The weak interaction, also known as the weak nuclear force or weak force, is one of the four fundamental forces of nature, alongside the strong interaction, electromagnetic force, and gravity. The weak interaction is responsible for several key processes in particle physics, particularly those involving the transformation of subatomic particles. Key characteristics of the weak interaction include: 1. **Range and Strength**: The weak force has a very short range, typically on the order of 0.
Fermi's interaction refers to the fundamental weak nuclear force that governs the interactions of elementary particles, particularly those involving leptons (like electrons and neutrinos) and quarks. This interaction is largely described within the framework of the electroweak theory, which unifies the electromagnetic force and the weak nuclear force. The term "Fermi interaction" is often associated with Enrico Fermi, who made significant contributions to the understanding of weak interactions in the early 20th century.
Articles by others on the same topic
The weak interaction changes particle species through the charged current and also acts through the neutral current. Familiar examples include beta-minus decay and neutrino scattering. It is short-range and chiral: its W boson and Z boson couplings distinguish chirality. Above the electroweak scale it belongs to the unbroken electroweak interaction. At much lower energies, W boson exchange is approximated by the Fermi interaction.
A particularly direct window into the weak interaction is the Wu experiment: a sample with oriented nuclear spins emits electrons preferentially toward one end of its spin axis. The comparison tests parity conservation, because spin is an axial vector and momentum is a polar vector. The polarized beta-decay angular distribution translates that geometric distinction into a measurable counting asymmetry.
Explains beta decay. TODO why/how.
Maybe a good view of why this force was needed given beta decay experiments is: in beta decay, a neutron is getting split up into an electron and a proton. Therefore, those charges must be contained inside the neutron somehow to start with. But then what could possibly make a positive and a negative particle separate?
- the electromagnetic force should hold them together
- the strong force seems to hold positive charges together. Could it then be pushing opposite-charges apart? Why not? In any case this force doesn't seem to act on electrons, only quarks.
- gravity is too weak
www.thestargarden.co.uk/Weak-nuclear-force.html gives a quick and dirty:Also interesting:
Beta decay could not be explained by the strong nuclear force, the force that's responsible for holding the atomic nucleus together, because this force doesn't affect electrons. It couldn't be explained by the electromagnetic force, because this does not affect neutrons, and the force of gravity is far too weak to be responsible. Since this new atomic force was not as strong as the strong nuclear force, it was dubbed the weak nuclear force.
While the photon 'carries' charge, and therefore mediates the electromagnetic force, the Z and W bosons are said to carry a property known as 'weak isospin'. W bosons mediate the weak force when particles with charge are involved, and Z bosons mediate the weak force when neutral particles are involved.
Weak Nuclear Force and Standard Model of particle physics by Physics Videos by Eugene Khutoryansky (2018)
Source. Some decent visualizations of the field lines.