Assoc. Prof. Jernej Fesel Kamenik (FMF, IJS): Flavor puzzle of elementary particles
All visible matter in the Universe consists of bound states of up and down quarks, and electrons. However, these particles (together with the associated neutrino) represent only one of three generations of so called elementary particle flavors. Namely, observations of high energy cosmic rays as well as experiments conducted at terrestrial particle colliders confirm the existence of additional two (more massive) flavors of each of our elementary constituents. The origin of three elementary particle generations has been puzzling researchers for the past 80 years and remains one of the biggest unsolved mysteries of fundamental physics. I will present theoretical arguments for why the solution has evaded us for so long despite the tremendous experimental progress.
The standard theory of elementary particles and interactions predicts that elementary forces act equally on all generations of matter. In the past decade however, several experiments have reported results, which challenge this prediction. These are measurements of the so called lepton flavor universality in decays of b-flavored hadrons. I will present some possible interpretations of these measurements, which could perhaps lead to a resolution of the flavor puzzle of elementary particles.