Scalar boson

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

Scalar

• 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.

Pseudoscalar

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

See also

• Scalar field theory
• Klein–Gordon equation
• Vector boson
• Higgs boson

References

1. "The scalar boson". ATLAS Collaboration. March 26, 2015. Retrieved May 22, 2021.
2. Nave, R. "Spin classification of particles". Retrieved June 8, 2021.
3. Thomson, Mark (2011). "Handout 9: The Weak Interaction and V-A" (PDF). Retrieved June 6, 2021.
4. "New results indicate that particle discovered at CERN is a Higgs boson" (Press release). 14 March 2013. Retrieved 22 May 2021.
5. "The Nobel Prize in Physics for 2013" (Press release). Nobel Media AB. 2013. Retrieved 22 May 2021.
6. 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.
7. Peskin, Michael E.; Schroeder, Daniel V. (1995). An Introduction to Quantum Field Theory. Westview Press. ISBN 978-0-201-50397-5.
8. Nave, R. "Hadrons, baryons, mesons". Retrieved May 23, 2021.