PX156 - G4 - strategies of drawing a feynmann diagram
what force is acting here?
| observation | interaction |
|---|---|
| electromagnetic | |
| charged weak | |
| net flavour change | charged weak |
| anything else | strong |
- there is a hierarchy of forces based on how fast the various interactions are
| stength | high | middle | weak |
|---|---|---|---|
| strong | EM | weak | |
| speed | fast | medium | slow |
- use the hierarchy to choose between forces if the choice exists
how to use this force to transition from the initial to the final state?
| pair appearing/disappearing | flavours of the particles | force(s) involved |
|---|---|---|
| same | ||
| different | ||
| same | ||
| different | ||
| same | ||
| same | ||
| nothing (internal emission/absorption) | nothing |
examples
-
eg: $$e^{-}(1)+e^{-}(2)\to e^{-}(3)+e^{-}(4)$$
- no obvious change
internal emission of - particles are leptons
- no obvious change
-
eg: $$n \to p^{+} + e^{-}+ \bar\nu_{e}$$
:-)