[u/mrichter/AliRoot.git] / STEER / AliESDcascade.cxx

/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/* $Id$ */

//-------------------------------------------------------------------------
//               Implementation of the cascade vertex class
//              This is part of the Event Summary Data 
//              which contains the result of the reconstruction
//              and is the main set of classes for analaysis
//    Origin: Christian Kuhn, IReS, Strasbourg, christian.kuhn@ires.in2p3.fr
//-------------------------------------------------------------------------

#include <TDatabasePDG.h>
#include <TMath.h>

#include "AliLog.h"
#include "AliExternalTrackParam.h"
#include "AliESDv0.h"
#include "AliESDcascade.h"

ClassImp(AliESDcascade)

AliESDcascade::AliESDcascade() : 
  AliESDv0(),
  fPdgCode(kXiMinus),
  fEffMass(TDatabasePDG::Instance()->GetParticle(kXiMinus)->Mass()),
  fChi2Xi(1.e+33),
  fDcaXiDaughters(999),
  fBachIdx(-1)
{
  //--------------------------------------------------------------------
  // Default constructor  (Xi-)
  //--------------------------------------------------------------------
  for (Int_t j=0; j<3; j++) {
    fPosXi[j]=0.;
    fBachMom[j]=0.;
  }

  fPosCovXi[0]=1e10;
  fPosCovXi[1]=fPosCovXi[2]=0.;
  fPosCovXi[3]=1e10;
  fPosCovXi[4]=0.;
  fPosCovXi[5]=1e10;

  fBachMomCov[0]=1e10;
  fBachMomCov[1]=fBachMomCov[2]=0.;
  fBachMomCov[3]=1e10;
  fBachMomCov[4]=0.;
  fBachMomCov[5]=1e10;
}

AliESDcascade::~AliESDcascade() {
}

AliESDcascade::AliESDcascade(const AliESDv0 &v,
			     const AliExternalTrackParam &t, Int_t i) : 
  AliESDv0(v),
  fPdgCode(kXiMinus),
  fEffMass(-1),
  fChi2Xi(1.e+33),
  fDcaXiDaughters(-1),
  fBachIdx(i)
{
  //---------------------------------------------------------------------------------------------
  // Main constructor  (Xi-)
  //---------------------------------------------------------------------------------------------

  Double_t r[3]; t.GetXYZ(r);
  Double_t x1=r[0], y1=r[1], z1=r[2]; // position of the bachelor
  Double_t p[3]; t.GetPxPyPz(p);
  Double_t px1=p[0], py1=p[1], pz1=p[2];// momentum of the bachelor track

  Double_t x2,y2,z2;          // position of the V0 
  v.GetXYZ(x2,y2,z2);    
  Double_t px2,py2,pz2;       // momentum of V0
  v.GetPxPyPz(px2,py2,pz2);

  Double_t a2=((x1-x2)*px2+(y1-y2)*py2+(z1-z2)*pz2)/(px2*px2+py2*py2+pz2*pz2);

  Double_t xm=x2+a2*px2;
  Double_t ym=y2+a2*py2;
  Double_t zm=z2+a2*pz2;

  //dca between V0 and bachelor
  
  fDcaXiDaughters = TMath::Sqrt((x1-xm)*(x1-xm) + (y1-ym)*(y1-ym) + (z1-zm)*(z1-zm));

  // position of the cascade decay
  
  fPosXi[0]=0.5*(x1+xm); fPosXi[1]=0.5*(y1+ym); fPosXi[2]=0.5*(z1+zm);
    

  // invariant mass of the cascade (default is Ximinus)
  
  Double_t e1=TMath::Sqrt(0.13957*0.13957 + px1*px1 + py1*py1 + pz1*pz1);
  Double_t e2=TMath::Sqrt(1.11568*1.11568 + px2*px2 + py2*py2 + pz2*pz2);
  
  fEffMass=TMath::Sqrt((e1+e2)*(e1+e2)-
    (px1+px2)*(px1+px2)-(py1+py2)*(py1+py2)-(pz1+pz2)*(pz1+pz2));


  // momenta of the bachelor and the V0
  
  fBachMom[0]=px1; fBachMom[1]=py1; fBachMom[2]=pz1; 

  //PH Covariance matrices: to be calculated correctly in the future
  fPosCovXi[0]=1e10;
  fPosCovXi[1]=fPosCovXi[2]=0.;
  fPosCovXi[3]=1e10;
  fPosCovXi[4]=0.;
  fPosCovXi[5]=1e10;

  fBachMomCov[0]=1e10;
  fBachMomCov[1]=fBachMomCov[2]=0.;
  fBachMomCov[3]=1e10;
  fBachMomCov[4]=0.;
  fBachMomCov[5]=1e10;

  fChi2Xi=7.;   

}

AliESDcascade::AliESDcascade(const AliESDcascade& cas) :
  AliESDv0(cas),
  fPdgCode(cas.fPdgCode),
  fEffMass(cas.fEffMass),
  fChi2Xi(cas.fChi2Xi),
  fDcaXiDaughters(cas.fDcaXiDaughters),
  fBachIdx(cas.fBachIdx)
{
  //copy constructor
  for (int i=0; i<3; i++) {
    fPosXi[i]     = cas.fPosXi[i];
    fBachMom[i] = cas.fBachMom[i];
  }
  for (int i=0; i<6; i++) {
    fPosCovXi[i]   = cas.fPosCovXi[i];
    fBachMomCov[i] = cas.fBachMomCov[i];
  }
}

Double_t AliESDcascade::ChangeMassHypothesis(Double_t &v0q, Int_t code) {
  //--------------------------------------------------------------------
  // This function changes the mass hypothesis for this cascade
  // and returns the "kinematical quality" of this hypothesis
  // together with the "quality" of associated V0 (argument v0q) 
  //--------------------------------------------------------------------
  Double_t nmass=0.13957, pmass=0.93827, ps0=0.101; 
  Double_t bmass=0.13957, mass =1.3213,  ps =0.139;

  fPdgCode=code;

  switch (code) {
  case 213: 
       bmass=0.93827; 
       break;
  case kXiMinus:
       break;
  case kXiPlusBar:
       nmass=0.93827; pmass=0.13957; 
       break;
  case kOmegaMinus: 
       bmass=0.49368; mass=1.67245; ps=0.211;
       break;
  case kOmegaPlusBar: 
       nmass=0.93827; pmass=0.13957; 
       bmass=0.49368; mass=1.67245; ps=0.211;
       break;
  default:
       AliError("Invalide PDG code !  Assuming XiMinus's...");
       fPdgCode=kXiMinus;
    break;
  }

  Double_t pxn=fNmom[0], pyn=fNmom[1], pzn=fNmom[2];
  Double_t pxp=fPmom[0], pyp=fPmom[1], pzp=fPmom[2];
  Double_t px0=pxn+pxp, py0=pyn+pyp, pz0=pzn+pzp;
  Double_t p0=TMath::Sqrt(px0*px0 + py0*py0 + pz0*pz0);

  Double_t e0=TMath::Sqrt(1.11568*1.11568 + p0*p0);
  Double_t beta0=p0/e0;
  Double_t pln=(pxn*px0 + pyn*py0 + pzn*pz0)/p0;
  Double_t plp=(pxp*px0 + pyp*py0 + pzp*pz0)/p0;
  Double_t pt2=pxp*pxp + pyp*pyp + pzp*pzp - plp*plp;

  Double_t a=(plp-pln)/(plp+pln);
  a -= (pmass*pmass-nmass*nmass)/(1.11568*1.11568);
  a = 0.25*beta0*beta0*1.11568*1.11568*a*a + pt2;


  v0q=a - ps0*ps0;


  Double_t pxb=fBachMom[0], pyb=fBachMom[1], pzb=fBachMom[2]; 

  Double_t eb=TMath::Sqrt(bmass*bmass + pxb*pxb + pyb*pyb + pzb*pzb);
  Double_t pxl=px0+pxb, pyl=py0+pyb, pzl=pz0+pzb;
  Double_t pl=TMath::Sqrt(pxl*pxl + pyl*pyl + pzl*pzl);
  
  fEffMass=TMath::Sqrt((e0+eb)*(e0+eb) - pl*pl);

  Double_t beta=pl/(e0+eb);
  Double_t pl0=(px0*pxl + py0*pyl + pz0*pzl)/pl;
  Double_t plb=(pxb*pxl + pyb*pyl + pzb*pzl)/pl;
  pt2=p0*p0 - pl0*pl0;

  a=(pl0-plb)/(pl0+plb);
  a -= (1.11568*1.11568-bmass*bmass)/(mass*mass);
  a = 0.25*beta*beta*mass*mass*a*a + pt2;

  return (a - ps*ps);
}

void 
AliESDcascade::GetPxPyPz(Double_t &px, Double_t &py, Double_t &pz) const {
  //--------------------------------------------------------------------
  // This function returns the cascade momentum (global)
  //--------------------------------------------------------------------
  px=fNmom[0]+fPmom[0]+fBachMom[0]; 
  py=fNmom[1]+fPmom[1]+fBachMom[1]; 
  pz=fNmom[2]+fPmom[2]+fBachMom[2]; 
}

void AliESDcascade::GetXYZcascade(Double_t &x, Double_t &y, Double_t &z) const {
  //--------------------------------------------------------------------
  // This function returns cascade position (global)
  //--------------------------------------------------------------------
  x=fPosXi[0];
  y=fPosXi[1];
  z=fPosXi[2];
}

Double_t AliESDcascade::GetDcascade(Double_t x0, Double_t y0, Double_t z0) const {
  //--------------------------------------------------------------------
  // This function returns the cascade impact parameter
  //--------------------------------------------------------------------

  Double_t x=fPosXi[0],y=fPosXi[1],z=fPosXi[2];
  Double_t px=fNmom[0]+fPmom[0]+fBachMom[0];
  Double_t py=fNmom[1]+fPmom[1]+fBachMom[1];
  Double_t pz=fNmom[2]+fPmom[2]+fBachMom[2];

  Double_t dx=(y0-y)*pz - (z0-z)*py; 
  Double_t dy=(x0-x)*pz - (z0-z)*px;
  Double_t dz=(x0-x)*py - (y0-y)*px;
  Double_t d=TMath::Sqrt((dx*dx+dy*dy+dz*dz)/(px*px+py*py+pz*pz));

  return d;
}

Double_t AliESDcascade::GetCascadeCosineOfPointingAngle(Double_t& refPointX, Double_t& refPointY, Double_t& refPointZ) const {
  // calculates the pointing angle of the cascade wrt a reference point

  Double_t momCas[3]; //momentum of the cascade
  GetPxPyPz(momCas[0],momCas[1],momCas[2]);

  Double_t deltaPos[3]; //vector between the reference point and the cascade vertex
  deltaPos[0] = fPosXi[0] - refPointX;
  deltaPos[1] = fPosXi[1] - refPointY;
  deltaPos[2] = fPosXi[2] - refPointZ;

  Double_t momCas2    = momCas[0]*momCas[0] + momCas[1]*momCas[1] + momCas[2]*momCas[2];
  Double_t deltaPos2 = deltaPos[0]*deltaPos[0] + deltaPos[1]*deltaPos[1] + deltaPos[2]*deltaPos[2];

  Double_t cosinePointingAngle = (deltaPos[0]*momCas[0] +
				  deltaPos[1]*momCas[1] +
				  deltaPos[2]*momCas[2] ) /
    TMath::Sqrt(momCas2 * deltaPos2);
  
  return cosinePointingAngle;
}

void AliESDcascade::GetPosCovXi(Double_t cov[6]) const {

  for (Int_t i=0; i<6; ++i) cov[i] = fPosCovXi[i];
}
Commit	Line	Data
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	/* $Id$ */
4f679a16	17
e23730c7	18	//-------------------------------------------------------------------------
e23730c7	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
e23730c7	24	//-------------------------------------------------------------------------
4f679a16	25
90e48c0c	26	#include <TDatabasePDG.h>
e23730c7	27	#include <TMath.h>
e23730c7	28
5f7789fc	29	#include "AliLog.h"
c7bafca9	30	#include "AliExternalTrackParam.h"
c7bafca9	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),
90e48c0c	39	fEffMass(TDatabasePDG::Instance()->GetParticle(kXiMinus)->Mass()),
c028b974	40	fChi2Xi(1.e+33),
c028b974	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	}
e23730c7	64
c028b974	65	AliESDcascade::~AliESDcascade() {
	66	}
	67
c7bafca9	68	AliESDcascade::AliESDcascade(const AliESDv0 &v,
c7bafca9	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)
c7bafca9	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)/(px2px2+py2py2+pz2pz2);
	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
c7bafca9	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(0.139570.13957 + px1px1 + py1py1 + pz1pz1);
	109	Double_t e2=TMath::Sqrt(1.115681.11568 + px2px2 + py2py2 + pz2pz2);
	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	{
c028b974	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];
c028b974	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(px0px0 + py0py0 + pz0*pz0);
	192
	193	Double_t e0=TMath::Sqrt(1.115681.11568 + p0p0);
	194	Double_t beta0=p0/e0;
	195	Double_t pln=(pxnpx0 + pynpy0 + pzn*pz0)/p0;
	196	Double_t plp=(pxppx0 + pyppy0 + pzp*pz0)/p0;
	197	Double_t pt2=pxppxp + pyppyp + pzppzp - plpplp;
	198
	199	Double_t a=(plp-pln)/(plp+pln);
	200	a -= (pmasspmass-nmassnmass)/(1.11568*1.11568);
	201	a = 0.25beta0beta01.115681.11568aa + 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(bmassbmass + pxbpxb + pybpyb + pzbpzb);
	210	Double_t pxl=px0+pxb, pyl=py0+pyb, pzl=pz0+pzb;
	211	Double_t pl=TMath::Sqrt(pxlpxl + pylpyl + pzl*pzl);
	212
	213	fEffMass=TMath::Sqrt((e0+eb)(e0+eb) - plpl);
	214
	215	Double_t beta=pl/(e0+eb);
	216	Double_t pl0=(px0pxl + py0pyl + pz0*pzl)/pl;
	217	Double_t plb=(pxbpxl + pybpyl + pzb*pzl)/pl;
	218	pt2=p0p0 - pl0pl0;
	219
	220	a=(pl0-plb)/(pl0+plb);
	221	a -= (1.115681.11568-bmassbmass)/(mass*mass);
	222	a = 0.25betabetamassmassaa + 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	}
e23730c7	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	}
e23730c7	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((dxdx+dydy+dzdz)/(pxpx+pypy+pzpz));
	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	}