Shape interpolation using two pdfs

Dear experts,

I have two signal mass points m1 and m2 and corresponding two pdfs which I get after fitting the mass observables Mgg and Mjj. Mgg fit is with Gaussian function and Mjj fit is with double-sided crystal ball function. I am sharing my workspace for m1=300 GeV and m2 = 400 GeV signal points at [1] (signal label = NMSSMX300ToY90H125 and NMSSMX400ToY90H125).

Since I do not have intermediate-mass simulation points (let’s say 350 GeV) between m1 and m2, I want to use an interpolation method using which I can get Mgg and Mjj pdfs for the 350 GeV signal point.

Could you please let me know if there is any straightforward way of doing this using roofit.



[1] interpolation – Google Drive

Hi @lata ,
we need @moneta or @jonas 's help here, let’s ping them.


It looks to me that your pdf’s are expressed in a functional form and not in term of an histogram. In this case you can maybe just interpolate the pdf parameters, that, if I have understood well you extract from a fit to the simulated data.
If this is not good enough you can try using a morphing algorithm available in RooFit and described by this example: ROOT: tutorials/roofit/rf705_linearmorph.C File Reference


Hello @moneta ! Thanks for sharing Roofit function. It seems to work fine. I have only one query in the example code you shared. Let say if I pick alpha=0.5 that means it will be interpolated to the mid-mass point of two given mass m1 and m2. (e.g. m1= 300 GeV and m2=400 GeV so with alpha=0.5 it will interpolated for m=350 GeV)

And depending upon the binning of the alpha parameter, the projection will be made for other intermediate-mass points (let say binning I set 10 for alpha range [0,1], then alpha=0.2 will correspond to intermediate-mass point 320 GeV)


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