IPTools.cc

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#include "DataFormats/GeometrySurface/interface/Line.h"
 
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
#include "TrackingTools/GeomPropagators/interface/AnalyticalTrajectoryExtrapolatorToLine.h"
#include "TrackingTools/GeomPropagators/interface/AnalyticalImpactPointExtrapolator.h"
#include "DataFormats/GeometryCommonDetAlgo/interface/Measurement1D.h"
#include "TrackingTools/TransientTrack/interface/TransientTrack.h"
#include "TrackingTools/IPTools/interface/IPTools.h"
#include "CLHEP/Vector/ThreeVector.h"
#include "CLHEP/Vector/LorentzVector.h"
#include "CLHEP/Matrix/Vector.h"
#include <string>
 
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "RecoVertex/VertexTools/interface/VertexDistance3D.h"
#include "RecoVertex/VertexTools/interface/VertexDistanceXY.h"
#include "RecoVertex/VertexPrimitives/interface/ConvertToFromReco.h"
 
namespace IPTools {
  using namespace std;
  using namespace reco;
 
  std::pair<bool, Measurement1D> absoluteImpactParameter(const TrajectoryStateOnSurface& tsos,
                                                         const reco::Vertex& vertex,
                                                         VertexDistance& distanceComputer) {
    if (!tsos.isValid()) {
      return pair<bool, Measurement1D>(false, Measurement1D(0., 0.));
    }
    GlobalPoint refPoint = tsos.globalPosition();
    GlobalError refPointErr = tsos.cartesianError().position();
    GlobalPoint vertexPosition = RecoVertex::convertPos(vertex.position());
    GlobalError vertexPositionErr = RecoVertex::convertError(vertex.error());
    return pair<bool, Measurement1D>(
        true,
        distanceComputer.distance(VertexState(vertexPosition, vertexPositionErr), VertexState(refPoint, refPointErr)));
  }
 
  std::pair<bool, Measurement1D> absoluteImpactParameter3D(const reco::TransientTrack& transientTrack,
                                                           const reco::Vertex& vertex) {
    AnalyticalImpactPointExtrapolator extrapolator(transientTrack.field());
    VertexDistance3D dist;
    return absoluteImpactParameter(
        extrapolator.extrapolate(transientTrack.impactPointState(), RecoVertex::convertPos(vertex.position())),
        vertex,
        dist);
  }
  std::pair<bool, Measurement1D> absoluteTransverseImpactParameter(const reco::TransientTrack& transientTrack,
                                                                   const reco::Vertex& vertex) {
    TransverseImpactPointExtrapolator extrapolator(transientTrack.field());
    VertexDistanceXY dist;
    return absoluteImpactParameter(
        extrapolator.extrapolate(transientTrack.impactPointState(), RecoVertex::convertPos(vertex.position())),
        vertex,
        dist);
  }
 
  pair<bool, Measurement1D> signedTransverseImpactParameter(const TransientTrack& track,
                                                            const GlobalVector& direction,
                                                            const Vertex& vertex) {
    //Extrapolate to closest point on transverse plane
    TransverseImpactPointExtrapolator extrapolator(track.field());
    TrajectoryStateOnSurface closestOnTransversePlaneState =
        extrapolator.extrapolate(track.impactPointState(), RecoVertex::convertPos(vertex.position()));
 
    //Compute absolute value
    VertexDistanceXY dist;
    pair<bool, Measurement1D> result = absoluteImpactParameter(closestOnTransversePlaneState, vertex, dist);
    if (!result.first)
      return result;
 
    //Compute Sign
    GlobalPoint impactPoint = closestOnTransversePlaneState.globalPosition();
    GlobalVector IPVec(impactPoint.x() - vertex.x(), impactPoint.y() - vertex.y(), 0.);
    double prod = IPVec.dot(direction);
    double sign = (prod >= 0) ? 1. : -1.;
 
    //Apply sign to the result
    return pair<bool, Measurement1D>(result.first, Measurement1D(sign * result.second.value(), result.second.error()));
  }
 
  pair<bool, Measurement1D> signedImpactParameter3D(const TransientTrack& track,
                                                    const GlobalVector& direction,
                                                    const Vertex& vertex) {
    //Extrapolate to closest point on transverse plane
    AnalyticalImpactPointExtrapolator extrapolator(track.field());
    TrajectoryStateOnSurface closestIn3DSpaceState =
        extrapolator.extrapolate(track.impactPointState(), RecoVertex::convertPos(vertex.position()));
 
    //Compute absolute value
    VertexDistance3D dist;
    pair<bool, Measurement1D> result = absoluteImpactParameter(closestIn3DSpaceState, vertex, dist);
    if (!result.first)
      return result;
 
    //Compute Sign
    GlobalPoint impactPoint = closestIn3DSpaceState.globalPosition();
    GlobalVector IPVec(impactPoint.x() - vertex.x(), impactPoint.y() - vertex.y(), impactPoint.z() - vertex.z());
    double prod = IPVec.dot(direction);
    double sign = (prod >= 0) ? 1. : -1.;
 
    //Apply sign to the result
    return pair<bool, Measurement1D>(result.first, Measurement1D(sign * result.second.value(), result.second.error()));
  }
 
  pair<bool, Measurement1D> signedDecayLength3D(const TrajectoryStateOnSurface& closestToJetState,
                                                const GlobalVector& direction,
                                                const Vertex& vertex) {
    //Check if extrapolation has been successfull
    if (!closestToJetState.isValid()) {
      return pair<bool, Measurement1D>(false, Measurement1D(0., 0.));
    }
 
    GlobalVector jetDirection = direction.unit();
    GlobalPoint vertexPosition(vertex.x(), vertex.y(), vertex.z());
 
    double decayLen = jetDirection.dot(closestToJetState.globalPosition() - vertexPosition);
 
    //error calculation
 
    AlgebraicVector3 j;
    j[0] = jetDirection.x();
    j[1] = jetDirection.y();
    j[2] = jetDirection.z();
    AlgebraicVector6 jj;
    jj[0] = jetDirection.x();
    jj[1] = jetDirection.y();
    jj[2] = jetDirection.z();
    jj[3] = 0.;
    jj[4] = 0.;
    jj[5] = 0.;  
 
    //TODO: FIXME: the extrapolation uncertainty is very relevant here should be taken into account!!
    double trackError2 = ROOT::Math::Similarity(jj, closestToJetState.cartesianError().matrix());
    double vertexError2 = ROOT::Math::Similarity(j, vertex.covariance());
 
    double decayLenError = sqrt(trackError2 + vertexError2);
 
    return pair<bool, Measurement1D>(true, Measurement1D(decayLen, decayLenError));
  }
 
  pair<bool, Measurement1D> linearizedSignedImpactParameter3D(const TrajectoryStateOnSurface& closestToJetState,
                                                              const GlobalVector& direction,
                                                              const Vertex& vertex) {
    //Check if extrapolation has been successfull
    if (!closestToJetState.isValid()) {
      return pair<bool, Measurement1D>(false, Measurement1D(0., 0.));
    }
 
    GlobalPoint vertexPosition(vertex.x(), vertex.y(), vertex.z());
    GlobalVector impactParameter = linearImpactParameter(closestToJetState, vertexPosition);
    GlobalVector jetDir = direction.unit();
    GlobalVector flightDistance(closestToJetState.globalPosition() - vertexPosition);
    double theDistanceAlongJetAxis = jetDir.dot(flightDistance);
    double signedIP = impactParameter.mag() *
                      ((theDistanceAlongJetAxis != 0) ? theDistanceAlongJetAxis / abs(theDistanceAlongJetAxis) : 1.);
 
    GlobalVector ipDirection = impactParameter.unit();
    //GlobalPoint closestPoint = closestToJetState.globalPosition();
    GlobalVector momentumAtClosestPoint = closestToJetState.globalMomentum();
    GlobalVector momentumDir = momentumAtClosestPoint.unit();
 
    AlgebraicVector3 deriv_v;
    deriv_v[0] = -ipDirection.x();
    deriv_v[1] = -ipDirection.y();
    deriv_v[2] = -ipDirection.z();
 
    AlgebraicVector6 deriv;
    deriv[0] = ipDirection.x();
    deriv[1] = ipDirection.y();
    deriv[2] = ipDirection.z();
    deriv[3] = -(momentumDir.dot(flightDistance) * ipDirection.x()) / momentumAtClosestPoint.mag();
    deriv[4] = -(momentumDir.dot(flightDistance) * ipDirection.y()) / momentumAtClosestPoint.mag();
    deriv[5] = -(momentumDir.dot(flightDistance) * ipDirection.z()) / momentumAtClosestPoint.mag();
 
    double trackError2 = ROOT::Math::Similarity(deriv, closestToJetState.cartesianError().matrix());
    double vertexError2 = ROOT::Math::Similarity(deriv_v, vertex.covariance());
    double ipError = sqrt(trackError2 + vertexError2);
 
    return pair<bool, Measurement1D>(true, Measurement1D(signedIP, ipError));
  }
 
  TrajectoryStateOnSurface closestApproachToJet(const TrajectoryStateOnSurface& state,
                                                const Vertex& vertex,
                                                const GlobalVector& direction,
                                                const MagneticField* field) {
    Line::PositionType pos(GlobalPoint(vertex.x(), vertex.y(), vertex.z()));
    Line::DirectionType dir(direction.unit());
    Line jetLine(pos, dir);
 
    AnalyticalTrajectoryExtrapolatorToLine extrapolator(field);
 
    return extrapolator.extrapolate(state, jetLine);
  }
 
  GlobalVector linearImpactParameter(const TrajectoryStateOnSurface& state, const GlobalPoint& point) {
    Line::PositionType pos(state.globalPosition());
    Line::DirectionType dir((state.globalMomentum()).unit());
    Line trackLine(pos, dir);
    const GlobalPoint& tmp = point;
    return trackLine.distance(tmp);
  }
 
  pair<double, Measurement1D> jetTrackDistance(const TransientTrack& track,
                                               const GlobalVector& direction,
                                               const Vertex& vertex) {
    double theLDist_err(0.);
 
    //FIXME
    float weight = 0.;  //vertex.trackWeight(track);
 
    TrajectoryStateOnSurface stateAtOrigin = track.impactPointState();
    if (!stateAtOrigin.isValid()) {
      //TODO: throw instead?
      return pair<bool, Measurement1D>(false, Measurement1D(0., 0.));
    }
 
    //get the Track line at origin
    Line::PositionType posTrack(stateAtOrigin.globalPosition());
    Line::DirectionType dirTrack((stateAtOrigin.globalMomentum()).unit());
    Line trackLine(posTrack, dirTrack);
    // get the Jet  line
    // Vertex vertex(vertex);
    GlobalVector jetVector = direction.unit();
    Line::PositionType posJet(GlobalPoint(vertex.x(), vertex.y(), vertex.z()));
    Line::DirectionType dirJet(jetVector);
    Line jetLine(posJet, dirJet);
 
    // now compute the distance between the two lines
    // If the track has been used to refit the Primary vertex then sign it positively, otherwise negative
    double theDistanceToJetAxis = (jetLine.distance(trackLine)).mag();
    if (weight < 1)
      theDistanceToJetAxis = -theDistanceToJetAxis;
 
    // ... and the flight distance along the Jet axis.
    GlobalPoint V = jetLine.position();
    GlobalVector Q = dirTrack - jetVector.dot(dirTrack) * jetVector;
    GlobalVector P = jetVector - jetVector.dot(dirTrack) * dirTrack;
    double theDistanceAlongJetAxis = P.dot(V - posTrack) / Q.dot(dirTrack);
 
    //
    // get the covariance matrix of the vertex and compute the error on theDistanceToJetAxis
    //
 
 
    // build the vector of closest approach between lines
 
    //FIXME: error not computed.
    GlobalVector H((jetVector.cross(dirTrack).unit()));
    CLHEP::HepVector Hh(3);
    Hh[0] = H.x();
    Hh[1] = H.y();
    Hh[2] = H.z();
 
    //  theLDist_err = sqrt(vertexError.similarity(Hh));
 
    //    cout << "distance to jet axis : "<< theDistanceToJetAxis <<" and error : "<< theLDist_err<<endl;
    // Now the impact parameter ...
 
    /*    GlobalPoint T0 = track.position();
      GlobalVector D = (T0-V)- (T0-V).dot(dir) * dir;
      double IP = D.mag();    
      GlobalVector Dold = distance(aTSOS, aJet.vertex(), jetDirection);
      double IPold = Dold.mag();
    */
 
    Measurement1D DTJA(theDistanceToJetAxis, theLDist_err);
 
    return pair<double, Measurement1D>(theDistanceAlongJetAxis, DTJA);
  }
 
}  // namespace IPTools