Determining a mediating force of an Interaction

[Wornstrom!!]

What kind of force mediates the reaction:

K- + alpha(ppnn) -> pi- + "hypernucleus"(ppn lambda)
s(u) + (uud + uud + udd + udd) -> d(u) + (uud + uud + udd + uds)
(u) is anti u

We need to explain which force mediates this reaction.

I am pretty sure it does not involve the weak force because there is no flavor change of any quarks, they are just rearranged. I am leaning towards the strong force because the interaction involves nucleons although I know that is a bad argument. Is there a change in isospin? In what interactions is isospin conserved and what interaction allow a change in isospin?

So I am leaning towards strong interaction but I really have no reason to support this

 

[mathman]

Since the reaction involves quarks being rearranged it has to be the strong force.