Abstract: The explicit breaking of the PQ symmetry by higher dimensional operators can spoil the dynamical relaxation of the strong CP angle to its minimum of zero. One solution to this PQ “quality problem” is to introduce heavy QCD axions. …

David Dunsky (LBNL) “Dark Radiation Constraints on Heavy QCD Axion Theories” Read More »

ABSTRACT: (This is a Hybrid/ZOOM Meeting) Gravitational waves offer a powerful probe of early Universe phenomena. A particularly well-motivated BSM target for gravitational wave experiments is a first order phase transition in a dark sector, where bubbles of true vacuum nucleate …

Bibhushan Shakya (DESY) – “Gravitational Wave Probes of the Dark Universe” Read More »