“…We also introduce a couple of functionals closely related to such equations; namely the full Yang-Mills-Higgs functional and the Kobayashi functional and we show that there exists a non trivial relation between these functionals. In Section 5 we review the 2k-Hitchin equations of Ward [35] from the point of view of a holomorphic vector bundle E −→ X, with X a compact Kähler manifold and we show that such equations can be seen as a set of four equations whose variables are pairs (h, Φ), with h an hermitian metric in E and Φ an holomorphic form of type (1, 0) of X with values in the bundle of endomorphisms of E. At this point, we will see that two of the equations can be "formally" solved if we consider the Chern connection and a Higgs field on E. Therefore, as far as Higgs bundles is concern, the 2k-Hitchin equations can be reduced to a set of only two equations defined in the space of hermitian metrics in the Higgs bundle. The remaining equations have some resemblance with Seiberg-Witten equations, and hence, following this resemblance we propose a natural functional H(h) associated to the 2k-Hitchin equations on a Higgs bundle; we call such a functional the non-abelian Seiberg-Witten functional.…”