Difference between revisions of "Mattione GlueX Kinematic Fitting"

#ifndef _DKinFitAction_Sample_
#define _DKinFitAction_Sample_
 
#include "JANA/JEventLoop.h"
#include "DANA/DApplication.h"
 
#include "ANALYSIS/DAnalysisAction.h"
#include "ANALYSIS/DKinFitter_GlueX.h"
#include "ANALYSIS/DKinFitParticle.h"
#include "ANALYSIS/DParticleCombo.h"
 
using namespace std;
using namespace jana;
 
class DKinFitAction_Sample : public DAnalysisAction
{
  public:
    DKinFitAction_Sample(const DReaction* locReaction, string locActionUniqueString = "") : 
    DAnalysisAction(locReaction, "KinFit_Sample", false, locActionUniqueString){}
 
  private:
    bool Perform_Action(JEventLoop* locEventLoop, const DParticleCombo* locParticleCombo, const deque<pair<const DParticleCombo*, bool> >& locPreviousParticleCombos);
    void Initialize(JEventLoop* locEventLoop);
 
    DKinFitter_GlueX dKinFitter;
 
    //define any histograms here
};
 
#endif // _DKinFitAction_Sample_

#include "DKinFitAction_Sample.h"
 
void DKinFitAction_Sample::Initialize(JEventLoop* locEventLoop)
{
  DApplication* locApplication = dynamic_cast<DApplication*>(locEventLoop->GetJApplication());
  dKinFitter.Set_BField(locApplication->GetBfield()); //need call only once
 
  //create any histograms here
}
 
bool DKinFitAction_Sample::Perform_Action(JEventLoop* locEventLoop, const DParticleCombo* locParticleCombo, const deque<pair<const DParticleCombo*, bool> >& locPreviousParticleCombos)
{
  //THIS ASSUMES DParticleCombo (read: DReaction) is setup as:
    //g, p -> K+, Lambda
    //Lambda -> p, pi-
 
  dKinFitter.Reset_NewEvent(); //need to call prior to use in each event (cleans up memory allocated from last event)
 
  //CREATE DKINFITPARTICLE OBJECTS FOR EACH PARTICLE
  const DBeamPhoton* locBeamPhoton = static_cast<const DBeamPhoton*>(locParticleCombo->Get_ParticleComboStep(0)->Get_InitialParticle_Measured());
  const DKinFitParticle* locKinFitParticle_BeamPhoton = dKinFitter.Make_BeamParticle(locBeamPhoton);
 
  const DKinFitParticle* locKinFitParticle_Target = dKinFitter.Make_TargetParticle(Proton);
  const DKinFitParticle* locKinFitParticle_Lambda = dKinFitter.Make_DecayingParticle(Lambda);
 
  const DChargedTrackHypothesis* locChargedTrackHypothesis_KPlus = static_cast<const DChargedTrackHypothesis*>(locParticleCombo->Get_ParticleComboStep(0)->Get_FinalParticle_Measured(0));
  const DKinFitParticle* locKinFitParticle_KPlus = dKinFitter.Make_DetectedParticle(locChargedTrackHypothesis_KPlus);
 
  const DChargedTrackHypothesis* locChargedTrackHypothesis_Proton = static_cast<const DChargedTrackHypothesis*>(locParticleCombo->Get_ParticleComboStep(1)->Get_FinalParticle_Measured(0));
  const DKinFitParticle* locKinFitParticle_Proton = dKinFitter.Make_DetectedParticle(locChargedTrackHypothesis_Proton);
 
  const DChargedTrackHypothesis* locChargedTrackHypothesis_PiMinus = static_cast<const DChargedTrackHypothesis*>(locParticleCombo->Get_ParticleComboStep(1)->Get_FinalParticle_Measured(1));
  const DKinFitParticle* locKinFitParticle_PiMinus = dKinFitter.Make_DetectedParticle(locChargedTrackHypothesis_PiMinus);
 
  // SETUP THE CONSTRAINTS
  dKinFitter.Reset_NewFit(); //disregards the constraints from the previous kinematic fit
  deque<const DKinFitParticle*> locInitialKinFitParticles, locFinalKinFitParticles;
 
  // first p4 constraint:
  locInitialKinFitParticles.push_back(locKinFitParticle_BeamPhoton);
  locInitialKinFitParticles.push_back(locKinFitParticle_Target);
  locFinalKinFitParticles.push_back(locKinFitParticle_KPlus);
  locFinalKinFitParticles.push_back(locKinFitParticle_Lambda);
  dKinFitter.Add_P4Constraint(locInitialKinFitParticles, locFinalKinFitParticles);
 
  // second p4 constraint:
  locInitialKinFitParticles.clear();
  locFinalKinFitParticles.clear();
  locInitialKinFitParticles.push_back(locKinFitParticle_Lambda);
  locFinalKinFitParticles.push_back(locKinFitParticle_PiMinus);
  locFinalKinFitParticles.push_back(locKinFitParticle_Proton);
  dKinFitter.Add_P4Constraint(locInitialKinFitParticles, locFinalKinFitParticles);
 
  // vertex constraint
  TVector3 locVertexGuess(locKinFitParticle_Proton->Get_Position()); //try to get a better vertex guess than this!
  locInitialKinFitParticles.clear();
  locFinalKinFitParticles.clear();
  locInitialKinFitParticles.push_back(locKinFitParticle_Lambda); //here the lambda isn't constraining the vertex (since it's only in one vertex fit); instead it's vertex will be defined by the fit result
  locFinalKinFitParticles.push_back(locKinFitParticle_PiMinus);
  locFinalKinFitParticles.push_back(locKinFitParticle_Proton);
  dKinFitter.Add_VertexConstraint(locInitialKinFitParticles, locFinalKinFitParticles, locVertexGuess);
 
  // PERFORM THE KINEMATIC FIT
  dKinFitter.Fit_Reaction();
 
  // GET THE FIT RESULTS
  double locConfidenceLevel = dKinFitter.Get_ConfidenceLevel();
  double locChiSq = dKinFitter.Get_ChiSq();
  unsigned int locNDF = dKinFitter.Get_NDF();
  const TMatrixDSym* locMeasuredParametersKinFitCovarianceMatrix = dKinFitter.Get_VEta();
  const TMatrixDSym* locUnknownParametersCovarianceMatrix = dKinFitter.Get_VXi();
 
  const DKinFitParticle* locKinFitParticle_Proton_Output = dKinFitter.Get_OutputKinFitParticle(locKinFitParticle_Proton);
  const DKinFitParticle* locKinFitParticle_PiMinus_Output = dKinFitter.Get_OutputKinFitParticle(locKinFitParticle_PiMinus);
  const DKinFitParticle* locKinFitParticle_KPlus_Output = dKinFitter.Get_OutputKinFitParticle(locKinFitParticle_KPlus);
  const DKinFitParticle* locKinFitParticle_Lambda_Output = dKinFitter.Get_OutputKinFitParticle(locKinFitParticle_Lambda);
  const DKinFitParticle* locKinFitParticle_BeamPhoton_Output = dKinFitter.Get_OutputKinFitParticle(locKinFitParticle_BeamPhoton);
  TVector3 locKinFitVertex = locKinFitParticle_PiMinus_Output->Get_CommonVertex(); //could also be grabbed from the proton or the lambda
 
  map<const DKinematicData*, map<DKinFitPullType, double> > locPulls; //map from input particle data to pull map //pull map: map from pull type to value (DKinFitPullType defined in DKinFitParticle.h)
  dKinFitter.Get_Pulls(locPulls);
  double locProtonPxPull = (locPulls[locChargedTrackHypothesis_Proton])[d_PxPull];
 
  //fill histograms, etc. here
  return (locConfidenceLevel >= 0.01); //cut if < 1% confidence level
}