Approaches to high energy physics

An overview of the present state of the art in high energy physics is presented highlighting the developments in hadron physics, field theory and nuclear democracy. To begin with, description of 'hadrons' is given on the basis of quantum electrodynamics. The role of the quantum numbers assigned to quarks are explained. Lepton-hadron scattering and hadron-hadron scattering are discussed. The quark-parton model of the nucleon is explained. The recently discovered Psi resonances and the consequent introduction of new quantum number 'charm' are mentioned. Next, Yang-Mills Gauge theories, the unification of weak and electromagnetic interactions and the concept of weak neutral currents are discussed. Gauge theories of strong interactions, quantum chromodynamics and the concept of 'Bags' are explained. Magnetic monopoles (solitons) are described with basis on non-linear field theories. High energy bounds in the axiomatic field theory are formulated. The general properties of S-matrix elements obtained in a quantum local field theory are mentioned. Lastly, the shifting of the reliance on field concepts to other approaches, specially through S-matrix and the application of Regge poles and cuts is explained. The duality hypothesis is postulated to explain processes such as pp→pp with the 'pomeron exchange' concept. Dual models of strong interactions are discussed. Future trends are indicated. (A.K.)