Analysis/VertexFit/include/VertexFit/SecondVertexFit.h

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#ifndef VertexFit_SecondVertexFit_H
#define VertexFit_SecondVertexFit_H
#include "VertexFit/TrackPool.h"
#include "VertexFit/VertexFit.h"
 
//--------------------------------------------------------------------------------
//
// Fitting Parameters Format:  (px, py, pz, E, xd, yd, zd, xp, yp, zp)
//
// Author   Date         Comments
// K.L He   11/21/2005   original version
// Xu Min   11/30/2006   Add interface of production vertex and decay vertex
// Martin   09/02/2010   Add some kindly comments
//
//--------------------------------------------------------------------------------
 
// You can find the corresponding tutorial on the following web page:
// http://docbes3.ihep.ac.cn/~offlinesoftware/index.php/Vertex_Fit
 
class SecondVertexFit : public TrackPool {
public:
  // constructor & deconstructor
  static SecondVertexFit* instance();
  ~SecondVertexFit();
 
  // initializtion must be called before SecondVertexFit each time
  void init();
 
  // set iteration number and chisq cut
  void setIterNumber( const int niter = 10 ) { m_niter = niter; }
  void setChisqCut( const double chicut = 500, const double chiter = 1.0e-2 ) {
    m_chicut = chicut;
    m_chiter = chiter;
  }
  // set decay point
  void setVpar( const VertexParameter vpar ) { m_vpar_secondary = vpar; }
  // set production point
  void setPrimaryVertex( const VertexParameter vpar ) {
    m_vpar_primary.setVx( vpar.Vx() );
    m_vpar_primary.setEvx( vpar.Evx() );
  }
  // set magnet correction factor
  void setMagCorrFactor( const double factor = 1.000 ) { m_factor = factor; }
 
  // fit function
  bool Fit();
 
  // fit results
  double chisq() const { return m_chisq; }
  double decayLength() const { return m_lxyz; }
  double decayLengthError() const { return m_lxyz_error; }
  double ctau() const { return m_ctau; }
  double ctauError() const { return m_ctau_error; }
  double factor() const { return m_factor; }
 
  HepLorentzVector  p4par() const { return m_p4par; }
  WTrackParameter   wpar() const { return m_wtrk; }
  VertexParameter   vpar() const { return m_vpar_secondary; }
  inline HepPoint3D crossPoint() const;
  inline Hep3Vector crossVector() const;
 
private:
  int    m_niter;      // number of iteration for second vertex fitting
  double m_chisq;      // fitting chisquare
  double m_chicut;     // chisquare upper limit
  double m_chiter;     // precision of iteration
  double m_lxyz;       // decay length
  double m_lxyz_error; // error of decay length
  double m_ctau;       // c times tau
  double m_ctau_error; // error of ctau
  double m_factor;     // B Field correction factor
 
  HepVector        m_crxyz;          // decay vertex in HepVector format
  HepLorentzVector m_p4par;          // HepLorentzVector of particle at decay vertex
  WTrackParameter  m_wtrk;           // WTrackParameter of particle at decay vertex
  VertexParameter  m_vpar_primary;   // production vertex
  VertexParameter  m_vpar_secondary; // decay vertex
 
  // Singleton Design
  SecondVertexFit();
  static SecondVertexFit* m_pointer;
};
 
inline HepPoint3D SecondVertexFit::crossPoint() const {
  return HepPoint3D( m_crxyz[0], m_crxyz[1], m_crxyz[2] );
}
 
inline Hep3Vector SecondVertexFit::crossVector() const {
  return Hep3Vector( m_crxyz[0] - m_vpar_primary.Vx()[0], m_crxyz[1] - m_vpar_primary.Vx()[1],
                     m_crxyz[2] - m_vpar_primary.Vx()[2] );
}
 
#endif // VertexFit_SecondVertexFit_H