Boson
Encyclopedia : B : BO : BOS : Boson
- For other uses, see Boson (disambiguation)}}}.
Boson properties
All elementary particles are either bosons or fermions (depending on their spin). The spin-statistics theorem identifies the resulting quantum statistics that differentiate fermions and bosons.Interaction of virtual bosons with real fermions are called fundamental interactions. Momentum conservation in these interactions mathematically results in all forces we know. The bosons involved in these interactions are called gauge bosons - such as the W vector bosons of the weak force, the gluons of the strong force, the photons of the electromagnetic force, and (in theory) the graviton of the gravitational force.
Particles composed of a number of other particles (such as protons or neutrons or nuclei) can be either fermions or bosons, depending on their total spin. Hence, many nuclei are in fact bosons. So even though the main three massive subatomic particles i.e. the proton, neutron, and electron are all fermions, it is possible for a single element such as helium to have some isotopes that are fermions (e.g. 3He) and other isotopes that are bosons (e.g. 4He). (3He) is composed of one neutron and two protons [PNP]. Likewise, the deuterium (2H), which is composed of one proton plus one neutron [NP] is a boson, while the tritium (3H), which is composed of two neutrons plus one proton [NPN] is a fermion.
While fermions obey the Pauli exclusion principle: "no more than one fermion can occupy a single quantum state", there is no exclusion property for bosons, which can occupy the same quantum state. The result is that the spectrum of photon gas of certain equilibrium temperature is Planck spectrum (one example of which is black-body radiation, another - hot radiation of early Universe seen today as microwave background radiation). Operation of lasers, the properties of superfluid helium-4 and recent formation of Bose-Einstein condensates, a particular state of matter are all consequences of statistics of bosons.
Of course, the difference between bosonic and fermionic statistics is only apparent at large densities - when their wave functions overlap. At low densities, both types of statistics reduce to Maxwell-Boltzmann statistics, so both the boson and fermion particles behave as classical particles.
Examples of bosons:
- Deuterium, an isotope of Hydrogen
- Helium-4 atoms
- Sodium-23 atoms
- Any nuclei with integer spins
- photons, which mediate the electromagnetic force
- W and Z bosons, which mediate the weak nuclear force
- gluons
- Higgs bosons
- phonons
See also
- Bosonic field
- Bose gas
- Fermions
- Identical particles
- List of particles
- Parastatistics
- Tonks-Girardeau gas
- Superconductivity
References
- Sakurai, J.J. (1994). Modern Quantum Mechanics (Revised Edition), pp 361-363. Addison-Wesley Publishing Company. ISBN 0-201-53929-2.
| Particles in physics - elementary particles | [http://encycl.opentopia.com/ edit ] |
| Fermions: Quarks: (Up · Down · Strange · Charm · Bottom · Top) | Leptons: (Electron · Muon · Tau · Neutrinos) | |
| Gauge bosons: Photon | W and Z bosons | Gluons | |
| Not yet observed: Higgs boson | Graviton | Other hypothetical particles | |
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