{
    TChain ch("DecayTree");
    ch.Add("MCBu2L0pJpsi_all_newmass.root/DecayTree");

    RooRealVar mass("MBu_jpsi", "", 5200, 5500);
    // RooRealVar mass("Bu_M", "", 5200, 5500);
    // mass.setBins(10000);
    TTree *datatree = ch.CopyTree("");
    RooDataSet *data = new RooDataSet("data","", datatree, mass);

    
    RooRealVar k0("k0", "", 0.9, 0.0, 1);
    RooChebychev pol("pol", "", mass, RooArgSet(k0));

    RooRealVar mean("mean", "", 5280,5276,5282);
    RooRealVar sigma("sigma", "", 3,2,4);
    RooGaussian sigpdf("sigpdf", "", mass, mean, sigma);

    
    RooRealVar nsig("nsig", "", 2140,0,10000);
    // RooRealVar nbkg("nbkg", "", 11845, 0,12500);
    RooRealVar nbkg("nbkg", "", 0);
    RooRealVar frac("frac", "", 0, 1);
    // RooAddPdf allpdf("allpdf", "", RooArgList(sigpdf, pol), RooArgList(nsig, nbkg));
    RooAddPdf allpdf("allpdf", "", RooArgList(sigpdf), RooArgList(nsig));
    RooFitResult *result = allpdf.fitTo(*data,  RooFit::SumW2Error(kTRUE),RooFit::Save());


    RooPlot* fr =mass.frame();
    fr->SetTitle("");
    fr->SetXTitle("Bu_M[][MeV/#font[32]{c}^{2}]");
    fr->SetYTitle(Form("Events / (%.2f MeV/#font[32]{c}^{2}])", 0.5));
    data->plotOn(fr, RooFit::MarkerSize(0.5), RooFit::MarkerStyle(8));
    allpdf.plotOn(fr);
    allpdf.plotOn(fr, RooFit::Components("pol"), RooFit::LineStyle(9), RooFit::LineColor(kBlue));
    allpdf.plotOn(fr, RooFit::Components("sigpdf"), RooFit::LineStyle(4), RooFit::LineColor(kRed));
    allpdf.paramOn(fr, RooFit::Layout(0.6,0.90,0.90)); 
    TCanvas c("c", "", 400, 300);
    c.cd();
    fr->Draw();

    TLatex lt;
    lt.DrawLatex(5350, 1500, "Fit to MC");
    c.SaveAs("fig/fitto_JpsiLp.pdf");
    result->Print("v");


}