fChi2=7.;
}
-
-void AliV0vertex::ChangeMassHypothesis(Int_t code) {
+/*
+Double_t AliV0vertex::ChangeMassHypothesis(Int_t code) {
//--------------------------------------------------------------------
// This function changes the mass hypothesis for this V0
+ // and returns the "kinematical quality" of this hypothesis
//--------------------------------------------------------------------
- Double_t nmass, pmass;
+ Double_t nmass=0.13957, pmass=0.13957, mass=0.49767, des=0;
+
+ fPdgCode=code;
switch (code) {
case kLambda0:
- nmass=0.13957; pmass=0.93827; break;
+ nmass=0.13957; pmass=0.93827; mass=1.1157; des=0.9437-0.1723; break;
case kLambda0Bar:
- pmass=0.13957; nmass=0.93827; break;
+ pmass=0.13957; nmass=0.93827; mass=1.1157; des=0.1723-0.9437; break;
case kK0Short:
- nmass=0.13957; pmass=0.13957; break;
+ break;
default:
cerr<<"AliV0vertex::ChangeMassHypothesis: ";
cerr<<"invalide PDG code ! Assuming K0s...\n";
- nmass=0.13957; pmass=0.13957; break;
+ fPdgCode=kK0Short;
+ break;
}
- Double_t px1=fNmom[0], py1=fNmom[1], pz1=fNmom[2];
- Double_t px2=fPmom[0], py2=fPmom[1], pz2=fPmom[2];
+ Double_t pxn=fNmom[0], pyn=fNmom[1], pzn=fNmom[2];
+ Double_t pxp=fPmom[0], pyp=fPmom[1], pzp=fPmom[2];
- Double_t e1=TMath::Sqrt(nmass*nmass + px1*px1 + py1*py1 + pz1*pz1);
- Double_t e2=TMath::Sqrt(pmass*pmass + 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));
+ Double_t en=TMath::Sqrt(nmass*nmass + pxn*pxn + pyn*pyn + pzn*pzn);
+ Double_t ep=TMath::Sqrt(pmass*pmass + pxp*pxp + pyp*pyp + pzp*pzp);
+ Double_t pxl=pxn+pxp, pyl=pyn+pyp, pzl=pzn+pzp;
+ Double_t pl=TMath::Sqrt(pxl*pxl + pyl*pyl + pzl*pzl);
+
+ fEffMass=TMath::Sqrt((en+ep)*(en+ep)-pl*pl);
+
+ Double_t gamma=(en+ep)/mass, betagamma=pl/mass;
+ Double_t pln=(pxn*pxl + pyn*pyl + pzn*pzl)/pl;
+ Double_t plp=(pxp*pxl + pyp*pyl + pzp*pzl)/pl;
+ Double_t plps=gamma*plp - betagamma*ep;
+
+ Double_t diff=2*gamma*plps + betagamma*des;
+
+ return (plp-pln-diff);
+}
+*/
+Double_t AliV0vertex::ChangeMassHypothesis(Int_t code) {
+ //--------------------------------------------------------------------
+ // This function changes the mass hypothesis for this V0
+ // and returns the "kinematical quality" of this hypothesis
+ //--------------------------------------------------------------------
+ Double_t nmass=0.13957, pmass=0.13957, mass=0.49767, ps=0.206;
+
fPdgCode=code;
+
+ switch (code) {
+ case kLambda0:
+ nmass=0.13957; pmass=0.93827; mass=1.1157; ps=0.101; break;
+ case kLambda0Bar:
+ pmass=0.13957; nmass=0.93827; mass=1.1157; ps=0.101; break;
+ case kK0Short:
+ break;
+ default:
+ cerr<<"AliV0vertex::ChangeMassHypothesis: ";
+ cerr<<"invalide PDG code ! Assuming K0s...\n";
+ fPdgCode=kK0Short;
+ 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 en=TMath::Sqrt(nmass*nmass + pxn*pxn + pyn*pyn + pzn*pzn);
+ Double_t ep=TMath::Sqrt(pmass*pmass + pxp*pxp + pyp*pyp + pzp*pzp);
+ Double_t pxl=pxn+pxp, pyl=pyn+pyp, pzl=pzn+pzp;
+ Double_t pl=TMath::Sqrt(pxl*pxl + pyl*pyl + pzl*pzl);
+
+ fEffMass=TMath::Sqrt((en+ep)*(en+ep)-pl*pl);
+
+ Double_t beta=pl/(en+ep);
+ Double_t pln=(pxn*pxl + pyn*pyl + pzn*pzl)/pl;
+ Double_t plp=(pxp*pxl + pyp*pyl + pzp*pzl)/pl;
+
+ Double_t pt2=pxp*pxp + pyp*pyp + pzp*pzp - plp*plp;
+
+ Double_t a=(plp-pln)/(plp+pln);
+ a -= (pmass*pmass-nmass*nmass)/(mass*mass);
+ a = 0.25*beta*beta*mass*mass*a*a + pt2;
+
+ return (a - ps*ps);
+
}
void AliV0vertex::GetPxPyPz(Double_t &px, Double_t &py, Double_t &pz) const {