AliMUONPairLight.cxx

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/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *      SigmaEffect_thetadegrees                                                                  *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
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 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpeateose. It is      *
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 **************************************************************************/

/* $Id$ */

//-----------------------------------------------------------------------------
//This class was prepared by INFN Cagliari, July 2006
//(authors: H.Woehri, A.de Falco)
// 
// Compact information for the generated muon pairs in the MUON arm 
// useful at the last stage of the analysis chain
// Pairs are built with two AliMUONTrackLight objects 
// Using the class AliMUONTrackLight this class combines the decay
// information ("history") of the reconstructed tracks and fills
// a series of flags for the formed reconstructed dimuon:
// fIsCorrelated, fCreationProcess, fIsFeedDown, ...
// for information about the dimuon, use PrintInfo with the appropriate
// printflag
// To be used together with AliMUONTrackLight
//-----------------------------------------------------------------------------


//MUON classes
#include "AliMUONPairLight.h"
//Root classes
#include "TString.h"

ClassImp(AliMUONPairLight) 

//====================================
AliMUONPairLight::AliMUONPairLight() : 
  TObject(), 
  fMu0(),
  fMu1(), 
  fCreationProcess(-999),
  fIsCorrelated(kFALSE), 
  fCauseOfCorrelation (-1),
  fIsFeedDown(kFALSE)
{
  ; 
}

//====================================

AliMUONPairLight::AliMUONPairLight(AliMUONPairLight &dimuCopy) 
  : TObject(dimuCopy),
    fMu0(dimuCopy.fMu0),
    fMu1(dimuCopy.fMu1), 
    fCreationProcess(dimuCopy.fCreationProcess),
    fIsCorrelated(dimuCopy.fIsCorrelated), 
    fCauseOfCorrelation (dimuCopy.fCauseOfCorrelation),
    fIsFeedDown(dimuCopy.fIsFeedDown)
{ 
  ;
}

//====================================

AliMUONPairLight::~AliMUONPairLight(){
}

//====================================

AliMUONPairLight& AliMUONPairLight::operator=(const AliMUONPairLight& dimuCopy)
{
  // check assignment to self
  if (this == &dimuCopy) return *this;

  // base class assignment
  TObject::operator=(dimuCopy);

  // assignment operator
  fMu0 = dimuCopy.fMu0;
  fMu1 = dimuCopy.fMu1; 
  fCreationProcess = dimuCopy.fCreationProcess;
  fIsCorrelated = dimuCopy.fIsCorrelated; 
  fCauseOfCorrelation  = dimuCopy.fCauseOfCorrelation;
  fIsFeedDown = dimuCopy.fIsFeedDown;

  return *this;
}

//====================================

Bool_t AliMUONPairLight::IsAResonance(){
  if (!fIsCorrelated) return kFALSE;   //if muons not correlated, cannot be a resonance
  //if muons are correlated, check if the PDG of the
  //common mother is a resonance
  Int_t nparents0 = fMu0.GetNParents(); 
  Int_t nparents1 = fMu1.GetNParents(); 

  Int_t minP = TMath::Min(nparents0, nparents1);
  for (Int_t i = 0 ; i < minP; i++) { 
    if (fMu0.IsMotherAResonance(nparents0-1-i) && fMu1.IsMotherAResonance(nparents1-1-i) && 
  fMu0.GetParentPythiaLine(nparents0-1-i)==fMu1.GetParentPythiaLine(nparents1-1-i)) {
      if (nparents0-1-i) SetFeedDown(nparents0-1-i);
      return kTRUE;
    }
  }
  return kFALSE; 
}

//====================================

AliMUONTrackLight* AliMUONPairLight::GetMuon(Int_t index)  { 
   if (index==0) return &fMu0;
   else if (index==1) return &fMu1; 
   else{ printf ("Index can be either 0 or 1\n"); return 0;}
   //   else return &fMu1; 
}

//====================================

Int_t AliMUONPairLight::GetMuonMotherPDG(Int_t imuon, Int_t mother) { 
  if (imuon==0) return fMu0.GetParentPDGCode(mother); 
  else if (imuon==1) return fMu1.GetParentPDGCode(mother); 
  else { printf ("Index must be only 0 or 1\n"); return -999; } 
}

//====================================
void AliMUONPairLight::SetProcess(){

  AliMUONTrackLight *mu1 = &fMu0;
  AliMUONTrackLight *mu2 = &fMu1;

  // check if the two muons are correlated
  // first check if they come from the same hadron (resonance or beauty/charm meson)
  Int_t npar1 = mu1->GetNParents(); 
  Int_t npar2 = mu2->GetNParents(); 
  for (Int_t imoth1 = npar1-1; imoth1>=0; imoth1--) { 
    Int_t lineMo1 = mu1->GetParentPythiaLine(imoth1);
    for (Int_t imoth2 = npar2-1; imoth2>=0; imoth2--) { 
      Int_t lineMo2 = mu2->GetParentPythiaLine(imoth2);
      if(lineMo1 == lineMo2) { 
  //reject "diquark" mothers
  if(mu1->IsDiquark(mu1->GetParentPDGCode(imoth1)))return;
//  if(IsDiquark(mu1->GetParentPDGCode(imoth1))) return;
  this->SetCorrelated(kTRUE); 
  this->SetCauseOfCorrelation(mu1->GetParentPDGCode(imoth1));
  if(!IsAResonance()) fCreationProcess = 3; 
  else fCreationProcess = -1;
  return;
      }
    }
  }

  //now, check if we have a correlated pi/K:
  if(this->IsDimuonFromCorrPiK()){
    this->SetCorrelated(kTRUE); 
    this->SetCauseOfCorrelation(mu1->GetParentPDGCode(0));
    fCreationProcess = -1;
  }

  // if Open Beauty/Charm we can have 3 creation processes 
  // (pair creation [0], gluon splitting [1] or flavour excitation [2])
  // 1.) gluon splitting: gluon (stored with index 2, id=21) must be the same 
  Int_t flavPar1 = mu1->GetParentFlavour(0);
  Int_t flavPar2 = mu2->GetParentFlavour(0);
  for (Int_t imoth1 = 0; imoth1 < 4; imoth1++) { 
    Int_t lineMo1 = mu1->GetQuarkPythiaLine(imoth1);
    for (Int_t imoth2 = 0; imoth2 < 4; imoth2++) { 
      Int_t lineMo2 = mu2->GetQuarkPythiaLine(imoth2);
      if(lineMo1 == lineMo2 && mu1->GetQuarkPDGCode(imoth1) == 21) {
  //now, check also that the string fragmented into two hadrons
  //of the same flavour (string usually splits into many hadrons
  //among which there are mostly soft particles)
  if(flavPar1 == flavPar2){
    this->SetCorrelated(kTRUE); 
    if(GetCauseOfCorrelation() == -1)
      this->SetCauseOfCorrelation(mu1->GetQuarkPDGCode(imoth1));

    fCreationProcess = 1; 
    return;
  }
      }
    }
  }

  Int_t line1 = mu1->GetQuarkPythiaLine(2); //[2] ... very first quark
  Int_t line2 = mu2->GetQuarkPythiaLine(2); 

  Int_t line6or7[2] = {-1, -1}; //holds the index of quark in line 6 or 7
  Int_t flavourLine6or7[2] = {-1, -1};
  // 2.) pair creation: if pythia line 6 of one track *and* pythia line 7 of second track
  // are filled with a Q and Qbar
  for (Int_t imoth1 = 3; imoth1>=0; imoth1--) { 
    Int_t lineMo1 = mu1->GetQuarkPythiaLine(imoth1);
    Int_t flavour1 = TMath::Abs(mu1->GetQuarkPDGCode(imoth1));
    if(lineMo1 == 6 || lineMo1 == 7){ //track 0 has a mother in line 6 or 7
      line6or7[0] = imoth1;
      flavourLine6or7[0] = flavour1;
    }
    for (Int_t imoth2 = 3; imoth2>=0; imoth2--) { 
      Int_t lineMo2 = mu2->GetQuarkPythiaLine(imoth2);
      Int_t flavour2 = TMath::Abs(mu2->GetQuarkPDGCode(imoth2));
      if(lineMo2 == 6 || lineMo2 == 7){ //track 1 has a mother in line 6 or 7
  line6or7[1] = imoth2;
  flavourLine6or7[1] = flavour2;
      }
      if((line6or7[0] > 0 && line6or7[1] > 0) && //both tracks must have an entry in line 6 or 7
   (flavourLine6or7[0] == 4 || flavourLine6or7[0] == 5) && //this entry must be a c or b quark
   (flavourLine6or7[1] == 4 || flavourLine6or7[1] == 5) && // == " ==
   (flavPar1 == flavPar2)){ //make sure that the first hadronised parents of the 2 tracks are of the same flavour 
  this->SetCorrelated(kTRUE);
  fCreationProcess = 0; 
  return;
      }
    }
  }

  // 3.)flavour excitation: if pythia line 6 of one track *and* pythia line 7 of second track
  // are filled with a Q and Qbar and if in addition there is another heavy quark in line(s) 4 and/or 5
  Int_t line2or3[2] = {-1, -1}; //holds the index of g/q in line 2 or 3
  Int_t flavourLine2or3[2] = {-1, -1};
  for (Int_t imoth1 = 3; imoth1>=0; imoth1--) { 
    Int_t lineMo1 = mu1->GetQuarkPythiaLine(imoth1);
    Int_t flavour1 = TMath::Abs(mu1->GetQuarkPDGCode(imoth1));
    if(lineMo1 == 2 || lineMo1 == 3){ //track 0 has a mother in line 2 or 3
      line2or3[0] = imoth1;
      flavourLine2or3[0] = flavour1;
    }
    for (Int_t imoth2 = 3; imoth2>=0; imoth2--) { 
      Int_t lineMo2 = mu2->GetQuarkPythiaLine(imoth2);
      Int_t flavour2 = TMath::Abs(mu2->GetQuarkPDGCode(imoth2));
      if(lineMo2 == 2 || lineMo2 == 3){ //track 1 has a mother in line 2 or 3
  line2or3[1] = imoth2;
  flavourLine2or3[1] = flavour2;
      }
      if(((line6or7[0] > 0 && (flavourLine6or7[0] == 4  || flavourLine6or7[0] == 5)) && //first track has Q in line 6 or 7
    (line2or3[1] > 0 && (flavourLine2or3[1] == 21 || flavourLine2or3[1] < 10))) || //second track has a g/q in line 2 or 3
   ((line6or7[1] > 0 && (flavourLine6or7[1] == 4 || flavourLine6or7[1] == 5)) &&  //or the same,
    (line2or3[0] > 0 && (flavourLine2or3[0] == 21 || flavourLine2or3[0] < 10)))){ // swapping the track's indices
  //now, check also that the string fragmented into two hadrons
  //of the same flavour (string usually splits into many hadrons
  //among which there are mostly soft particles)
  if(flavPar1 == flavPar2){
    this->SetCorrelated(kTRUE);
    fCreationProcess = 2;
    return;
  }
      }
    }
  } 

  //now flag (rare) processes in which only the incoming parton in line 2 or 3
  //radiates a gluon which produces a QQbar pair:
  //exclude the light quarks
  if(line1 == line2 && (line1 == 2 || line1 == 3)){
    if((TMath::Abs(mu1->GetQuarkPDGCode(1)) == 4 && TMath::Abs(mu2->GetQuarkPDGCode(1)) == 4) ||
       (TMath::Abs(mu1->GetQuarkPDGCode(1)) == 5 && TMath::Abs(mu2->GetQuarkPDGCode(1)) == 5)){

      //now, check also that the string fragmented into two hadrons
      //of the same flavour (string usually splits into many hadrons
      //among which there are mostly soft particles)
      if(flavPar1 == flavPar2){

  this->SetCorrelated(kTRUE);
  fCreationProcess = 1;
  if(GetCauseOfCorrelation() == -1){
    this->SetCauseOfCorrelation(mu1->GetQuarkPDGCode(1));
  }
  return;
      }
    }
  }

  //in initial-state-radiation produced QQbar events the "mother quark"
  //is acknowledged as the second quark [1] and sits in line 2 or 3
  //is part of gluon splitting
  line1 = mu1->GetQuarkPythiaLine(1); //[1] ... direct mother quark of outgoing quark in [0]
  line2 = mu2->GetQuarkPythiaLine(1); 
  if(line1 == line2 && (line1 == 2 || line1 == 3)){
    if((TMath::Abs(mu1->GetQuarkPDGCode(0)) == 4 && TMath::Abs(mu2->GetQuarkPDGCode(0)) == 4) ||
       (TMath::Abs(mu1->GetQuarkPDGCode(0)) == 5 && TMath::Abs(mu2->GetQuarkPDGCode(0)) == 5)){

      //now, check also that the string fragmented into two hadrons
      //of the same flavour (string usually splits into many hadrons
      //among which there are mostly soft particles)
      if(flavPar1 == flavPar2){
  
  this->SetCorrelated(kTRUE);
  fCreationProcess = 1;
  if(GetCauseOfCorrelation() == -1){
    this->SetCauseOfCorrelation(mu1->GetQuarkPDGCode(1)); //should be flagged as initial state radiation?
  }
  return;
      }
    }
  }

  //in final-state-radiation produced QQbar events the "mother quark"
  //is acknowledged as the first quark [1] and sits in line 6 or 7
  //is part of gluon splitting
  line1 = mu1->GetQuarkPythiaLine(1); //[1] ... direct mother quark 
  line2 = mu2->GetQuarkPythiaLine(1); 
  if(line1 == line2 && (line1 == 6 || line1 == 7)){
    if((TMath::Abs(mu1->GetQuarkPDGCode(0)) == 4 && TMath::Abs(mu2->GetQuarkPDGCode(0)) == 4) ||
       (TMath::Abs(mu1->GetQuarkPDGCode(0)) == 5 && TMath::Abs(mu2->GetQuarkPDGCode(0)) == 5)){

      //now, check also that the string fragmented into two hadrons
      //of the same flavour (string usually splits into many hadrons
      //among which there are mostly soft particles)
      if(flavPar1 == flavPar2){
  
  this->SetCorrelated(kTRUE);
  fCreationProcess = 1;
  if(GetCauseOfCorrelation() == -1){
    this->SetCauseOfCorrelation(mu1->GetQuarkPDGCode(1));
  }
  return;
      }
    }
  }
}

//====================================
void AliMUONPairLight::SetMuons(const AliMUONTrackLight& mu0, const AliMUONTrackLight& mu1){
  fMu0 = mu0; 
  fMu1 = mu1; 
  this->SetProcess();
} 

//====================================
void AliMUONPairLight::PrintInfo(const Option_t* opt){
  TString options(opt);
  options.ToUpper();

  if(options.Contains("H") || options.Contains("A")){//muon decay histories

    AliMUONTrackLight *mu1 = &fMu0;
    AliMUONTrackLight *mu2 = &fMu1;

    printf("========= History =======================\n");
    printf("first muon");
    mu1->PrintInfo("H");
    printf("second muon");
    mu2->PrintInfo("H");
    printf("=========================================\n");
  }
  if(options.Contains("F") || options.Contains("A")){//flags
    printf("the flags set for this muon pair are:\n");
    printf("=====================================\n");
    if(this->IsOneTrackNotAMuon()) printf("(*) one rec. track is not a muon\n");
    fIsCorrelated ? printf("(*) it is a correlated pair\n") : printf("(*) it is not a correlated pair\n");
    if(IsOpenCharm()) printf("(*) correlated open charm: ");
    if(IsOpenBeauty()) printf("(*) correlated open beauty: ");
    if(IsOpenCharm() || IsOpenBeauty()){
      switch(fCreationProcess){
      case 0:
  printf("pair creation");
  break;
      case 1:
  printf("gluon splitting");
  break;
      case 2:
  printf("flavour excitation");
  break;
      case 3:
  printf("both muons come from same fragmented mother");
  break;
      }
      if(this->GetMuon(0)->GetOscillation() || this->GetMuon(1)->GetOscillation()) 
  printf("... where oscillation occured\n");
      else{
  if(IsOpenBeauty())
    printf(" (no oscillation)\n");
  else
    printf("\n");
      }
    }
    IsAResonance() ? printf("(*) it is a resonance: %d\n", this->GetMuonMotherPDG(0, fIsFeedDown)) : printf("(*) it is not a resonance\n");
    fIsFeedDown ? printf("(*) mother has feed-down: %d --> %d\n", this->GetMuonMotherPDG(0,fMu0.GetNParents()-2), this->GetMuonMotherPDG(0,fMu0.GetNParents()-1)) : printf("(*) no feed-down\n");
    printf("=====================================\n");
  }
  if(options.Contains("K") || options.Contains("A")){//dimuon kinematics
    Double_t *vtx = this->GetMuon(0)->GetVertex();
    TLorentzVector momRec = this->GetPRec();
    TLorentzVector momGen = this->GetPGen();
    printf("the dimuon charge is %d\n", this->GetCharge());
    printf("primary Vertex: Vx = %1.3f, Vy = %1.3f, Vz = %1.3f\n", vtx[0], vtx[1], vtx[2]);
    printf("Generated:     Px = %1.3f, Py = %1.3f, Pz = %1.3f\n", momGen.Px(), momGen.Py(), momGen.Pz());
    printf("Reconstructed: Px = %1.3f, Py = %1.3f, Pz = %1.3f\n", momRec.Px(), momRec.Py(), momRec.Pz());
    //rapidity, pT, angles, ...
    printf("Rec. variables: mass %1.3f, pT %1.3f, pseudo-rapidity %1.3f, openingAngle %1.3f (%1.3f degree), theta %1.3f (%1.3f degree), phi %1.3f (%1.3f degree)\n", 
     momRec.M(), momRec.Pt(), momRec.Eta(), 
     TMath::Pi()/180.*this->GetOpeningAngle(), this->GetOpeningAngle(), 
     momRec.Theta(), 180./TMath::Pi() * momRec.Theta(), 
     momRec.Phi(), 180./TMath::Pi() * momRec.Phi());
  }
}

//====================================
Double_t AliMUONPairLight::GetOpeningAngle() { 
  TLorentzVector pRecMu0 =  fMu0.GetPRec();
  TLorentzVector pRecMu1 =  fMu1.GetPRec();
  TVector3 pRecMu03 = pRecMu0.Vect();
  TVector3 pRecMu13 = pRecMu1.Vect();
  Double_t scalar = pRecMu03.Dot(pRecMu13);
  Double_t modMu0 = pRecMu03.Mag();
  Double_t modMu1 = pRecMu13.Mag();
  Double_t theta = (TMath::ACos(scalar/(modMu0*modMu1)))*(180./TMath::Pi());
  return theta; 
}
//================================================
Bool_t AliMUONPairLight::IsDimuonFromCorrPiK(){

  AliMUONTrackLight *mu0 = this->GetMuon(0), *mu1 = this->GetMuon(1);
  Bool_t fromSameLine = kFALSE;
  if (mu0->IsParentPionOrKaon() &&
      mu1->IsParentPionOrKaon() &&
      mu1->GetQuarkPythiaLine() == mu0->GetQuarkPythiaLine()
      ) fromSameLine = kTRUE;

  return fromSameLine;
}