The "Particle Zoo"


The Standard model (Youtube) provided by CERN 

The Standard model


    Leptons and quarks are the basic building blocks of matter, i.e., they are seen as the "elementary particles". There are six leptons in the present structure, the electron, muon, and tau particles and their associated neutrinos. The different varieties of the elementary particles are commonly called "flavors", and the neutrinos here are considered to have distinctly different flavor. 

Definition provided by Hyperphysics


    Quarks and Leptons are the building blocks which build up matter, i.e., they are seen as the "elementary particles". In the present standard model, there are six "flavors" of quarks. They can successfully account for all known mesons and baryons (over 200). The most familiar baryons are the proton and neutron, which are each constructed from up and down quarks. Quarks are observed to occur only in combinations of two quarks (mesons), three quarks (baryons). There was a recent claim of observation of particles with five quarks (pentaquark), but further experimentation has not borne it out. 


Definition provided by Hyperphysics


     Color is the strong interaction analog to charge in the electromagnetic force. The term "color" was introduced to label a property of the quarks which allowed apparently identical quarks to reside in the same particle, for example, two "up" quarks in the proton. To allow three particles to coexist and satisfy the Pauli exclusion principle, a property with three values was needed. The idea of three primary colors like red, green, and blue making white light was attractive, and language about "colorless" particles sprang up. It has nothing whatever to do with real color, but provides three distinct quantum states. The property can be considered something like a "color charge" with three distinct values, with only color neutral particles allowed.     The terms "color force" and even "quantum chromodynamics" have been used, extending the identification with color terms. The antiquarks have anti-colors, so the mesons can be colorless by having a red and an "anti-red" quark. The idea of color is supported by the fact that all commonly observed particles have either three quarks (baryons) or two (mesons), the combinations which can be "colorless" or "color neutral" with the three values of color. This does not exclude "di-baryons" with 6 quarks and other combinations of more than three. The only experimental indication of the presence of such particles is recent evidence for a penta-quark particle. 

Definition provided by Hyperphysics