Under Construction 
On one hand there is quantum mechanics and the standard model, which describes the world of the very small. On the other hand there is general relativity, which describes gravity and the world of the very large. With one exception, all of the particles listed below are explained by the standard model. The exception is the graviton, the force particle behind gravity.
Superstring theorists believe they are on their way to developing a framework that incorporates both general relativity and quantum mechanics. If they succeed, they will have discovered a theory that solves the greatest problem in physicsÑthat of unifying the laws of nature.
If superstring theory turns out to be true, every one of the "fundamental" particles below are made of identical strings, with the only difference between the strings being their vibrational patterns.
BOSONS - Forces
In particle processes the forces are described as due to the exchange of particles; for each type of force there is an associated carrier particle.
| Particle | Context | Range | Effects |
| Gravitation | Gravity | infinite | No effect at nuclear level |
| Photon | Electro-
magnetism | infinite | Holds molecules together and electrons to the nucleus in an atom.
| | Gamma ray is the name given a photon from a nuclear transition. |
| Gluon | Strong force | 10-13 m | Holds quarks together to form hadrons; Keeps positive charged protons from flying apart from electrical force.
| | The alpha particle is a helium nucleus - one of the products of a nuclear fission, a residual strong interaction effect . Fission is the breakup of a massive nucleus into smaller nuclei; this occurs when the sum of the masses of the smaller nuclei is less than the mass of the parent nucleus. |
| Weak Gauge Bosons | weak force | 10-16 m | Nuclear interactions associated with particle decay.
| | Weak interactions are the only processes in which a quark can change to another type of quark, or a lepton to another lepton. in a nucleus where there is sufficient energy a neutron becomes a proton and gives off an electron and an antielectron neutrino. This decay changes the atomic number of the nucleus. Beta ray is the name given to the emerging electron. |
| Higgs Boson | weak force | ? |
Responsible for mass.
| | In 1964 Scottish physicist Peter W. Higgs of Edinburgh Univ. proposed a way to explain how the fundamental particles could have mass. He theorized that the whole of space is permeated by a field, now called the Higgs field, and as particles tragvel through this field, and if they interact with it they acquire what appears to be mass. |
FERMIONS - Matter See Particle Physics.
Leptons -
Electron - Atoms
Electron Neutrino - Radioactive Decay
Quarks - Atomic Nuclei
Particles have attributes of spin, mass and charge.
Spin - Intrinsic angular momentum
Charge - Relative to a proton
Mass - E/c2 where E is electronvolts (eV)
See Also:
Electromagnetic Spectrum
Elementary Particles at NOVA
Probing the Nucleus
last updated 26 Dec 2005
| 
Science