Finding the Mass of the Higgs Boson - Part 2

Adding up the masses of the particles from the Higgs decay doesn't work, because these particles have enormous kinetic energy compared to their rest mass energy (remember, for a particle at rest, E = mc²). This happens because the mass of the Higgs boson is much greater than the masses of its final decay products, so the remaining energy has to go somewhere, and it goes into the kinetic energy of the decay products. Relativity tells us to use the equation below to calculate the "invariant mass" of the set of the particles from the decay, which then gives us the mass of the "parent", the Higgs boson.