1. The problem statement, all variables and given/known data See Image The bit about Spectral lines, I couldn't explain why 2. Relevant equations ΔEΔt≈h 3. The attempt at a solution I expected the histogram to peak at the given mass in question and to have a width of about 0.08 MeV calculated as ΔE from the Energy-time uncertainty, but I don't understand how the standard deviation is 52±3 in the CMS graph, this is so far away from my calculation, plus, is this the only difference? I would also suspect that i misunderstood the question maybe. I haven't dealt with such graphs before!