TwoBodyDecayTrajectory.cc

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#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include "TrackingTools/TrajectoryState/interface/FreeTrajectoryState.h"
#include "DataFormats/GeometrySurface/interface/Surface.h"
#include "Alignment/ReferenceTrajectories/interface/TwoBodyDecayTrajectory.h"
#include "DataFormats/CLHEP/interface/AlgebraicObjects.h"
#include "DataFormats/Math/interface/Error.h"
#include "Alignment/TwoBodyDecay/interface/TwoBodyDecayParameters.h"

#include "Geometry/CommonDetUnit/interface/GeomDet.h"

#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"

TwoBodyDecayTrajectory::TwoBodyDecayTrajectory(const TwoBodyDecayTrajectoryState& tsos,
                                               const ConstRecHitCollection& recHits,
                                               const MagneticField* magField,
                                               const reco::BeamSpot& beamSpot,
                                               const ReferenceTrajectoryBase::Config& config)
    : ReferenceTrajectoryBase(
          TwoBodyDecayParameters::dimension,
          recHits.first.size() + recHits.second.size(),
          (config.materialEffects >= breakPoints) ? 2 * (recHits.first.size() + recHits.second.size()) - 4 : 0,
          (config.materialEffects >= breakPoints) ? 2 * (recHits.first.size() + recHits.second.size()) - 3 : 1),
      materialEffects_(config.materialEffects),
      propDir_(config.propDir),
      useRefittedState_(config.useRefittedState),
      constructTsosWithErrors_(config.constructTsosWithErrors)

{
  if (config.hitsAreReverse) {
    TransientTrackingRecHit::ConstRecHitContainer::const_reverse_iterator itRecHits;
    ConstRecHitCollection fwdRecHits;

    fwdRecHits.first.reserve(recHits.first.size());
    for (itRecHits = recHits.first.rbegin(); itRecHits != recHits.first.rend(); ++itRecHits) {
      fwdRecHits.first.push_back(*itRecHits);
    }

    fwdRecHits.second.reserve(recHits.second.size());
    for (itRecHits = recHits.second.rbegin(); itRecHits != recHits.second.rend(); ++itRecHits) {
      fwdRecHits.second.push_back(*itRecHits);
    }

    theValidityFlag = this->construct(tsos, fwdRecHits, magField, beamSpot);
  } else {
    theValidityFlag = this->construct(tsos, recHits, magField, beamSpot);
  }
}

TwoBodyDecayTrajectory::TwoBodyDecayTrajectory(void)
    : ReferenceTrajectoryBase(0, 0, 0, 0),
      materialEffects_(none),
      propDir_(anyDirection),
      useRefittedState_(false),
      constructTsosWithErrors_(false) {}

bool TwoBodyDecayTrajectory::construct(const TwoBodyDecayTrajectoryState& state,
                                       const ConstRecHitCollection& recHits,
                                       const MagneticField* field,
                                       const reco::BeamSpot& beamSpot) {
  const TwoBodyDecayTrajectoryState::TsosContainer& tsos = state.trajectoryStates(useRefittedState_);
  const TwoBodyDecayTrajectoryState::Derivatives& deriv = state.derivatives();
  double mass = state.particleMass();

  //
  // first track
  //

  // construct a trajectory (hits should be already in correct order)
  ReferenceTrajectoryBase::Config config(materialEffects_, propDir_, mass);
  config.useBeamSpot = false;
  config.hitsAreReverse = false;

  ReferenceTrajectory trajectory1(tsos.first, recHits.first, field, beamSpot, config);

  // check if construction of trajectory was successful
  if (!trajectory1.isValid())
    return false;

  //
  // second track
  //

  ReferenceTrajectory trajectory2(tsos.second, recHits.second, field, beamSpot, config);

  if (!trajectory2.isValid())
    return false;

  //
  // combine both tracks
  //
  unsigned int nLocal = deriv.first.num_row();
  unsigned int nTbd = deriv.first.num_col();

  if (materialEffects_ >= localGBL) {
    // GBL trajectory inputs
    // convert to Eigen::MatrixXd
    Eigen::MatrixXd tbdToLocal1{nLocal, nTbd};
    for (unsigned int row = 0; row < nLocal; ++row) {
      for (unsigned int col = 0; col < nTbd; ++col) {
        tbdToLocal1(row, col) = deriv.first[row][col];
      }
    }
    // add first body
    theGblInput.push_back(
        std::make_pair(trajectory1.gblInput().front().first, trajectory1.gblInput().front().second * tbdToLocal1));
    // convert to Eigen::MatrixXd
    Eigen::MatrixXd tbdToLocal2{nLocal, nTbd};
    for (unsigned int row = 0; row < nLocal; ++row) {
      for (unsigned int col = 0; col < nTbd; ++col) {
        tbdToLocal2(row, col) = deriv.second[row][col];
      }
    }
    // add second body
    theGblInput.push_back(
        std::make_pair(trajectory2.gblInput().front().first, trajectory2.gblInput().front().second * tbdToLocal2));
    // add virtual mass measurement
    theGblExtDerivatives.resize(1, nTbd);
    theGblExtDerivatives.setZero();
    theGblExtDerivatives(0, TwoBodyDecayParameters::mass) = 1.0;
    theGblExtMeasurements.resize(1);
    theGblExtMeasurements(0) = state.primaryMass() - state.decayParameters()[TwoBodyDecayParameters::mass];
    theGblExtPrecisions.resize(1);
    theGblExtPrecisions(0) = 1.0 / (state.primaryWidth() * state.primaryWidth());
    // nominal field
    theNomField = trajectory1.nominalField();
  } else {
    unsigned int nHitMeas1 = trajectory1.numberOfHitMeas();
    unsigned int nVirtualMeas1 = trajectory1.numberOfVirtualMeas();
    unsigned int nPar1 = trajectory1.numberOfPar();
    unsigned int nVirtualPar1 = trajectory1.numberOfVirtualPar();

    // derivatives of the trajectory w.r.t. to the decay parameters
    AlgebraicMatrix fullDeriv1 = trajectory1.derivatives().sub(1, nHitMeas1 + nVirtualMeas1, 1, nLocal) *
                                 trajectory1.localToTrajectory() * deriv.first;

    unsigned int nHitMeas2 = trajectory2.numberOfHitMeas();
    unsigned int nVirtualMeas2 = trajectory2.numberOfVirtualMeas();
    unsigned int nPar2 = trajectory2.numberOfPar();
    unsigned int nVirtualPar2 = trajectory2.numberOfVirtualPar();

    AlgebraicMatrix fullDeriv2 = trajectory2.derivatives().sub(1, nHitMeas2 + nVirtualMeas2, 1, nLocal) *
                                 trajectory2.localToTrajectory() * deriv.second;

    theNumberOfRecHits.first = recHits.first.size();
    theNumberOfRecHits.second = recHits.second.size();

    theNumberOfHits = trajectory1.numberOfHits() + trajectory2.numberOfHits();
    theNumberOfPars = nPar1 + nPar2;
    theNumberOfVirtualPars = nVirtualPar1 + nVirtualPar2;
    theNumberOfVirtualMeas = nVirtualMeas1 + nVirtualMeas2 + 1;  // add virtual mass measurement

    // hit measurements from trajectory 1
    int rowOffset = 1;
    int colOffset = 1;
    theDerivatives.sub(rowOffset, colOffset, fullDeriv1.sub(1, nHitMeas1, 1, nTbd));
    colOffset += nTbd;
    theDerivatives.sub(
        rowOffset, colOffset, trajectory1.derivatives().sub(1, nHitMeas1, nLocal + 1, nPar1 + nVirtualPar1));
    // hit measurements from trajectory 2
    rowOffset += nHitMeas1;
    colOffset = 1;
    theDerivatives.sub(rowOffset, colOffset, fullDeriv2.sub(1, nHitMeas2, 1, nTbd));
    colOffset += (nPar1 + nVirtualPar1 + nTbd - nLocal);
    theDerivatives.sub(
        rowOffset, colOffset, trajectory2.derivatives().sub(1, nHitMeas2, nLocal + 1, nPar2 + nVirtualPar2));
    // MS measurements from trajectory 1
    rowOffset += nHitMeas2;
    colOffset = 1;
    theDerivatives.sub(rowOffset, colOffset, fullDeriv1.sub(nHitMeas1 + 1, nHitMeas1 + nVirtualMeas1, 1, nTbd));
    colOffset += nTbd;
    theDerivatives.sub(
        rowOffset,
        colOffset,
        trajectory1.derivatives().sub(nHitMeas1 + 1, nHitMeas1 + nVirtualMeas1, nLocal + 1, nPar1 + nVirtualPar1));
    // MS measurements from trajectory 2
    rowOffset += nVirtualMeas1;
    colOffset = 1;
    theDerivatives.sub(rowOffset, colOffset, fullDeriv2.sub(nHitMeas2 + 1, nHitMeas2 + nVirtualMeas2, 1, nTbd));
    colOffset += (nPar1 + nVirtualPar1 + nTbd - nLocal);
    theDerivatives.sub(
        rowOffset,
        colOffset,
        trajectory2.derivatives().sub(nHitMeas2 + 1, nHitMeas2 + nVirtualMeas2, nLocal + 1, nPar2 + nVirtualPar2));

    theMeasurements.sub(1, trajectory1.measurements().sub(1, nHitMeas1));
    theMeasurements.sub(nHitMeas1 + 1, trajectory2.measurements().sub(1, nHitMeas2));
    theMeasurements.sub(nHitMeas1 + nHitMeas2 + 1,
                        trajectory1.measurements().sub(nHitMeas1 + 1, nHitMeas1 + nVirtualMeas1));
    theMeasurements.sub(nHitMeas1 + nHitMeas2 + nVirtualMeas1 + 1,
                        trajectory2.measurements().sub(nHitMeas2 + 1, nHitMeas2 + nVirtualMeas2));

    theMeasurementsCov.sub(1, trajectory1.measurementErrors().sub(1, nHitMeas1));
    theMeasurementsCov.sub(nHitMeas1 + 1, trajectory2.measurementErrors().sub(1, nHitMeas2));
    theMeasurementsCov.sub(nHitMeas1 + nHitMeas2 + 1,
                           trajectory1.measurementErrors().sub(nHitMeas1 + 1, nHitMeas1 + nVirtualMeas1));
    theMeasurementsCov.sub(nHitMeas1 + nHitMeas2 + nVirtualMeas1 + 1,
                           trajectory2.measurementErrors().sub(nHitMeas2 + 1, nHitMeas2 + nVirtualMeas2));

    theTrajectoryPositions.sub(1, trajectory1.trajectoryPositions());
    theTrajectoryPositions.sub(nHitMeas1 + 1, trajectory2.trajectoryPositions());

    theTrajectoryPositionCov =
        state.decayParameters().covariance().similarity(theDerivatives.sub(1, nHitMeas1 + nHitMeas2, 1, 9));

    theParameters = state.decayParameters().parameters();

    // add virtual mass measurement
    rowOffset += nVirtualMeas2;
    int indMass = rowOffset - 1;
    theMeasurements[indMass] = state.primaryMass() - state.decayParameters()[TwoBodyDecayParameters::mass];
    theMeasurementsCov[indMass][indMass] = state.primaryWidth() * state.primaryWidth();
    theDerivatives[indMass][TwoBodyDecayParameters::mass] = 1.0;
  }

  theRecHits.insert(theRecHits.end(), recHits.first.begin(), recHits.first.end());
  theRecHits.insert(theRecHits.end(), recHits.second.begin(), recHits.second.end());

  if (constructTsosWithErrors_) {
    constructTsosVecWithErrors(trajectory1, trajectory2, field);
  } else {
    theTsosVec.insert(theTsosVec.end(), trajectory1.trajectoryStates().begin(), trajectory1.trajectoryStates().end());

    theTsosVec.insert(theTsosVec.end(), trajectory2.trajectoryStates().begin(), trajectory2.trajectoryStates().end());
  }

  return true;
}

void TwoBodyDecayTrajectory::constructTsosVecWithErrors(const ReferenceTrajectory& traj1,
                                                        const ReferenceTrajectory& traj2,
                                                        const MagneticField* field) {
  int iTsos = 0;

  std::vector<TrajectoryStateOnSurface>::const_iterator itTsos;

  for (itTsos = traj1.trajectoryStates().begin(); itTsos != traj1.trajectoryStates().end(); itTsos++) {
    constructSingleTsosWithErrors(*itTsos, iTsos, field);
    iTsos++;
  }

  for (itTsos = traj2.trajectoryStates().begin(); itTsos != traj2.trajectoryStates().end(); itTsos++) {
    constructSingleTsosWithErrors(*itTsos, iTsos, field);
    iTsos++;
  }
}

void TwoBodyDecayTrajectory::constructSingleTsosWithErrors(const TrajectoryStateOnSurface& tsos,
                                                           int iTsos,
                                                           const MagneticField* field) {
  AlgebraicSymMatrix55 localErrors;
  const double coeff = 1e-2;

  double invP = tsos.localParameters().signedInverseMomentum();
  LocalVector p = tsos.localParameters().momentum();

  // rough estimate for the errors of q/p, dx/dz and dy/dz, assuming that
  // sigma(px) = sigma(py) = sigma(pz) = coeff*p.
  float dpinv = coeff * (fabs(p.x()) + fabs(p.y()) + fabs(p.z())) * invP * invP;
  float dxdir = coeff * (fabs(p.x()) + fabs(p.z())) / p.z() / p.z();
  float dydir = coeff * (fabs(p.y()) + fabs(p.z())) / p.z() / p.z();
  localErrors[0][0] = dpinv * dpinv;
  localErrors[1][1] = dxdir * dxdir;
  localErrors[2][2] = dydir * dydir;

  // exact values for the errors on local x and y
  localErrors[3][3] = theTrajectoryPositionCov[nMeasPerHit * iTsos][nMeasPerHit * iTsos];
  localErrors[3][4] = theTrajectoryPositionCov[nMeasPerHit * iTsos][nMeasPerHit * iTsos + 1];
  localErrors[4][4] = theTrajectoryPositionCov[nMeasPerHit * iTsos + 1][nMeasPerHit * iTsos + 1];

  // construct tsos with local errors
  theTsosVec[iTsos] = TrajectoryStateOnSurface(
      tsos.localParameters(), LocalTrajectoryError(localErrors), tsos.surface(), field, tsos.surfaceSide());
}