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e23730c7 | 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 | ||
4f679a16 | 16 | /* $Id$ */ |
17 | ||
e23730c7 | 18 | //------------------------------------------------------------------------- |
19 | // Implementation of the cascade vertex class | |
4f679a16 | 20 | // This is part of the Event Summary Data |
21 | // which contains the result of the reconstruction | |
22 | // and is the main set of classes for analaysis | |
e23730c7 | 23 | // Origin: Christian Kuhn, IReS, Strasbourg, christian.kuhn@ires.in2p3.fr |
24 | //------------------------------------------------------------------------- | |
4f679a16 | 25 | |
90e48c0c | 26 | #include <TDatabasePDG.h> |
e23730c7 | 27 | #include <TMath.h> |
28 | ||
5f7789fc | 29 | #include "AliLog.h" |
c7bafca9 | 30 | #include "AliExternalTrackParam.h" |
31 | #include "AliESDv0.h" | |
e23730c7 | 32 | #include "AliESDcascade.h" |
e23730c7 | 33 | |
34 | ClassImp(AliESDcascade) | |
35 | ||
90e48c0c | 36 | AliESDcascade::AliESDcascade() : |
c028b974 | 37 | AliESDv0(), |
90e48c0c | 38 | fPdgCode(kXiMinus), |
39 | fEffMass(TDatabasePDG::Instance()->GetParticle(kXiMinus)->Mass()), | |
c028b974 | 40 | fChi2Xi(1.e+33), |
41 | fDcaXiDaughters(999), | |
bfb36bff | 42 | fBachIdx(-1) |
90e48c0c | 43 | { |
e23730c7 | 44 | //-------------------------------------------------------------------- |
45 | // Default constructor (Xi-) | |
46 | //-------------------------------------------------------------------- | |
bfb36bff | 47 | for (Int_t j=0; j<3; j++) { |
c028b974 | 48 | fPosXi[j]=0.; |
bfb36bff | 49 | fBachMom[j]=0.; |
50 | } | |
51 | ||
c028b974 | 52 | fPosCovXi[0]=1e10; |
53 | fPosCovXi[1]=fPosCovXi[2]=0.; | |
54 | fPosCovXi[3]=1e10; | |
55 | fPosCovXi[4]=0.; | |
56 | fPosCovXi[5]=1e10; | |
bfb36bff | 57 | |
58 | fBachMomCov[0]=1e10; | |
59 | fBachMomCov[1]=fBachMomCov[2]=0.; | |
60 | fBachMomCov[3]=1e10; | |
61 | fBachMomCov[4]=0.; | |
62 | fBachMomCov[5]=1e10; | |
e23730c7 | 63 | } |
64 | ||
c028b974 | 65 | AliESDcascade::~AliESDcascade() { |
66 | } | |
67 | ||
c7bafca9 | 68 | AliESDcascade::AliESDcascade(const AliESDv0 &v, |
69 | const AliExternalTrackParam &t, Int_t i) : | |
c028b974 | 70 | AliESDv0(v), |
c7bafca9 | 71 | fPdgCode(kXiMinus), |
fe12e09c | 72 | fEffMass(-1), |
c028b974 | 73 | fChi2Xi(1.e+33), |
fe12e09c | 74 | fDcaXiDaughters(-1), |
c7bafca9 | 75 | fBachIdx(i) |
76 | { | |
c028b974 | 77 | //--------------------------------------------------------------------------------------------- |
c7bafca9 | 78 | // Main constructor (Xi-) |
c028b974 | 79 | //--------------------------------------------------------------------------------------------- |
c7bafca9 | 80 | |
81 | Double_t r[3]; t.GetXYZ(r); | |
82 | Double_t x1=r[0], y1=r[1], z1=r[2]; // position of the bachelor | |
83 | Double_t p[3]; t.GetPxPyPz(p); | |
84 | Double_t px1=p[0], py1=p[1], pz1=p[2];// momentum of the bachelor track | |
85 | ||
86 | Double_t x2,y2,z2; // position of the V0 | |
87 | v.GetXYZ(x2,y2,z2); | |
88 | Double_t px2,py2,pz2; // momentum of V0 | |
89 | v.GetPxPyPz(px2,py2,pz2); | |
90 | ||
91 | Double_t a2=((x1-x2)*px2+(y1-y2)*py2+(z1-z2)*pz2)/(px2*px2+py2*py2+pz2*pz2); | |
92 | ||
93 | Double_t xm=x2+a2*px2; | |
94 | Double_t ym=y2+a2*py2; | |
95 | Double_t zm=z2+a2*pz2; | |
96 | ||
c028b974 | 97 | //dca between V0 and bachelor |
98 | ||
99 | fDcaXiDaughters = TMath::Sqrt((x1-xm)*(x1-xm) + (y1-ym)*(y1-ym) + (z1-zm)*(z1-zm)); | |
100 | ||
c7bafca9 | 101 | // position of the cascade decay |
102 | ||
c028b974 | 103 | fPosXi[0]=0.5*(x1+xm); fPosXi[1]=0.5*(y1+ym); fPosXi[2]=0.5*(z1+zm); |
c7bafca9 | 104 | |
105 | ||
106 | // invariant mass of the cascade (default is Ximinus) | |
107 | ||
108 | Double_t e1=TMath::Sqrt(0.13957*0.13957 + px1*px1 + py1*py1 + pz1*pz1); | |
109 | Double_t e2=TMath::Sqrt(1.11568*1.11568 + px2*px2 + py2*py2 + pz2*pz2); | |
110 | ||
111 | fEffMass=TMath::Sqrt((e1+e2)*(e1+e2)- | |
112 | (px1+px2)*(px1+px2)-(py1+py2)*(py1+py2)-(pz1+pz2)*(pz1+pz2)); | |
113 | ||
114 | ||
115 | // momenta of the bachelor and the V0 | |
116 | ||
117 | fBachMom[0]=px1; fBachMom[1]=py1; fBachMom[2]=pz1; | |
c7bafca9 | 118 | |
bfb36bff | 119 | //PH Covariance matrices: to be calculated correctly in the future |
c028b974 | 120 | fPosCovXi[0]=1e10; |
121 | fPosCovXi[1]=fPosCovXi[2]=0.; | |
122 | fPosCovXi[3]=1e10; | |
123 | fPosCovXi[4]=0.; | |
124 | fPosCovXi[5]=1e10; | |
bfb36bff | 125 | |
126 | fBachMomCov[0]=1e10; | |
127 | fBachMomCov[1]=fBachMomCov[2]=0.; | |
128 | fBachMomCov[3]=1e10; | |
129 | fBachMomCov[4]=0.; | |
130 | fBachMomCov[5]=1e10; | |
c7bafca9 | 131 | |
c028b974 | 132 | fChi2Xi=7.; |
c7bafca9 | 133 | |
134 | } | |
135 | ||
c028b974 | 136 | AliESDcascade::AliESDcascade(const AliESDcascade& cas) : |
fe12e09c | 137 | AliESDv0(cas), |
138 | fPdgCode(cas.fPdgCode), | |
139 | fEffMass(cas.fEffMass), | |
140 | fChi2Xi(cas.fChi2Xi), | |
141 | fDcaXiDaughters(cas.fDcaXiDaughters), | |
142 | fBachIdx(cas.fBachIdx) | |
c028b974 | 143 | { |
144 | //copy constructor | |
c028b974 | 145 | for (int i=0; i<3; i++) { |
146 | fPosXi[i] = cas.fPosXi[i]; | |
147 | fBachMom[i] = cas.fBachMom[i]; | |
148 | } | |
149 | for (int i=0; i<6; i++) { | |
150 | fPosCovXi[i] = cas.fPosCovXi[i]; | |
151 | fBachMomCov[i] = cas.fBachMomCov[i]; | |
152 | } | |
153 | } | |
154 | ||
e23730c7 | 155 | Double_t AliESDcascade::ChangeMassHypothesis(Double_t &v0q, Int_t code) { |
156 | //-------------------------------------------------------------------- | |
157 | // This function changes the mass hypothesis for this cascade | |
158 | // and returns the "kinematical quality" of this hypothesis | |
159 | // together with the "quality" of associated V0 (argument v0q) | |
160 | //-------------------------------------------------------------------- | |
161 | Double_t nmass=0.13957, pmass=0.93827, ps0=0.101; | |
162 | Double_t bmass=0.13957, mass =1.3213, ps =0.139; | |
163 | ||
164 | fPdgCode=code; | |
165 | ||
166 | switch (code) { | |
167 | case 213: | |
168 | bmass=0.93827; | |
169 | break; | |
170 | case kXiMinus: | |
171 | break; | |
172 | case kXiPlusBar: | |
173 | nmass=0.93827; pmass=0.13957; | |
174 | break; | |
175 | case kOmegaMinus: | |
176 | bmass=0.49368; mass=1.67245; ps=0.211; | |
177 | break; | |
178 | case kOmegaPlusBar: | |
179 | nmass=0.93827; pmass=0.13957; | |
180 | bmass=0.49368; mass=1.67245; ps=0.211; | |
181 | break; | |
182 | default: | |
5f7789fc | 183 | AliError("Invalide PDG code ! Assuming XiMinus's..."); |
e23730c7 | 184 | fPdgCode=kXiMinus; |
185 | break; | |
186 | } | |
187 | ||
c028b974 | 188 | Double_t pxn=fNmom[0], pyn=fNmom[1], pzn=fNmom[2]; |
189 | Double_t pxp=fPmom[0], pyp=fPmom[1], pzp=fPmom[2]; | |
e23730c7 | 190 | Double_t px0=pxn+pxp, py0=pyn+pyp, pz0=pzn+pzp; |
191 | Double_t p0=TMath::Sqrt(px0*px0 + py0*py0 + pz0*pz0); | |
192 | ||
193 | Double_t e0=TMath::Sqrt(1.11568*1.11568 + p0*p0); | |
194 | Double_t beta0=p0/e0; | |
195 | Double_t pln=(pxn*px0 + pyn*py0 + pzn*pz0)/p0; | |
196 | Double_t plp=(pxp*px0 + pyp*py0 + pzp*pz0)/p0; | |
197 | Double_t pt2=pxp*pxp + pyp*pyp + pzp*pzp - plp*plp; | |
198 | ||
199 | Double_t a=(plp-pln)/(plp+pln); | |
200 | a -= (pmass*pmass-nmass*nmass)/(1.11568*1.11568); | |
201 | a = 0.25*beta0*beta0*1.11568*1.11568*a*a + pt2; | |
202 | ||
203 | ||
204 | v0q=a - ps0*ps0; | |
205 | ||
206 | ||
207 | Double_t pxb=fBachMom[0], pyb=fBachMom[1], pzb=fBachMom[2]; | |
208 | ||
209 | Double_t eb=TMath::Sqrt(bmass*bmass + pxb*pxb + pyb*pyb + pzb*pzb); | |
210 | Double_t pxl=px0+pxb, pyl=py0+pyb, pzl=pz0+pzb; | |
211 | Double_t pl=TMath::Sqrt(pxl*pxl + pyl*pyl + pzl*pzl); | |
212 | ||
213 | fEffMass=TMath::Sqrt((e0+eb)*(e0+eb) - pl*pl); | |
214 | ||
215 | Double_t beta=pl/(e0+eb); | |
216 | Double_t pl0=(px0*pxl + py0*pyl + pz0*pzl)/pl; | |
217 | Double_t plb=(pxb*pxl + pyb*pyl + pzb*pzl)/pl; | |
218 | pt2=p0*p0 - pl0*pl0; | |
219 | ||
220 | a=(pl0-plb)/(pl0+plb); | |
221 | a -= (1.11568*1.11568-bmass*bmass)/(mass*mass); | |
222 | a = 0.25*beta*beta*mass*mass*a*a + pt2; | |
223 | ||
224 | return (a - ps*ps); | |
225 | } | |
226 | ||
227 | void | |
228 | AliESDcascade::GetPxPyPz(Double_t &px, Double_t &py, Double_t &pz) const { | |
229 | //-------------------------------------------------------------------- | |
230 | // This function returns the cascade momentum (global) | |
231 | //-------------------------------------------------------------------- | |
c028b974 | 232 | px=fNmom[0]+fPmom[0]+fBachMom[0]; |
233 | py=fNmom[1]+fPmom[1]+fBachMom[1]; | |
234 | pz=fNmom[2]+fPmom[2]+fBachMom[2]; | |
e23730c7 | 235 | } |
236 | ||
c028b974 | 237 | void AliESDcascade::GetXYZcascade(Double_t &x, Double_t &y, Double_t &z) const { |
e23730c7 | 238 | //-------------------------------------------------------------------- |
239 | // This function returns cascade position (global) | |
240 | //-------------------------------------------------------------------- | |
c028b974 | 241 | x=fPosXi[0]; |
242 | y=fPosXi[1]; | |
243 | z=fPosXi[2]; | |
e23730c7 | 244 | } |
245 | ||
c028b974 | 246 | Double_t AliESDcascade::GetDcascade(Double_t x0, Double_t y0, Double_t z0) const { |
e23730c7 | 247 | //-------------------------------------------------------------------- |
248 | // This function returns the cascade impact parameter | |
249 | //-------------------------------------------------------------------- | |
250 | ||
c028b974 | 251 | Double_t x=fPosXi[0],y=fPosXi[1],z=fPosXi[2]; |
252 | Double_t px=fNmom[0]+fPmom[0]+fBachMom[0]; | |
253 | Double_t py=fNmom[1]+fPmom[1]+fBachMom[1]; | |
254 | Double_t pz=fNmom[2]+fPmom[2]+fBachMom[2]; | |
e23730c7 | 255 | |
256 | Double_t dx=(y0-y)*pz - (z0-z)*py; | |
257 | Double_t dy=(x0-x)*pz - (z0-z)*px; | |
258 | Double_t dz=(x0-x)*py - (y0-y)*px; | |
259 | Double_t d=TMath::Sqrt((dx*dx+dy*dy+dz*dz)/(px*px+py*py+pz*pz)); | |
260 | ||
261 | return d; | |
262 | } | |
263 | ||
c028b974 | 264 | Double_t AliESDcascade::GetCascadeCosineOfPointingAngle(Double_t& refPointX, Double_t& refPointY, Double_t& refPointZ) const { |
265 | // calculates the pointing angle of the cascade wrt a reference point | |
266 | ||
267 | Double_t momCas[3]; //momentum of the cascade | |
268 | GetPxPyPz(momCas[0],momCas[1],momCas[2]); | |
269 | ||
270 | Double_t deltaPos[3]; //vector between the reference point and the cascade vertex | |
271 | deltaPos[0] = fPosXi[0] - refPointX; | |
272 | deltaPos[1] = fPosXi[1] - refPointY; | |
273 | deltaPos[2] = fPosXi[2] - refPointZ; | |
274 | ||
275 | Double_t momCas2 = momCas[0]*momCas[0] + momCas[1]*momCas[1] + momCas[2]*momCas[2]; | |
276 | Double_t deltaPos2 = deltaPos[0]*deltaPos[0] + deltaPos[1]*deltaPos[1] + deltaPos[2]*deltaPos[2]; | |
277 | ||
278 | Double_t cosinePointingAngle = (deltaPos[0]*momCas[0] + | |
279 | deltaPos[1]*momCas[1] + | |
280 | deltaPos[2]*momCas[2] ) / | |
281 | TMath::Sqrt(momCas2 * deltaPos2); | |
282 | ||
283 | return cosinePointingAngle; | |
284 | } | |
074f017b | 285 | |
286 | void AliESDcascade::GetPosCovXi(Double_t cov[6]) const { | |
287 | ||
288 | for (Int_t i=0; i<6; ++i) cov[i] = fPosCovXi[i]; | |
289 | } |