Interactions that quench regularized Galileon instabilities

Identify interactions that quench the dynamical instabilities leading to divergences in the higher-derivative ghostly regularized formulation of Galileon effective field theory.

Background

The regularized Galileon formulation is locally well posed for sufficiently smooth initial data, but the paper finds that sufficiently large amplitudes can trigger dynamical instabilities associated with the ghost sector. If these instabilities remain unquenched, the evolution develops divergences.

The authors explicitly identify the construction of interactions capable of suppressing or quenching these instabilities as an unresolved research direction. Such interactions could potentially improve the long-term behavior of the regularized theory; the paper points to mechanisms based on non-derivative interactions as an example of the relevant type of extension.