# Thomson, Modern Particle Physics, Problem 6.7

1. Oct 7, 2015

### blankvin

In Mark Thomson's Modern Particle Physics, Problem 6.7, I am wondering how we obtain:

2(ms, 0, 0, 0) and -2(ms, 0, 0, 0)

for the RL and LR helicities (likewise for the muon) in the electron currents using helicity combinations. My solutions for the other helicities (RR, LL) work out, but I am not sure how these are obtained for the other helicities (RL, LR). I get (0, 0, 0, 0).

The problem can be viewed here:

Thanks,
blankvin.

Last edited: Oct 7, 2015
2. Oct 7, 2015

### blankvin

I was considering the ultra-relatistic regime (E>>m), so abandoned the mass term in my calculation. Using the normalization constant $\sqrt{E+m}$ fixed my problem.

Cheers,
blankvin.

3. Oct 8, 2015

### Drakkith

Staff Emeritus
It looks like your link goes to a page that's not available. Could you type the question out or something instead?