HLT/trigger/AliHLTD0toKpi.cxx

   1 // $Id$
   2 #include "AliHLTD0toKpi.h"
   3 #include "TDatabasePDG.h"
   4 #include "TMath.h"
   5 #include "AliESDtrack.h"
   6 #include "TVector3.h"
   7 #include "AliAODVertex.h"
   8 #include "AliESDVertex.h"
   9 #include "TObjArray.h"
  10 #include "AliVertexerTracks.h"
  11 #include "AliHLTGlobalBarrelTrack.h"
  12 #include "AliExternalTrackParam.h"
  13 #include "AliKFVertex.h"
  14
  15 ClassImp(AliHLTD0toKpi)
  16
  17 AliHLTD0toKpi::AliHLTD0toKpi()
  18 {
  19 }
  20
  21 Double_t AliHLTD0toKpi::InvMass(const AliExternalTrackParam* d1, const AliExternalTrackParam* d2)
  22 {
  23   Double_t mpi=TDatabasePDG::Instance()->GetParticle(211)->Mass();
  24   Double_t mK=TDatabasePDG::Instance()->GetParticle(321)->Mass();
  25
  26   Double_t energy[2];
  27   energy[1] = TMath::Sqrt(mK*mK+d1->GetP()*d1->GetP());
  28   energy[0] = TMath::Sqrt(mpi*mpi+d2->GetP()*d2->GetP());
  29
  30   Double_t p1[3],p2[3];
  31   d1->GetPxPyPz(p1);
  32   d2->GetPxPyPz(p2);
  33
  34   Double_t momTot2 = (p1[0]+p2[0])*(p1[0]+p2[0])+
  35                      (p1[1]+p2[1])*(p1[1]+p2[1])+
  36                      (p1[2]+p2[2])*(p1[2]+p2[2]);
  37
  38   return TMath::Sqrt((energy[0]+energy[1])*(energy[0]+energy[1])-momTot2);
  39
  40 }
  41 void AliHLTD0toKpi::CosThetaStar(const AliExternalTrackParam* d1, const AliExternalTrackParam* d2,Double_t &D0,Double_t &D0bar)
  42 {
  43   Double_t mD0 = TDatabasePDG::Instance()->GetParticle(421)->Mass();
  44   Double_t mpi=TDatabasePDG::Instance()->GetParticle(211)->Mass();
  45   Double_t mK=TDatabasePDG::Instance()->GetParticle(321)->Mass();
  46
  47   Double_t pStar = TMath::Sqrt(TMath::Power(mD0*mD0-mK*mK-mpi*mpi,2.)-4.*mK*mK*mpi*mpi)/(2.*mD0);
  48
  49   Double_t px = d1->Px()+d2->Px();
  50   Double_t py = d1->Py()+d2->Py();
  51   Double_t pz = d1->Pz()+d2->Pz();
  52   Double_t p = TMath::Sqrt(px*px+py*py+pz*pz);
  53   Double_t energy = TMath::Sqrt(p*p+mD0*mD0);
  54
  55   Double_t beta = p/energy;
  56   Double_t gamma = energy/mD0;
  57
  58   Double_t qL;
  59   TVector3 mom(d1->Px(),d1->Py(),d1->Pz());
  60   TVector3 momD(px,py,pz);
  61   qL = mom.Dot(momD)/momD.Mag();
  62
  63   D0 = (qL/gamma-beta*TMath::Sqrt(pStar*pStar+mK*mK))/pStar;
  64
  65   TVector3 mom2(d2->Px(),d2->Py(),d2->Pz());
  66   TVector3 momD2(px,py,pz);
  67   qL = mom2.Dot(momD2)/momD2.Mag();
  68
  69   D0bar = (qL/gamma-beta*TMath::Sqrt(pStar*pStar+mK*mK))/pStar;
  70
  71 }
  72 Double_t AliHLTD0toKpi::PointingAngle(const AliExternalTrackParam* n, const AliExternalTrackParam* p, const Double_t *pv, const Double_t *sv)
  73 {
  74
  75   TVector3 mom(n->Px()+p->Px(),n->Py()+p->Py(),n->Pz()+p->Pz());
  76   TVector3 flight(sv[0]-pv[0],sv[1]-pv[1],sv[2]-pv[2]);
  77
  78   double pta = mom.Angle(flight);
  79
  80   return TMath::Cos(pta);
  81 }
  82
  83 AliAODVertex* AliHLTD0toKpi::ReconstructSecondaryVertex(TObjArray *trkArray, Double_t b, const AliESDVertex *v, bool useKF)
  84 {
  85
  86   AliESDVertex *vertexESD = 0;
  87   AliAODVertex *vertexAOD = 0;
  88
  89   if(!useKF){
  90     AliVertexerTracks *vertexer = new AliVertexerTracks(b);
  91     AliESDVertex* vertex = new AliESDVertex(*((AliESDVertex*)v));
  92     //AliESDVertex* vertex =  const_cast<AliESDVertex*>(v);
  93     vertexer->SetVtxStart(vertex);
  94     vertexESD = (AliESDVertex*)vertexer->VertexForSelectedESDTracks(trkArray);
  95     delete vertexer; vertexer=NULL;
  96     delete vertex;
  97
  98     if(!vertexESD) return vertexAOD;
  99
 100     if(vertexESD->GetNContributors()!=trkArray->GetEntriesFast()) {
 101       //AliDebug(2,"vertexing failed");
 102       delete vertexESD; vertexESD=NULL;
 103       return vertexAOD;
 104     }
 105   }
 106   else{
 107     AliKFParticle::SetField(b);
 108
 109     AliKFVertex vertexKF;
 110
 111     Int_t nTrks = trkArray->GetEntriesFast();
 112     for(Int_t i=0; i<nTrks; i++) {
 113       AliESDtrack *esdTrack = (AliESDtrack*)trkArray->At(i);
 114       AliKFParticle daughterKF(*esdTrack,211);
 115       vertexKF.AddDaughter(daughterKF);
 116     }
 117     vertexESD = new AliESDVertex(vertexKF.Parameters(),
 118                                  vertexKF.CovarianceMatrix(),
 119                                  vertexKF.GetChi2(),
 120                                  vertexKF.GetNContributors());
 121   }
 122   // convert to AliAODVertex
 123   Double_t pos[3],cov[6],chi2perNDF;
 124   vertexESD->GetXYZ(pos); // position
 125   vertexESD->GetCovMatrix(cov); //covariance matrix
 126   chi2perNDF = vertexESD->GetChi2toNDF();
 127   //dispersion = vertexESD->GetDispersion();
 128   delete vertexESD; vertexESD=NULL;
 129
 130   Int_t nprongs= trkArray->GetEntriesFast();
 131   vertexAOD = new AliAODVertex(pos,cov,chi2perNDF,0x0,-1,AliAODVertex::kUndef,nprongs);
 132
 133   return vertexAOD;
 134
 135 }
 136 Double_t AliHLTD0toKpi::Pt(const AliExternalTrackParam* d1, const AliExternalTrackParam* d2)
 137 {
 138   Double_t p1[3],p2[3];
 139   d1->GetPxPyPz(p1);
 140   d2->GetPxPyPz(p2);
 141
 142   Double_t pt2 = (p1[0]+p2[0])*(p1[0]+p2[0]) + (p1[1]+p2[1])*(p1[1]+p2[1]);
 143
 144   return TMath::Sqrt(pt2);
 145 }