1. The problem statement, all variables and given/known data A Higgs boson has mass 125 GeV/c2, decaying into a pair of Z bosons, mass 91 GeV/c2. In the lab frame, one of the Z bosons is at rest. Determine the kinetic energy for the other Z boson in this laboratory frame. 2. Relevant equations E = γmc2 γ=1/√(1-β2) 3. The attempt at a solution My basic issue surrounding the problem is the derived value for gamma. First, treating the problem in the center mass frame, I stated: Mhc2=2γmzc2 thus γ=125Gev/(2*91GeV)= 0.6868 this is where my dilemma lies. Seeing that the Z boson is at rest in the lab frame I assumed γ= 0.6868; however as Kh= (γ-1)E (0.6868-1)(125 GeV)= -39.14 GeV What confuses me is that the Kinetic Energy would be negative, thus I assumed my approach to the problem was erroneous. Thus I alternately attempted to derive velocity from gamma in order to perform a lorentz transformation, but then as γ= 0.6868 v=c√(1-(1/γ2) there would be a negative within the square root.