Scalar boson

Standard Model of particle physics
Elementary particles of the Standard Model
Background Particle physics Standard Model Quantum field theory Gauge theory Spontaneous symmetry breaking Higgs mechanism
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Scientists Rutherford Thomson Chadwick Bose Sudarshan Davis Jr Anderson Fermi Dirac Feynman Rubbia Gell-Mann Kendall Taylor Friedman Powell Anderson Glashow Iliopoulos Lederman Maiani Meer Cowan Nambu Chamberlain Cabibbo Schwartz Perl Majorana Weinberg Lee Ward Salam Kobayashi Maskawa Mills Yang Yukawa 't Hooft Veltman Gross Pais Pauli Politzer Reines Schwinger Wilczek Cronin Fitch Vleck Higgs Englert Brout Hagen Guralnik Kibble de Mayolo Lattes Zweig
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A scalar boson is a boson whose spin equals zero.^[1] A boson is a particle whose wave function is symmetric under particle exchange and therefore follows Bose–Einstein statistics. The spin–statistics theorem implies that all bosons have an integer-valued spin.^[2] Scalar bosons are the subset of bosons with zero-valued spin.

The name scalar boson arises from quantum field theory, which demands that fields of spin-zero particles transform like a scalar under Lorentz transformation (i.e. are Lorentz invariant).

A pseudoscalar boson is a scalar boson that has odd parity, whereas "regular" scalar bosons have even parity.^[3]

Examples

The only fundamental scalar boson in the Standard Model of particle physics is the Higgs boson,^[1] the existence of which was confirmed on 14 March 2013 at the Large Hadron Collider by CMS and ATLAS.^[4] As a result of this confirmation, the 2013 Nobel Prize in physics was awarded to Peter Higgs and François Englert.^[5]
Various known composite particles are scalar bosons, e.g. the alpha particle and scalar mesons.^[6]
The φ⁴-theory or quartic interaction is a popular "toy model" quantum field theory that uses scalar bosonic fields, used in many introductory quantum textbooks^[7]^{[page needed]} to introduce basic concepts in field theory.

There are no fundamental pseudoscalars in the Standard Model, but there are pseudoscalar mesons, like the pion.^[8]

^ ^a ^b "The scalar boson". ATLAS Collaboration. March 26, 2015. Retrieved May 22, 2021.
^ Nave, R. "Spin classification of particles". Retrieved June 8, 2021.
^ Thomson, Mark (2011). "Handout 9: The Weak Interaction and V-A" (PDF). Retrieved June 6, 2021.
^ "New results indicate that particle discovered at CERN is a Higgs boson" (Press release). 14 March 2013. Retrieved 22 May 2021.
^ "The Nobel Prize in Physics for 2013" (Press release). Nobel Media AB. 2013. Retrieved 22 May 2021.
^ Qaim, Syed M.; Spahn, Ingo; Scholten, Bernhard; Neumaier, Bernd (8 June 2016). "Uses of alpha particles, especially in nuclear reaction studies and medical radionuclide production". Radiochimica Acta. 104 (9): 601. doi:10.1515/ract-2015-2566. S2CID 56100709. Retrieved 22 May 2021.
^ Peskin, Michael E.; Schroeder, Daniel V. (1995). An Introduction to Quantum Field Theory. Westview Press. ISBN 978-0-201-50397-5.
^ Nave, R. "Hadrons, baryons, mesons". Retrieved May 23, 2021.

Quarks	Up (quark antiquark) Down (quark antiquark) Charm (quark antiquark) Strange (quark antiquark) Top (quark antiquark) Bottom (quark antiquark)
Leptons	Electron Positron Muon Antimuon Tau Antitau Neutrino Electron neutrino Electron antineutrino Muon neutrino Muon antineutrino Tau neutrino Tau antineutrino

Gauge	Photon Gluon W and Z bosons
Scalar	Higgs boson

Gauginos	Gluino Gravitino Photino
Others	Axino Chargino Higgsino Neutralino Sfermion (Stop squark)

Others

Baryons	Nucleon Proton Antiproton Neutron Antineutron Delta baryon Lambda baryon Sigma baryon Xi baryon Omega baryon
Mesons	Pion Rho meson Eta and eta prime mesons Bottom eta meson Phi meson J/psi meson Omega meson Upsilon meson Kaon B meson D meson Quarkonium
Exotic hadrons	Tetraquark (Double-charm tetraquark) Pentaquark