ParticleBase.h

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//****************************************************************************
//*                   This file is part of PandaRoot.                        *
//*                                                                          *
//*            PandaRoot is distributed under the terms of the               *
//*              GNU General Public License (GPL) version 3,                 *
//*                 copied verbatim in the file "LICENSE".                   *
//*                                                                          *
//*  Copyright (C) 2006 - 2024 FAIR GmbH and copyright holders of PandaRoot  *
//*     The copyright holders are listed in the file "COPYRIGHTHOLDERS".     *
//*               The authors are listed in the file "AUTHORS".              *
//****************************************************************************

// ******************************************************
// DecayTreeFitter Package
// We thank the original author Wouter Hulsbergen
// (BaBar, LHCb) for providing the sources.
// http://arxiv.org/abs/physics/0503191v1 (2005)
// Adaptation & Development for PANDA: Ralf Kliemt (2015)
// ******************************************************
#ifndef PARTICLEBASE_H
#define PARTICLEBASE_H 1
#include "Rtypes.h"

#include <string>
#include <vector>
#include "Constraint.h"
#include "Projection.h"
#include "ChiSquare.h"

#include "RhoCandidate.h"

namespace DecayTreeFitter {
class FitParams;
class Configuration;

class ParticleBase {
 public:
  enum ParticleType { kInteractionPoint, kRecoComposite, kRecoResonance, kInternalParticle, kRecoTrack, kResonance, kRecoPhoton, kMissingParticle };
  typedef std::vector<ParticleBase *> ParticleContainer;

  // 'default' constructor
  ParticleBase(RhoCandidate *bc, const ParticleBase *mother);

  // constructor used for InteractionPoint
  ParticleBase(const std::string &name);

  virtual ~ParticleBase();

  static ParticleBase *createParticle(RhoCandidate *bc, const ParticleBase *mother, const Configuration &config);

  virtual int dim() const = 0;
  virtual void updateIndex(int &offset);
  virtual ErrCode initPar1(FitParams *) = 0; // init everything that does not need mother vtx
  virtual ErrCode initPar2(FitParams *) = 0; // everything else
  virtual ErrCode initCov(FitParams *) const;
  virtual std::string parname(int index) const;
  virtual void print(const FitParams *) const;

  const ParticleBase *locate(RhoCandidate *bc) const;
  //    void locate(RhoCandidateID& pid, ParticleContainer& result ) ;
  RhoCandidate *particle() const { return m_particle; }

  virtual int index() const { return m_index; }
  const ParticleBase *mother() const { return m_mother; }
  const std::string &name() const { return m_name; }

  virtual ErrCode projectGeoConstraint(const FitParams *, Projection &) const;
  virtual ErrCode projectMassConstraint(const FitParams *, Projection &) const;
  virtual ErrCode projectConstraint(Constraint::Type, const FitParams *, Projection &) const;

  // indices to fit parameters
  virtual int type() const = 0;
  virtual int posIndex() const { return -1; }
  virtual int lenIndex() const { return -1; }
  virtual int momIndex() const { return -1; }

  // does the particle have a 3-momentum or a 4-momentum ?
  virtual bool hasEnergy() const { return false; }

  // does the particle have is own decay vertex ? (resonances and
  // recoparticles do not)
  virtual bool hasPosition() const { return false; }

  int eneIndex() const { return hasEnergy() ? momIndex() + 3 : -1; }

  // calculates the global chisquare (pretty useless)
  virtual double chiSquareD(const FitParams *) const;

  // access to particle PDT parameters
  double pdtMass() const { return m_pdtMass; }
  double pdtWidth() const { return m_pdtWidth; }
  double pdtCLifeTime() const { return m_pdtCLifeTime; }
  double pdtTau() const { return m_pdtMass > 0 ? m_pdtCLifeTime / m_pdtMass : 0; }
  int charge() const { return m_charge; }

  // return a trajectory
  //    virtual const LHCb::Trajectory* trajectory() const { return 0 ; }

  // access to daughters
  typedef std::vector<ParticleBase *> daucontainer;
  typedef daucontainer::const_iterator const_iterator;

  const daucontainer &daughters() const { return m_daughters; }
  const_iterator begin() const { return m_daughters.begin(); }
  const_iterator end() const { return m_daughters.end(); }
  ParticleBase *addDaughter(RhoCandidate *, const Configuration &config);
  void removeDaughter(const ParticleBase *pb);

  typedef std::vector<std::pair<const ParticleBase *, int>> indexmap;
  virtual void retrieveIndexMap(indexmap &anindexmap) const;

  void setMother(const ParticleBase *m) { m_mother = m; }

  typedef std::vector<DecayTreeFitter::Constraint> constraintlist;
  virtual void addToConstraintList(constraintlist &alist, int depth) const = 0;
  virtual int nFinalChargedCandidates() const;
  void setParticle(RhoCandidate *bc) { m_particle = bc; }

  // collect all particles emitted from vertex with position posindex
  void collectVertexDaughters(daucontainer &particles, int posindex);
  // set the mass constraint for this particle. return true if value changed
  bool setMassConstraint(bool add)
  {
    std::swap(add, m_hasMassConstraint);
    return add != m_hasMassConstraint;
  }
  // set the mass of the mass constraint (use with care!)
  void setMassConstraint(double mass)
  {
    m_hasMassConstraint = true;
    m_pdtMass = mass;
  }

  ChiSquare chiSquare(const FitParams *fitparams) const;

 protected:
  static double pdtCLifeTime(RhoCandidate *bc);
  // static bool isAResonance(RhoCandidate* bc) ;
  static bool isAResonance(const TParticlePDG *bc); // TODO
  // static double bFieldOverC() { return RhoCalculationTools::GetBz ( TVector3(0.,0.,0.) ) / TMath::C() ; } //FIXME: Is that an issue???   // Bz/c
  static double bFieldOverC(); // FIXME: Is that an issue???   // Bz/c
  ErrCode initTau(FitParams *par) const;
  void makeName(RhoCandidate *bc);
  daucontainer &daughters() { return m_daughters; }
  bool hasMassConstraint() const { return m_hasMassConstraint; }

 protected:
  void setIndex(int i) { m_index = i; }
  void setName(const std::string &n) { m_name = n; }

 private:
  RhoCandidate *m_particle;
  const ParticleBase *m_mother;
  ParticleContainer m_daughters;
  const TParticlePDG *m_prop;
  int m_index;
  double m_pdtMass;      // cached mass
  double m_pdtWidth;     // particle width (for mass constraints)
  double m_pdtCLifeTime; // cached lifetime
  int m_charge;          // charge
  std::string m_name;
  bool m_hasMassConstraint;
  ClassDef(ParticleBase, 1)
};

} // namespace DecayTreeFitter

#endif