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f826d409 | 1 | //--------------------------------------------------------------------------------- |
2 | // The AliKFParticleBase class | |
3 | // . | |
4 | // @author S.Gorbunov, I.Kisel | |
5 | // @version 1.0 | |
6 | // @since 13.05.07 | |
7 | // | |
8 | // Class to reconstruct and store the decayed particle parameters. | |
9 | // The method is described in CBM-SOFT note 2007-003, | |
10 | // ``Reconstruction of decayed particles based on the Kalman filter'', | |
11 | // http://www.gsi.de/documents/DOC-2007-May-14-1.pdf | |
12 | // | |
13 | // This class describes general mathematics which is used by AliKFParticle class | |
14 | // | |
15 | // -= Copyright © ALICE HLT Group =- | |
16 | //_________________________________________________________________________________ | |
17 | ||
18 | ||
19 | ||
20 | #ifndef ALIKFPARTICLEBASE_H | |
21 | #define ALIKFPARTICLEBASE_H | |
22 | ||
23 | #include "TObject.h" | |
24 | ||
25 | class AliKFParticleBase :public TObject { | |
26 | ||
27 | public: | |
28 | ||
29 | //* | |
30 | //* ABSTRACT METHODS HAVE TO BE DEFINED IN USER CLASS | |
31 | //* | |
32 | ||
33 | //* Virtual method to access the magnetic field | |
34 | ||
35 | virtual void GetFieldValue(const Double_t xyz[], Double_t B[]) const = 0; | |
36 | ||
37 | //* Virtual methods needed for particle transportation | |
38 | //* One can use particular implementations for collider (only Bz component) | |
39 | //* geometry and for fixed-target (CBM-like) geometry which are provided below | |
40 | //* in TRANSPORT section | |
41 | ||
42 | //* Get dS to xyz[] space point | |
43 | ||
44 | virtual Double_t GetDStoPoint( const Double_t xyz[] ) const = 0; | |
45 | ||
46 | //* Get dS to other particle p (dSp for particle p also returned) | |
47 | ||
48 | virtual void GetDStoParticle( const AliKFParticleBase &p, | |
49 | Double_t &DS, Double_t &DSp ) const = 0; | |
50 | ||
51 | //* Transport on dS value along trajectory, output to P,C | |
52 | ||
53 | virtual void Transport( Double_t dS, Double_t P[], Double_t C[] ) const = 0; | |
54 | ||
55 | ||
56 | ||
57 | //* | |
58 | //* INITIALIZATION | |
59 | //* | |
60 | ||
61 | //* Constructor | |
62 | ||
63 | AliKFParticleBase(); | |
64 | ||
65 | //* Destructor | |
66 | ||
e7b09c95 | 67 | virtual ~AliKFParticleBase() { ; } |
68 | ||
69 | //* Initialisation from "cartesian" coordinates ( X Y Z Px Py Pz ) | |
70 | //* Parameters, covariance matrix, charge, and mass hypothesis should be provided | |
71 | ||
72 | void Initialize( const Double_t Param[], const Double_t Cov[], Int_t Charge, Double_t Mass ); | |
f826d409 | 73 | |
74 | //* Initialise covariance matrix and set current parameters to 0.0 | |
75 | ||
76 | void Initialize(); | |
77 | ||
78 | //* Set decay vertex parameters for linearisation | |
79 | ||
80 | void SetVtxGuess( Double_t x, Double_t y, Double_t z ); | |
81 | ||
82 | //* | |
83 | //* ACCESSORS | |
84 | //* | |
85 | ||
86 | //* Simple accessors | |
87 | ||
88 | Double_t GetX () const { return fP[0]; } | |
89 | Double_t GetY () const { return fP[1]; } | |
90 | Double_t GetZ () const { return fP[2]; } | |
91 | Double_t GetPx () const { return fP[3]; } | |
92 | Double_t GetPy () const { return fP[4]; } | |
93 | Double_t GetPz () const { return fP[5]; } | |
94 | Double_t GetE () const { return fP[6]; } | |
95 | Double_t GetS () const { return fP[7]; } | |
96 | Int_t GetQ () const { return fQ; } | |
97 | Double_t GetChi2 () const { return fChi2; } | |
98 | Int_t GetNDF () const { return fNDF; } | |
99 | ||
100 | Double_t GetParameter ( Int_t i ) const { return fP[i]; } | |
101 | Double_t GetCovariance( Int_t i ) const { return fC[i]; } | |
102 | Double_t GetCovariance( Int_t i, Int_t j ) const { return fC[IJ(i,j)]; } | |
103 | ||
104 | //* Accessors with calculations( &value, &estimated sigma ) | |
105 | //* error flag returned (0 means no error during calculations) | |
106 | ||
107 | Int_t GetMomentum ( Double_t &P, Double_t &SigmaP ) const ; | |
108 | Int_t GetMass ( Double_t &M, Double_t &SigmaM ) const ; | |
109 | Int_t GetDecayLength ( Double_t &L, Double_t &SigmaL ) const ; | |
110 | Int_t GetLifeTime ( Double_t &T, Double_t &SigmaT ) const ; | |
111 | ||
112 | //* | |
113 | //* MODIFIERS | |
114 | //* | |
115 | ||
116 | Double_t & X () { return fP[0]; } | |
117 | Double_t & Y () { return fP[1]; } | |
118 | Double_t & Z () { return fP[2]; } | |
119 | Double_t & Px () { return fP[3]; } | |
120 | Double_t & Py () { return fP[4]; } | |
121 | Double_t & Pz () { return fP[5]; } | |
122 | Double_t & E () { return fP[6]; } | |
123 | Double_t & S () { return fP[7]; } | |
124 | Int_t & Q () { return fQ; } | |
125 | Double_t & Chi2 () { return fChi2; } | |
126 | Int_t & NDF () { return fNDF; } | |
127 | ||
128 | Double_t & Parameter ( Int_t i ) { return fP[i]; } | |
129 | Double_t & Covariance( Int_t i ) { return fC[i]; } | |
130 | Double_t & Covariance( Int_t i, Int_t j ) { return fC[IJ(i,j)]; } | |
131 | ||
132 | ||
133 | //* | |
134 | //* CONSTRUCTION OF THE PARTICLE BY ITS DAUGHTERS AND MOTHER | |
135 | //* USING THE KALMAN FILTER METHOD | |
136 | //* | |
137 | ||
138 | ||
139 | //* Simple way to add daughter ex. D0+= Pion; | |
140 | ||
141 | void operator +=( const AliKFParticleBase &Daughter ); | |
142 | ||
143 | //* Add daughter track to the particle | |
144 | ||
145 | void AddDaughter( const AliKFParticleBase &Daughter ); | |
146 | ||
147 | //* Set production vertex | |
148 | ||
149 | void SetProductionVertex( const AliKFParticleBase &Vtx ); | |
150 | ||
e7b09c95 | 151 | //* Set mass constraint |
f826d409 | 152 | |
e7b09c95 | 153 | void SetMassConstraint( Double_t Mass, Double_t SigmaMass = 0 ); |
f826d409 | 154 | |
e7b09c95 | 155 | //* Set no decay length for resonances |
156 | ||
157 | void SetNoDecayLength(); | |
158 | ||
159 | ||
f826d409 | 160 | //* Everything in one go |
161 | ||
162 | void Construct( const AliKFParticleBase *vDaughters[], Int_t NDaughters, | |
163 | const AliKFParticleBase *ProdVtx=0, Double_t Mass=-1 ); | |
164 | ||
165 | ||
166 | //* | |
167 | //* TRANSPORT | |
168 | //* | |
169 | //* ( main transportation parameter is S = SignedPath/Momentum ) | |
170 | //* ( parameters of decay & production vertices are stored locally ) | |
171 | //* | |
172 | ||
173 | ||
174 | //* Transport the particle to its decay vertex | |
175 | ||
176 | void TransportToDecayVertex(); | |
177 | ||
178 | //* Transport the particle to its production vertex | |
179 | ||
180 | void TransportToProductionVertex(); | |
181 | ||
182 | //* Transport the particle on dS parameter (SignedPath/Momentum) | |
183 | ||
184 | void TransportToDS( Double_t dS ); | |
185 | ||
186 | //* Particular extrapolators one can use | |
187 | ||
188 | Double_t GetDStoPointBz( Double_t Bz, const Double_t xyz[] ) const; | |
189 | ||
190 | void GetDStoParticleBz( Double_t Bz, const AliKFParticleBase &p, | |
191 | Double_t &dS, Double_t &dS1 ) const ; | |
192 | ||
193 | // Double_t GetDStoPointCBM( const Double_t xyz[] ) const; | |
194 | ||
195 | void TransportBz( Double_t Bz, Double_t dS, Double_t P[], Double_t C[] ) const; | |
196 | void TransportCBM( Double_t dS, Double_t P[], Double_t C[] ) const; | |
197 | ||
198 | ||
199 | //* | |
200 | //* OTHER UTILITIES | |
201 | //* | |
202 | ||
203 | //* Calculate distance from another object [cm] | |
204 | ||
205 | Double_t GetDistanceFromVertex( const Double_t vtx[] ) const; | |
206 | Double_t GetDistanceFromVertex( const AliKFParticleBase &Vtx ) const; | |
616ffc76 | 207 | Double_t GetDistanceFromParticle( const AliKFParticleBase &p ) const; |
f826d409 | 208 | |
209 | //* Calculate sqrt(Chi2/ndf) deviation from vertex | |
210 | //* v = [xyz], Cv=[Cxx,Cxy,Cyy,Cxz,Cyz,Czz]-covariance matrix | |
211 | ||
212 | Double_t GetDeviationFromVertex( const Double_t v[], | |
213 | const Double_t Cv[]=0 ) const; | |
214 | Double_t GetDeviationFromVertex( const AliKFParticleBase &Vtx ) const; | |
616ffc76 | 215 | Double_t GetDeviationFromParticle( const AliKFParticleBase &p ) const; |
f826d409 | 216 | |
217 | //* Subtract the particle from the vertex | |
218 | ||
219 | void SubtractFromVertex( Double_t v[], Double_t Cv[], | |
220 | Double_t &vChi2, Int_t vNDF ) const ; | |
221 | ||
222 | protected: | |
223 | ||
224 | static Int_t IJ( Int_t i, Int_t j ){ | |
225 | return ( j<=i ) ? i*(i+1)/2+j :j*(j+1)/2+i; | |
226 | } | |
227 | ||
228 | Double_t & Cij( Int_t i, Int_t j ){ return fC[IJ(i,j)]; } | |
229 | ||
230 | void Convert( bool ToProduction ); | |
231 | void TransportLine( Double_t S, Double_t P[], Double_t C[] ) const ; | |
232 | Double_t GetDStoPointLine( const Double_t xyz[] ) const; | |
233 | ||
234 | static void MultQSQt( const Double_t Q[], const Double_t S[], | |
235 | Double_t SOut[] ); | |
236 | ||
616ffc76 | 237 | void GetMeasurement( const Double_t XYZ[], Double_t m[], Double_t V[] ) const ; |
f826d409 | 238 | |
239 | Double_t fP[8]; //* Main particle parameters {X,Y,Z,Px,Py,Pz,E,S[=DecayLength/P]} | |
240 | Double_t fC[36]; //* Low-triangle covariance matrix of fP | |
241 | Int_t fQ; //* Particle charge | |
242 | Int_t fNDF; //* Number of degrees of freedom | |
243 | Double_t fChi2; //* Chi^2 | |
244 | ||
245 | Double_t fSFromDecay; //* Distance from decay vertex to current position | |
246 | ||
247 | Bool_t fAtProductionVertex; //* Flag shows that the particle error along | |
248 | //* its trajectory is taken from production vertex | |
249 | ||
250 | Double_t fVtxGuess[3]; //* Guess for the position of the decay vertex | |
251 | //* ( used for linearisation of equations ) | |
252 | ||
253 | Bool_t fIsLinearized; //* Flag shows that the guess is present | |
254 | ||
255 | ClassDef( AliKFParticleBase, 1 ); | |
256 | }; | |
257 | ||
258 | #endif |