How to use Roofit to fit polynomial which is not normalized?

Roofit and RooStats
1

I want to use RooPolynomial to fit data and get a non-normalized polynomial, but when I use fitTo(data) I just get P.D.F(that means the function is normalized). Is there any way I can use RooPolynomial to get a non-normalized function?

2

Hi,

It is complicated to do in RooFit. I would just use ROOT, TH1::Fit or Graph::Fit for doing this

Lorenzo

3

[quote=“moneta”]Hi,

It is complicated to do in RooFit. I would just use ROOT, TH1::Fit or Graph::Fit for doing this

Lorenzo[/quote]
Hi Lorenzo,

I need to add polynomial function and Breit-Weigner function to fit the curve. So it will be easy to use Roofit. if possible, could you please tell me where I can find how to do this in RooFit?

Thanks,
Zhaozhou

4

HI,

The RooFit polynomial is always normalised in the definition. You can define an extended pdf based on the polynomial, which will contain the normalisation term. You then relate te normalisation coefficient
and the polynomial coefficients to a non-normalised polynomial definition.

Lorenzo