Talks

A review of asymptotic (more generally, boundary) symmetries will be given in the context of the Hamiltonian formulation. General features (such as the form of the symmetry generators and the structure of the algebra) as well as specific examples will be covered.  A particular attention will be paid to asymptotically flat spaces and the asymptotic BMS algebra, where nonlinear redefinitions will be shown to yield a supertranslation-invariant angular momentum.

I describe a new solution to the Higgs hierarchy problem based on a dynamical vacuum selection mechanism in a landscape which scans the Higgs mass. The Higgs potential only admits a stable minimum when its mass is less than a critical value, cosmologically crunching away patches with a heavier Higgs. This critical value is set by the instability scale where the Higgs quartic turns negative. I consider the phenomenology of two explicit models that address the hierarchy problem in this context.

The standard models of particle physics and cosmology predict the existence of a cosmological magnetic field. Estimates of the magnetic field strength and coherence scale are derived from MHD simulations and new MHD invariants. Such magnetic fields are consistent with upper and lower bounds obtained from various cosmological observations.