Multiple scattering

[geoduck]

In a high energy physics experiment, do you ever scatter more than 2 particles at a time?

Suppose you scatter 4 incoming particles and get 4 outgoing particles. Do you only look at connected diagrams with 8 external lines? Or do you also have to take into account the product of disconnected graphs with 4 external lines?

I know a beam of particles is used, but do the particles in the beam collide one at a time with the target, or can two particles in the beam collide at the same time with the target?

 

[mfb]

I know a beam of particles is used, but do the particles in the beam collide one at a time with the target, or can two particles in the beam collide at the same time with the target?

In principle, the collision products from one collision could hit another particle. This is extremely unlikely, however.

Something you can have in proton-proton collisions are multi-parton interactions, but at high energies even those are more like two separate event coming from the same protons.
At low energies, you can have interactions where the whole proton participates. If you consider that as collection of partons, you can probably say multiple incoming partons participated.