rf209_anaconv.C

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/// \file
/// \ingroup tutorial_roofit
/// \notebook -js
///  'ADDITION AND CONVOLUTION' RooFit tutorial macro #209
///
///  Decay function p.d.fs with optional B physics
///  effects (mixing and CP violation) that can be
///  analytically convolved with e.g. Gaussian resolution
///  functions
///
///  pdf1 = decay(t,tau) (x) delta(t)
///  pdf2 = decay(t,tau) (x) gauss(t,m,s)
///  pdf3 = decay(t,tau) (x) (f*gauss1(t,m1,s1) + (1-f)*gauss2(t,m1,s1))
///
/// \macro_image
/// \macro_output
/// \macro_code
/// \author 07/2008 - Wouter Verkerke 
 
 
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussModel.h"
#include "RooAddModel.h"
#include "RooTruthModel.h"
#include "RooDecay.h"
#include "RooPlot.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "TH1.h"
using namespace RooFit ;
 
 
 
void rf209_anaconv()
{
   // B - p h y s i c s   p d f   w i t h   t r u t h   r e s o l u t i o n
   // ---------------------------------------------------------------------
 
   // Variables of decay p.d.f.
   RooRealVar dt("dt","dt",-10,10) ;
   RooRealVar tau("tau","tau",1.548) ;
 
   // Build a truth resolution model (delta function)
   RooTruthModel tm1("tm","truth model",dt) ;
 
   // Construct decay(t) (x) delta(t)
   RooDecay decay_tm("decay_tm","decay",dt,tau,tm1,RooDecay::DoubleSided) ;
 
   // Plot p.d.f. (dashed)
   RooPlot* frame = dt.frame(Title("Bdecay (x) resolution")) ;
   decay_tm.plotOn(frame,LineStyle(kDashed)) ;
 
 
   // B - p h y s i c s   p d f   w i t h   G a u s s i a n   r e s o l u t i o n
   // ----------------------------------------------------------------------------
 
   // Build a gaussian resolution model
   RooRealVar bias1("bias1","bias1",0) ;
   RooRealVar sigma1("sigma1","sigma1",1) ;
   RooGaussModel gm1("gm1","gauss model 1",dt,bias1,sigma1) ;
 
   // Construct decay(t) (x) gauss1(t)
   RooDecay decay_gm1("decay_gm1","decay",dt,tau,gm1,RooDecay::DoubleSided) ;
 
   // Plot p.d.f. 
   decay_gm1.plotOn(frame) ;
 
 
   // B - p h y s i c s   p d f   w i t h   d o u b l e   G a u s s i a n   r e s o l u t i o n
   // ------------------------------------------------------------------------------------------
 
   // Build another gaussian resolution model
   RooRealVar bias2("bias2","bias2",0) ;
   RooRealVar sigma2("sigma2","sigma2",5) ;
   RooGaussModel gm2("gm2","gauss model 2",dt,bias2,sigma2) ;
 
   // Build a composite resolution model f*gm1+(1-f)*gm2
   RooRealVar gm1frac("gm1frac","fraction of gm1",0.5) ;
   RooAddModel gmsum("gmsum","sum of gm1 and gm2",RooArgList(gm1,gm2),gm1frac) ;
 
   // Construct decay(t) (x) (f*gm1 + (1-f)*gm2)
   RooDecay decay_gmsum("decay_gmsum","decay",dt,tau,gmsum,RooDecay::DoubleSided) ;
 
   // Plot p.d.f. (red)
   decay_gmsum.plotOn(frame,LineColor(kRed)) ;
 
 
   // Draw all frames on canvas
   new TCanvas("rf209_anaconv","rf209_anaconv",600, 600);
   gPad->SetLeftMargin(0.15) ; frame->GetYaxis()->SetTitleOffset(1.6) ; frame->Draw() ;
 
}