Hi,

I tried to include the background + convolution model-

```
RooRealVar t("t", "t", 1800, 2400); //1800 2500
t.setBins(10000, "cache");
RooDataHist* data = new RooDataHist("data", "data", t, Import(*decayEnergy));
//landau function
RooRealVar ml("ml", "mean landau", 2100, 1900, 2300); // 2100 1800 2400
RooRealVar sl("sl", "sigma landau", 10, 10, 150);
RooLandau landau("lx", "lx", t, ml, sl);
//gaussian function
RooRealVar mg("mg","mg",2100, 1800, 2500); //1800 2400,decayEnergy->GetMean()
RooRealVar sg("sg", "sg",70 , 40, 150);//decayEnergy->GetRMS()
RooGaussian gauss("gauss", "gauss", t, mg, sg);
//Background Model -
RooRealVar c("c", "c", 0,-1,2);
RooRealVar c2("c2","c2",0 ,-1,2);
RooPolynomial Pol("Pol", "Pol", t, RooArgSet(c,c2));
RooFFTConvPdf lxgfft("lxg","landau (X) gauss",t,landau,gauss);
RooAddPdf model("model", "lxcg + background", RooArgList(Pol,lxgfft),coeff);
```

But, will not improve the fit. !

Screenshot 2020-06-15 at 10.55.52 AM|690x415