boson

The name boson was coined by Paul Dirac{{cite book|title=Notes on Dirac's lecture Developments in Atomic Theory at Le Palais de la Découverte, 6 December 1945|publisher=UKNATARCHI Dirac Papers|id=BW83/2/257889}}{{Cite book|last=Farmelo|first=Graham|url=https://books.google.com/books?id=qsodmIGD0fMC&q=farmelo+graham+the+strangest+man|title=The Strangest Man: The Hidden Life of Paul Dirac, Mystic of the Atom|date=2009-08-25|publisher=Basic Books|isbn=9780465019922|pages=331|language=en}} to commemorate the contribution of Satyendra Nath Bose, an Indian physicist. When Bose was a reader (later professor) at the University of Dhaka, Bengal (now in Bangladesh),{{cite news|last=Daigle|first=Katy|date=10 July 2012|title=India: Enough about Higgs, let's discuss the boson|agency=Associated Press|url=http://apnews.excite.com/article/20120710/D9VU1DRG0.html|access-date=10 July 2012}}{{cite news|last=Bal|first=Hartosh Singh|date=19 September 2012|title=The Bose in the Boson|work=The New York Times|department=Latitude (blog)|url=http://latitude.blogs.nytimes.com/2012/09/19/indians-clamor-for-credit-for-the-bose-in-boson/|url-status=dead|access-date=21 September 2012|archive-url=https://web.archive.org/web/20120922024310/http://latitude.blogs.nytimes.com/2012/09/19/indians-clamor-for-credit-for-the-bose-in-boson/|archive-date=22 September 2012}} he and Albert Einstein developed the theory characterising such particles, now known as Bose–Einstein statistics and Bose–Einstein condensate.{{cite news|date=4 July 2012|title=Higgs boson: The poetry of subatomic particles|work=BBC News|url=https://www.bbc.co.uk/news/magazine-18708741|access-date=6 July 2012}}

{{Standard model of particle physics|cTopic=Elementary particles}}

{{See also|List of particles#Bosons}}

All observed elementary particles are either bosons (with integer spin) or fermions (with odd half-integer spin).{{cite book|author=Carroll, Sean|title=Guidebook|publisher=The Teaching Company|year=2007|isbn=978-1598033502|series=Dark Matter, Dark Energy: The dark side of the universe|at=Part 2, p. 43|quote=... boson: A force-carrying particle, as opposed to a matter particle (fermion). Bosons can be piled on top of each other without limit. Examples are photons, gluons, gravitons, weak bosons, and the Higgs boson. The spin of a boson is always an integer: 0, 1, 2, and so on ...}} Whereas the elementary particles that make up ordinary matter (leptons and quarks) are fermions, elementary bosons occupy a special role in particle physics. They act either as force carriers which give rise to forces between other particles, or in one case give rise to the phenomenon of mass.

According to the Standard Model of Particle Physics there are five elementary bosons:

• One scalar boson (spin = 0)
• {{Subatomic particle|link=yes|Higgs boson}} 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:
• {{Subatomic particle|link=yes|photon}} photon – the force carrier of the electromagnetic field
• {{Subatomic particle|link=yes|gluon}} gluons (eight different types) – force carriers that mediate the strong force
• {{Subatomic particle|link=yes|Z boson}} neutral weak boson – the force carrier that mediates the weak force
• {{Subatomic particle|link=yes|W boson+-}} 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.{{efn|

Despite being the carrier of the gravitational force which interacts with mass, most attempts at quantum gravity have expected the graviton to have no mass, just like the photon has no electric charge, and the W and Z bosons have no "flavour".

}}

{{see also|Spin–statistics theorem#Composite particles|List of particles#Composite particles}}

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),

{{cite journal

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|last3=Scholten |first3=Bernhard |last4=Neumaier |first4=Bernd

|date=June 8, 2016

|title=Uses of alpha particles, especially in nuclear reaction studies and medical radionuclide production

|journal=Radiochimica Acta

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|doi=10.1515/ract-2015-2566 |s2cid=56100709

|url=https://www.degruyter.com/document/doi/10.1515/ract-2015-2566/html

|access-date=May 22, 2021

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carbon-12, lead-208, and many others.

Even-mass-number nuclides comprise {{sfrac| 153 | 254 }} = 60% of all stable nuclides. They are bosons, i.e. they have integer spin, and almost all of them (148 of the 153) are even-proton / even-neutron (EE) nuclides. The EE nuclides necessarily have spin 0 because of pairing. The remaining 5 stable bosonic nuclides are odd-proton / odd-neutron (OO) stable nuclides (see {{section link|Even and odd atomic nuclei#Odd proton, odd neutron}}). The five odd–odd bosonic nuclides are:

{{div col begin|colwidth=3em}}

: {{nuclide|Hydrogen|2|link=yes}}

: {{nuclide|Lithium|6|link=yes}}

: {{nuclide|Boron|10|link=yes}}

: {{nuclide|Nitrogen|14|link=yes}}

: Tantalum-180m

{{div col end}}

Each of the five has integer, nonzero spin.

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.Monique Combescot and Shiue-Yuan Shiau, "Excitons and Cooper Pairs: Two Composite Bosons in Many-Body Physics", Oxford University Press ({{ISBN|9780198753735}}).

Certain quasiparticles are observed to behave as bosons and to follow Bose–Einstein statistics, including Cooper pairs, plasmons and phonons.{{cite book|author1-link=|author=Poole, Charles P. Jr.|url=https://books.google.com/books?id=CXwrqM2hU0EC|title=Encyclopedic Dictionary of Condensed Matter Physics|date=11 March 2004|publisher=Academic Press|isbn=978-0-08-054523-3}}{{rp|130}}

• {{annotated link|Anyon}}
• {{annotated link|Bose gas}}
• {{annotated link|Parastatistics}}

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Category:Quantum field theory

Category:Atomic physics

Category:Condensed matter physics