Relativistic Decay: Calculating Pion Momentum

[FilipLand]

Homework Statement

A Sigma^+ decays at rest into a neutron and a pion^+ meson, i.e. according to the reaction

$$\Sigma \rightarrow n + \pi$$
The n and π masses are assumed known. The kinetic energy of the π + is measured to be 92 MeV.

Determine the momentum of the pion.

Homework Equations

The Attempt at a Solution

I have tried to use four-momentum and that $m_\sigma$ = $m_\pi$ + $m_n$ but can't just use these relation to solve the problem. I think its really easy once one just know how to do it...

 

[Orodruin]

Hint: There is a lot of superfluous information.

 

[FilipLand]

Hint: There is a lot of superfluous information.

Yes well of course?
I tried solve for v in the formula for rel. Kinetic energy and plug into p=\gamma m*v but don’t get the right answer..

 

[Orodruin]

Hint: Kinetic energy is total energy minus rest energy. There is no need to start involving gamma factors or the velocity.