Weak nuclear interactions

Article By:

Commins, Eugene D. Department of Physics, University of California, Berkeley, California.

Last reviewed:August 2020

DOI:https://doi.org/10.1036/1097-8542.742200

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• Weak nuclear interactions, published 2014:Download PDF Get Adobe Acrobat Reader

Fundamental interactions of nature that play a significant role in elementary-particle and nuclear physics, and are distinguished from other such interactions by special properties such as participation of all the fundamental fermions and failure to conserve parity and to respect particle–antiparticle symmetry. According to present understanding, the four fundamental forces of nature are the gravitational, the electromagnetic, the strong, and the weak. The weak force has short range (less than 10⁻¹⁷ m) and at low energies is very feeble compared to the strong and electromagnetic forces, but it can be distinguished from the latter by its special character. For example, all of matter (with the possible exception of dark matter) appears to consist of certain basic constituents, the quarks and leptons, collectively called the fundamental fermions (Table 1). While only quarks participate in strong interactions, and only the quarks and the charged leptons (e^±, μ^±, τ^±) participate in electromagnetic interactions, all of the fundamental fermions, including neutrinos, engage in weak interactions. Moreover, while the strong and electromagnetic interactions respect spatial inversion symmetry (parity) and are also particle–antiparticle (charge conjugation) symmetric, the weak interaction violates these two symmetries. See also: Dark matter; Fundamental interactions; Lepton; Parity (quantum mechanics); Quarks; Symmetry laws (physics)

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