rf310_sliceplot.C

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/// \file
/// \ingroup tutorial_roofit
/// \notebook
/// Multidimensional models: projecting p.d.f and data slices in discrete observables
///
/// \macro_image
/// \macro_output
/// \macro_code
/// \author 07/2008 - Wouter Verkerke

#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussModel.h"
#include "RooDecay.h"
#include "RooBMixDecay.h"
#include "RooCategory.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "RooPlot.h"
using namespace RooFit;

void rf310_sliceplot()
{

   // C r e a t e   B   d e c a y   p d f   w it h   m i x i n g
   // ----------------------------------------------------------

   // Decay time observables
   RooRealVar dt("dt", "dt", -20, 20);

   // Discrete observables mixState (B0tag==B0reco?) and tagFlav (B0tag==B0(bar)?)
   RooCategory mixState("mixState", "B0/B0bar mixing state");
   RooCategory tagFlav("tagFlav", "Flavour of the tagged B0");

   // Define state labels of discrete observables
   mixState.defineType("mixed", -1);
   mixState.defineType("unmixed", 1);
   tagFlav.defineType("B0", 1);
   tagFlav.defineType("B0bar", -1);

   // Model parameters
   RooRealVar dm("dm", "delta m(B)", 0.472, 0., 1.0);
   RooRealVar tau("tau", "B0 decay time", 1.547, 1.0, 2.0);
   RooRealVar w("w", "Flavor Mistag rate", 0.03, 0.0, 1.0);
   RooRealVar dw("dw", "Flavor Mistag rate difference between B0 and B0bar", 0.01);

   // Build a gaussian resolution model
   RooRealVar bias1("bias1", "bias1", 0);
   RooRealVar sigma1("sigma1", "sigma1", 0.01);
   RooGaussModel gm1("gm1", "gauss model 1", dt, bias1, sigma1);

   // Construct a decay pdf, smeared with single gaussian resolution model
   RooBMixDecay bmix_gm1("bmix", "decay", dt, mixState, tagFlav, tau, dm, w, dw, gm1, RooBMixDecay::DoubleSided);

   // Generate BMixing data with above set of event errors
   RooDataSet *data = bmix_gm1.generate(RooArgSet(dt, tagFlav, mixState), 20000);

   // P l o t   f u l l   d e c a y   d i s t r i b u t i o n
   // ----------------------------------------------------------

   // Create frame, plot data and pdf projection (integrated over tagFlav and mixState)
   RooPlot *frame = dt.frame(Title("Inclusive decay distribution"));
   data->plotOn(frame);
   bmix_gm1.plotOn(frame);

   // P l o t   d e c a y   d i s t r .   f o r   m i x e d   a n d   u n m i x e d   s l i c e   o f   m i x S t a t e
   // ------------------------------------------------------------------------------------------------------------------

   // Create frame, plot data (mixed only)
   RooPlot *frame2 = dt.frame(Title("Decay distribution of mixed events"));
   data->plotOn(frame2, Cut("mixState==mixState::mixed"));

   // Position slice in mixState at "mixed" and plot slice of pdf in mixstate over data (integrated over tagFlav)
   bmix_gm1.plotOn(frame2, Slice(mixState, "mixed"));

   // Create frame, plot data (unmixed only)
   RooPlot *frame3 = dt.frame(Title("Decay distribution of unmixed events"));
   data->plotOn(frame3, Cut("mixState==mixState::unmixed"));

   // Position slice in mixState at "unmixed" and plot slice of pdf in mixstate over data (integrated over tagFlav)
   bmix_gm1.plotOn(frame3, Slice(mixState, "unmixed"));

   TCanvas *c = new TCanvas("rf310_sliceplot", "rf310_sliceplot", 1200, 400);
   c->Divide(3);
   c->cd(1);
   gPad->SetLeftMargin(0.15);
   frame->GetYaxis()->SetTitleOffset(1.4);
   gPad->SetLogy();
   frame->Draw();
   c->cd(2);
   gPad->SetLeftMargin(0.15);
   frame2->GetYaxis()->SetTitleOffset(1.4);
   gPad->SetLogy();
   frame2->Draw();
   c->cd(3);
   gPad->SetLeftMargin(0.15);
   frame3->GetYaxis()->SetTitleOffset(1.4);
   gPad->SetLogy();
   frame3->Draw();
}