Speaker: Shinji Mukohyama (Kyoto U. and Yukawa Inst.)
Title: Black holes in scalar-tensor theory
After reviewing the effect field theory (EFT) approach to scalar-tensor theories, I will revisit the issue of strong coupling of perturbations around stealth solutions, i.e. backgrounds with the same forms of the metric as in general relativity but with non-trivial configurations of the scalar field. In particular I will argue that a controlled detuning of the degeneracy condition, which is called scordatura, renders the perturbations weakly coupled without changing the properties of the stealth solutions at astrophysical scales. Finally, I will explore the possibility to use disformal field redefinitions to investigate new regions of the solution space of scalar tensor theories, and present new hairy black holes solutions beyond the stealth sector.
Room: Zoom videoconference (contact email@example.com for URL)