Particle Physics Fundamental Particles • Fundamental particles are the smallest building blocks of the universe. The key characteristic of fundamental particles is that they have no internal structure. In other words, they are not made up of anything else. There are two types of fundamental particles: • 1. Particles that make up all matter, called fermions • 2. Particles that carry force, called bosons What are the Fundamental Forces? • Gravity Gravity is the attraction between two objects that have mass or energy. It also turns out to be the weakest of the fundamental forces, especially at the molecular and atomic scales. • The weak force The weak force, is responsible for particle decay. This is the literal change of one type of subatomic particle into another. In the weak force, the bosons are charged particles called W and Z bosons. When subatomic particles such as protons, neutrons and electrons come within 10^-18 meters, or 0.1% of the diameter of a proton, of one another, they can exchange these bosons. What are the Fundamental Forces? • Electromagnetism The electromagnetic force, also called the Lorentz force, acts between charged particles, like negatively charged electrons and positively charged protons. Electromagnetic forces are transferred between charged particles through the exchange of massless, force-carrying bosons called photons, which are also the particle components of light. The electromagnetic force is responsible for some of the most commonly experienced phenomena: friction, elasticity, the normal force and the force holding solids together in a given shape. • The strong force The strong nuclear force, is the strongest of the four fundamental forces of nature. It's 6 thousand trillion trillion trillion times stronger than the force of gravity. And that's because it binds the fundamental particles of matter together to form larger particles. It holds together the quarks that make up protons and neutrons, and part of the strong force also keeps the protons and neutrons of an atom's nucleus together. What are gauge bosons, and hadrons? • Hadrons are strongly interacting particles. They are divided into baryons and mesons. The baryons are a class of fermions, including the proton and neutron, and other particles which in a decay always produce another baryon, and ultimately a proton. The mesons, are bosons. Mesons can decay without necessarily producing other hadrons. • In particle physics, a gauge boson is a force carrier, a bosonic particle that carries any of the fundamental interactions of nature, commonly called forces. The Standard Model of particle physics recognizes four kinds of gauge bosons: photons, which carry the electromagnetic interaction; W and Z bosons, which carry the weak interaction; and gluons, which carry the strong interaction. What are leptons? • The word lepton comes from the Greek leptos, which means “small”, “fine”, or “thin”. The term was chosen to refer to particles of small mass. These elementary particles are over 200 times more massive than electrons, but have only about one-ninth the mass of a proton. Along with quarks, leptons are the basic building blocks of matter, and are therefore seen as “elementary particles”. A type of lepton What are quarks? Quarks are one of the fundamental parts of all matter. They're particles that combine together to form what are known as hadrons, some of which are protons and neutrons—the basic components of atomic nuclei. Different types of Quark’s and their properties? • There are six types, of quarks: up, down, strange, charm, bottom, and top. Up and down quarks have the lowest masses of all quarks. The heavier quarks rapidly change into up and down quarks through a process of particle decay: the transformation from a higher mass state to a lower mass state. Because of this, up and down quarks are generally stable and the most common in the universe, whereas strange, charm, bottom, and top quarks can only be produced in high energy collisions. • Quarks have various properties, including electric charge, mass, colour charge, and spin. They are the only elementary particles in the Standard Model of particle physics to experience all four fundamental forces Structure of Hadrons • Hadrons are categorized into two families: baryons, made of an odd number of quarks – usually three quarks – and mesons, made of an even number of quarks—usually one quark and one antiquark..