Flavor and Symmetries

Dr Claudia Hagedorn (Technical University of Munich)

The Standard Model of particle physics has been very successful in describing gauge interactions, however it cannot answer the fundamental questions of the flavor sector: why are there three generations of elementary particles; why do they have the same gauge quantum numbers, but vastly different masses; why is the mass hierarchy among charged fermions much stronger than among neutrinos and why are the quark mixing angles small, while two of the mixing angles in the lepton sector are large and might be described with special mixing patterns. 

In many extensions of the Standard Model these fundamental questions are also not addressed.  Even more, in such extensions additional particles and interactions are present which induce excessive flavor violating signals, if the flavor structure is not highly constrained.  Flavor symmetries which act on the space of the three generations of particles, very much like the color gauge group SU(3) on the color indices of the quarks, can play the key role in understanding the features of fermion masses and mixing and can help to efficiently suppress flavor violating signals in theories beyond the Standard Model. 

The focus of this talk is on symmetries and approaches which can explain the observed lepton mixing angles and make predictions for the yet unknown leptonic CP phases.  In addition, two classes of models are presented in which branching ratios of lepton flavor violating processes are kept below their experimental limits with the help of a flavor symmetry.

Wed, 7 May 2014
2.15 PM

Laby Theatre (David Caro Building)