Scalar fields are ubiquitous in string theory compactifications, arising both from geometric moduli and as descendants of higher-dimensional p-forms. In cosmology, they provide natural candidates to drive accelerated expansion, both during early (inflationary) and late (dark energy) time evolution of the Universe.
In single-field models, scalar potentials are typically too steep to sustain slow-roll evolution. However, in multifield scenarios, accelerated expansion can occur even for steep potentials, when the scalar fields move along strongly non-geodesic trajectories in field space. Such dynamics not only enable inflation or dark energy but can also evade recent quantum gravity swampland constraints.
In this talk, I will show how to extend the dynamical systems (DS) toolkit to include both kinetic and potential couplings between fields - features that naturally arise in string-theoretic constructions. Within this framework, I will present a compact and general expression for the non-geodesicity parameter, which offers a simple and transparent diagnostic of truly multifield evolution. I will also discuss connections with previous work on inflationary dynamics, where related mechanisms play a central role.
