The exchange of particles in an interaction can be visualised using Feynman diagrams. In a Feynman diagram the particles and the exchange particle are shown. The paths (arrows) do not represent the actual direction through space-time of the particles, it is just a visualisation
|1. Electrostatic repulsion between two electrons.
|The electrons exchange a virtual photon which transfers momentum and causes a repulsive force. Note that no charge is transferred by the virtual photon.|
|2. Nuclear strong force binding a proton and neutron
Because a positive pi-meson is the exchange particle then charge is transferred and the proton and neutron swap places. If a neutral pi-meson had been the exchange particle then obviously this wouldn't have happened!
What is actually happening is that the proton (uud) looses an up quark and a down / antidown pair (dd) are temporarily created. The down quark stays to form the neutron (udd). The remaining up and antidown quarks form the pi-meson (ud) which then joins with the neutron. Now the reverse happens ... the antidown annihilates with a down in the neutron and the up fills the empty place.
|3. Consider a weak interaction: beta decay where a neutron decays
to form a proton and an electron
n --> p+ + e- + νe
This is a weak interaction mediated by a boson.
The neutron becomes a proton.
A down quark has transformed to become an up quark and the W- boson which has to be negative to conserve charge.
The boson then decays to form the electron and antineutrino
Consider the conservation laws:
In all respects the conservation laws are obeyed
|4. A weak interaction for delta particle decay
|This is a weak interaction as the strange quark is changed to another flavour|
|5. A weak interaction between lepton and hadron
|The consevation of lepton number dictates the creation of the positron, it would not have been possible to create a muon and still conserve lepton number. Baryon number is conserved.|
|6. Strong Interaction between Baryons and Mesons
|From the properties of the strong interaction it is possible to predict exactly what the unidentified particle will be - this is not possible with the weak interaction where flavour is not conserved.|
|7. Multiple decay process of an excited psi meson
|The excited psi meson (cc) decays via the strong interaction to form the unexcited psi meson and a pair of pi-mesons. The charm quarks then annhilate and a pair of leptons are created.|