In general terms my research focus is on field theoretical systems and topics related to quantum gravity. The systems include Einstein gravity at strong coupling, higher derivative gravity, symmetry reductions of gravity, and non-compact nonlinear sigma-models. One key topic is the asymptotic safety property on which a non-perturbative notion of renormalizability can be based, overcoming the long-known perturbative non-renormalizability. A second core topic is a gravity specific form of spontaneous symmetry breaking rooted in the impossibility to perform non-boring group averages over remnants of the diffeomorphism group after gauge fixing.
- " Gravitational fixed points and asymptotic safety from perturbation theory " , Nucl. Phys. B 833, 226 (2010).
- " Dimensionally reduced gravity theories are asymptotically safe " , Nucl. Phys. B 673, 1331 (2003).
- " Perturbative and non-perturbative correspondences between compact and non-compact nonlinear sigma-models " (with E. Seiler and P. Weisz), Nucl. Phys. B 788, 89 (2008).
- "Structure of the space of ground states in systems with non-amenable symmetries " (with E. Seiler), Commun. Math. Phys. 270, 373 (2007).
- " A quantum cure for the Ostrogradski instability " , Ann. Phys. 327, 329 (2012).