How to fit two distributions with same parameters?

Hi everyone:

I have a special situation here. For example, I have two distribution:

To fit distribution 1, I need to use these parameters: A, B, p1, p2, p3.
To fit distribution 2, I need to use these parameters: A, B, p4, p5, p6.

Since here A and B are representing the same thing, only p1~p6 are different. So is it possible to fit these two distributions simultaneously with the same A and B parameters in ROOFIT ? and how?

Thanks in advance!


Yes this is possible with RooSimultaneous, see the tutorial macros (for example … pdf.C.html) and/or the RooFit user manual.


– Gregory