1. The problem statement, all variables and given/known data The particle J/Ψ can be produced in both proton-proton collisions and electron-positron collisions. a) Consider a proton beam incident upon a ﬁxed hydrogen target. Calculate the energy of the proton beam in the reaction p1 + p2 → p + p + J/Ψ b) Consider two counter propagating beams of electrons and positrons respectively. The two beams have identical energy. Calculate the value of the electron energy in the reaction e+ + e− → J/Ψ 2. Equations: (a) E + mc2 = 2E' + EJ P = 2P' + PJ (Proton energy before and after are denoted as E and E') (b) 2Ee = mJc2 Pe+ + Pe- = 0 3. Attempt: I applied the law of energy and momentum conservation. (a) I tend to use E'2 = (p'c)2 + (mc2)2 to get E in terms of P and PJ, but then I would have problem as I don't know about PJ. (b) The positron and electron have equal and opposite momenta so the meson must only have rest mass energy mJc2. So, I can try to solve for Ee. Can anyone please tell if my approach is correct?