What is meant by the 'fine structure constant'? Explain what the fine structure constant tells us about the relative probability of the formation of a three particle event (muon antimuon and photon) compared with the formation of a muon and antimuon pair.
The fine structure constant is a measure of how strong charged particles interact with photons. Put differently, it is a measure of how strong the electromagnetic interaction is. The electric charge is also a measure of this force, however, unlike the fine structure constant, the value of the electric charge is unit dependent (it is not dimensionless). The relation between the fine structure constant and the elementary charge e is:
alpha = e^2/(4 pi ...
A detailed explanation is given.