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I thought you knew, that was I asked (haven't read all of this yet).

However, the four parameters you have found on google are the traditional four parameters of particle physics models for dark matter. There is nothing you can do to reduce them further, except plugging the theory into a more fundamental one. But then you are trading those free parameters by others and the model starts to be more complicated. I am pretty convinced those are not the four parameters mentioned in your post (I cannot fund any reference to them in the scientific paper actually :p )

Anyway, I will check myself over the week end :)

Ok, thanks for the clarification. I don't know. I did some research, but not that deep ;)