The Einstein-Hilbert action with cosmological constant as a functional of generic form

The geometrical underpinnings of a specific class of Dirac operators are discussed. It is demonstrated how this class of Dirac operators allows to relate various geometrical functionals like the Yang-Mills action and the functional of non-linear sigma-models (i.e., of (Dirac) harmonic maps). These functionals are shown to be similar to the Einstein-Hilbert action with cosmological constant (EHC). The EHC may thus be regarded as a "generic functional." As a byproduct, the geometrical setup presented also allows to avoid the issue of "fermion doubling" as usually encountered, for instance, in the geometrical discussion of the Standard Model in terms of Dirac operators. Furthermore, it is demonstrated how the geometrical setup presented allows to derive the cosmological constant term of the EHC from the Einstein-Hilbert functional and the action of a purely gauge coupling Higgs field. (C) 2015 AIP Publishing LLC.