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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 |
3e27a419 | 24 | // Modified by: Antonin Maire,IPHC, Antonin.Maire@ires.in2p3.fr |
25 | // and Boris Hippolyte,IPHC, hippolyt@in2p3.fr | |
e23730c7 | 26 | //------------------------------------------------------------------------- |
4f679a16 | 27 | |
90e48c0c | 28 | #include <TDatabasePDG.h> |
e23730c7 | 29 | #include <TMath.h> |
3e27a419 | 30 | #include <TVector3.h> |
e23730c7 | 31 | |
32 | #include "AliESDcascade.h" | |
97135b34 | 33 | #include "AliLog.h" |
e23730c7 | 34 | |
35 | ClassImp(AliESDcascade) | |
36 | ||
90e48c0c | 37 | AliESDcascade::AliESDcascade() : |
c028b974 | 38 | AliESDv0(), |
8668c148 | 39 | fEffMassXi(TDatabasePDG::Instance()->GetParticle(kXiMinus)->Mass()), |
562dd0b4 | 40 | fChi2Xi(1024), |
41 | fDcaXiDaughters(1024), | |
42 | fPdgCodeXi(kXiMinus), | |
bfb36bff | 43 | fBachIdx(-1) |
90e48c0c | 44 | { |
e23730c7 | 45 | //-------------------------------------------------------------------- |
46 | // Default constructor (Xi-) | |
47 | //-------------------------------------------------------------------- | |
bfb36bff | 48 | for (Int_t j=0; j<3; j++) { |
c028b974 | 49 | fPosXi[j]=0.; |
bfb36bff | 50 | fBachMom[j]=0.; |
51 | } | |
52 | ||
562dd0b4 | 53 | fPosCovXi[0]=1024; |
c028b974 | 54 | fPosCovXi[1]=fPosCovXi[2]=0.; |
562dd0b4 | 55 | fPosCovXi[3]=1024; |
c028b974 | 56 | fPosCovXi[4]=0.; |
562dd0b4 | 57 | fPosCovXi[5]=1024; |
bfb36bff | 58 | |
562dd0b4 | 59 | fBachMomCov[0]=1024; |
bfb36bff | 60 | fBachMomCov[1]=fBachMomCov[2]=0.; |
562dd0b4 | 61 | fBachMomCov[3]=1024; |
bfb36bff | 62 | fBachMomCov[4]=0.; |
562dd0b4 | 63 | fBachMomCov[5]=1024; |
e23730c7 | 64 | } |
65 | ||
3e27a419 | 66 | AliESDcascade::AliESDcascade(const AliESDcascade& cas) : |
67 | AliESDv0(cas), | |
68 | fEffMassXi(cas.fEffMassXi), | |
69 | fChi2Xi(cas.fChi2Xi), | |
70 | fDcaXiDaughters(cas.fDcaXiDaughters), | |
71 | fPdgCodeXi(cas.fPdgCodeXi), | |
72 | fBachIdx(cas.fBachIdx) | |
73 | { | |
74 | //-------------------------------------------------------------------- | |
75 | // The copy constructor | |
76 | //-------------------------------------------------------------------- | |
77 | for (int i=0; i<3; i++) { | |
78 | fPosXi[i] = cas.fPosXi[i]; | |
79 | fBachMom[i] = cas.fBachMom[i]; | |
80 | } | |
81 | for (int i=0; i<6; i++) { | |
82 | fPosCovXi[i] = cas.fPosCovXi[i]; | |
83 | fBachMomCov[i] = cas.fBachMomCov[i]; | |
84 | } | |
c028b974 | 85 | } |
86 | ||
c7bafca9 | 87 | AliESDcascade::AliESDcascade(const AliESDv0 &v, |
88 | const AliExternalTrackParam &t, Int_t i) : | |
c028b974 | 89 | AliESDv0(v), |
562dd0b4 | 90 | fEffMassXi(TDatabasePDG::Instance()->GetParticle(kXiMinus)->Mass()), |
91 | fChi2Xi(1024), | |
92 | fDcaXiDaughters(1024), | |
8668c148 | 93 | fPdgCodeXi(kXiMinus), |
c7bafca9 | 94 | fBachIdx(i) |
95 | { | |
3e27a419 | 96 | //-------------------------------------------------------------------- |
c7bafca9 | 97 | // Main constructor (Xi-) |
3e27a419 | 98 | //-------------------------------------------------------------------- |
c7bafca9 | 99 | |
100 | Double_t r[3]; t.GetXYZ(r); | |
101 | Double_t x1=r[0], y1=r[1], z1=r[2]; // position of the bachelor | |
102 | Double_t p[3]; t.GetPxPyPz(p); | |
103 | Double_t px1=p[0], py1=p[1], pz1=p[2];// momentum of the bachelor track | |
104 | ||
105 | Double_t x2,y2,z2; // position of the V0 | |
106 | v.GetXYZ(x2,y2,z2); | |
107 | Double_t px2,py2,pz2; // momentum of V0 | |
108 | v.GetPxPyPz(px2,py2,pz2); | |
109 | ||
110 | Double_t a2=((x1-x2)*px2+(y1-y2)*py2+(z1-z2)*pz2)/(px2*px2+py2*py2+pz2*pz2); | |
111 | ||
112 | Double_t xm=x2+a2*px2; | |
113 | Double_t ym=y2+a2*py2; | |
114 | Double_t zm=z2+a2*pz2; | |
115 | ||
116 | // position of the cascade decay | |
117 | ||
c028b974 | 118 | fPosXi[0]=0.5*(x1+xm); fPosXi[1]=0.5*(y1+ym); fPosXi[2]=0.5*(z1+zm); |
c7bafca9 | 119 | |
120 | ||
121 | // invariant mass of the cascade (default is Ximinus) | |
122 | ||
123 | Double_t e1=TMath::Sqrt(0.13957*0.13957 + px1*px1 + py1*py1 + pz1*pz1); | |
124 | Double_t e2=TMath::Sqrt(1.11568*1.11568 + px2*px2 + py2*py2 + pz2*pz2); | |
125 | ||
8668c148 | 126 | fEffMassXi=TMath::Sqrt((e1+e2)*(e1+e2)- |
c7bafca9 | 127 | (px1+px2)*(px1+px2)-(py1+py2)*(py1+py2)-(pz1+pz2)*(pz1+pz2)); |
128 | ||
129 | ||
130 | // momenta of the bachelor and the V0 | |
131 | ||
132 | fBachMom[0]=px1; fBachMom[1]=py1; fBachMom[2]=pz1; | |
c7bafca9 | 133 | |
d8e40f75 | 134 | // Setting pdg code and fixing charge |
135 | if (t.Charge()<0) | |
136 | fPdgCodeXi = kXiMinus; | |
137 | else | |
138 | fPdgCodeXi = kXiPlusBar; | |
139 | ||
bfb36bff | 140 | //PH Covariance matrices: to be calculated correctly in the future |
562dd0b4 | 141 | fPosCovXi[0]=1024; |
c028b974 | 142 | fPosCovXi[1]=fPosCovXi[2]=0.; |
562dd0b4 | 143 | fPosCovXi[3]=1024; |
c028b974 | 144 | fPosCovXi[4]=0.; |
562dd0b4 | 145 | fPosCovXi[5]=1024; |
bfb36bff | 146 | |
562dd0b4 | 147 | fBachMomCov[0]=1024; |
bfb36bff | 148 | fBachMomCov[1]=fBachMomCov[2]=0.; |
562dd0b4 | 149 | fBachMomCov[3]=1024; |
bfb36bff | 150 | fBachMomCov[4]=0.; |
562dd0b4 | 151 | fBachMomCov[5]=1024; |
c7bafca9 | 152 | |
d8e40f75 | 153 | fChi2Xi=1024.; |
c7bafca9 | 154 | |
155 | } | |
156 | ||
3e27a419 | 157 | AliESDcascade& AliESDcascade::operator=(const AliESDcascade& cas) |
c028b974 | 158 | { |
3e27a419 | 159 | //-------------------------------------------------------------------- |
160 | // The assignment operator | |
161 | //-------------------------------------------------------------------- | |
732a24fe | 162 | |
163 | if(this==&cas) return *this; | |
164 | AliESDv0::operator=(cas); | |
165 | ||
166 | fEffMassXi = cas.fEffMassXi; | |
167 | fChi2Xi = cas.fChi2Xi; | |
168 | fDcaXiDaughters = cas.fDcaXiDaughters; | |
169 | fPdgCodeXi = cas.fPdgCodeXi; | |
170 | fBachIdx = cas.fBachIdx; | |
171 | for (int i=0; i<3; i++) { | |
172 | fPosXi[i] = cas.fPosXi[i]; | |
173 | fBachMom[i] = cas.fBachMom[i]; | |
174 | } | |
175 | for (int i=0; i<6; i++) { | |
176 | fPosCovXi[i] = cas.fPosCovXi[i]; | |
177 | fBachMomCov[i] = cas.fBachMomCov[i]; | |
178 | } | |
179 | return *this; | |
180 | } | |
181 | ||
182 | void AliESDcascade::Copy(TObject &obj) const { | |
183 | ||
184 | // this overwrites the virtual TOBject::Copy() | |
185 | // to allow run time copying without casting | |
186 | // in AliESDEvent | |
187 | ||
188 | if(this==&obj)return; | |
189 | AliESDcascade *robj = dynamic_cast<AliESDcascade*>(&obj); | |
190 | if(!robj)return; // not an AliESDcascade | |
191 | *robj = *this; | |
3e27a419 | 192 | } |
732a24fe | 193 | |
3e27a419 | 194 | AliESDcascade::~AliESDcascade() { |
195 | //-------------------------------------------------------------------- | |
196 | // Empty destructor | |
197 | //-------------------------------------------------------------------- | |
732a24fe | 198 | } |
199 | ||
646c9704 | 200 | // Start with AliVParticle functions |
201 | Double_t AliESDcascade::E() const { | |
202 | //-------------------------------------------------------------------- | |
203 | // This gives the energy assuming the ChangeMassHypothesis was called | |
204 | //-------------------------------------------------------------------- | |
3e27a419 | 205 | return E(fPdgCodeXi); |
206 | } | |
207 | ||
208 | Double_t AliESDcascade::Y() const { | |
209 | //-------------------------------------------------------------------- | |
210 | // This gives the energy assuming the ChangeMassHypothesis was called | |
211 | //-------------------------------------------------------------------- | |
212 | return Y(fPdgCodeXi); | |
213 | } | |
214 | ||
215 | // Then extend AliVParticle functions | |
216 | Double_t AliESDcascade::E(Int_t pdg) const { | |
217 | //-------------------------------------------------------------------- | |
218 | // This gives the energy with the particle hypothesis as argument | |
219 | //-------------------------------------------------------------------- | |
220 | Double_t mass = TDatabasePDG::Instance()->GetParticle(pdg)->Mass(); | |
646c9704 | 221 | return TMath::Sqrt(mass*mass+P()*P()); |
222 | } | |
223 | ||
3e27a419 | 224 | Double_t AliESDcascade::Y(Int_t pdg) const { |
225 | //-------------------------------------------------------------------- | |
226 | // This gives the rapidity with the particle hypothesis as argument | |
227 | //-------------------------------------------------------------------- | |
228 | return 0.5*TMath::Log((E(pdg)+Pz())/(E(pdg)-Pz()+1.e-13)); | |
229 | } | |
230 | ||
231 | // Now the functions for analysis consistency | |
232 | Double_t AliESDcascade::RapXi() const { | |
233 | //-------------------------------------------------------------------- | |
234 | // This gives the pseudorapidity assuming a (Anti) Xi particle | |
235 | //-------------------------------------------------------------------- | |
236 | return Y(kXiMinus); | |
237 | } | |
238 | ||
239 | Double_t AliESDcascade::RapOmega() const { | |
240 | //-------------------------------------------------------------------- | |
241 | // This gives the pseudorapidity assuming a (Anti) Omega particle | |
242 | //-------------------------------------------------------------------- | |
243 | return Y(kOmegaMinus); | |
244 | } | |
245 | ||
246 | Double_t AliESDcascade::AlphaXi() const { | |
247 | //-------------------------------------------------------------------- | |
248 | // This gives the Armenteros-Podolanski alpha | |
249 | //-------------------------------------------------------------------- | |
250 | TVector3 momBach(fBachMom[0],fBachMom[1],fBachMom[2]); | |
251 | TVector3 momV0(fNmom[0]+fPmom[0],fNmom[1]+fPmom[1],fNmom[2]+fPmom[2]); | |
252 | TVector3 momTot(Px(),Py(),Pz()); | |
253 | ||
97135b34 | 254 | Double_t lQlBach = momBach.Dot(momTot)/momTot.Mag(); |
255 | Double_t lQlV0 = momV0.Dot(momTot)/momTot.Mag(); | |
3e27a419 | 256 | |
97135b34 | 257 | return 1.-2./(1.+lQlBach/lQlV0); |
3e27a419 | 258 | } |
259 | ||
260 | Double_t AliESDcascade::PtArmXi() const { | |
261 | //-------------------------------------------------------------------- | |
262 | // This gives the Armenteros-Podolanski ptarm | |
263 | //-------------------------------------------------------------------- | |
264 | TVector3 momBach(fBachMom[0],fBachMom[1],fBachMom[2]); | |
265 | TVector3 momTot(Px(),Py(),Pz()); | |
266 | ||
267 | return momBach.Perp(momTot); | |
268 | } | |
269 | ||
646c9704 | 270 | // Then the older functions |
e23730c7 | 271 | Double_t AliESDcascade::ChangeMassHypothesis(Double_t &v0q, Int_t code) { |
272 | //-------------------------------------------------------------------- | |
273 | // This function changes the mass hypothesis for this cascade | |
274 | // and returns the "kinematical quality" of this hypothesis | |
275 | // together with the "quality" of associated V0 (argument v0q) | |
276 | //-------------------------------------------------------------------- | |
277 | Double_t nmass=0.13957, pmass=0.93827, ps0=0.101; | |
278 | Double_t bmass=0.13957, mass =1.3213, ps =0.139; | |
279 | ||
d8e40f75 | 280 | if (Charge()*code<0) |
281 | fPdgCodeXi = code; | |
282 | else { | |
283 | AliWarning("Chosen PDG code does not match the sign of the bachelor... Corrected !!"); | |
284 | fPdgCodeXi = -code; | |
285 | } | |
e23730c7 | 286 | |
d8e40f75 | 287 | switch (fPdgCodeXi) { |
e23730c7 | 288 | case kXiMinus: |
289 | break; | |
290 | case kXiPlusBar: | |
291 | nmass=0.93827; pmass=0.13957; | |
292 | break; | |
293 | case kOmegaMinus: | |
294 | bmass=0.49368; mass=1.67245; ps=0.211; | |
295 | break; | |
296 | case kOmegaPlusBar: | |
297 | nmass=0.93827; pmass=0.13957; | |
298 | bmass=0.49368; mass=1.67245; ps=0.211; | |
299 | break; | |
300 | default: | |
d8e40f75 | 301 | AliError("Invalide PDG code ! Assuming a Xi particle..."); |
302 | if (Charge()<0) { | |
303 | fPdgCodeXi=kXiMinus; | |
304 | } | |
305 | else { | |
306 | fPdgCodeXi=kXiPlusBar; | |
307 | nmass=0.93827; pmass=0.13957; | |
308 | } | |
e23730c7 | 309 | break; |
310 | } | |
311 | ||
c028b974 | 312 | Double_t pxn=fNmom[0], pyn=fNmom[1], pzn=fNmom[2]; |
313 | Double_t pxp=fPmom[0], pyp=fPmom[1], pzp=fPmom[2]; | |
8668c148 | 314 | |
e23730c7 | 315 | Double_t px0=pxn+pxp, py0=pyn+pyp, pz0=pzn+pzp; |
316 | Double_t p0=TMath::Sqrt(px0*px0 + py0*py0 + pz0*pz0); | |
317 | ||
318 | Double_t e0=TMath::Sqrt(1.11568*1.11568 + p0*p0); | |
319 | Double_t beta0=p0/e0; | |
320 | Double_t pln=(pxn*px0 + pyn*py0 + pzn*pz0)/p0; | |
321 | Double_t plp=(pxp*px0 + pyp*py0 + pzp*pz0)/p0; | |
322 | Double_t pt2=pxp*pxp + pyp*pyp + pzp*pzp - plp*plp; | |
323 | ||
324 | Double_t a=(plp-pln)/(plp+pln); | |
325 | a -= (pmass*pmass-nmass*nmass)/(1.11568*1.11568); | |
326 | a = 0.25*beta0*beta0*1.11568*1.11568*a*a + pt2; | |
327 | ||
328 | ||
329 | v0q=a - ps0*ps0; | |
330 | ||
331 | ||
332 | Double_t pxb=fBachMom[0], pyb=fBachMom[1], pzb=fBachMom[2]; | |
333 | ||
334 | Double_t eb=TMath::Sqrt(bmass*bmass + pxb*pxb + pyb*pyb + pzb*pzb); | |
335 | Double_t pxl=px0+pxb, pyl=py0+pyb, pzl=pz0+pzb; | |
336 | Double_t pl=TMath::Sqrt(pxl*pxl + pyl*pyl + pzl*pzl); | |
337 | ||
60e55aee | 338 | fEffMassXi=TMath::Sqrt(((e0+eb)-pl)*((e0+eb)+pl)); |
e23730c7 | 339 | |
340 | Double_t beta=pl/(e0+eb); | |
341 | Double_t pl0=(px0*pxl + py0*pyl + pz0*pzl)/pl; | |
342 | Double_t plb=(pxb*pxl + pyb*pyl + pzb*pzl)/pl; | |
343 | pt2=p0*p0 - pl0*pl0; | |
344 | ||
345 | a=(pl0-plb)/(pl0+plb); | |
346 | a -= (1.11568*1.11568-bmass*bmass)/(mass*mass); | |
347 | a = 0.25*beta*beta*mass*mass*a*a + pt2; | |
348 | ||
349 | return (a - ps*ps); | |
350 | } | |
351 | ||
352 | void | |
353 | AliESDcascade::GetPxPyPz(Double_t &px, Double_t &py, Double_t &pz) const { | |
354 | //-------------------------------------------------------------------- | |
355 | // This function returns the cascade momentum (global) | |
356 | //-------------------------------------------------------------------- | |
8668c148 | 357 | px=fNmom[0]+fPmom[0]+fBachMom[0]; |
c028b974 | 358 | py=fNmom[1]+fPmom[1]+fBachMom[1]; |
359 | pz=fNmom[2]+fPmom[2]+fBachMom[2]; | |
e23730c7 | 360 | } |
361 | ||
c028b974 | 362 | void AliESDcascade::GetXYZcascade(Double_t &x, Double_t &y, Double_t &z) const { |
e23730c7 | 363 | //-------------------------------------------------------------------- |
364 | // This function returns cascade position (global) | |
365 | //-------------------------------------------------------------------- | |
c028b974 | 366 | x=fPosXi[0]; |
367 | y=fPosXi[1]; | |
368 | z=fPosXi[2]; | |
e23730c7 | 369 | } |
370 | ||
c028b974 | 371 | Double_t AliESDcascade::GetDcascade(Double_t x0, Double_t y0, Double_t z0) const { |
e23730c7 | 372 | //-------------------------------------------------------------------- |
373 | // This function returns the cascade impact parameter | |
374 | //-------------------------------------------------------------------- | |
375 | ||
c028b974 | 376 | Double_t x=fPosXi[0],y=fPosXi[1],z=fPosXi[2]; |
377 | Double_t px=fNmom[0]+fPmom[0]+fBachMom[0]; | |
378 | Double_t py=fNmom[1]+fPmom[1]+fBachMom[1]; | |
379 | Double_t pz=fNmom[2]+fPmom[2]+fBachMom[2]; | |
e23730c7 | 380 | |
381 | Double_t dx=(y0-y)*pz - (z0-z)*py; | |
382 | Double_t dy=(x0-x)*pz - (z0-z)*px; | |
383 | Double_t dz=(x0-x)*py - (y0-y)*px; | |
384 | Double_t d=TMath::Sqrt((dx*dx+dy*dy+dz*dz)/(px*px+py*py+pz*pz)); | |
385 | ||
386 | return d; | |
387 | } | |
388 | ||
97135b34 | 389 | Double_t AliESDcascade::GetCascadeCosineOfPointingAngle(Double_t refPointX, Double_t refPointY, Double_t refPointZ) const { |
c028b974 | 390 | // calculates the pointing angle of the cascade wrt a reference point |
391 | ||
392 | Double_t momCas[3]; //momentum of the cascade | |
393 | GetPxPyPz(momCas[0],momCas[1],momCas[2]); | |
394 | ||
395 | Double_t deltaPos[3]; //vector between the reference point and the cascade vertex | |
396 | deltaPos[0] = fPosXi[0] - refPointX; | |
397 | deltaPos[1] = fPosXi[1] - refPointY; | |
398 | deltaPos[2] = fPosXi[2] - refPointZ; | |
399 | ||
400 | Double_t momCas2 = momCas[0]*momCas[0] + momCas[1]*momCas[1] + momCas[2]*momCas[2]; | |
401 | Double_t deltaPos2 = deltaPos[0]*deltaPos[0] + deltaPos[1]*deltaPos[1] + deltaPos[2]*deltaPos[2]; | |
402 | ||
403 | Double_t cosinePointingAngle = (deltaPos[0]*momCas[0] + | |
404 | deltaPos[1]*momCas[1] + | |
405 | deltaPos[2]*momCas[2] ) / | |
406 | TMath::Sqrt(momCas2 * deltaPos2); | |
407 | ||
408 | return cosinePointingAngle; | |
409 | } | |
074f017b | 410 | |
411 | void AliESDcascade::GetPosCovXi(Double_t cov[6]) const { | |
412 | ||
413 | for (Int_t i=0; i<6; ++i) cov[i] = fPosCovXi[i]; | |
414 | } |