/data/refman/pasoursint/CMSSW_4_4_5_patch3/src/RecoParticleFlow/PFClusterTools/src/LinkByRecHit.cc

Go to the documentation of this file.

#include "RecoParticleFlow/PFClusterTools/interface/LinkByRecHit.h"
#include "DataFormats/Math/interface/normalizedPhi.h"
#include "DataFormats/ParticleFlowReco/interface/PFRecHit.h"
#include "TMath.h"

// to enable debugs
//#define PFLOW_DEBUG

double 
LinkByRecHit::testTrackAndClusterByRecHit ( const reco::PFRecTrack& track, 
                                            const reco::PFCluster&  cluster,
                                            bool isBrem,
                                            bool debug)  {
  
#ifdef PFLOW_DEBUG
  if( debug ) 
    std::cout<<"entering test link by rechit function"<<std::endl;
#endif
  
  //cluster position
  double clustereta  = cluster.positionREP().Eta();
  double clusterphi  = cluster.positionREP().Phi();
  double clusterX    = cluster.position().X();
  double clusterY    = cluster.position().Y();
  double clusterZ    = cluster.position().Z();

  bool barrel = false;
  bool hcal = false;
  double distance = 999999.9;

  //track extrapolation
  const reco::PFTrajectoryPoint& atVertex 
    = track.extrapolatedPoint( reco::PFTrajectoryPoint::ClosestApproach );
  const reco::PFTrajectoryPoint& atECAL 
    = track.extrapolatedPoint( reco::PFTrajectoryPoint::ECALShowerMax );

  //track at calo's
  double tracketa = 999999.9;
  double trackphi = 999999.9;
  double track_X  = 999999.9;
  double track_Y  = 999999.9;
  double track_Z  = 999999.9;
  double dHEta = 0.;
  double dHPhi = 0.;

  // Quantities at vertex
  double trackPt = isBrem ? 999. : sqrt(atVertex.momentum().Vect().Perp2());
  // double trackEta = isBrem ? 999. : atVertex.momentum().Vect().Eta();


  switch (cluster.layer()) {
  case PFLayer::ECAL_BARREL: barrel = true;
  case PFLayer::ECAL_ENDCAP:
#ifdef PFLOW_DEBUG
    if( debug )
      std::cout << "Fetching Ecal Resolution Maps"
           << std::endl;
#endif
    // did not reach ecal, cannot be associated with a cluster.
    if( ! atECAL.isValid() ) return -1.;   
    
    tracketa = atECAL.positionREP().Eta();
    trackphi = atECAL.positionREP().Phi();
    track_X  = atECAL.position().X();
    track_Y  = atECAL.position().Y();
    track_Z  = atECAL.position().Z();

    distance 
      = std::sqrt( (track_X-clusterX)*(track_X-clusterX)
                  +(track_Y-clusterY)*(track_Y-clusterY)
                  +(track_Z-clusterZ)*(track_Z-clusterZ)
                   );
                                   
    break;
   
  case PFLayer::HCAL_BARREL1: barrel = true; 
  case PFLayer::HCAL_ENDCAP:  
#ifdef PFLOW_DEBUG
    if( debug )
      std::cout << "Fetching Hcal Resolution Maps"
           << std::endl;
#endif
    if( isBrem ) {  
      return  -1.;
    } else { 
      hcal=true;
      const reco::PFTrajectoryPoint& atHCAL 
        = track.extrapolatedPoint( reco::PFTrajectoryPoint::HCALEntrance );
      const reco::PFTrajectoryPoint& atHCALExit 
        = track.extrapolatedPoint( reco::PFTrajectoryPoint::HCALExit );
      // did not reach hcal, cannot be associated with a cluster.
      if( ! atHCAL.isValid() ) return -1.;   
      
      // The link is computed between 0 and ~1 interaction length in HCAL
      dHEta = atHCALExit.positionREP().Eta()-atHCAL.positionREP().Eta();
      dHPhi = atHCALExit.positionREP().Phi()-atHCAL.positionREP().Phi(); 
      if ( dHPhi > M_PI ) dHPhi = dHPhi - 2.*M_PI;
      else if ( dHPhi < -M_PI ) dHPhi = dHPhi + 2.*M_PI; 
      tracketa = atHCAL.positionREP().Eta() + 0.1*dHEta;
      trackphi = atHCAL.positionREP().Phi() + 0.1*dHPhi;
      track_X  = atHCAL.position().X();
      track_Y  = atHCAL.position().Y();
      track_Z  = atHCAL.position().Z();
      distance 
        = -std::sqrt( (track_X-clusterX)*(track_X-clusterX)
                     +(track_Y-clusterY)*(track_Y-clusterY)
                     +(track_Z-clusterZ)*(track_Z-clusterZ)
                     );
                                   
    }
    break;
  case PFLayer::PS1:
  case PFLayer::PS2:
    //Note Alex: Nothing implemented for the
    //PreShower (No resolution maps yet)
#ifdef PFLOW_DEBUG
    if( debug )
      std::cout << "No link by rechit possible for pre-shower yet!"
           << std::endl;
#endif
    return -1.;
  default:
    return -1.;
  }


  // Check that, if the cluster is in the endcap, 
  // 0) the track indeed points to the endcap at vertex (DISABLED)
  // 1) the track extrapolation is in the endcap too !
  // 2) the track is in the same end-cap !
  // PJ - 10-May-09
  if ( !barrel ) { 
    // if ( fabs(trackEta) < 1.0 ) return -1; 
    if ( !hcal && fabs(track_Z) < 300. ) return -1.;
    if ( track_Z * clusterZ < 0. ) return -1.;
  }
  // Check that, if the cluster is in the barrel, 
  // 1) the track is in the barrel too !
  if ( barrel ) 
    if ( !hcal && fabs(track_Z) > 300. ) return -1.;

  // Finally check that, if the track points to the central barrel (|eta| < 1), 
  // it cannot be linked to a cluster in Endcaps (avoid low pt loopers)


  double dist = LinkByRecHit::computeDist( clustereta, clusterphi, 
                                         tracketa, trackphi);
  
#ifdef PFLOW_DEBUG
  if(debug) std::cout<<"test link by rechit "<< dist <<" "<<std::endl;
  if(debug){
    std::cout<<" clustereta "  << clustereta 
        <<" clusterphi "  << clusterphi 
        <<" tracketa " << tracketa
        <<" trackphi " << trackphi << std::endl;
  }
#endif
  
  //Testing if Track can be linked by rechit to a cluster.
  //A cluster can be linked to a track if the extrapolated position 
  //of the track to the ECAL ShowerMax/HCAL entrance falls within 
  //the boundaries of any cell that belongs to this cluster.

  const std::vector< reco::PFRecHitFraction >& 
    fracs = cluster.recHitFractions();
  
  bool linkedbyrechit = false;
  //loop rechits
  for(unsigned int rhit = 0; rhit < fracs.size(); ++rhit){

    const reco::PFRecHitRef& rh = fracs[rhit].recHitRef();
    double fraction = fracs[rhit].fraction();
    if(fraction < 1E-4) continue;
    if(rh.isNull()) continue;
    
    //getting rechit center position
    const reco::PFRecHit& rechit_cluster = *rh;
    const math::XYZPoint& posxyz 
      = rechit_cluster.position();
    const reco::PFRecHit::REPPoint& posrep 
      = rechit_cluster.positionREP();
    
    //getting rechit corners
    const std::vector< math::XYZPoint >& 
      cornersxyz = rechit_cluster.getCornersXYZ();
    const std::vector<reco::PFRecHit::REPPoint>& corners = 
      rechit_cluster.getCornersREP();
    assert(corners.size() == 4);
    
    if( barrel || hcal ){ // barrel case matching in eta/phi 
                          // (and HCAL endcap too!)
      
      //rechit size determination 
      // blown up by 50% (HCAL) to 100% (ECAL) to include cracks & gaps
      // also blown up to account for multiple scattering at low pt.
      double rhsizeEta 
        = fabs(corners[0].Eta() - corners[2].Eta());
      double rhsizePhi 
        = fabs(corners[0].Phi() - corners[2].Phi());
      if ( rhsizePhi > M_PI ) rhsizePhi = 2.*M_PI - rhsizePhi;
      if ( hcal ) { 
        rhsizeEta = rhsizeEta * (1.50 + 0.5/fracs.size()) + 0.2*fabs(dHEta);
        rhsizePhi = rhsizePhi * (1.50 + 0.5/fracs.size()) + 0.2*fabs(dHPhi); 
        
      } else { 
        rhsizeEta *= 2.00 + 1.0/fracs.size()/std::min(1.,trackPt/2.);
        rhsizePhi *= 2.00 + 1.0/fracs.size()/std::min(1.,trackPt/2.); 
      }
      
#ifdef PFLOW_DEBUG
      if( debug ) {
        std::cout << rhit         << " Hcal RecHit=" 
             << posrep.Eta() << " " 
             << posrep.Phi() << " "
             << rechit_cluster.energy() 
             << std::endl; 
        for ( unsigned jc=0; jc<4; ++jc ) 
          std::cout<<"corners "<<jc<<" "<<corners[jc].Eta()
              <<" "<<corners[jc].Phi()<<std::endl;
        
        std::cout << "RecHit SizeEta=" << rhsizeEta
             << " SizePhi=" << rhsizePhi << std::endl;
      }
#endif
      
      //distance track-rechit center
      // const math::XYZPoint& posxyz 
      // = rechit_cluster.position();
      double deta = fabs(posrep.Eta() - tracketa);
      double dphi = fabs(posrep.Phi() - trackphi);
      if ( dphi > M_PI ) dphi = 2.*M_PI - dphi;
      
#ifdef PFLOW_DEBUG
      if( debug ){
        std::cout << "distance=" 
             << deta << " " 
             << dphi << " ";
        if(deta < (rhsizeEta/2.) && dphi < (rhsizePhi/2.))
          std::cout << " link here !" << std::endl;
        else std::cout << std::endl;
      }
#endif
      
      if(deta < (rhsizeEta/2.) && dphi < (rhsizePhi/2.)){ 
        linkedbyrechit = true;
        break;
      }
    }
    else { //ECAL & PS endcap case, matching in X,Y
      
#ifdef PFLOW_DEBUG
      if( debug ){
        const math::XYZPoint& posxyz 
          = rechit_cluster.position();
        
        std::cout << "RH " << posxyz.X()
             << " "   << posxyz.Y()
             << std::endl;
        
        std::cout << "TRACK " << track_X
             << " "      << track_Y
             << std::endl;
      }
#endif
      
      double x[5];
      double y[5];
      
      for ( unsigned jc=0; jc<4; ++jc ) {
        math::XYZPoint cornerposxyz = cornersxyz[jc];
        x[jc] = cornerposxyz.X() + (cornerposxyz.X()-posxyz.X())
          * (1.00+0.50/fracs.size()/std::min(1.,trackPt/2.));
        y[jc] = cornerposxyz.Y() + (cornerposxyz.Y()-posxyz.Y())
          * (1.00+0.50/fracs.size()/std::min(1.,trackPt/2.));
        
#ifdef PFLOW_DEBUG
        if( debug ){
          std::cout<<"corners "<<jc
              << " " << cornerposxyz.X()
              << " " << cornerposxyz.Y()
              << std::endl;
        }
#endif
      }//loop corners
      
      //need to close the polygon in order to
      //use the TMath::IsInside fonction from root lib
      x[4] = x[0];
      y[4] = y[0];
      
      //Check if the extrapolation point of the track falls 
      //within the rechit boundaries
      bool isinside = TMath::IsInside(track_X,
                                      track_Y,
                                      5,x,y);
      
      if( isinside ){
        linkedbyrechit = true;
        break;
      }
    }//
    
  }//loop rechits
  
  if( linkedbyrechit ) {
#ifdef PFLOW_DEBUG
    if( debug ) 
      std::cout << "Track and Cluster LINKED BY RECHIT" << std::endl;
#endif
    /*    
    //if ( distance > 40. || distance < -100. ) 
    double clusterr = std::sqrt(clusterX*clusterX+clusterY*clusterY);
    double trackr = std::sqrt(track_X*track_X+track_Y*track_Y);
    if ( distance > 40. ) 
    std::cout << "Distance = " << distance 
    << ", Barrel/Hcal/Brem ? " << barrel << " " << hcal << " " << isBrem << std::endl
    << " Cluster " << clusterr << " " << clusterZ << " " << clusterphi << " " << clustereta << std::endl
    << " Track   " << trackr << " " << track_Z << " " << trackphi << " " << tracketa << std::endl;
    if ( !barrel && fabs(trackEta) < 1.0 ) { 
      double clusterr = std::sqrt(clusterX*clusterX+clusterY*clusterY);
      double trackr = std::sqrt(track_X*track_X+track_Y*track_Y);
      std::cout << "TrackEta/Pt = " << trackEta << " " << trackPt << ", distance = " << distance << std::endl 
                << ", Barrel/Hcal/Brem ? " << barrel << " " << hcal << " " << isBrem << std::endl
                << " Cluster " << clusterr << " " << clusterZ << " " << clusterphi << " " << clustereta << std::endl
                << " Track   " << trackr << " " << track_Z << " " << trackphi << " " << tracketa << " " << trackEta << " " << trackPt << std::endl;
    } 
    */
    return dist;
  } else {
    return -1.;
  }

}



double
LinkByRecHit::testECALAndPSByRecHit( const reco::PFCluster& clusterECAL, 
                                     const reco::PFCluster& clusterPS,
                                     bool debug)  {

// 0.19 <-> strip_pitch
// 6.1  <-> strip_length
  static double resPSpitch = 0.19/sqrt(12.);
  static double resPSlength = 6.1/sqrt(12.);

  // Check that clusterECAL is in ECAL endcap and that clusterPS is a preshower cluster
  if ( clusterECAL.layer() != PFLayer::ECAL_ENDCAP ||
       ( clusterPS.layer() != PFLayer::PS1 && 
         clusterPS.layer() != PFLayer::PS2 ) ) return -1.;

#ifdef PFLOW_DEBUG
  if( debug ) 
    std::cout<<"entering test link by rechit function for ECAL and PS"<<std::endl;
#endif

  //ECAL cluster position
  double zECAL  = clusterECAL.position().Z();
  double xECAL  = clusterECAL.position().X();
  double yECAL  = clusterECAL.position().Y();

  // PS cluster position, extrapolated to ECAL
  double zPS = clusterPS.position().Z();
  double xPS = clusterPS.position().X(); //* zECAL/zPS;
  double yPS = clusterPS.position().Y(); //* zECAL/zPS;
// MDN jan09 : check that zEcal and zPs have the same sign
        if (zECAL*zPS <0.) return -1.;
  double deltaX = 0.;
  double deltaY = 0.;
  double sqr12 = std::sqrt(12.);
  switch (clusterPS.layer()) {
  case PFLayer::PS1:
    // vertical strips, measure x with pitch precision
    deltaX = resPSpitch * sqr12;
    deltaY = resPSlength * sqr12;
    break;
  case PFLayer::PS2:
    // horizontal strips, measure y with pitch precision
    deltaY = resPSpitch * sqr12;
    deltaX = resPSlength * sqr12;
    break;
  default:
    break;
  }

  // Get the rechits
  const std::vector< reco::PFRecHitFraction >&  fracs = clusterECAL.recHitFractions();
  bool linkedbyrechit = false;
  //loop rechits
  for(unsigned int rhit = 0; rhit < fracs.size(); ++rhit){

    const reco::PFRecHitRef& rh = fracs[rhit].recHitRef();
    double fraction = fracs[rhit].fraction();
    if(fraction < 1E-4) continue;
    if(rh.isNull()) continue;

    //getting rechit center position
    const reco::PFRecHit& rechit_cluster = *rh;
    
    //getting rechit corners
    const std::vector< math::XYZPoint >&  corners = rechit_cluster.getCornersXYZ();
    assert(corners.size() == 4);
    
    const math::XYZPoint& posxyz = rechit_cluster.position() * zPS/zECAL;
#ifdef PFLOW_DEBUG
    if( debug ){
      std::cout << "Ecal rechit " << posxyz.X() << " "   << posxyz.Y() << std::endl;
      std::cout << "PS cluster  " << xPS << " " << yPS << std::endl;
    }
#endif
    
    double x[5];
    double y[5];
    for ( unsigned jc=0; jc<4; ++jc ) {
      // corner position projected onto the preshower
      math::XYZPoint cornerpos = corners[jc] * zPS/zECAL;
      // Inflate the size by the size of the PS strips, and by 5% to include ECAL cracks.
      x[jc] = cornerpos.X() + (cornerpos.X()-posxyz.X()) * (0.05 +1.0/fabs((cornerpos.X()-posxyz.X()))*deltaX/2.);
      y[jc] = cornerpos.Y() + (cornerpos.Y()-posxyz.Y()) * (0.05 +1.0/fabs((cornerpos.Y()-posxyz.Y()))*deltaY/2.);
      
#ifdef PFLOW_DEBUG
      if( debug ){
        std::cout<<"corners "<<jc
            << " " << cornerpos.X() << " " << x[jc] 
            << " " << cornerpos.Y() << " " << y[jc]
            << std::endl;
      }
#endif
    }//loop corners
    
    //need to close the polygon in order to
    //use the TMath::IsInside fonction from root lib
    x[4] = x[0];
    y[4] = y[0];
    
    //Check if the extrapolation point of the track falls 
    //within the rechit boundaries
    bool isinside = TMath::IsInside(xPS,yPS,5,x,y);
      
    if( isinside ){
      linkedbyrechit = true;
      break;
    }

  }//loop rechits
  
  if( linkedbyrechit ) {
    if( debug ) std::cout << "Cluster PS and Cluster ECAL LINKED BY RECHIT" << std::endl;
    double dist = computeDist( xECAL/1000.,yECAL/1000.,
                               xPS/1000.  ,yPS/1000, 
                               false);    
    return dist;
  } else { 
    return -1.;
  }

}



double 
LinkByRecHit::testHFEMAndHFHADByRecHit(const reco::PFCluster& clusterHFEM, 
                                      const reco::PFCluster& clusterHFHAD,
                                      bool debug) {
  
  math::XYZPoint posxyzEM = clusterHFEM.position();
  math::XYZPoint posxyzHAD = clusterHFHAD.position();

  double dX = posxyzEM.X()-posxyzHAD.X();
  double dY = posxyzEM.Y()-posxyzHAD.Y();
  double sameZ = posxyzEM.Z()*posxyzHAD.Z();

  if(sameZ<0) return -1.;

  double dist2 = dX*dX + dY*dY; 

  if( dist2 < 0.1 ) {
    // less than one mm
    double dist = sqrt( dist2 );
    return dist;;
  }
  else 
    return -1.;

}

double
LinkByRecHit::computeDist( double eta1, double phi1, 
                           double eta2, double phi2,
                           bool etaPhi )  {
  
  double phicor = etaPhi ? normalizedPhi(phi1 - phi2) : phi1 - phi2;
  
  // double chi2 =  
  //  (eta1 - eta2)*(eta1 - eta2) / ( reta1*reta1+ reta2*reta2 ) +
  //  phicor*phicor / ( rphi1*rphi1+ rphi2*rphi2 );

  double dist = std::sqrt( (eta1 - eta2)*(eta1 - eta2) 
                          + phicor*phicor);

  return dist;

}