The weak interaction (or ‘weak force’) is one of the four known fundamental types of interactions in physics. It is only stronger than the gravitational force, but the range over which weak interaction occurs is very short (m), thus making its effects even harder to detect accurately. The weak interactions affect markedly all of the left–handed leptons and the very heavy quarks, such as the top and bottom quarks. Main (electroweak) field carriers of the weak interaction are the W and Z bosons. The weak interaction is the only interaction that violates parity and changes flavours, thus allowing for the heavier (less stable) quarks decay. The electroweak interaction is also responsible for the beta decay process, and thus is part of many naturally occuring radiation processes. An unified quantum treatment of the electroweak interaction and elctromagnetic field theory (QED), with the former involving the symmetry of the ‘special unitary’ Lie group SU(2), was first reported by Physics Nobel Laureate Stephen Weinberg (for a recent textbook by the latter please see ref. [1]). The SU(2) symmetry is currently part of the Standard Model (SUSY) of physics.

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