{
    using namespace RooFit;
    
    TFile *fin = new TFile("example_data.root");
    TNtupleD* nt = (TNtupleD *)fin->Get("nt");
    
    RooRealVar mass("mass","mass",0.,2.);
    RooDataSet data("data","data",nt,RooArgSet(mass));
    
    RooRealVar mu("mu","mu",1.0,0.5,1.5);
    RooRealVar sigma("sigma","sigma",0.05,0.001,0.15);
    RooGaussian gaus("gaus","gaus",mass,mu,sigma);
    
    RooRealVar slope("slope","slope",-0.3,-10.,10.);
    RooPolynomial linear("linear","linear",mass,RooArgSet(slope));
    
    RooRealVar ns("ns","ns",2000,0.,20000.);
    RooRealVar nb("nb","nb",8000,0.,20000.);
    RooAddPdf model("model","model",RooArgList(gaus,linear),RooArgList(ns,nb));
    
    model.fitTo(data,Minos(true));
    
    RooPlot* frame = mass.frame();
    data.plotOn(frame);
    model.plotOn(frame);
    model.plotOn(frame,Components(linear),LineStyle(7),LineColor(kRed));
    frame->Draw();
}