Hi Wouter
I think that RooPolynomial is good option to fit the shape which we have as attached. I was looking at
post
Fitting polynomial using roofit
Where you mentioned that RooPolynomial is not good for shape is which vanish at x=0. I think it is applicable to our data shape as well. What do you think? This mean I can’t use RooPolynomial as well as RooChebchev for one or another reason 
. Is it correct??
Thanks for your feedback!
Regards-Sunil
