ABSTRACT
This chapter considers a classical field theory described by a Lagrangian which has certain continuous symmetries. The Lagrangians for the field theories possess certain invariance properties, such as translational, rotational, gauge invariance. Generally, the ground state of the field theory, called the vacuum state, shares the symmetry property of the Lagrangian. Lagrangian formulation of mechanics is an alternative formulation to that based on Newton’s laws of motion. The Lagrangian formulation for particle mechanics involves a finite number of degrees of freedom. Hyperons are unstable particles which are heavier than the nucleon possessing nonzero strangeness. The study of weak interaction decays of strange particles has revealed the operation of certain selection rules. R. P. Feynman proposed a parton model of hadrons for describing inclusive spectral distributions of hadrons originating in high energy collisions of hadrons. In quantum field theories involving chiral fermions and gauge bosons, the gauge bosons have different interaction strengths when coupled to left- or right-handed fermions.
