Newbie Fit/RooFit Question

[jonas]

Hi @katrina09,

indeed, RooFit is well suited for this!

You can find the necessary code snippets for your task in the RooFit tutorials. In particular, take a look at:

• ROOT: tutorials/roofit/rf706_histpdf.C File Reference, which tells you how to build a pdf based of template histograms
• ROOT: tutorials/roofit/rf201_composite.C File Reference, which tells you how to create the normalized sum of two pdfs

Note that in ht e tutorial overview, there are also links to the Python version of both tutorials.

In summary, you have to:

1. Wrap all you histograms in a RooDataHist
2. Create two RooHistPdf from the mc-based data-hists
3. Create a RooAddPdf from the two RooHistPdf
4. Fit the RooAddPdf to the RooDataHist with the data

It will do a binned likelihood fit by the way, not a chi-square fit. If your data histogram is representing events, the likelihood fit is the right thing to do.

Let us know if you have any follow-up questions!
Jonas