Covariant Mickelsson-Faddeev extensions of gauge and diffeomorphism algebras

We construct new extensions of current and diffeomorphism algebras in N>3 dimensions, which are related to the Mickelsson-Faddeev algebra. The result is compatible with Dzhumadil’daev’s classification of diffeomorphism cocycles. We also construct an extension of the current algebra in N>=5 dimensions which depends on the fourth Casimir operator.