1. The problem statement, all variables and given/known data A pi meson (pion) and a proton can briefly join together to form a Δ particle. A measurement of the energy of the ∏p system shows a peak at 1236 MeV, corresponding to the rest energy of the Δ particle, with an experimental spread of 120 MeV. What is the lifetime of the Δ? A graph is given of the reaction probability as a function of energy, peaking at energy 1236 MeV. There are arrows on both sides of the peak labeled 120 MeV. 2. Relevant equations ΔE*Δt ~ h-bar 3. The attempt at a solution I am mainly unsure as to what an experimental spread is. My guess is that the experimental spread is equal to ΔE, and so the solution is simply (h-bar)/(120MeV), but that seems too simple.