 
by the kinematics of the previous interaction.<br/> 
For a double rescattering, when both incoming partons have already scattered, 
there is no obvious way to retain the invariant mass of the system in the
first approach, so the second is always used. 
  

<h3>Colour flow</h3>

The colour flows in the separate subprocesses defined in the 
multiparton-interactions scenario are tied together via the assignment
of colour flow in the beam remnant. This is not an unambiguous 
procedure, but currently no parame