# Feynman diagram

## Homework Statement

What observation of the process: (anti muon neutrino) + (electron) -> (anti muon neutrino) + (electron) constitutes unambiguous evidence for weak neutral currents,

whereas the observation of (anti electron neutrino) + (electron) -> (anti electron neutrino) + (electron)

## The Attempt at a Solution

The solution is the first one:

{www}.scribbleproductions.co.uk/stuff/fine1.jpg

Since the second reaction can undergo via W+ as well as Z0:

{www}.scribbleproductions.co.uk/stuff/fine2.jpg

My question is in the Feynman diagrams, why could you not have this for example:

An electron decaying to a muon neutrino ?

{www}.scribbleproductions.co.uk/stuff/fine3.jpg

Apparently the weak interaction also violates charge conservation, but I have never seen a possible reaction with a Feynman diagram that is violated at the vertices's.

Many thanks for any help :)

nrqed
Homework Helper
Gold Member

## Homework Statement

What observation of the process: (anti muon neutrino) + (electron) -> (anti muon neutrino) + (electron) constitutes unambiguous evidence for weak neutral currents,

whereas the observation of (anti electron neutrino) + (electron) -> (anti electron neutrino) + (electron)

## The Attempt at a Solution

The solution is the first one:

{www}.scribbleproductions.co.uk/stuff/fine1.jpg

Since the second reaction can undergo via W+ as well as Z0:

{www}.scribbleproductions.co.uk/stuff/fine2.jpg

My question is in the Feynman diagrams, why could you not have this for example:

An electron decaying to a muon neutrino ?

{www}.scribbleproductions.co.uk/stuff/fine3.jpg

Apparently the weak interaction also violates charge conservation, but I have never seen a possible reaction with a Feynman diagram that is violated at the vertices's.

Many thanks for any help :)

The weak interaction does NOT violate charge conservation! So your third diagram is impossible. Charge is always conserved

The weak interaction does NOT violate charge conservation! So your third diagram is impossible. Charge is always conserved

Thanks for that, I was a bit uneasy to see charge violation.

Does weak violate anything to do with charge? I remember seeing something about charge violation that only the weak does not strong or e.m

Regards,