Particle Collisions Producing Same or Different Particles?

I just wanted to ask if when two elementary particles collide with each other, does the result is always two or more DIFFERENT particles, or can it be that they can just bounce of eachother and go other directions? Because if we assume elementary particles should be treated like points, shouldnt they always bounce at eachother at 180 degrees? I mean fly back where they came from?
- Lucas (age 31)
Poland

Good question.   If two high energy particles collide they can simply bounce off of each other, in which case it's called an elastic collision in the trade.  They can bounce off at angles different that 180^o just like billiard balls on a pool table.   An inelastic collision occurs when different particles or states are produced.  This may include an excited state of one of the particles or it might involve completely different particles such as e⁺ + e^- --> μ⁺+ μ^-. In either case energy and momentum as well as relevant quantum numbers must be conserved.

 

LeeH

(published on 11/04/2013)