Minimum energy positron electron collision producing Z-boson

[khallil]

Homework Statement

Homework Equations

m² = E² - p² ([/B]

The Attempt at a Solution

I got stuck by not knowing how to handle the frames and I thought you can view the Z boson (CoM) frame, but then you simply get that m_z = 2m_e

 

[vela]

The Attempt at a Solution

I got stuck by not knowing how to handle the frames

What does that mean?

and I thought you can view the Z boson (CoM) frame, but then you simply get that m_z = 2m_e

How did you get that?