Is Conservation of Momentum Essential for Understanding Particle Interactions?

[matpo39]

if you have a photon with momentum $$p_\gamma$$ traveling in the +x direction which is then deflected off a free electron and now the photon has momentum $$p_\gamma'$$ and isin the +y direction.
so the components of momentum for the electron would be
p_e = $$p_\gamma'$$ in the -y direction and for the x component

$$p_ex= \sqrt{p_\gamma^2-p_\gamma'^2-p_ey^2}$$

does this seem like the correct approach to this problem?

 

[andrevdh]

What was the question?
Could this be the answer? That is the components of the momentum of the system before the interaction should be equal to the components of the momentum of the system after the interaction.