1 /*************************************************************************
2 * Copyright(c) 1998-2009, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
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12 * about the suitability of this software for any purpose. It is *
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14 **************************************************************************/
16 ///////////////////////////////////////////////////////////////////////////
18 // Dielectron Pair class. Internally it makes use of AliKFParticle. //
20 ///////////////////////////////////////////////////////////////////////////
23 #include <TDatabasePDG.h>
24 #include <AliVTrack.h>
25 #include <AliVVertex.h>
27 #include <AliExternalTrackParam.h>
28 #include <AliESDEvent.h>
30 #include "AliDielectronPair.h"
32 ClassImp(AliDielectronPair)
34 Double_t AliDielectronPair::fBeamEnergy=-1.;
36 AliDielectronPair::AliDielectronPair() :
48 // Default Constructor
53 //______________________________________________
54 AliDielectronPair::AliDielectronPair(AliVTrack * const particle1, Int_t pid1,
55 AliVTrack * const particle2, Int_t pid2, Char_t type) :
67 // Constructor with tracks
69 SetTracks(particle1, pid1, particle2, pid2);
72 //______________________________________________
73 AliDielectronPair::AliDielectronPair(const AliKFParticle * const particle1,
74 const AliKFParticle * const particle2,
75 AliVTrack * const refParticle1,
76 AliVTrack * const refParticle2, Char_t type) :
88 // Constructor with tracks
90 SetTracks(particle1, particle2,refParticle1,refParticle2);
93 //______________________________________________
94 AliDielectronPair::~AliDielectronPair()
102 //______________________________________________
103 void AliDielectronPair::SetTracks(AliVTrack * const particle1, Int_t pid1,
104 AliVTrack * const particle2, Int_t pid2)
107 // Sort particles by pt, first particle larget Pt
108 // set AliKF daughters and pair
109 // refParticle1 and 2 are the original tracks. In the case of track rotation
110 // they are needed in the framework
116 AliKFParticle kf1(*particle1,pid1);
117 AliKFParticle kf2(*particle2,pid2);
119 fPair.AddDaughter(kf1);
120 fPair.AddDaughter(kf2);
122 if (particle1->Pt()>particle2->Pt()){
134 //______________________________________________
135 void AliDielectronPair::SetGammaTracks(AliVTrack * const particle1, Int_t pid1,
136 AliVTrack * const particle2, Int_t pid2)
139 // Sort particles by pt, first particle larget Pt
140 // set AliKF daughters and a GAMMA pair
141 // refParticle1 and 2 are the original tracks. In the case of track rotation
142 // they are needed in the framework
147 AliKFParticle kf1(*particle1,pid1);
148 AliKFParticle kf2(*particle2,pid2);
149 fPair.ConstructGamma(kf1,kf2);
151 if (particle1->Pt()>particle2->Pt()){
164 //______________________________________________
165 void AliDielectronPair::SetTracks(const AliKFParticle * const particle1,
166 const AliKFParticle * const particle2,
167 AliVTrack * const refParticle1,
168 AliVTrack * const refParticle2)
171 // Sort particles by pt, first particle larget Pt
172 // set AliKF daughters and pair
173 // refParticle1 and 2 are the original tracks. In the case of track rotation
174 // they are needed in the framework
180 AliKFParticle kf1(*particle1);
181 AliKFParticle kf2(*particle2);
183 fPair.AddDaughter(kf1);
184 fPair.AddDaughter(kf2);
186 if (kf1.GetPt()>kf2.GetPt()){
187 fRefD1 = refParticle1;
188 fRefD2 = refParticle2;
192 fRefD1 = refParticle2;
193 fRefD2 = refParticle1;
199 //______________________________________________
200 void AliDielectronPair::GetThetaPhiCM(Double_t &thetaHE, Double_t &phiHE, Double_t &thetaCS, Double_t &phiCS) const
203 // Calculate theta and phi in helicity and Collins-Soper coordinate frame
205 Double_t pxyz1[3]={fD1.GetPx(),fD1.GetPy(),fD1.GetPz()};
206 Double_t pxyz2[3]={fD2.GetPx(),fD2.GetPy(),fD2.GetPz()};
207 Double_t eleMass=AliPID::ParticleMass(AliPID::kElectron);
208 Double_t proMass=AliPID::ParticleMass(AliPID::kProton);
210 // AliVParticle *d1 = static_cast<AliVParticle*>(fRefD1.GetObject());
211 // AliVParticle *d2 = static_cast<AliVParticle*>(fRefD2.GetObject());
213 // d1->PxPyPz(pxyz1);
214 // d2->PxPyPz(pxyz2);
216 TLorentzVector projMom(0.,0.,-fBeamEnergy,TMath::Sqrt(fBeamEnergy*fBeamEnergy+proMass*proMass));
217 TLorentzVector targMom(0.,0., fBeamEnergy,TMath::Sqrt(fBeamEnergy*fBeamEnergy+proMass*proMass));
219 // first & second daughter 4-mom
220 TLorentzVector p1Mom(pxyz1[0],pxyz1[1],pxyz1[2],
221 TMath::Sqrt(pxyz1[0]*pxyz1[0]+pxyz1[1]*pxyz1[1]+pxyz1[2]*pxyz1[2]+eleMass*eleMass));
222 TLorentzVector p2Mom(pxyz2[0],pxyz2[1],pxyz2[2],
223 TMath::Sqrt(pxyz2[0]*pxyz2[0]+pxyz2[1]*pxyz2[1]+pxyz2[2]*pxyz2[2]+eleMass*eleMass));
224 // J/Psi 4-momentum vector
225 TLorentzVector motherMom=p1Mom+p2Mom;
227 // boost all the 4-mom vectors to the mother rest frame
228 TVector3 beta = (-1.0/motherMom.E())*motherMom.Vect();
235 TVector3 zAxisHE = (motherMom.Vect()).Unit();
236 TVector3 zAxisCS = ((projMom.Vect()).Unit()-(targMom.Vect()).Unit()).Unit();
237 TVector3 yAxis = ((projMom.Vect()).Cross(targMom.Vect())).Unit();
238 TVector3 xAxisHE = (yAxis.Cross(zAxisHE)).Unit();
239 TVector3 xAxisCS = (yAxis.Cross(zAxisCS)).Unit();
241 // fill theta and phi
243 thetaHE = zAxisHE.Dot((p1Mom.Vect()).Unit());
244 thetaCS = zAxisCS.Dot((p1Mom.Vect()).Unit());
245 phiHE = TMath::ATan2((p1Mom.Vect()).Dot(yAxis), (p1Mom.Vect()).Dot(xAxisHE));
246 phiCS = TMath::ATan2((p1Mom.Vect()).Dot(yAxis), (p1Mom.Vect()).Dot(xAxisCS));
248 thetaHE = zAxisHE.Dot((p2Mom.Vect()).Unit());
249 thetaCS = zAxisCS.Dot((p2Mom.Vect()).Unit());
250 phiHE = TMath::ATan2((p2Mom.Vect()).Dot(yAxis), (p2Mom.Vect()).Dot(xAxisHE));
251 phiCS = TMath::ATan2((p2Mom.Vect()).Dot(yAxis), (p2Mom.Vect()).Dot(xAxisCS));
256 //______________________________________________
257 Double_t AliDielectronPair::PsiPair(Double_t MagField) const
259 //Following idea to use opening of colinear pairs in magnetic field from e.g. PHENIX
260 //to ID conversions. Adapted from AliTRDv0Info class
266 Double_t m1[3] = {0,0,0};
267 Double_t m2[3] = {0,0,0};
277 Double_t deltat = 1.;
278 deltat = TMath::ATan(m2[2]/(TMath::Sqrt(m2[0]*m2[0] + m2[1]*m2[1])+1.e-13))-
279 TMath::ATan(m1[2]/(TMath::Sqrt(m1[0]*m1[0] + m1[1]*m1[1])+1.e-13));//difference of angles of the two daughter tracks with z-axis
281 Double_t radiussum = TMath::Sqrt(x*x + y*y) + 50;//radius to which tracks shall be propagated
283 Double_t mom1Prop[3];
284 Double_t mom2Prop[3];
286 AliExternalTrackParam *d1 = static_cast<AliExternalTrackParam*>(fRefD1.GetObject());
287 AliExternalTrackParam *d2 = static_cast<AliExternalTrackParam*>(fRefD2.GetObject());
289 AliExternalTrackParam nt(*d1), pt(*d2);
291 Double_t fPsiPair = 4.;
292 if(nt.PropagateTo(radiussum,MagField) == 0)//propagate tracks to the outside
294 if(pt.PropagateTo(radiussum,MagField) == 0)
296 pt.GetPxPyPz(mom1Prop);//Get momentum vectors of tracks after propagation
297 nt.GetPxPyPz(mom2Prop);
302 TMath::Sqrt(mom2Prop[0]*mom2Prop[0]+mom2Prop[1]*mom2Prop[1]+mom2Prop[2]*mom2Prop[2]);//absolute momentum val
304 TMath::Sqrt(mom1Prop[0]*mom1Prop[0]+mom1Prop[1]*mom1Prop[1]+mom1Prop[2]*mom1Prop[2]);//absolute momentum val
306 Double_t scalarproduct =
307 mom1Prop[0]*mom2Prop[0]+mom1Prop[1]*mom2Prop[1]+mom1Prop[2]*mom2Prop[2];//scalar product of propagated posit
309 Double_t chipair = TMath::ACos(scalarproduct/(pEle*pPos));//Angle between propagated daughter tracks
311 fPsiPair = TMath::Abs(TMath::ASin(deltat/chipair));
317 //______________________________________________
318 Double_t AliDielectronPair::ThetaPhiCM(const AliVParticle* d1, const AliVParticle* d2,
319 Bool_t isHE, Bool_t isTheta)
321 // The function calculates theta and phi in the mother rest frame with
322 // respect to the helicity coordinate system and Collins-Soper coordinate system
323 // TO DO: generalize for different decays (only J/Psi->e+e- now)
325 // Laboratory frame 4-vectors:
326 // projectile beam & target beam 4-mom
327 Double_t px1=d1->Px();
328 Double_t py1=d1->Py();
329 Double_t pz1=d1->Pz();
330 Double_t px2=d2->Px();
331 Double_t py2=d2->Py();
332 Double_t pz2=d2->Pz();
333 Double_t eleMass=AliPID::ParticleMass(AliPID::kElectron);
334 Double_t proMass=AliPID::ParticleMass(AliPID::kProton);
335 // printf(" beam energy %f \n ", fBeamEnergy);
336 TLorentzVector projMom(0.,0.,-fBeamEnergy,TMath::Sqrt(fBeamEnergy*fBeamEnergy+proMass*proMass));
337 TLorentzVector targMom(0.,0., fBeamEnergy,TMath::Sqrt(fBeamEnergy*fBeamEnergy+proMass*proMass));
339 // first & second daughter 4-mom
340 TLorentzVector p1Mom(px1,py1,pz1,TMath::Sqrt(px1*px1+py1*py1+pz1*pz1+eleMass*eleMass));
341 TLorentzVector p2Mom(px2,py2,pz2,TMath::Sqrt(px2*px2+py2*py2+pz2*pz2+eleMass*eleMass));
342 // J/Psi 4-momentum vector
343 TLorentzVector motherMom=p1Mom+p2Mom;
345 // boost all the 4-mom vectors to the mother rest frame
346 TVector3 beta = (-1.0/motherMom.E())*motherMom.Vect();
354 if(isHE) zAxis = (motherMom.Vect()).Unit();
355 else zAxis = ((projMom.Vect()).Unit()-(targMom.Vect()).Unit()).Unit();
356 TVector3 yAxis = ((projMom.Vect()).Cross(targMom.Vect())).Unit();
357 TVector3 xAxis = (yAxis.Cross(zAxis)).Unit();
359 // return either theta or phi
362 return zAxis.Dot((p1Mom.Vect()).Unit());
364 return zAxis.Dot((p2Mom.Vect()).Unit());
369 return TMath::ATan2((p1Mom.Vect()).Dot(yAxis), (p1Mom.Vect()).Dot(xAxis));
371 return TMath::ATan2((p2Mom.Vect()).Dot(yAxis), (p2Mom.Vect()).Dot(xAxis));
375 //______________________________________________
376 Double_t AliDielectronPair::ThetaPhiCM(Bool_t isHE, Bool_t isTheta) const {
377 // The function calculates theta and phi in the mother rest frame with
378 // respect to the helicity coordinate system and Collins-Soper coordinate system
379 // TO DO: generalize for different decays (only J/Psi->e+e- now)
381 // Laboratory frame 4-vectors:
382 // projectile beam & target beam 4-mom
383 AliVParticle *d1 = static_cast<AliVParticle*>(fRefD1.GetObject());
384 AliVParticle *d2 = static_cast<AliVParticle*>(fRefD2.GetObject());
386 Double_t px1=d1->Px();
387 Double_t py1=d1->Py();
388 Double_t pz1=d1->Pz();
389 Double_t px2=d2->Px();
390 Double_t py2=d2->Py();
391 Double_t pz2=d2->Pz();
392 Double_t eleMass=AliPID::ParticleMass(AliPID::kElectron);
393 Double_t proMass=AliPID::ParticleMass(AliPID::kProton);
395 TLorentzVector projMom(0.,0.,-fBeamEnergy,TMath::Sqrt(fBeamEnergy*fBeamEnergy+proMass*proMass));
396 TLorentzVector targMom(0.,0., fBeamEnergy,TMath::Sqrt(fBeamEnergy*fBeamEnergy+proMass*proMass));
398 // first & second daughter 4-mom
399 // first & second daughter 4-mom
400 TLorentzVector p1Mom(px1,py1,pz1,TMath::Sqrt(px1*px1+py1*py1+pz1*pz1+eleMass*eleMass));
401 TLorentzVector p2Mom(px2,py2,pz2,TMath::Sqrt(px2*px2+py2*py2+pz2*pz2+eleMass*eleMass));
402 // J/Psi 4-momentum vector
403 TLorentzVector motherMom=p1Mom+p2Mom;
405 // boost all the 4-mom vectors to the mother rest frame
406 TVector3 beta = (-1.0/motherMom.E())*motherMom.Vect();
414 if(isHE) zAxis = (motherMom.Vect()).Unit();
415 else zAxis = ((projMom.Vect()).Unit()-(targMom.Vect()).Unit()).Unit();
416 TVector3 yAxis = ((projMom.Vect()).Cross(targMom.Vect())).Unit();
417 TVector3 xAxis = (yAxis.Cross(zAxis)).Unit();
419 // return either theta or phi
422 return zAxis.Dot((p1Mom.Vect()).Unit());
424 return zAxis.Dot((p2Mom.Vect()).Unit());
428 return TMath::ATan2((p1Mom.Vect()).Dot(yAxis), (p1Mom.Vect()).Dot(xAxis));
430 return TMath::ATan2((p2Mom.Vect()).Dot(yAxis), (p2Mom.Vect()).Dot(xAxis));
433 //______________________________________________
434 Double_t AliDielectronPair::GetCosPointingAngle(const AliVVertex *primVtx) const
437 // Calculate the poiting angle of the pair to the primary vertex and take the cosine
439 if(!primVtx) return -1.;
441 Double_t deltaPos[3]; //vector between the reference point and the V0 vertex
442 deltaPos[0] = fPair.GetX() - primVtx->GetX();
443 deltaPos[1] = fPair.GetY() - primVtx->GetY();
444 deltaPos[2] = fPair.GetZ() - primVtx->GetZ();
446 Double_t momV02 = Px()*Px() + Py()*Py() + Pz()*Pz();
447 Double_t deltaPos2 = deltaPos[0]*deltaPos[0] + deltaPos[1]*deltaPos[1] + deltaPos[2]*deltaPos[2];
449 Double_t cosinePointingAngle = (deltaPos[0]*Px() + deltaPos[1]*Py() + deltaPos[2]*Pz()) / TMath::Sqrt(momV02 * deltaPos2);
451 return TMath::Abs(cosinePointingAngle);
455 //______________________________________________
456 Double_t AliDielectronPair::GetArmAlpha() const
459 // Calculate the Armenteros-Podolanski Alpha
461 Int_t qD1 = fD1.GetQ();
463 TVector3 momNeg( (qD1<0?fD1.GetPx():fD2.GetPx()),
464 (qD1<0?fD1.GetPy():fD2.GetPy()),
465 (qD1<0?fD1.GetPz():fD2.GetPz()) );
466 TVector3 momPos( (qD1<0?fD2.GetPx():fD1.GetPx()),
467 (qD1<0?fD2.GetPy():fD1.GetPy()),
468 (qD1<0?fD2.GetPz():fD1.GetPz()) );
469 TVector3 momTot(Px(),Py(),Pz());
471 Double_t lQlNeg = momNeg.Dot(momTot)/momTot.Mag();
472 Double_t lQlPos = momPos.Dot(momTot)/momTot.Mag();
474 return ((lQlPos - lQlNeg)/(lQlPos + lQlNeg));
477 //______________________________________________
478 Double_t AliDielectronPair::GetArmPt() const
481 // Calculate the Armenteros-Podolanski Pt
483 Int_t qD1 = fD1.GetQ();
485 TVector3 momNeg( (qD1<0?fD1.GetPx():fD2.GetPx()),
486 (qD1<0?fD1.GetPy():fD2.GetPy()),
487 (qD1<0?fD1.GetPz():fD2.GetPz()) );
488 TVector3 momTot(Px(),Py(),Pz());
490 return (momNeg.Perp(momTot));
493 //______________________________________________
494 void AliDielectronPair::GetDCA(const AliVVertex *primVtx, Double_t d0z0[2]) const
497 // Calculate the dca of the mother with respect to the primary vertex
501 d0z0[0] = TMath::Sqrt(TMath::Power(Xv()-primVtx->GetX(),2) +
502 TMath::Power(Yv()-primVtx->GetY(),2) );
504 d0z0[1] = Zv() - primVtx->GetZ();
509 // //______________________________________________
510 // Double_t AliDielectronPair::GetLXY(const AliVVertex * const vtx) const
513 // // Calculate the decay length in XY taking into account the primary vertex position
515 // if(!vtx) return 0;
516 // return ( (Xv()-vtx->GetX()) * Px() + (Yv()-vtx->GetY()) * Py() )/Pt() ;
519 // //______________________________________________
520 // Double_t AliDielectronPair::GetPseudoProperTime(const AliVVertex * const vtx) const
523 // // Calculate the pseudo proper time
525 // Double_t lxy=GetLXY(vtx);
526 // Double_t psProperDecayLength = lxy*(TDatabasePDG::Instance()->GetParticle(443)->Mass())/Pt();
527 // return psProperDecayLength;
531 //______________________________________________
532 Double_t AliDielectronPair::PhivPair(Double_t MagField) const
534 //Following idea to use opening of colinear pairs in magnetic field from e.g. PHENIX
535 //to ID conversions. Angle between ee plane and magnetic field is calculated.
537 //Define local buffer variables for leg properties
538 Double_t px1=-9999.,py1=-9999.,pz1=-9999.;
539 Double_t px2=-9999.,py2=-9999.,pz2=-9999.;
579 Double_t px = px1+px2;
580 Double_t py = py1+py2;
581 Double_t pz = pz1+pz2;
582 Double_t dppair = TMath::Sqrt(px*px+py*py+pz*pz);
584 //unit vector of (pep+pem)
585 Double_t pl = dppair;
589 Double_t ax = uy/TMath::Sqrt(ux*ux+uy*uy);
590 Double_t ay = -ux/TMath::Sqrt(ux*ux+uy*uy);
592 //momentum of e+ and e- in (ax,ay,az) axis. Note that az=0 by
594 //Double_t ptep = iep->Px()*ax + iep->Py()*ay;
595 //Double_t ptem = iem->Px()*ax + iem->Py()*ay;
604 //vector product of pep X pem
605 Double_t vpx = pyep*pzem - pzep*pyem;
606 Double_t vpy = pzep*pxem - pxep*pzem;
607 Double_t vpz = pxep*pyem - pyep*pxem;
608 Double_t vp = sqrt(vpx*vpx+vpy*vpy+vpz*vpz);
609 //Double_t thev = acos(vpz/vp);
611 //unit vector of pep X pem
612 Double_t vx = vpx/vp;
613 Double_t vy = vpy/vp;
614 Double_t vz = vpz/vp;
616 //The third axis defined by vector product (ux,uy,uz)X(vx,vy,vz)
617 Double_t wx = uy*vz - uz*vy;
618 Double_t wy = uz*vx - ux*vz;
619 //Double_t wz = ux*vy - uy*vx;
620 //Double_t wl = sqrt(wx*wx+wy*wy+wz*wz);
621 // by construction, (wx,wy,wz) must be a unit vector.
622 // measure angle between (wx,wy,wz) and (ax,ay,0). The angle between them
623 // should be small if the pair is conversion
625 Double_t cosPhiV = wx*ax + wy*ay;
626 Double_t phiv = TMath::ACos(cosPhiV);
632 //______________________________________________
633 Double_t AliDielectronPair::GetPairPlaneAngle(Double_t v0rpH2, Int_t VariNum)const
636 // Calculate the angle between electron pair plane and variables
637 // kv0rpH2 is reaction plane angle using V0-A,C,AC,Random
639 Double_t px1=-9999.,py1=-9999.,pz1=-9999.;
640 Double_t px2=-9999.,py2=-9999.,pz2=-9999.;
651 Double_t px = px1+px2;
652 Double_t py = py1+py2;
653 Double_t pz = pz1+pz2;
655 // normal vector of ee plane
656 Double_t pnorx = py1*pz2 - pz1*py2;
657 Double_t pnory = pz1*px2 - px1*pz2;
658 Double_t pnorz = px1*py2 - py1*px2;
659 Double_t pnor = TMath::Sqrt( pnorx*pnorx + pnory*pnory + pnorz*pnorz );
662 Double_t upnx = -9999.;
663 Double_t upny = -9999.;
664 Double_t upnz = -9999.;
674 Double_t ax = -9999.;
675 Double_t ay = -9999.;
676 Double_t az = -9999.;
679 //seeing the angle between ee decay plane and reaction plane by using V0-A,C,AC,Random
681 ax = TMath::Sin(v0rpH2);
682 ay = -TMath::Cos(v0rpH2);
688 //seeing the angle between ee decay plane and (p1+p2) rot ez
689 else if (VariNum == 2 ){
696 //seeing the angle between ee decay plane and (p1+p2) rot (p1+p2)x'z
697 else if (VariNum == 3 ){
698 Double_t rotpx = px*TMath::Cos(v0rpH2)+py*TMath::Sin(v0rpH2);
699 //Double_t rotpy = 0.0;
700 // Double_t rotpz = pz;
708 //seeing the angle between ee decay plane and (p1+p2) rot ey'
709 else if (VariNum == 4){
715 Double_t denomHelper = ax*ax + ay*ay +az*az;
716 Double_t uax = -9999.;
717 Double_t uay = -9999.;
718 Double_t uaz = -9999.;
720 if (denomHelper !=0) {
721 uax = ax/TMath::Sqrt(denomHelper);
722 uay = ay/TMath::Sqrt(denomHelper);
723 uaz = az/TMath::Sqrt(denomHelper);
726 //PM is the angle between Pair plane and a plane decided by using variable 1-4
728 Double_t cosPM = upnx*uax + upny*uay + upnz*uaz;
729 Double_t PM = TMath::ACos(cosPM);
731 //keep interval [0,pi/2]
732 if(PM > TMath::Pi()/2){
741 //_______________________________________________
742 Double_t AliDielectronPair::PairPlaneMagInnerProduct(Double_t ZDCrpH1) const
745 // Calculate inner product of the strong magnetic field and electron pair plane
747 if(ZDCrpH1 == 0.) return -9999.;
749 Double_t px1=-9999.,py1=-9999.,pz1=-9999.;
750 Double_t px2=-9999.,py2=-9999.,pz2=-9999.;
761 // normal vector of ee plane
762 Double_t pnorx = py2*pz1 - pz2*py1;
763 Double_t pnory = pz2*px1 - px2*pz1;
764 Double_t pnorz = px2*py1 - py2*px1;
765 Double_t pnor = TMath::Sqrt( pnorx*pnorx + pnory*pnory + pnorz*pnorz );
768 Double_t upnx = -9999.;
769 Double_t upny = -9999.;
770 //Double_t upnz = -9999.;
772 if (pnor == 0) return -9999.;
777 //direction of strong magnetic field
778 Double_t magx = TMath::Cos(ZDCrpH1+(TMath::Pi()/2));
779 Double_t magy = TMath::Sin(ZDCrpH1+(TMath::Pi()/2));
781 //inner product of strong magnetic field and ee plane
782 Double_t upnmag = upnx*magx + upny*magy;
788 //______________________________________________
789 void AliDielectronPair::SetBeamEnergy(AliVEvent *ev, Double_t beamEbyHand)
792 // set the beam energy (by hand in case of AODs)
794 if(ev->IsA()==AliESDEvent::Class())
795 fBeamEnergy = ((AliESDEvent*)ev)->GetBeamEnergy();
797 fBeamEnergy = beamEbyHand;