# Homework Help: Longitudinal Decay Width

1. Jun 26, 2012

### PLuz

1. The problem statement, all variables and given/known data
Hello,

Given the decay: $H \rightarrow W^{-} + \bar{s} + c$, where it only matters that $\bar{s}$ and $c$ are fermions and $W^{-}$ is the W boson. If one knows the total width of the process how can we calculate the longitudinal width?

2. Relevant equations
In the frame where de boson has velocity zero the longitudinal polarization vector is given by: $\epsilon_{\mu}(k)=(0,0,0,1)$

In the frame where $W^{-}$ moves at velocity $\overrightarrow{\beta}$:
$\epsilon_{\mu}(k)=(\gamma \beta, \gamma \frac{\overrightarrow{\beta}}{\beta})$

3. The attempt at a solution

I'm completly clueless of how to even start. Can anyone help me?

Thank you