Quark-flavor symmetries and their violation in quantum chromodynamics

Resumo

In Quantum Chromodynamics, the hadrons consisting of light (u, d, s) and heavy (c, b) quarks are subject to approximate flavor symmetries, providing the basis for powerful effective theories. I will briefly overview the origin of these symmetries and the scale of their violation. The current precision tests of Standard Model in the electroweak decays of hadrons demand an accurate quantitative account of flavor-symmetry violation effects. I will discuss the continuum (non-lattice) QCD calculation of these effects in hadronic matrix elements, taking as an example the decay constants of heavy–light hadrons.