RooFit Simultaneous pdf for PDF created via RooClassFactory

[AllenM]

Greetings:

I want to fit multiple histograms simultaneously to pdfs created via RooClassFactory. If these were of type RooAbsPdf, then I could just create a category and then do something like

RooSimultaneous mysimpdf(“mysimpdf”,”mysimpdf”,mycategory) mysimpdf.addPdf(mypdf,”mycategoryindex”);

But is there a way to do something equivalent when mypdf is not a RooAbsPdf?

Thanks for any help.

Best regards,
Allen

[Danilo]

Dear Allen,

Thanks for this post. I add in the loop @jonas , our RooFit expert . In the meantime, could you perhaps clarify what kind of objects you’d like to fit to a RooDataset made of multiple histograms?

Cheers,
Danilo

[AllenM]

Dear Danilo:

Thank you for your message. By “objects” do you mean what sort of functions I am using or what the histograms are?

The histograms are of data taken under different beam conditions (different number of interactions per bunch crossing, mu). The functions are convolutions which depend on mu. These are calculated by taking a function f0, finding its Fourier transform via FFT, taking an exponential to a mu dependent power of the transform, and then taking the inverse transform. The parameters of f0 are mu independent, so they are shared for all histograms. I implemented the pdf’s for these functions in C++ and used RooClassFactory to create a pdf from the C++ code. This worked fine for individual histograms. Since the parameters of f0 are shared and only the number of convolutions changes with mu, I want to now do a simultaneous fit to all the histograms.

Let me know if this is sufficient information.

Best regards,
Allen

[AllenM]

I created the pdf with RooClassFactory::makePdf(…)