T2Track.h

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/*
  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
*/
/**********************************************************************************
 * @project: HLT, PESA algorithms
 * @package: TrigT2BeamSpot
 * @class  : T2Track
 *
 * @brief Helper class that provides an interface to Trk::Track
 *        with some additional functionality used by the beam spot algorithm
 *
 * @author Rainer Bartoldus, SLAC, <bartoldu@slac.stanford.edu>
 * @author David W. Miller, SLAC/Stanford University, <David.W.Miller@cern.ch>
 *
 **********************************************************************************/
#ifndef TRIGT2BEAMSPOT_T2TRACK_H
#define TRIGT2BEAMSPOT_T2TRACK_H
#include "TrkTrack/Track.h"
#include "TrkTrackSummary/TrackSummary.h"
#include "GaudiKernel/SystemOfUnits.h"
// Amg::error
#include "EventPrimitives/EventPrimitivesHelpers.h"
#include <string>
#include <vector>
#include <cmath>
#include <iostream>
#include "TMath.h"
 
namespace PESA {
 
  class T2Track
  {
  public:
 
    // Constructor
    T2Track( const Trk::Track& track )
    {
 
      const Trk::TrackParameters* trackPars = track.perigeeParameters();
      if (trackPars) {
        m_D0 = trackPars->parameters()[Trk::d0];
        m_Z0 = trackPars->parameters()[Trk::z0];
        if (trackPars->covariance()) {
          m_D0err = Amg::error(*(trackPars->covariance()),Trk::d0);
          m_Z0err = Amg::error(*(trackPars->covariance()),Trk::z0);
        }
        m_Phi = trackPars->parameters()[Trk::phi0];
        float theta = trackPars->parameters()[Trk::theta];
        m_Eta = -log(tan(0.5*theta));
        float qOverP = trackPars->parameters()[Trk::qOverP];
        m_Pt = std::abs(std::sin(theta)/qOverP)/Gaudi::Units::GeV;
 
        const Trk::FitQuality* fq = track.fitQuality();
        m_Qual = 1e8;
        if (fq) {
          if(fq->numberDoF()!=0) {
            m_Qual = fq->chiSquared()/fq->numberDoF();
          }
        }
        int nPix=0;
        int nSct=0;
        if( track.trackSummary() != nullptr){
          nPix =    track.trackSummary()->get(Trk::numberOfPixelHits);
          nSct =  track.trackSummary()->get(Trk::numberOfSCTHits);
        } else {
          for(auto tSOS = track.trackStateOnSurfaces()->begin();
              tSOS!=track.trackStateOnSurfaces()->end(); ++tSOS) {
            if ((*tSOS)->type(Trk::TrackStateOnSurface::Perigee) == false) {
              const Trk::FitQualityOnSurface& fq =  (*tSOS)->fitQualityOnSurface();
              if(!fq) continue;
              int nd = fq.numberDoF();
              if(nd==2) nPix++;
              if(nd==1) nSct++;
            }
          }
        }
        m_PIXHits = nPix;
        m_SCTHits = nSct/2;
        m_SiHits = m_PIXHits + m_SCTHits;
        m_NDF = (m_PIXHits + m_SCTHits)*2 - 5;
        m_TRTHits = 0; //for now: FTF tracks have no TRT extension in any case
      }
      m_Chi2Prob = -1;
      const double chi2 = m_Qual * m_NDF;
      if ( m_NDF  > 0  &&  chi2 > 0. && ! std::isinf( chi2 ) )
        {
          m_Chi2Prob = TMath::Prob(chi2,m_NDF);
        }
    }
 
    T2Track(const T2Track& track) = default;
 
 
    // Accessors
    double Pt      () const { return m_Pt      ; }
    double Eta     () const { return m_Eta     ; }
    double Phi     () const { return m_Phi     ; }
    double Z0      () const { return m_Z0      ; }
    double D0      () const { return m_D0      ; }
    double Z0err   () const { return m_Z0err   ; }
    double D0err   () const { return m_D0err   ; }
    double NDF     () const { return m_NDF     ; }
    double Qual    () const { return m_Qual    ; }
    double Chi2Prob() const { return m_Chi2Prob; }
    int    SiHits  () const { return m_SiHits  ; }
    int    PIXHits () const { return m_PIXHits ; }
    int    SCTHits () const { return m_SCTHits ; }
    int    TRTHits () const { return m_TRTHits ; }
 
  private:
 
    static double trackChi2Prob(int ndf, double chi2);
 
    // Data members
    double m_Pt;
    double m_Eta;
    double m_Phi;
    double m_Z0;
    double m_D0;
    double m_Z0err;
    double m_D0err;
    double m_NDF;
    double m_Qual;
    double m_Chi2Prob;
    int    m_SiHits;
    int    m_PIXHits;
    int    m_SCTHits;
    int    m_TRTHits;
  };
 
  std::ostream& operator<<( std::ostream& os, const T2Track& track );
 
} // end namespace
 
#endif