PARTICLE PHYSICS

My main research interests move along the boundary between inflationary cosmology, string theory and string phenomenology, and higher-dimensional field theory including supergravity, with some forays into quantum cosmology. Cosmological inflation is described by an effective field theory which is sensitive to quantum gravity effects potentially spoiling the slow-roll flatness of the inflaton scalar field potential driving the inflationary process. Reining in this sensitivity to Planck scale suppressed corrections requires an embedding of inflation into candidate theories of quantum gravity like string theory. Such a description of in particular high-scale inflation with a potentially detectable primordial gravitational wave signal in string theory needs to derive the appearance of a protective shift symmetry controlling the dangerous quantum gravity corrections as well as its controlled breaking leading to slow-roll inflation. Recent progress builds on the multi-valuedness of non-perturbative sectors of string theory coupled to the multiple axion fields generically present in string compactifications. This so-called axion monodromy can provide the underlying dynamics of controlled high-scale and “large-field” inflation models in string theory, and even more recently, also of shift-symmetry protected electro-weak hierarchy generation via relaxation.

Academic career

Memberships, awards, honours