TrackFitResultEstimator.cc

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
 
#include <analysis/modules/TrackFitResultEstimator/TrackFitResultEstimator.h>
 
#include <framework/geometry/BFieldManager.h>
 
#include <analysis/DecayDescriptor/DecayDescriptor.h>
 
#include <TDatabasePDG.h>
#include <Math/Vector3D.h>
 
#include <cmath>
 
using namespace Belle2;
using namespace ROOT::Math;
 
//-----------------------------------------------------------------
//                 Register the Module
//-----------------------------------------------------------------
REG_MODULE(TrackFitResultEstimator);
 
//-----------------------------------------------------------------
//                 Implementation
//-----------------------------------------------------------------
 
TrackFitResultEstimatorModule::TrackFitResultEstimatorModule() : Module()
{
  // Set module properties
  setDescription(R"DOC(
Create a TrackFitResult from the momentum of the Particle assuming it originates from the IP and make a relation between them. The
covariance, detector hit information, and fit-related information (pValue, NDF) are assigned meaningless values. The input
Particles must not have already Track or TrackFitResult and thus are supposed to be composite particles, recoil, dummy particles,
and so on. Since the source type is not overwritten as Track, not all track-related variables are guaranteed to be available.
)DOC");
  setPropertyFlags(c_ParallelProcessingCertified);
 
  // Parameter definitions
  addParam("inputListName", m_inputListName,
           "The name of input ParticleList.",
           std::string(""));
}
 
void TrackFitResultEstimatorModule::initialize()
{
  DecayDescriptor decaydescriptor;
  bool valid = decaydescriptor.init(m_inputListName);
  if (!valid)
    B2ERROR("Invalid input ParticleList name: " << m_inputListName);
 
  const int pdg = decaydescriptor.getMother()->getPDGCode();
  if (std::abs(TDatabasePDG::Instance()->GetParticle(pdg)->Charge()) > 3)
    B2WARNING("The absolute value of charge of input ParticleList is greater than 1. Helix requires abs(charge) <= 1. "
              "The sign of charge will be used instead.");
 
  m_inputparticleList.isRequired(m_inputListName);
  m_particles.registerRelationTo(m_trackfitresults);
}
 
void TrackFitResultEstimatorModule::event()
{
 
  TMatrixDSym dummyCovariance(6);
  for (int row = 0; row < 6; ++row) {
    dummyCovariance(row, row) = 10000;
  }
 
  XYZVector position(0,0,0);
  if (m_beamSpotDB)
    position = m_beamSpotDB->getIPPosition();
 
  const double bfield = BFieldManager::getFieldInTesla(position).Z();
 
  for (unsigned i = 0; i < m_inputparticleList->getListSize(); i++) {
    Particle* part = m_inputparticleList->getParticle(i);
 
    if (part->getTrack() or part->getTrackFitResult())
      B2ERROR("Particle is already related to the Track or TrackFitResult object.");
 
    int charge = part->getCharge();
    if (std::abs(charge)>1)
      charge = charge / std::abs(charge);
 
    TrackFitResult* trkfit = m_trackfitresults.appendNew(position,
                                                         part->getMomentum(),
                                                         dummyCovariance,
                                                         charge,
                                                         Const::ParticleType(part->getPDGCode()),
                                                         -1, // pValue
                                                         bfield,
                                                         0, 0, // CDC, VXD hit-pattern
                                                         0 // NDF
                                                        );
    part->addRelationTo(trkfit);
  }
 
}