New terms for scalar multi-Galileon models and application to SO(N) and SU(N) group representations

Understand

We investigate a new class of scalar multi-galileon models, which is not included in the commonly admitted general formulation of generalized multi-galileons.

• The Lagrangians of this class of models, some of them having already been introduced in previous works, are specific to multi-galileon theories, and vanish in the single galileon case.
• We examine them in details, discussing in particular some hidden symmetry properties which can be made explicit by adding total derivatives to these Lagrangians.
• These properties allow us to describe the possible dynamics for these new Lagrangians in the case of multi-galileons in the fundamental representation of a SO(N) and SU(N) global symmetry group, as well as in the adjoint representation of a SU(N) global symmetry group.