Which Lepton Processes are Most Probable?

[LineIntegral]

Homework Statement

Compare the probabilities for the following processes to happen:

1. e^+ + e^- \to \nu_\mu + \bar{\nu}_\mu
2. e^+ + e^- \to \nu_\mu + \bar{\nu}_e
3. e^+ + e^- \to \nu_e + \bar{\nu}_e

Homework Equations

N/A

The Attempt at a Solution

I really have no idea how to solve this. Any help will be appreciated.

 

[Mike Pemulis]

There are really two parts to this. First, try to see if any of those reactions is impossible (at least one is).

Secondly, for any or all reactions that are possible, you can try to draw the Feynman diagrams for those reactions. Some reactions may have more than one diagram; you need to find all of them (at least, all the diagrams with no loops).