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
  14 ClassImp(AliHLTD0toKpi)
  15
  16 AliHLTD0toKpi::AliHLTD0toKpi()
  17 {
  18 }
  19
  20 Double_t AliHLTD0toKpi::InvMass(AliExternalTrackParam* d1, AliExternalTrackParam* d2)
  21 {
  22   Double_t mpi=TDatabasePDG::Instance()->GetParticle(211)->Mass();
  23   Double_t mK=TDatabasePDG::Instance()->GetParticle(321)->Mass();
  24
  25   Double_t energy[2];
  26   energy[1] = TMath::Sqrt(mK*mK+d1->GetP()*d1->GetP());
  27   energy[0] = TMath::Sqrt(mpi*mpi+d2->GetP()*d2->GetP());
  28
  29   Double_t p1[3],p2[3];
  30   d1->GetPxPyPz(p1);
  31   d2->GetPxPyPz(p2);
  32
  33   Double_t momTot2 = (p1[0]+p2[0])*(p1[0]+p2[0])+
  34                      (p1[1]+p2[1])*(p1[1]+p2[1])+
  35                      (p1[2]+p2[2])*(p1[2]+p2[2]);
  36
  37   return TMath::Sqrt((energy[0]+energy[1])*(energy[0]+energy[1])-momTot2);
  38
  39 }
  40 void AliHLTD0toKpi::cosThetaStar(AliExternalTrackParam* d1, AliExternalTrackParam* d2,Double_t &D0,Double_t &D0bar)
  41 {
  42   Double_t mD0 = TDatabasePDG::Instance()->GetParticle(421)->Mass();
  43   Double_t mpi=TDatabasePDG::Instance()->GetParticle(211)->Mass();
  44   Double_t mK=TDatabasePDG::Instance()->GetParticle(321)->Mass();
  45
  46   Double_t pStar = TMath::Sqrt(TMath::Power(mD0*mD0-mK*mK-mpi*mpi,2.)-4.*mK*mK*mpi*mpi)/(2.*mD0);
  47
  48   Double_t px = d1->Px()+d2->Px();
  49   Double_t py = d1->Py()+d2->Py();
  50   Double_t pz = d1->Pz()+d2->Pz();
  51   Double_t p = TMath::Sqrt(px*px+py*py+pz*pz);
  52   Double_t energy = TMath::Sqrt(p*p+mD0*mD0);
  53
  54   Double_t beta = p/energy;
  55   Double_t gamma = energy/mD0;
  56
  57   Double_t qL;
  58   TVector3 mom(d1->Px(),d1->Py(),d1->Pz());
  59   TVector3 momD(px,py,pz);
  60   qL = mom.Dot(momD)/momD.Mag();
  61
  62   D0 = (qL/gamma-beta*TMath::Sqrt(pStar*pStar+mK*mK))/pStar;
  63
  64   TVector3 mom2(d2->Px(),d2->Py(),d2->Pz());
  65   TVector3 momD2(px,py,pz);
  66   qL = mom2.Dot(momD2)/momD2.Mag();
  67
  68   D0bar = (qL/gamma-beta*TMath::Sqrt(pStar*pStar+mK*mK))/pStar;
  69
  70 }
  71 Double_t AliHLTD0toKpi::pointingAngle(AliExternalTrackParam* n, AliExternalTrackParam* p, Double_t *pv, Double_t *sv)
  72 {
  73
  74   TVector3 mom(n->Px()+p->Px(),n->Py()+p->Py(),n->Pz()+p->Pz());
  75   TVector3 flight(sv[0]-pv[0],sv[1]-pv[1],sv[2]-pv[2]);
  76
  77   double pta = mom.Angle(flight);
  78
  79   return TMath::Cos(pta);
  80 }
  81
  82 AliAODVertex* AliHLTD0toKpi::ReconstructSecondaryVertex(TObjArray *trkArray, Double_t b, AliESDVertex *v)
  83 {
  84
  85   AliESDVertex *vertexESD = 0;
  86   AliAODVertex *vertexAOD = 0;
  87
  88   AliVertexerTracks *vertexer = new AliVertexerTracks(b);
  89   vertexer->SetVtxStart(v);
  90   //if(isESD){vertexESD = (AliESDVertex*)vertexer->VertexForSelectedESDTracks(trkArray);}
  91   UShort_t *id = new UShort_t[2];
  92   AliHLTGlobalBarrelTrack *t1 = (AliHLTGlobalBarrelTrack*) trkArray->At(0);
  93   AliHLTGlobalBarrelTrack *t2 = (AliHLTGlobalBarrelTrack*) trkArray->At(1);
  94   id[0]=(UShort_t) t1->GetID();
  95   id[1]=(UShort_t) t2->GetID();
  96   vertexESD = (AliESDVertex*)vertexer->VertexForSelectedTracks(trkArray,id);
  97   delete id;
  98   delete vertexer; vertexer=NULL;
  99
 100   if(!vertexESD) return vertexAOD;
 101
 102   if(vertexESD->GetNContributors()!=trkArray->GetEntriesFast()) {
 103     //AliDebug(2,"vertexing failed");
 104     delete vertexESD; vertexESD=NULL;
 105     return vertexAOD;
 106   }
 107
 108   // convert to AliAODVertex
 109   Double_t pos[3],cov[6],chi2perNDF;
 110   vertexESD->GetXYZ(pos); // position
 111   vertexESD->GetCovMatrix(cov); //covariance matrix
 112   chi2perNDF = vertexESD->GetChi2toNDF();
 113   //dispersion = vertexESD->GetDispersion();
 114   delete vertexESD; vertexESD=NULL;
 115
 116   Int_t nprongs= trkArray->GetEntriesFast();
 117   vertexAOD = new AliAODVertex(pos,cov,chi2perNDF,0x0,-1,AliAODVertex::kUndef,nprongs);
 118
 119   return vertexAOD;
 120
 121 }