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1 | /************************************************************************** | |
2 | * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. * | |
3 | * * | |
4 | * Author: The ALICE Off-line Project. * | |
5 | * Contributors are mentioned in the code where appropriate. * | |
6 | * * | |
7 | * Permission to use, copy, modify and distribute this software and its * | |
8 | * documentation strictly for non-commercial purposes is hereby granted * | |
9 | * without fee, provided that the above copyright notice appears in all * | |
10 | * copies and that both the copyright notice and this permission notice * | |
11 | * appear in the supporting documentation. The authors make no claims * | |
12 | * about the suitability of this software for any purpose. It is * | |
13 | * provided "as is" without express or implied warranty. * | |
14 | **************************************************************************/ | |
15 | ||
16 | //////////////////////////////////////////////////////////////////////////////// | |
17 | // | |
18 | // This class implements a candidate resonance. It has two pointers to its | |
19 | // two candidate daughters, whose 4-momenta are combined to obtain the mother | |
20 | // invariant mass and other kinematical quantities. | |
21 | // This class contains also some methods used to compute kinematical relations | |
22 | // between the candidate resonance and other particles. | |
23 | // | |
24 | // authors: A. Pulvirenti (alberto.pulvirenti@ct.infn.it) | |
25 | // M. Vala (martin.vala@cern.ch) | |
26 | // | |
27 | //////////////////////////////////////////////////////////////////////////////// | |
28 | ||
29 | #include <Riostream.h> | |
30 | #include <TVector3.h> | |
31 | ||
32 | #include "AliAODMCParticle.h" | |
33 | #include "AliMCParticle.h" | |
34 | #include "AliRsnEvent.h" | |
35 | ||
36 | #include "AliRsnMother.h" | |
37 | ||
38 | ClassImp(AliRsnMother) | |
39 | ||
40 | //__________________________________________________________________________________________________ | |
41 | AliRsnMother::AliRsnMother(const AliRsnMother &obj) : | |
42 | TObject(obj), | |
43 | fRefEvent(obj.fRefEvent), | |
44 | fSum(obj.fSum), | |
45 | fSumMC(obj.fSumMC), | |
46 | fRef(obj.fRef), | |
47 | fRefMC(obj.fRefMC) | |
48 | { | |
49 | // | |
50 | // Copy constructor. | |
51 | // Does not duplicate pointers. | |
52 | // | |
53 | ||
54 | Int_t i; | |
55 | for (i = 0; i < 2; i++) fDaughter[i] = obj.fDaughter[i]; | |
56 | } | |
57 | ||
58 | //__________________________________________________________________________________________________ | |
59 | AliRsnMother& AliRsnMother::operator=(const AliRsnMother &obj) | |
60 | { | |
61 | // | |
62 | // Assignment operator. | |
63 | // Does not duplicate pointers. | |
64 | // | |
65 | ||
66 | fSum = obj.fSum; | |
67 | fRef = obj.fRef; | |
68 | fSumMC = obj.fSumMC; | |
69 | fRefMC = obj.fRefMC; | |
70 | fRefEvent = obj.fRefEvent; | |
71 | fDaughter[0] = obj.fDaughter[0]; | |
72 | fDaughter[1] = obj.fDaughter[1]; | |
73 | ||
74 | return (*this); | |
75 | } | |
76 | ||
77 | //__________________________________________________________________________________________________ | |
78 | AliRsnMother::~AliRsnMother() | |
79 | { | |
80 | // | |
81 | // Desctructor. | |
82 | // Does nothing, since pointers are not created in this class. | |
83 | // | |
84 | } | |
85 | ||
86 | //_______________________________________________________________________________________________________________________ | |
87 | void AliRsnMother::Reset() | |
88 | { | |
89 | // | |
90 | // Resets the mother, zeroing all data members. | |
91 | // | |
92 | ||
93 | Int_t i; | |
94 | for (i = 0; i < 2; i++) fDaughter[i] = 0x0; | |
95 | fRefEvent = 0x0; | |
96 | fSum.SetXYZM(0.0, 0.0, 0.0, 0.0); | |
97 | fRef.SetXYZM(0.0, 0.0, 0.0, 0.0); | |
98 | } | |
99 | ||
100 | //__________________________________________________________________________________________________ | |
101 | Int_t AliRsnMother::CommonMother() const | |
102 | { | |
103 | // | |
104 | // If MC info is available, checks if the two tracks in the pair have the same mother. | |
105 | // If the mother label is the same, the function returns the PDG code of mother, | |
106 | // otherwise it returns 0. | |
107 | // The two arguments passed by reference contain the GEANT labels of the mother | |
108 | // of the two particles to which the two daughters point. This is for being able | |
109 | // to check if they are really coming from a resonance (indexes >= 0) or not. | |
110 | // | |
111 | ||
112 | Int_t m1 = fDaughter[0]->GetMother(); | |
113 | Int_t m2 = fDaughter[1]->GetMother(); | |
114 | Int_t out = 0; | |
115 | ||
116 | // a true mother makes sense only if both mothers | |
117 | // are not-negative and equal | |
118 | if (m1 >= 0 && m2 >= 0 && m1 == m2) { | |
119 | out = TMath::Abs(fDaughter[0]->GetMotherPDG()); | |
120 | AliDebugClass(1, Form("Mothers are: %d %d --> EQUAL (PDG = %d)", m1, m2, out)); | |
121 | } | |
122 | ||
123 | return out; | |
124 | } | |
125 | ||
126 | //__________________________________________________________________________________________________ | |
127 | Double_t AliRsnMother::AngleToLeading(Bool_t &success) | |
128 | { | |
129 | // | |
130 | // Compute the angle betwee this and the leading particls | |
131 | // of the reference event (if this was set properly). | |
132 | // In case one of the two daughters is the leading, return | |
133 | // a meaningless value, in order to skip this pair. | |
134 | // if second argument is kTRUE, use MC values. | |
135 | // | |
136 | ||
137 | if (!fRefEvent) { | |
138 | success = kFALSE; | |
139 | return -99.0; | |
140 | } | |
141 | ||
142 | Int_t id1 = fDaughter[0]->GetID(); | |
143 | Int_t id2 = fDaughter[1]->GetID(); | |
144 | Int_t idL = fRefEvent->GetLeadingIndex(); | |
145 | ||
146 | if (id1 == idL || id2 == idL) { | |
147 | success = kFALSE; | |
148 | return -99.0; | |
149 | } | |
150 | ||
151 | AliRsnDaughter leading = fRefEvent->GetDaughter(idL, kFALSE); | |
152 | AliVParticle *ref = leading.GetRef(); | |
153 | Double_t angle = ref->Phi() - fSum.Phi(); | |
154 | ||
155 | //return angle w.r.t. leading particle in the range -pi/2, 3/2pi | |
156 | while (angle >= 1.5 * TMath::Pi()) angle -= 2 * TMath::Pi(); | |
157 | while (angle < -0.5 * TMath::Pi()) angle += 2 * TMath::Pi(); | |
158 | success = kTRUE; | |
159 | ||
160 | return angle; | |
161 | } | |
162 | ||
163 | //__________________________________________________________________________________________________ | |
164 | void AliRsnMother::ComputeSum(Double_t mass0, Double_t mass1, Double_t motherMass) | |
165 | { | |
166 | // | |
167 | // Sets the masses for the 4-momenta of the daughters and then | |
168 | // sums them, taking into account that the space part is set to | |
169 | // each of them when the reference object is set (see AliRsnDaughter::SetRef) | |
170 | // | |
171 | ||
172 | fDaughter[0]->FillP(mass0); | |
173 | fDaughter[1]->FillP(mass1); | |
174 | ||
175 | // sum | |
176 | fSum = fDaughter[0]->Prec() + fDaughter[1]->Prec(); | |
177 | fSumMC = fDaughter[0]->Psim() + fDaughter[1]->Psim(); | |
178 | ||
179 | // reference | |
180 | fRef.SetXYZM(fSum.X(), fSum.Y(), fSum.Z(), motherMass); | |
181 | fRefMC.SetXYZM(fSumMC.X(), fSumMC.Y(), fSumMC.Z(), motherMass); | |
182 | } | |
183 | ||
184 | //__________________________________________________________________________________________________ | |
185 | Double_t AliRsnMother::CosThetaStar(Bool_t first, Bool_t useMC) | |
186 | { | |
187 | // | |
188 | // Computes the cosine of theta*, which is the angle of one of the daughters | |
189 | // with respect to the total momentum of the resonance, in its rest frame. | |
190 | // The arguments are needed to choose which of the daughters one want to use | |
191 | // and if reconstructed or MC momentum must be used. | |
192 | // [Contribution from Z. Feckova] | |
193 | // | |
194 | ||
195 | TLorentzVector &mother = Sum(useMC); | |
196 | TLorentzVector &daughter0 = (first ? fDaughter[0]->P(useMC) : fDaughter[1]->P(useMC)); | |
197 | TLorentzVector &daughter1 = (first ? fDaughter[1]->P(useMC) : fDaughter[0]->P(useMC)); | |
198 | TVector3 momentumM(mother.Vect()); | |
199 | TVector3 normal(mother.Y() / momentumM.Mag(), -mother.X() / momentumM.Mag(), 0.0); | |
200 | ||
201 | // Computes first the invariant mass of the mother | |
202 | Double_t mass0 = fDaughter[0]->P(useMC).M(); | |
203 | Double_t mass1 = fDaughter[1]->P(useMC).M(); | |
204 | Double_t p0 = daughter0.Vect().Mag(); | |
205 | Double_t p1 = daughter1.Vect().Mag(); | |
206 | Double_t E0 = TMath::Sqrt(mass0 * mass0 + p0 * p0); | |
207 | Double_t E1 = TMath::Sqrt(mass1 * mass1 + p1 * p1); | |
208 | Double_t MotherMass = TMath::Sqrt((E0 + E1) * (E0 + E1) - (p0 * p0 + 2.0 * daughter0.Vect().Dot(daughter1.Vect()) + p1 * p1)); | |
209 | MotherMass = fSum.M(); | |
210 | ||
211 | // Computes components of beta | |
212 | Double_t betaX = -mother.X() / mother.E(); | |
213 | Double_t betaY = -mother.Y() / mother.E(); | |
214 | Double_t betaZ = -mother.Z() / mother.E(); | |
215 | ||
216 | // Computes Lorentz transformation of the momentum of the first daughter | |
217 | // into the rest frame of the mother and theta* | |
218 | daughter0.Boost(betaX, betaY, betaZ); | |
219 | TVector3 momentumD = daughter0.Vect(); | |
220 | ||
221 | Double_t cosThetaStar = normal.Dot(momentumD) / momentumD.Mag(); | |
222 | ||
223 | return cosThetaStar; | |
224 | } | |
225 | ||
226 | //__________________________________________________________________________________________________ | |
227 | void AliRsnMother::PrintInfo(const Option_t * /*option*/) const | |
228 | { | |
229 | // | |
230 | // Print some info of the pair. | |
231 | // The options are passed to the AliRsnDaughter::Print() method | |
232 | // | |
233 | ||
234 | AliInfo("======== BEGIN PAIR INFO ==========="); | |
235 | AliInfo("Track #1"); | |
236 | fDaughter[0]->Print(); | |
237 | AliInfo("Track #2"); | |
238 | fDaughter[1]->Print(); | |
239 | AliInfo("========= END PAIR INFO ==========="); | |
240 | } | |
241 | ||
242 | //__________________________________________________________________________________________________ | |
243 | Bool_t AliRsnMother::CheckPair(Bool_t checkMC) const | |
244 | { | |
245 | // | |
246 | // Checks that the pair is well initialized: | |
247 | // - both daughters are good pointers | |
248 | // - if MC is required, both daughters have a MC reference | |
249 | // | |
250 | ||
251 | if (!fDaughter[0] || !fDaughter[1]) { | |
252 | AliError("One of the two tracks is NULL in this pair!"); | |
253 | return kFALSE; | |
254 | } | |
255 | ||
256 | if (checkMC) { | |
257 | if (fDaughter[0]->GetRefMC() == 0x0 || fDaughter[1]->GetRefMC() == 0x0) { | |
258 | AliError("Required MC info but not all MC refs are available"); | |
259 | return kFALSE; | |
260 | } | |
261 | } | |
262 | ||
263 | return kTRUE; | |
264 | } |