Couplings and asymptotic freedom

Each of the four fundamental interactions can be characterized by a dimensionless parameter expressed in terms of universal constants, the coupling constant. In the lagrangian of strong interactions, the coupling constant is parameterized by the gauge coupling parameter,, giving in natural units . However, in a general field theory, the effective coupling constant is not a constant, … Continue reading Couplings and asymptotic freedom


Weak Interactions

Although weak interactions can be described by a non--Abelian group too, the phenomenology of Nature complicates the form of the corresponding Lagrangian. The CP violation can be formalized assuming that weak interactions should act only on left--chirality states. Left--handed fermions therefore form a weak isospin doublet where the left--handed states are The electron neutrino, known to … Continue reading Weak Interactions