-dimensional simply connected manifold with complete nonnegatively curved metrics whose souls are nondiffeomorphic, homeomorphic, and have codimension 2. We give a diffeomorphism classification of the pairs (N,soul) when N   is the total space of a nontrivial complex line bundle over S7×CP2S7×CP2; up to diffeomorphism there are precisely three such pairs, distinguished by their nondiffeomorphic souls.