Systematic construction of basis invariants in the 2HDM

Understand

A new systematic method for the explicit construction of (basis-)invariants is introduced and employed to construct the full ring of basis invariants of the Two-Higgs-Doublet-Model (2HDM) scalar sector.

• Co- and invariant quantities are obtained by the use of hermitian projection operators.
• These projection operators are constructed from Young tableaux via birdtrack diagrams and they are used in two steps.
• First, to extract basis-covariant quantities, and second, to combine the covariants in order to obtain the actual basis invariants.