Phase Space

The 3D position space is thought to be along 3 axes, such that a set of three numbers (x,y, and z) can fully describe the location of an object. However, in a collision event, there are many other observable features that are crucial for adequately describing the particles that are formed, such as the angles and momenta of the outgoing particles or the quantity of each type of particle created. These observable features can uniquely define a single collision event in a high-dimensional "phase space”. Therefore, phase space is a good approach to picture particle collisions since different types of processes will be found in different sections of it.