[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() : 
  TObject(),
  fPdgCode(kXiMinus),
  fEffMass(TDatabasePDG::Instance()->GetParticle(kXiMinus)->Mass()),
  fChi2(1.e+33),
  fBachIdx(0)
{
  //--------------------------------------------------------------------
  // Default constructor  (Xi-)
  //--------------------------------------------------------------------
  fPos[0]=fPos[1]=fPos[2]=0.;
  fPosCov[0]=fPosCov[1]=fPosCov[2]=fPosCov[3]=fPosCov[4]=fPosCov[5]=0.;
}

AliESDcascade::AliESDcascade(const AliESDv0 &v,
			     const AliExternalTrackParam &t, Int_t i) : 
  TObject(),
  fPdgCode(kXiMinus),
  fEffMass(TDatabasePDG::Instance()->GetParticle(kXiMinus)->Mass()),
  fChi2(1.e+33),
  fBachIdx(i)
{
  //--------------------------------------------------------------------
  // Main constructor  (Xi-)
  //--------------------------------------------------------------------

  fV0idx[0]=v.GetNindex(); fV0idx[1]=v.GetPindex();

  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;

  // position of the cascade decay
  
  fPos[0]=0.5*(x1+xm); fPos[1]=0.5*(y1+ym); fPos[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; 
  v.GetNPxPyPz(px2,py2,pz2);
  fV0mom[0][0]=px2; fV0mom[0][1]=py2; fV0mom[0][2]=pz2;
  v.GetPPxPyPz(px2,py2,pz2);
  fV0mom[1][0]=px2; fV0mom[1][1]=py2; fV0mom[1][2]=pz2;


  fChi2=7.;   

}

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=fV0mom[0][0], pyn=fV0mom[0][1], pzn=fV0mom[0][2];
  Double_t pxp=fV0mom[1][0], pyp=fV0mom[1][1], pzp=fV0mom[1][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=fV0mom[0][0]+fV0mom[1][0]+fBachMom[0]; 
  py=fV0mom[0][1]+fV0mom[1][1]+fBachMom[1]; 
  pz=fV0mom[0][2]+fV0mom[1][2]+fBachMom[2]; 
}

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

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

  Double_t x=fPos[0],y=fPos[1],z=fPos[2];
  Double_t px=fV0mom[0][0]+fV0mom[1][0]+fBachMom[0];
  Double_t py=fV0mom[0][1]+fV0mom[1][1]+fBachMom[1];
  Double_t pz=fV0mom[0][2]+fV0mom[1][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;
}
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() :
	37	TObject(),
	38	fPdgCode(kXiMinus),
	39	fEffMass(TDatabasePDG::Instance()->GetParticle(kXiMinus)->Mass()),
	40	fChi2(1.e+33),
	41	fBachIdx(0)
	42	{
e23730c7	43	//--------------------------------------------------------------------
	44	// Default constructor (Xi-)
	45	//--------------------------------------------------------------------
e23730c7	46	fPos[0]=fPos[1]=fPos[2]=0.;
	47	fPosCov[0]=fPosCov[1]=fPosCov[2]=fPosCov[3]=fPosCov[4]=fPosCov[5]=0.;
	48	}
	49
c7bafca9	50	AliESDcascade::AliESDcascade(const AliESDv0 &v,
	51	const AliExternalTrackParam &t, Int_t i) :
	52	TObject(),
	53	fPdgCode(kXiMinus),
	54	fEffMass(TDatabasePDG::Instance()->GetParticle(kXiMinus)->Mass()),
	55	fChi2(1.e+33),
	56	fBachIdx(i)
	57	{
	58	//--------------------------------------------------------------------
	59	// Main constructor (Xi-)
	60	//--------------------------------------------------------------------
	61
	62	fV0idx[0]=v.GetNindex(); fV0idx[1]=v.GetPindex();
	63
	64	Double_t r[3]; t.GetXYZ(r);
	65	Double_t x1=r[0], y1=r[1], z1=r[2]; // position of the bachelor
	66	Double_t p[3]; t.GetPxPyPz(p);
	67	Double_t px1=p[0], py1=p[1], pz1=p[2];// momentum of the bachelor track
	68
	69	Double_t x2,y2,z2; // position of the V0
	70	v.GetXYZ(x2,y2,z2);
	71	Double_t px2,py2,pz2; // momentum of V0
	72	v.GetPxPyPz(px2,py2,pz2);
	73
	74	Double_t a2=((x1-x2)px2+(y1-y2)py2+(z1-z2)pz2)/(px2px2+py2py2+pz2pz2);
	75
	76	Double_t xm=x2+a2*px2;
	77	Double_t ym=y2+a2*py2;
	78	Double_t zm=z2+a2*pz2;
	79
	80	// position of the cascade decay
	81
	82	fPos[0]=0.5(x1+xm); fPos[1]=0.5(y1+ym); fPos[2]=0.5*(z1+zm);
	83
	84
	85	// invariant mass of the cascade (default is Ximinus)
	86
	87	Double_t e1=TMath::Sqrt(0.139570.13957 + px1px1 + py1py1 + pz1pz1);
	88	Double_t e2=TMath::Sqrt(1.115681.11568 + px2px2 + py2py2 + pz2pz2);
	89
	90	fEffMass=TMath::Sqrt((e1+e2)*(e1+e2)-
	91	(px1+px2)(px1+px2)-(py1+py2)(py1+py2)-(pz1+pz2)*(pz1+pz2));
	92
	93
	94	// momenta of the bachelor and the V0
	95
	96	fBachMom[0]=px1; fBachMom[1]=py1; fBachMom[2]=pz1;
	97	v.GetNPxPyPz(px2,py2,pz2);
	98	fV0mom[0][0]=px2; fV0mom[0][1]=py2; fV0mom[0][2]=pz2;
	99	v.GetPPxPyPz(px2,py2,pz2);
	100	fV0mom[1][0]=px2; fV0mom[1][1]=py2; fV0mom[1][2]=pz2;
	101
	102
	103	fChi2=7.;
	104
	105	}
	106
e23730c7	107	Double_t AliESDcascade::ChangeMassHypothesis(Double_t &v0q, Int_t code) {
	108	//--------------------------------------------------------------------
	109	// This function changes the mass hypothesis for this cascade
	110	// and returns the "kinematical quality" of this hypothesis
	111	// together with the "quality" of associated V0 (argument v0q)
	112	//--------------------------------------------------------------------
	113	Double_t nmass=0.13957, pmass=0.93827, ps0=0.101;
	114	Double_t bmass=0.13957, mass =1.3213, ps =0.139;
	115
	116	fPdgCode=code;
	117
	118	switch (code) {
	119	case 213:
	120	bmass=0.93827;
	121	break;
	122	case kXiMinus:
	123	break;
	124	case kXiPlusBar:
	125	nmass=0.93827; pmass=0.13957;
	126	break;
	127	case kOmegaMinus:
	128	bmass=0.49368; mass=1.67245; ps=0.211;
	129	break;
	130	case kOmegaPlusBar:
	131	nmass=0.93827; pmass=0.13957;
	132	bmass=0.49368; mass=1.67245; ps=0.211;
	133	break;
	134	default:
5f7789fc	135	AliError("Invalide PDG code ! Assuming XiMinus's...");
e23730c7	136	fPdgCode=kXiMinus;
	137	break;
	138	}
	139
	140	Double_t pxn=fV0mom[0][0], pyn=fV0mom[0][1], pzn=fV0mom[0][2];
	141	Double_t pxp=fV0mom[1][0], pyp=fV0mom[1][1], pzp=fV0mom[1][2];
	142	Double_t px0=pxn+pxp, py0=pyn+pyp, pz0=pzn+pzp;
	143	Double_t p0=TMath::Sqrt(px0px0 + py0py0 + pz0*pz0);
	144
	145	Double_t e0=TMath::Sqrt(1.115681.11568 + p0p0);
	146	Double_t beta0=p0/e0;
	147	Double_t pln=(pxnpx0 + pynpy0 + pzn*pz0)/p0;
	148	Double_t plp=(pxppx0 + pyppy0 + pzp*pz0)/p0;
	149	Double_t pt2=pxppxp + pyppyp + pzppzp - plpplp;
	150
	151	Double_t a=(plp-pln)/(plp+pln);
	152	a -= (pmasspmass-nmassnmass)/(1.11568*1.11568);
	153	a = 0.25beta0beta01.115681.11568aa + pt2;
	154
	155
	156	v0q=a - ps0*ps0;
	157
	158
	159	Double_t pxb=fBachMom[0], pyb=fBachMom[1], pzb=fBachMom[2];
	160
	161	Double_t eb=TMath::Sqrt(bmassbmass + pxbpxb + pybpyb + pzbpzb);
	162	Double_t pxl=px0+pxb, pyl=py0+pyb, pzl=pz0+pzb;
	163	Double_t pl=TMath::Sqrt(pxlpxl + pylpyl + pzl*pzl);
	164
	165	fEffMass=TMath::Sqrt((e0+eb)(e0+eb) - plpl);
	166
	167	Double_t beta=pl/(e0+eb);
	168	Double_t pl0=(px0pxl + py0pyl + pz0*pzl)/pl;
	169	Double_t plb=(pxbpxl + pybpyl + pzb*pzl)/pl;
	170	pt2=p0p0 - pl0pl0;
	171
	172	a=(pl0-plb)/(pl0+plb);
	173	a -= (1.115681.11568-bmassbmass)/(mass*mass);
	174	a = 0.25betabetamassmassaa + pt2;
	175
	176	return (a - ps*ps);
	177	}
	178
	179	void
	180	AliESDcascade::GetPxPyPz(Double_t &px, Double_t &py, Double_t &pz) const {
	181	//--------------------------------------------------------------------
	182	// This function returns the cascade momentum (global)
	183	//--------------------------------------------------------------------
	184	px=fV0mom[0][0]+fV0mom[1][0]+fBachMom[0];
	185	py=fV0mom[0][1]+fV0mom[1][1]+fBachMom[1];
	186	pz=fV0mom[0][2]+fV0mom[1][2]+fBachMom[2];
	187	}
	188
	189	void AliESDcascade::GetXYZ(Double_t &x, Double_t &y, Double_t &z) const {
	190	//--------------------------------------------------------------------
	191	// This function returns cascade position (global)
	192	//--------------------------------------------------------------------
	193	x=fPos[0];
	194	y=fPos[1];
	195	z=fPos[2];
	196	}
	197
	198	Double_t AliESDcascade::GetD(Double_t x0, Double_t y0, Double_t z0) const {
	199	//--------------------------------------------------------------------
200	// This function returns the cascade impact parameter
201	//--------------------------------------------------------------------
202
203	Double_t x=fPos[0],y=fPos[1],z=fPos[2];
204	Double_t px=fV0mom[0][0]+fV0mom[1][0]+fBachMom[0];
205	Double_t py=fV0mom[0][1]+fV0mom[1][1]+fBachMom[1];
206	Double_t pz=fV0mom[0][2]+fV0mom[1][2]+fBachMom[2];
207
208	Double_t dx=(y0-y)pz - (z0-z)py;
209	Double_t dy=(x0-x)pz - (z0-z)px;
210	Double_t dz=(x0-x)py - (y0-y)px;
211	Double_t d=TMath::Sqrt((dxdx+dydy+dzdz)/(pxpx+pypy+pzpz));
212
213	return d;
214	}
215