A Domino Theory of Flavor

We argue that the fermion masses and mixings are organized in a specific pattern. The approximately equal hierarchies between successive generations, the sizes of the mixing angles, the heaviness of just the top quark, and the approximate down-lepton equality can all be accommodated by many flavor models but can appear ad hoc. We present a simple, predictive mechanism to explain these patterns. All generations are treated democratically and the flavor symmetries are broken collectively by only two allowed couplings in flavor-space, a vector and matrix, with arbitrary O(1) entries. Repeated use of these flavor symmetry breaking spurions radiatively generates the Yukawa couplings with a natural hierarchy. We demonstrate this idea with two models in a split supersymmetric grand unified framework, with minimal additional particle content at the unification scale. Although flavor is generated at the GUT scale, there are several potentially testable predictions. In our minimal model the usual prediction of exact b-tau unification is replaced by the SU(5) breaking relation m_tau / m_b = 3 / 2, in better agreement with observations. Other SU(5) breaking effects in the fermion masses can easily arise directly from the flavor model itself. The symmetry breaking that triggers the generation of flavor necessarily gives rise to an axion, solving the strong CP problem. These theories contain long-lived particles whose decays could give striking signatures at the LHC and may solve the primordial Lithium problems. These models also give novel proton decay signatures which can be probed by the next generation of experiments. Measurement of the various proton decay channels directly probes the flavor symmetry breaking couplings. In this scenario the Higgs mass is predicted to lie in a range near 150 GeV.Comment: 33 pages, 11 figures, 5 tables. v2: Refs added, version to appear in PR

Byron and the Greek Sublime

Le destin aura voulu que le premier paysage sublime grec qu’a vu Byron depuis la terre ferme soit également le dernier sur lequel ont reposé ses yeux avant sa mort : les paysages terrestres et maritimes de la ville de Messolonghi, un mélange de montagnes rocailleuses et des plateaux marécageux surmontés d’un ciel vaste aux lumières changeantes reflété dans les eaux calmes d’un lagon et les eaux plus troubles du golfe de Patras. Malgré d’importants changements apportés à la ville elle-même au cours du dernier siècle, le paysage terrestre et les lagunes de Messolonghi restent à peu près inchangés. Suivant une brève présentation sur l’histoire et la géographie de la région, nous regarderons un court-métrage sur le sublime paysage d’Étolie-Akarnanie qui entourait Messolonghi à l’époque de Byron et qui, en grande partie intacte, l’entoure encore