Boson



In particle physics, bosons are fermions, several bosons can occupy the same quantum state. Thus, bosons with the same energy can occupy the same place in space.

While most bosons are composite particles, four bosons (the graviton.[1]

Basic properties

All elementary and composite particles are either bosons or fermions, depending on their spin. Particles with half-integer spin are Fermi-Dirac statistics and the Pauli exclusion principle. They "resist" being placed close to each other. So, fermions possess "rigidness" and thus sometimes are considered to be "particles of matter". The properties of Bose–Einstein condensates are all consequences of statistics of bosons. Another result is that the spectrum of a photon gas in thermal equilibrium is a Planck spectrum, one example of which is black-body radiation; another is the thermal radiation of the opaque early Universe seen today as microwave background radiation). Interaction of virtual bosons with real fermions are called fundamental interactions, and these result in all forces we know. The bosons involved in these interactions are called graviton of the gravitational force.

In large systems, 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 are well approximated by Maxwell-Boltzmann statistics, which is described by classical mechanics.

Composite bosons

Particles composed of a number of other particles (such as deuteron (2H+), which is composed of a proton and a neutron, is a boson, however the neutral deuterium atom, which also has an electron, is a fermion.

Composite bosons exhibit bosonic behavior only at distances large compared to their structure size. At a small distance they behave according to properties of their constituent particles. For example, despite the fact that an alpha particle is a boson, at high energy it interacts with another alpha particle not as a boson but as an ensemble of fermions.

Examples of bosons

Main article: List of particles#Bosons (integer spin)

See also

References

  1. ^ Standard Model of Particle Physics at Standford Linear Collider
  • Sakurai, J.J. (1994). Modern Quantum Mechanics (Revised Edition), pp 361-363. Addison-Wesley Publishing Company. ISBN 0-201-53929-2.
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