Fit mass of resonance

[bdrum]

Here is ρ' resonance.

According with PDG description
The best fit could be obtained with the hypothesis of ρ-like resonances at 1420 and 1770 MeV, with widths of about 250 MeV.

I can create two BW model and fit resonance by them.

[bdrum]

Here is the first result of fit with one and two bw according with PDG:

Open questions:

• How to improve fit quality? Now reduce $\chi^2 / ndf$ is about 50.
• Fit heavy pair mass with rho zero models:
  

[bdrum]

[bdrum]

I have 4 fits:

• $\rho(0)$
• $\rho'$ one B-W
• $\rho'$ two B-W
• background

Now it's hardcoded, so I've to add a function which returns pd.DataFrame with original data and fitting results.