How to use a .root histogram as a background function to fit the data .root histogram

[tsa]

i want to use 4 body phase space background along with Breit Wigner fit on .root data. How can i do.
Secondly how to use a .root histogram as a background function to fit the data .root histogram

[StephanH]

Hi,

you didn’t say much about your data. Here are some tutorials to get you started (you can also find them in your ROOT folder):

• Importing data from a histogram or tree:
  https://root.cern.ch/doc/master/rf102__dataimport_8C.html
• Making a model that is the sum of multiple PDFs (so you can do something like sSignal + sBackground, where signal could be a BreitWigner and your background could be from a histogram):
  https://root.cern.ch/doc/master/rf502__wspacewrite_8C.html
• The RooBreitWigner documentation:
  https://root.cern.ch/doc/master/classRooBreitWigner.html
• Make a PDF from a histogram (for your background):
  https://root.cern.ch/doc/master/rf706__histpdf_8C.html
• And specifically how to make a RooDataHist given a “normal” ROOT histogram:
  https://root.cern.ch/doc/master/classRooDataHist.html#a1e30c1430e864be4ebdc0e0ee62b79e0

I hope that this can get you started!

[tsa]

Dear Stephan
Thanks for your attention.
I want to fit my data file like given diagram:

I need .c file for it