Particle Physics

Particle physics is a branch of physics that studies the elementary constituents of matter and radiation, and the interactions between them. It is also called “high energy physics”, because, many elementary particles do not occur under normal circumstances in nature, but can be created and detected during energetic collisions of other particles, as is done in particle accelerators. Modern particle physics research is focused on sub-atomic particles, which have less structure than atoms. These include atomic constituents such as electrons, protons and neutrons (protons and neutrons are actually composite particles made up of quarks), particles produced by radioactive and scattering processes, such as photons, neutrinos as muons, as well as a wide range of exotic particles. Strictly speaking, the term particle is a misnomer because the dynamics of particle physics are governed by quantum mechanics. As such, they exhibit wave-particle duality, displaying particle-like behaviour under certain experimental conditions and wave-like behaviour in others (they are described more technically by state vectors in Hilbert space). All the particles and their interactions observed to date can be described by a quantum field theory called the Standard Model. The Standard Model has 40 species 0f elementary particles (24 fermions, 12 vector bosons and 4 scalars), which can combine to form composite particles, accounting for the hundreds of other species of particles discovered since the 1960’s.