StRoot: StarRoot/KFParticleBase.h Source File

00001 //---------------------------------------------------------------------------------
00002 // The KFParticleBase class
00003 // .
00004 // @author  S.Gorbunov, I.Kisel
00005 // @version 1.0
00006 // @since   13.05.07
00007 // 
00008 // Class to reconstruct and store the decayed particle parameters.
00009 // The method is described in CBM-SOFT note 2007-003, 
00010 // ``Reconstruction of decayed particles based on the Kalman filter'', 
00011 // http://www.gsi.de/documents/DOC-2007-May-14-1.pdf
00012 //
00013 // This class describes general mathematics which is used by KFParticle class
00014 // 
00015 //  -= Copyright &copy ALICE HLT Group =-
00016 //_________________________________________________________________________________
00017 #ifndef KFParticleBASE_H
00018 #define KFParticleBASE_H
00019 #include "TObject.h"
00020 class KFParticleBase : public TObject {
00021  public:
00022   //  ABSTRACT METHODS HAVE TO BE DEFINED IN USER CLASS 
00023   //  Virtual method to access the magnetic field
00024   virtual void GetFieldValue(const Double_t xyz[], Double_t B[]) const = 0;
00025   //  Virtual methods needed for particle transportation 
00026   //  One can use particular implementations for collider (only Bz component) 
00027   //  geometry and for fixed-target (CBM-like) geometry which are provided below 
00028   //  in TRANSPORT section
00029  
00030   //  Get dS to xyz[] space point 
00031   virtual Double_t GetDStoPoint( const Double_t xyz[] ) const = 0;
00032   //  Get dS to other particle p (dSp for particle p also returned) 
00033   virtual void GetDStoParticle( const KFParticleBase &p, 
00034                                 Double_t &DS, Double_t &DSp ) const = 0;
00035   //  Transport on dS value along trajectory, output to P,C
00036   virtual void Transport( Double_t dS, Double_t P[], Double_t C[] ) const = 0;
00037   KFParticleBase();
00038   virtual ~KFParticleBase() {}
00039   //  Initialisation from "cartesian" coordinates ( X Y Z Px Py Pz )
00040   //  Parameters, covariance matrix, charge, and mass hypothesis should be provided 
00041   void Initialize( const Double_t Param[], const Double_t Cov[], Int_t Charge, Double_t Mass );
00042   //  Initialise covariance matrix and set current parameters to 0.0 
00043   void Initialize();
00044   //  Set decay vertex parameters for linearisation 
00045   void SetVtxGuess( Double_t x, Double_t y, Double_t z );
00046   void SetID(Int_t id=0) {fID = id;}
00047   //   ACCESSORS
00048   Int_t  GetID() const {return fID;}
00049   Double_t GetX    () const { return fP[0]; }
00050   Double_t GetY    () const { return fP[1]; }
00051   Double_t GetZ    () const { return fP[2]; }
00052   Double_t GetPx   () const { return fP[3]; }
00053   Double_t GetPy   () const { return fP[4]; }
00054   Double_t GetPz   () const { return fP[5]; }
00055   Double_t GetE    () const { return fP[6]; }
00056   Double_t GetS    () const { return fP[7]; }
00057   Int_t    GetQ    () const { return fQ;    }
00058   Double_t GetChi2 () const { return fChi2; }
00059   Int_t    GetNDF  () const { return fNDF;  }
00060   
00061   Double_t GetParameter ( Int_t i )        const { return fP[i];       }
00062   Double_t GetCovariance( Int_t i )        const { return fC[i];       }
00063   Double_t GetCovariance( Int_t i, Int_t j ) const { return fC[IJ(i,j)]; }
00064   
00065   //  Accessors with calculations( &value, &estimated sigma )
00066   //  error flag returned (0 means no error during calculations) 
00067   
00068   Int_t GetMomentum    ( Double_t &P, Double_t &SigmaP ) const ;
00069   Int_t GetPt          ( Double_t &Pt, Double_t &SigmaPt ) const ;
00070   Int_t GetEta         ( Double_t &Eta, Double_t &SigmaEta ) const ;
00071   Int_t GetPhi         ( Double_t &Phi, Double_t &SigmaPhi ) const ;
00072   Int_t GetMass        ( Double_t &M, Double_t &SigmaM ) const ;
00073   Int_t GetDecayLength ( Double_t &L, Double_t &SigmaL ) const ;
00074   Int_t GetDecayLengthXY ( Double_t &L, Double_t &SigmaL ) const ;
00075   Int_t GetLifeTime    ( Double_t &T, Double_t &SigmaT ) const ;
00076   Int_t GetR           ( Double_t &R, Double_t &SigmaR ) const ;
00077   
00078   // 
00079   //   MODIFIERS
00080   // 
00081   
00082   Double_t & X    () { return fP[0]; }
00083   Double_t & Y    () { return fP[1]; }
00084   Double_t & Z    () { return fP[2]; }
00085   Double_t & Px   () { return fP[3]; }
00086   Double_t & Py   () { return fP[4]; }
00087   Double_t & Pz   () { return fP[5]; }
00088   Double_t & E    () { return fP[6]; }
00089   Double_t & S    () { return fP[7]; }
00090   Int_t    & Q    () { return fQ;    }
00091   Double_t & Chi2 () { return fChi2; }
00092   Int_t    & NDF  () { return fNDF;  }
00093 
00094   Double_t & Parameter ( Int_t i )        { return fP[i];       }
00095   Double_t & Covariance( Int_t i )        { return fC[i];       }
00096   Double_t & Covariance( Int_t i, Int_t j ) { return fC[IJ(i,j)]; }
00097 
00098 
00099   //  
00100   //  CONSTRUCTION OF THE PARTICLE BY ITS DAUGHTERS AND MOTHER
00101   //  USING THE KALMAN FILTER METHOD
00102   // 
00103 
00104 
00105   //  Simple way to add daughter ex. D0+= Pion; 
00106 
00107   void operator +=( const KFParticleBase &Daughter );  
00108 
00109   //  Add daughter track to the particle 
00110 
00111   void AddDaughter( const KFParticleBase &Daughter );
00112 
00113   //  Set production vertex 
00114 
00115   void SetProductionVertex( const KFParticleBase &Vtx );
00116 
00117   //  Set mass constraint 
00118 
00119   void SetMassConstraint( Double_t Mass, Double_t SigmaMass = 0 );
00120   
00121   //  Set no decay length for resonances
00122 
00123   void SetNoDecayLength();
00124 
00125 
00126   //  Everything in one go  
00127 
00128   void Construct( const KFParticleBase *vDaughters[], Int_t NDaughters, 
00129                   const KFParticleBase *ProdVtx=0,   Double_t Mass=-1, Bool_t IsConstrained=0  );
00130   
00131 
00132   // 
00133   //                    TRANSPORT
00134   //  
00135   //   ( main transportation parameter is S = SignedPath/Momentum )
00136   //   ( parameters of decay & production vertices are stored locally )
00137   // 
00138 
00139 
00140   //  Transport the particle to its decay vertex 
00141 
00142   void TransportToDecayVertex();
00143 
00144   //  Transport the particle to its production vertex 
00145 
00146   void TransportToProductionVertex();
00147 
00148   //  Transport the particle on dS parameter (SignedPath/Momentum) 
00149 
00150   void TransportToDS( Double_t dS );
00151 
00152   //  Particular extrapolators one can use 
00153 
00154   Double_t GetDStoPointBz( Double_t Bz, const Double_t xyz[] ) const;
00155   
00156   void GetDStoParticleBz( Double_t Bz, const KFParticleBase &p, 
00157                           Double_t &dS, Double_t &dS1       ) const ;
00158  
00159   // Double_t GetDStoPointCBM( const Double_t xyz[] ) const;
00160  
00161    void TransportBz( Double_t Bz, Double_t dS, Double_t P[], Double_t C[] ) const;
00162    void TransportCBM( Double_t dS, Double_t P[], Double_t C[] ) const;  
00163 
00164 
00165   //  
00166   //  OTHER UTILITIES
00167   // 
00168 
00169   //  Calculate distance from another object [cm]
00170 
00171   Double_t GetDistanceFromVertex( const Double_t vtx[] ) const;
00172   Double_t GetDistanceFromVertex( const KFParticleBase &Vtx ) const;
00173   Double_t GetDistanceFromParticle( const KFParticleBase &p ) const;
00174 
00175   //  Calculate sqrt(Chi2/ndf) deviation from vertex
00176   //  v = [xyz], Cv=[Cxx,Cxy,Cyy,Cxz,Cyz,Czz]-covariance matrix
00177 
00178   Double_t GetDeviationFromVertex( const Double_t v[], 
00179                                    const Double_t Cv[]=0 ) const;
00180   Double_t GetDeviationFromVertex( const KFParticleBase &Vtx ) const;
00181   Double_t GetDeviationFromParticle( const KFParticleBase &p ) const;  
00182 
00183   //  Subtract the particle from the vertex  
00184 
00185   void SubtractFromVertex( KFParticleBase &Vtx ) const ;
00186 
00187     //  Special method for creating gammas
00188 
00189   void ConstructGammaBz( const KFParticleBase &daughter1,
00190                          const KFParticleBase &daughter2, Double_t Bz  );
00191   virtual void Print(Option_t *opt="") const;
00192   Int_t           IdTruth() const { return fIdTruth;}
00193   Int_t           QaTruth() const { return fQuality; }
00194   Int_t           IdParentVx() const {return fIdParentVx;}
00195   
00196   void         SetIdTruth(Int_t idtru,Int_t qatru=0) {fIdTruth = (UShort_t) idtru; fQuality = (UShort_t) qatru;}
00197   void         SetIdParentVx(Int_t id) {fIdParentVx = id;}
00198  protected:
00199 
00200   static Int_t IJ( Int_t i, Int_t j ){ 
00201     return ( j<=i ) ? i*(i+1)/2+j :j*(j+1)/2+i;
00202   }
00203 
00204   Double_t & Cij( Int_t i, Int_t j ){ return fC[IJ(i,j)]; }
00205 
00206   void Convert( Bool_t ToProduction );
00207   void TransportLine( Double_t S, Double_t P[], Double_t C[] ) const ;
00208   Double_t GetDStoPointLine( const Double_t xyz[] ) const;
00209 
00210   static Bool_t InvertSym3( const Double_t A[], Double_t Ainv[] );
00211 
00212   static void MultQSQt( const Double_t Q[], const Double_t S[], 
00213                         Double_t SOut[] );
00214 
00215   static Double_t GetSCorrection( const Double_t Part[], const Double_t XYZ[] );
00216 
00217   void GetMeasurement( const Double_t XYZ[], Double_t m[], Double_t V[] ) const ;
00218 
00219   Int_t  fID;
00220   Double_t fP[8];  //  Main particle parameters {X,Y,Z,Px,Py,Pz,E,S[=DecayLength/P]}
00221   Double_t fC[36]; //  Low-triangle covariance matrix of fP
00222   Int_t    fQ;     //  Particle charge 
00223   Int_t    fNDF;   //  Number of degrees of freedom 
00224   Double_t fChi2;  //  Chi^2
00225 
00226   Double_t fSFromDecay; //  Distance from decay vertex to current position
00227   
00228   Bool_t fAtProductionVertex; //  Flag shows that the particle error along
00229   //  its trajectory is taken from production vertex    
00230 
00231   Double_t fVtxGuess[3];  //  Guess for the position of the decay vertex 
00232                           //  ( used for linearisation of equations )
00233   
00234   Bool_t fIsLinearized;   //  Flag shows that the guess is present
00235   UShort_t      fIdTruth; // MC track id 
00236   UShort_t      fQuality; // quality of this information (percentage of hits coming from the above MC track)
00237   Int_t         fIdParentVx;
00238   
00239   ClassDef(KFParticleBase,1)                        
00240 };
00241 ostream&  operator<<(ostream& os, KFParticleBase const & particle);
00242 #endif