rf708_bphysics.C File Reference

'SPECIAL PDFS' RooFit tutorial macro #708 More...

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Detailed Description

'SPECIAL PDFS' RooFit tutorial macro #708

Special decay pdf for B physics with mixing and/or CP violation

#ifndef __CINT__
#include "RooGlobalFunc.h"
#endif
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooConstVar.h"
#include "RooCategory.h"
#include "RooBMixDecay.h"
#include "RooBCPEffDecay.h"
#include "RooBDecay.h"
#include "RooFormulaVar.h"
#include "RooTruthModel.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "RooPlot.h"
using namespace RooFit ;

void rf708_bphysics()
{
  ////////////////////////////////////////////////////
  // B - D e c a y   w i t h   m i x i n g          //
  ////////////////////////////////////////////////////

  // C o n s t r u c t   p d f 
  // -------------------------
  
  // Observable
  RooRealVar dt("dt","dt",-10,10) ;
  dt.setBins(40) ;

  // Parameters
  RooRealVar dm("dm","delta m(B0)",0.472) ;
  RooRealVar tau("tau","tau (B0)",1.547) ;
  RooRealVar w("w","flavour mistag rate",0.1) ;
  RooRealVar dw("dw","delta mistag rate for B0/B0bar",0.1) ;

  RooCategory mixState("mixState","B0/B0bar mixing state") ;
  mixState.defineType("mixed",-1) ;
  mixState.defineType("unmixed",1) ;

  RooCategory tagFlav("tagFlav","Flavour of the tagged B0") ;
  tagFlav.defineType("B0",1) ;
  tagFlav.defineType("B0bar",-1) ;

  // Use delta function resolution model
  RooTruthModel tm("tm","truth model",dt) ;

  // Construct Bdecay with mixing
  RooBMixDecay bmix("bmix","decay",dt,mixState,tagFlav,tau,dm,w,dw,tm,RooBMixDecay::DoubleSided) ;



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

  // Generate some data
  RooDataSet* data = bmix.generate(RooArgSet(dt,mixState,tagFlav),10000) ;

  // Plot B0 and B0bar tagged data separately
  // For all plots below B0 and B0 tagged data will look somewhat differently
  // if the flavor tagging mistag rate for B0 and B0 is different (i.e. dw!=0)
  RooPlot* frame1 = dt.frame(Title("B decay distribution with mixing (B0/B0bar)")) ;

  data->plotOn(frame1,Cut("tagFlav==tagFlav::B0")) ;
  bmix.plotOn(frame1,Slice(tagFlav,"B0")) ;

  data->plotOn(frame1,Cut("tagFlav==tagFlav::B0bar"),MarkerColor(kCyan)) ;
  bmix.plotOn(frame1,Slice(tagFlav,"B0bar"),LineColor(kCyan)) ;


  // Plot mixed slice for B0 and B0bar tagged data separately
  RooPlot* frame2 = dt.frame(Title("B decay distribution of mixed events (B0/B0bar)")) ;

  data->plotOn(frame2,Cut("mixState==mixState::mixed&&tagFlav==tagFlav::B0")) ;
  bmix.plotOn(frame2,Slice(tagFlav,"B0"),Slice(mixState,"mixed")) ;

  data->plotOn(frame2,Cut("mixState==mixState::mixed&&tagFlav==tagFlav::B0bar"),MarkerColor(kCyan)) ;
  bmix.plotOn(frame2,Slice(tagFlav,"B0bar"),Slice(mixState,"mixed"),LineColor(kCyan)) ;


  // Plot unmixed slice for B0 and B0bar tagged data separately
  RooPlot* frame3 = dt.frame(Title("B decay distribution of unmixed events (B0/B0bar)")) ;

  data->plotOn(frame3,Cut("mixState==mixState::unmixed&&tagFlav==tagFlav::B0")) ;
  bmix.plotOn(frame3,Slice(tagFlav,"B0"),Slice(mixState,"unmixed")) ;

  data->plotOn(frame3,Cut("mixState==mixState::unmixed&&tagFlav==tagFlav::B0bar"),MarkerColor(kCyan)) ;
  bmix.plotOn(frame3,Slice(tagFlav,"B0bar"),Slice(mixState,"unmixed"),LineColor(kCyan)) ;





  ///////////////////////////////////////////////////////
  // B - D e c a y   w i t h   C P   v i o l a t i o n //
  ///////////////////////////////////////////////////////

  // C o n s t r u c t   p d f 
  // -------------------------
  
  // Additional parameters needed for B decay with CPV
  RooRealVar CPeigen("CPeigen","CP eigen value",-1) ;
  RooRealVar absLambda("absLambda","|lambda|",1,0,2) ;
  RooRealVar argLambda("absLambda","|lambda|",0.7,-1,1) ;
  RooRealVar effR("effR","B0/B0bar reco efficiency ratio",1) ;

  // Construct Bdecay with CP violation
  RooBCPEffDecay bcp("bcp","bcp", dt, tagFlav, tau, dm, w, CPeigen, absLambda, argLambda, effR, dw, tm, RooBCPEffDecay::DoubleSided) ;
      


  // P l o t   s c e n a r i o   1   -   s i n ( 2 b )   =   0 . 7 ,   | l | = 1 
  // ---------------------------------------------------------------------------

  // Generate some data
  RooDataSet* data2 = bcp.generate(RooArgSet(dt,tagFlav),10000) ;

  // Plot B0 and B0bar tagged data separately
  RooPlot* frame4 = dt.frame(Title("B decay distribution with CPV(|l|=1,Im(l)=0.7) (B0/B0bar)")) ;

  data2->plotOn(frame4,Cut("tagFlav==tagFlav::B0")) ;
  bcp.plotOn(frame4,Slice(tagFlav,"B0")) ;

  data2->plotOn(frame4,Cut("tagFlav==tagFlav::B0bar"),MarkerColor(kCyan)) ;
  bcp.plotOn(frame4,Slice(tagFlav,"B0bar"),LineColor(kCyan)) ;



  // P l o t   s c e n a r i o   2   -   s i n ( 2 b )   =   0 . 7 ,   | l | = 0 . 7 
  // -------------------------------------------------------------------------------

  absLambda=0.7 ;

  // Generate some data
  RooDataSet* data3 = bcp.generate(RooArgSet(dt,tagFlav),10000) ;

  // Plot B0 and B0bar tagged data separately (sin2b = 0.7 plus direct CPV |l|=0.5)
  RooPlot* frame5 = dt.frame(Title("B decay distribution with CPV(|l|=0.7,Im(l)=0.7) (B0/B0bar)")) ;  

  data3->plotOn(frame5,Cut("tagFlav==tagFlav::B0")) ;
  bcp.plotOn(frame5,Slice(tagFlav,"B0")) ;

  data3->plotOn(frame5,Cut("tagFlav==tagFlav::B0bar"),MarkerColor(kCyan)) ;
  bcp.plotOn(frame5,Slice(tagFlav,"B0bar"),LineColor(kCyan)) ;



  //////////////////////////////////////////////////////////////////////////////////
  // G e n e r i c   B   d e c a y  w i t h    u s e r   c o e f f i c i e n t s  //
  //////////////////////////////////////////////////////////////////////////////////

  // C o n s t r u c t   p d f 
  // -------------------------
  
  // Model parameters
  RooRealVar DGbG("DGbG","DGamma/GammaAvg",0.5,-1,1);
  RooRealVar Adir("Adir","-[1-abs(l)**2]/[1+abs(l)**2]",0);
  RooRealVar Amix("Amix","2Im(l)/[1+abs(l)**2]",0.7);
  RooRealVar Adel("Adel","2Re(l)/[1+abs(l)**2]",0.7);
  
  // Derived input parameters for pdf
  RooFormulaVar DG("DG","Delta Gamma","@1/@0",RooArgList(tau,DGbG));
  
  // Construct coefficient functions for sin,cos,sinh modulations of decay distribution
  RooFormulaVar fsin("fsin","fsin","@0*@1*(1-2*@2)",RooArgList(Amix,tagFlav,w));
  RooFormulaVar fcos("fcos","fcos","@0*@1*(1-2*@2)",RooArgList(Adir,tagFlav,w));
  RooFormulaVar fsinh("fsinh","fsinh","@0",RooArgList(Adel));
  
  // Construct generic B decay pdf using above user coefficients
  RooBDecay bcpg("bcpg","bcpg",dt,tau,DG,RooConst(1),fsinh,fcos,fsin,dm,tm,RooBDecay::DoubleSided);
  
  
  
  // P l o t   -   I m ( l ) = 0 . 7 ,   R e ( l ) = 0 . 7   | l | = 1,   d G / G = 0 . 5 
  // -------------------------------------------------------------------------------------
  
  // Generate some data
  RooDataSet* data4 = bcpg.generate(RooArgSet(dt,tagFlav),10000) ;
  
  // Plot B0 and B0bar tagged data separately 
  RooPlot* frame6 = dt.frame(Title("B decay distribution with CPV(Im(l)=0.7,Re(l)=0.7,|l|=1,dG/G=0.5) (B0/B0bar)")) ;  
  
  data4->plotOn(frame6,Cut("tagFlav==tagFlav::B0")) ;
  bcpg.plotOn(frame6,Slice(tagFlav,"B0")) ;
  
  data4->plotOn(frame6,Cut("tagFlav==tagFlav::B0bar"),MarkerColor(kCyan)) ;
  bcpg.plotOn(frame6,Slice(tagFlav,"B0bar"),LineColor(kCyan)) ;
  
 
 

  TCanvas* c = new TCanvas("rf708_bphysics","rf708_bphysics",1200,800) ;
  c->Divide(3,2) ;
  c->cd(1) ; gPad->SetLeftMargin(0.15) ; frame1->GetYaxis()->SetTitleOffset(1.6) ; frame1->Draw() ;
  c->cd(2) ; gPad->SetLeftMargin(0.15) ; frame2->GetYaxis()->SetTitleOffset(1.6) ; frame2->Draw() ;
  c->cd(3) ; gPad->SetLeftMargin(0.15) ; frame3->GetYaxis()->SetTitleOffset(1.6) ; frame3->Draw() ;
  c->cd(4) ; gPad->SetLeftMargin(0.15) ; frame4->GetYaxis()->SetTitleOffset(1.6) ; frame4->Draw() ;
  c->cd(5) ; gPad->SetLeftMargin(0.15) ; frame5->GetYaxis()->SetTitleOffset(1.6) ; frame5->Draw() ;
  c->cd(6) ; gPad->SetLeftMargin(0.15) ; frame6->GetYaxis()->SetTitleOffset(1.6) ; frame6->Draw() ;
  
}

Author

07/2008 - Wouter Verkerke

Definition in file rf708_bphysics.C.