So I'm looking at a two-body decay question for the $h\rightarrow\gamma\gamma$ decay channel for the Higgs Boson. I am asked to find the invariant mass of the Higgs boson.
I'm not too sure how to tackle this question. However, I have started with considering the centre of mass frame for this reaction
$$ s=(E_1+E_2)^2-(p_1+p_2)^2 $$
This gives me,
$$ s=E_1^{2}+E_2^{2}+2E_1E_2-p_1^{2}+p_2^{2}+2p_1p_2 $$
I'm a little confused what to do with this now, all I know is that the mass of the photon is $0$, and that I should probably write out the 4-momenta of the two photons...which I think is this:
$$ p_1=(E_1,E_1\sin{\theta},0,E_1\cos{\theta}) $$ $$ p_2=(E_2,-E_2\sin{\theta},0,-E_2\cos{\theta}) $$
Could anyone please advise and help on this one! Thank you...
