Everything about Bosons totally explained
In
particle physics,
bosons are
particles with an
integer spin, as opposed to
fermions which have
half-integer spin. From a behaviour point of view, fermions are particles that obey the
Fermi-Dirac statistics while bosons are particles that obey the
Bose-Einstein statistics. They may be either
elementary, like the
photon, or
composite, as
mesons. All
force carrier particles are bosons. They are named after
Satyendra Nath Bose. In contrast to
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
gauge bosons) are
elementary particles not known to be composed of other particles. The only boson in the
Standard Model that's yet to be discovered experimentally is the
Higgs boson.
Basic properties
All elementary and composite particles in 3 dimensional space are either bosons or fermions, depending on their
spin. Particles with
half-integer spin are
fermions; particles with
integer spin are bosons. The
spin-statistics theorem identifies the resulting
quantum statistics that differentiate fermions and bosons. Bosons obey
Bose–Einstein statistics. Fermions, on the other hand, can't occupy the same quantum state as each other; they obey the
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
lasers and
masers,
superfluid helium-4 and
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
gauge bosons. These include the
W and Z bosons of the
weak force, the
gluons of the
strong force, the
photons of the
electromagnetic force, and, in
quantum gravity, the yet to be verified
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
protons,
neutrons or
nuclei) can be either fermions or bosons, depending on their total spin. Hence, many nuclei are bosons. For instance, consider
3He. It is made of 2 protons, a neutron and 2 electrons. Since the spins of these five fermions must add to a half integer,
3He is a fermion. On the other hand
4He, which is made of six fermions, is a boson. Likewise, the
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
Further Information
Get more info on 'Bosons'.
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