What do we know?

1. Momentum is conserved.
2. The total momentum of the system is zero before the proton and anti-proton collide.
3. Momentum is a vector.
4. These 2D events largely occurred in the plane of the paper on which the event display is printed.
5. Physicists know that with a careful choice of units, it is possible to equate momentum and energy in a way that is similar to the way mass and energy are related. Specifically, it may be shown that the momentum of the collision debris has the same numerical value as the energy or mass of the particles. In other words, E (in GeV) = p (in GeV) = m (in GeV) (GigaelectronVolts). This shows, then, that the total energy that came from the two top quarks that were formed is equal to the numerical sum of all the momenta discovered in the collision.

Quark Event 1

Quark Event 2

Quark Event 3