The Z boson is a neutral particle that, along with the W⁺ and W⁻ bosons, mediates the weak nuclear force. While the W bosons are charged and involved in charged current interactions, the Z boson mediates neutral current interactions, where particles exchange energy or momentum without changing their electric charge.
Key properties of the Z boson:
- It is electrically neutral.
- It is very massive, slightly heavier than the W boson—around 91 times the mass of a proton.
- It has a very short range, meaning weak neutral interactions occur only over subatomic distances.
Examples of Z boson-mediated processes include:
- Neutrino scattering off electrons or nucleons without changing type.
- Elastic scattering of electrons or quarks via weak interactions.
The Z boson, like the W bosons, gains its mass through the Higgs mechanism and was a crucial prediction of the electroweak theory, which unifies the electromagnetic and weak forces.
Its discovery at CERN in 1983 was a landmark achievement, confirming the electroweak theory and solidifying the Standard Model. The Z boson continues to be an essential probe in high-energy physics experiments, especially in precision tests of fundamental symmetries.