11:00: Joe Davighi (Zurich)
Gauge flavour unification: from stable protons to the flavour puzzle
The idea of unification attempts to explain the complicated structure of the Standard Model (SM) in terms of fewer fundamental forces and/or matter fields. However, traditional GUTs based on SU(5) and Spin(10) say nothing about the existence of three generations, nor the distinctive pattern of their Yukawa couplings. These puzzles remain as mysterious as they are in the SM. In this talk I will discuss two routes for unifying the SM gauge symmetry with its 3-family flavour symmetries: firstly, unifying flavour and colour via an SU(12) x SU(2)
x SU(2) gauge theory; secondly, unifying flavour with electroweak symmetries via the group SU(4) x Sp(6) x Sp(6). In the larger part of the talk, I will describe how the latter model of "electroweak flavour unification" offers a compelling new explanation of hierarchical fermion masses and CKM angles. We will also see that gauge flavour unification can have unexpected spin offs that are not obviously related to flavour. In particular, the SU(12) x SU(2) x SU(2) symmetry, when broken, typically leaves behind remnant discrete gauge symmetries that serve to exactly stabilize the proton to all orders.
13:00: Sarah Geller (MIT)
Primordial Black Holes from Multifield Inflation with Non-minimal Couplings
Primordial Black Holes (PBHs), first postulated more than half a century ago, remain an active and fascinating area of research and provide an exciting prospect for accounting for Dark Matter. In this talk I will discuss the possibilities for production of PBHs near to Dark Matter mass scales from realistic multi-field inflation models that arise naturally from supergravity. These models fit neatly within the current status of inflationary models as constrained by CMB observations; they behave effectively as a single-field models for much of their evolution, and the isocurvature modes remain heavy throughout. Moreover, such models yield efficient post-inflation reheating with $N_{\rm reh} \sim O(1)$ e-folds after the end of inflation. I will demonstrate how our two-field model in particular gives rise to inflationary dynamics that yield predictions for observables in close agreement with recent empirical data, such as the spectral index and ratio of power spectra for tensor to scalar perturbations. As has been noted in previous studies of PBH formation resulting from a period of ultra slow-roll inflation, we found that at least one dimensionless parameter must be highly fine-tuned, but I will show that we nonetheless find such models yield accurate predictions for a significant number of observable quantities using a smaller number of free parameters.