Boson

, the other being fermions. All subatomic particles must be one or the other. A composite particle (hadron) may fall into either class depending on its composition. In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value (0, 1, 2, ...). The class of bosons is one of the two fundamental classes of subatomic particle, the other being fermions, which have half odd-integer spin (1/2, 3/2, 5/2, ...). Every observed subatomic particle is either a boson or a fermion. Paul Dirac coined the term boson to classify the fundamental particles that obey Bose–Einstein statistics, the quantum framework pioneered by Satyendra Nath Bose. Some bosons are elementary particles occupying a special role in particle physics, distinct from the role of fermions (which are sometimes described as the constituents of "ordinary matter"). Certain elementary bosons (e.g. gluons) act as force carriers, which give rise to forces between other particles, while one (the Higgs boson) contributes to the phenomenon of mass. Other bosons, such as mesons, are composite particles made up of smaller constituents.…

, the other being fermions. All subatomic particles must be one or the other. A composite particle (hadron) may fall into either class depending on its composition.]] In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value (0, 1, 2, ...). The class of bosons is one of the two fundamental classes of subatomic particle, the other being fermions, which have half odd-integer spin (1/2, 3/2, 5/2, ...). Every observed subatomic particle is either a boson or a fermion. Paul Dirac coined the term boson to classify the fundamental particles that obey Bose–Einstein statistics, the quantum framework pioneered by Satyendra Nath Bose. Some bosons are elementary particles occupying a special role in particle physics, distinct from the role of fermions (which are sometimes described as the constituents of "ordinary matter"). Certain elementary bosons (e.g. gluons) act as force carriers, which give rise to forces between other particles, while one (the Higgs boson) contributes to the phenomenon of mass. Other bosons, such as mesons, are composite particles made up of smaller constituents. Outside the realm of particle physics, multiple identical composite bosons behave at high densities or low temperatures in a characteristic manner described by Bose–Einstein statistics: for example, a gas of helium-4 atoms becomes a superfluid at temperatures close to absolute zero. Similarly, superconductivity arises because some quasiparticles, such as Cooper pairs, behave in this characteristic manner. One scalar boson (spin = 0) Higgs boson – the particle that contributes to the phenomenon of mass via the Higgs mechanism Four vector bosons (spin = 1) that act as force carriers. These are the gauge bosons: photon – the force carrier of the electromagnetic field gluons (eight different types) – force carriers that mediate the strong force neutral weak boson – the force carrier that mediates the weak force charged weak bosons (two types) – also force carriers that mediate the weak force A second-order tensor boson (spin = 2) called the graviton (G) has been hypothesised as the force carrier for gravity, but so far all attempts to incorporate gravity into the Standard Model have failed. Composite particles (such as hadrons, nuclei, and atoms) can be bosons or fermions depending on their constituents. Since bosons have integer spin and fermions half odd-integer spin, any composite particle made up of an even number of fermions is a boson (e.g., 1/2 + 1/2 + 1/2 + 1/2 = 2 for the three quarks and an electron in a hydrogen atom). Composite bosons include: All mesons of every type Stable nuclei with even mass numbers such as deuterium, helium-4 (the alpha particle), carbon-12, lead-208, and many others. As quantum particles, the behaviour of multiple indistinguishable bosons at high densities is described by Bose–Einstein statistics. One characteristic which becomes important in superfluidity and other applications of Bose–Einstein condensates is that there is no restriction on the number of bosons that may occupy the same quantum state. As a consequence, when for example a gas of helium-4 atoms is cooled to temperatures very close to absolute zero and the kinetic energy of the particles becomes negligible, it condenses into a low-energy state and becomes a superfluid. Other examples in condensed matter systems include Cooper pairs in superconductors and excitons in semiconductors.

Text derived from https://en.wikipedia.org/w/index.php?oldid=1374585804 under CC BY-SA 4.0; modifications have been made.