# Homework Help: Finding cross sections for top quark production

1. Nov 10, 2015

### saybrook1

1. The problem statement, all variables and given/known data
The problem asks me to find $\frac{d\sigma}{dz}$ for $u\bar{u} \rightarrow t\bar{t}$ via the strong interaction and then to find the total cross section via QCD. I'm wondering what the difference is? I was just going to write the feynman rules for QCD to get the amplitude and subsequently the cross section. How will this look different finding it via the strong interaction?

2. Relevant equations
$u\bar{u} \rightarrow t\bar{t}$
$\frac{d\sigma}{dz}$

3. The attempt at a solution
Feynman rules for QCD to get amplitude then cross section

2. Nov 11, 2015

### Staff: Mentor

The difference is not the strong interaction (both parts use it), the difference is the total cross-section.

There are higher-order processes but I guess you have to consider leading order only here.