Collision of particles (relativity)

[Frillth]

Homework Statement

An incident positron (e+) with rest mass m_e and with energy E strikes an electron (e−) at rest, also with rest mass me. They annihilate such that the liberated energy produces a top quark (t) and an anti-top quark (ṯ), each with rest mass of m_t.

Find an expression for the minimum incident energy E of the positron that will allow this reaction to happen.

Homework Equations

E^2 = P^2*m^2 + m^2*c^4

The Attempt at a Solution

I know I'm supposed to use the center of mass reference frame somehow, but I don't really have any idea how that helps. Can somebody please point me in the right direction?

Edit: I got it. Please ignore this post.

 

[Redbelly98]

Just responding to "un-blue" this post in the list of threads.