void ToyMCTest()
{
  TFile *fTemplatesBkg = TFile::Open("templates_Bkg_2016.root");

  RooWorkspace *wTemplatesBkg = (RooWorkspace *)fTemplatesBkg->Get("w");

  RooRealVar mTop("mTop", "mTop", 50., 300.);
  RooAbsPdf *pdf_qcd_2b = (RooAbsPdf *)wTemplatesBkg->pdf("qcd_pdf");

  RooRealVar *kQCD2b = new RooRealVar("kQCD_2b", "kQCD_2b", 1e-3, -1, 1);
  kQCD2b->setConstant(false);

  RooRealVar *nFitQCD2b = new RooRealVar("nFitQCD_2b", "nFitQCD_2b", 10000, 0, 10e+4);

  RooFormulaVar qcdCor_2b("qcdCor_2b", "1+@0*@1", RooArgList(mTop, *kQCD2b));

  RooEffProd pdf_qcdCor_2b("qcdCor_pdf_2b", "qcdCor_pdf_2b", *pdf_qcd_2b, qcdCor_2b);

  RooProduct prod("prod", "prod", RooArgList(*pdf_qcd_2b, qcdCor_2b));

  RooRealSumPdf sum("sum", "sum", RooArgList(prod), RooArgList(RooFit::RooConst(1.)));

  RooPlot *frame = mTop.frame();
  pdf_qcdCor_2b.plotOn(frame, RooFit::LineColor(kRed));
  prod.plotOn(frame);

  frame->Draw();
}