Is the Hard Sphere Collision Cross Section for 3-Body Systems Always Zero?

[brad sue]

Hi everybody,

I was reading an article and I have this affirmation i don't know if correct:
the hard sphere collision cross section for 3 bodies always equal to zero. Is it true?

Why should it be?
Thank you

 

[Dr Lots-o'watts]

You might want to provide a reference or at least a definition for "hard sphere".

In the classical sense, it is surely unlikely that three bodies make contact simultaneously. But are you talking of a classical or a quantum system?

 

[brad sue]

You might want to provide a reference or at least a definition for "hard sphere".

In the classical sense, it is surely unlikely that three bodies make contact simultaneously. But are you talking of a classical or a quantum system?

Hard sphere is the "normal" cross section we have in classical physics namely pi*radius^2.
we are in quantum system and usually thr cross section is function of the particle speeds.

I am trying to understand this 3 body cross section with the quantum energy bound states but all those curves drive me crazy! maybe it is not the good way to approach it...