>>12797297>Does smashing two existing particles together somehow create a new one?Smashing two existing particle with enough energy has a probability of creating a new particle, among many other decay channels. Smash millions of particles together and you obtain various particles in different quantities. These new particles are often unstable and then successively decay into showers of more stable particles before they can reach the detector.
You detect the final decay products and by measuring their momentum you can reconstruct their trajectory up to the moment they were created: this gives you information on the short-lived particles that you can't directly detect.
You now have terabytes of data on momentum, rapidity, energy... for individual events. By comparing these distributions to theoretical simulations you can either measure some properties of a particle more precisely (mass, lifetime...) or realise that you are missing something in the theory.
