1. The problem statement, all variables and given/known data The Y Meson has a rest mass of 9.6 GeV/c2 and a measured width of (Delta)E= 51keV. What is its approximate lifetime (delta)t? 2. Relevant equations E=MC2 And.. who knows? 3. The attempt at a solution We came to the conclusion that 9.6 GeV/c2 was related to E=MC2.. and we pretty much had no idea with the measured width of (Delta)E= 51keV ( we thought it might be related to electric fields though).