Getting Started with a 2Dfit

Roofit and RooStats
1

Dear Experts,

I am trying to do a 2D fit and I am referring here. Here’s the macro and root file that I am using multibody_2D_model_data.C (6.8 KB) , kpipi0_semileptonic.root (238.4 KB). Also, here are the other files that one needs to reproduce the result myRooJohnsonSU.h (1.1 KB) myRooJohnsonSU.cpp (1.9 KB) myRooPolBG.cpp (1.8 KB) myRooPolBG.h (929 Bytes) .

Now, as I am doing such a fit for the first time, I am not able to understand whether the fit is working or not.

Will you please help me in this?

Regards,
Sanjeeda

2

Looking at the result and the many errors printed, I would say the fit is not really successful, but fore more details I’ll let @moneta comment on this.

3

Dear @bellenot,

If you just comment the lines:
//total.plotOn(xyframe,Components(johnsonx),LineStyle(kDotted),LineColor(kRed));
//total.plotOn(xyframe,Components(expy),LineStyle(kDashed),LineColor(kCyan));
//total.plotOn(xyframe,Components(bkg_mass),LineStyle(kDashed),LineColor(kGreen + 2),Name(“bkg_mass”));

then I think the errors will be lesser. The lines start at 173

4

OK, fine, but still, you can see that your fit doesn’t really fit your data…

5

Yes, I am also working on it, I think I have managed to improve the situation a bit although I am still not sure. Will you please try this macro?
multibody_2D_model_data.C (6.8 KB) .

It looks like, my model fits the data, but no mater what I do, I am not able to get:
From MIGRAD: CONVERGED & Error Matrix:ACCURATE, HESSE:OK & Error Matrix:ACCURATE

Thanks

6

Yes, it’s better