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QuantumTomography.cxx
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QuantumTomography.cxx
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//_____________________________________________________________________________
/* - The following are code snippets adapted from the AliAODDimuon class.
- The problem is that that class was adapted specifically for the
- inclusive people's analysis, hence it is not fit for the UPC...
-
*/
Double_t AliAnalysisTaskUPCforward::CosThetaCollinsSoper( TLorentzVector muonPositive,
TLorentzVector muonNegative,
TLorentzVector possibleJPsi )
{
/* - This function computes the Collins-Soper cos(theta) for the
- helicity of the J/Psi.
- The idea should be to get back to a reference frame where it
- is easier to compute and to define the proper z-axis.
-
*/
/* - Half of the energy per pair of the colliding nucleons.
-
*/
Double_t HalfSqrtSnn = 2510.;
Double_t MassOfLead208 = 193.6823;
Double_t MomentumBeam = TMath::Sqrt( HalfSqrtSnn*HalfSqrtSnn*208*208 - MassOfLead208*MassOfLead208 );
/* - Fill the Lorentz vector for projectile and target.
- For the moment we do not consider the crossing angle.
- Projectile runs towards the MUON arm.
-
*/
TLorentzVector pProjCM(0.,0., -MomentumBeam, HalfSqrtSnn*208); // projectile
TLorentzVector pTargCM(0.,0., MomentumBeam, HalfSqrtSnn*208); // target
/* - Translate the dimuon parameters in the dimuon rest frame
-
*/
TVector3 beta = ( -1./possibleJPsi.E() ) * possibleJPsi.Vect();
TLorentzVector pMu1Dimu = muonPositive;
TLorentzVector pMu2Dimu = muonNegative;
TLorentzVector pProjDimu = pProjCM;
TLorentzVector pTargDimu = pTargCM;
pMu1Dimu.Boost(beta);
pMu2Dimu.Boost(beta);
pProjDimu.Boost(beta);
pTargDimu.Boost(beta);
/* - Determine the z axis for the CS angle.
-
*/
TVector3 zaxisCS=(((pProjDimu.Vect()).Unit())-((pTargDimu.Vect()).Unit())).Unit();
/* - Determine the CS angle (angle between mu+ and the z axis defined above)
-
*/
Double_t CosThetaCS = zaxisCS.Dot((pMu1Dimu.Vect()).Unit());
return CosThetaCS;
}
//_____________________________________________________________________________
Double_t AliAnalysisTaskUPCforward::CosPhiCollinsSoper( TLorentzVector muonPositive,
TLorentzVector muonNegative,
TLorentzVector possibleJPsi )
{
/* - This function computes the Collins-Soper PHI for the
- helicity of the J/Psi.
- The idea should be to get back to a reference frame where it
- is easier to compute and to define the proper z-axis.
-
*/
/* - Half of the energy per pair of the colliding nucleons.
-
*/
Double_t HalfSqrtSnn = 2510.;
Double_t MassOfLead208 = 193.6823;
Double_t MomentumBeam = TMath::Sqrt( HalfSqrtSnn*HalfSqrtSnn*208*208 - MassOfLead208*MassOfLead208 );
/* - Fill the Lorentz vector for projectile and target.
- For the moment we do not consider the crossing angle.
- Projectile runs towards the MUON arm.
-
*/
TLorentzVector pProjCM(0.,0., -MomentumBeam, HalfSqrtSnn*208); // projectile
TLorentzVector pTargCM(0.,0., MomentumBeam, HalfSqrtSnn*208); // target
/* - Translate the dimuon parameters in the dimuon rest frame
-
*/
TVector3 beta = ( -1./possibleJPsi.E() ) * possibleJPsi.Vect();
TLorentzVector pMu1Dimu = muonPositive;
TLorentzVector pMu2Dimu = muonNegative;
TLorentzVector pProjDimu = pProjCM;
TLorentzVector pTargDimu = pTargCM;
pMu1Dimu.Boost(beta);
pMu2Dimu.Boost(beta);
pProjDimu.Boost(beta);
pTargDimu.Boost(beta);
/* - Determine the z axis for the CS angle.
-
*/
TVector3 zaxisCS=(((pProjDimu.Vect()).Unit())-((pTargDimu.Vect()).Unit())).Unit();
//
// --- Determine the CS angle (angle between mu+ and the z axis defined above)
//
TVector3 yaxisCS=(((pProjDimu.Vect()).Unit()).Cross((pTargDimu.Vect()).Unit())).Unit();
TVector3 xaxisCS=(yaxisCS.Cross(zaxisCS)).Unit();
Double_t phi = TMath::ATan2((pMu1Dimu.Vect()).Dot(yaxisCS),((pMu1Dimu.Vect()).Dot(xaxisCS)));
return phi;
}
//_____________________________________________________________________________
/* -
- Quantum Tomography for CS.
-
*/
Double_t AliAnalysisTaskUPCforwardMC::CosThetaQuantumTomCS( TLorentzVector muonPositive,
TLorentzVector muonNegative,
TLorentzVector possibleJPsi )
{
/* - This function computes the Collins-Soper cos(theta) for the
- helicity of the J/Psi.
- The idea should be to get back to a reference frame where it
- is easier to compute and to define the proper z-axis.
-
*/
/* - Half of the energy per pair of the colliding nucleons.
-
*/
Double_t HalfSqrtSnn = 2510.;
Double_t MassOfLead208 = 193.6823;
Double_t MomentumBeam = TMath::Sqrt( HalfSqrtSnn*HalfSqrtSnn*208*208 - MassOfLead208*MassOfLead208 );
/* - Fill the Lorentz vector for projectile and target.
- For the moment we do not consider the crossing angle.
- Projectile runs towards the MUON arm.
-
*/
TLorentzVector pProjCM(0.,0., -MomentumBeam, HalfSqrtSnn*208); // projectile
TLorentzVector pTargCM(0.,0., MomentumBeam, HalfSqrtSnn*208); // target
TLorentzVector VectorMeson = possibleJPsi;
// cout << "Vector meson Px: " << VectorMeson.Px() << " X: " << VectorMeson.X() << endl;
// cout << "Vector meson Py: " << VectorMeson.Py() << " Y: " << VectorMeson.Y() << endl;
// cout << "Vector meson Pz: " << VectorMeson.Pz() << " Z: " << VectorMeson.Z() << endl;
// cout << "pProjCM Px: " << pProjCM.Px() << " X: " << pProjCM.X() << endl;
// cout << "pProjCM Py: " << pProjCM.Py() << " Y: " << pProjCM.Y() << endl;
// cout << "pProjCM Pz: " << pProjCM.Pz() << " Z: " << pProjCM.Z() << endl;
// cout << "pTargCM Px: " << pTargCM.Px() << " X: " << pTargCM.X() << endl;
// cout << "pTargCM Py: " << pTargCM.Py() << " Y: " << pTargCM.Y() << endl;
// cout << "pTargCM Pz: " << pTargCM.Pz() << " Z: " << pTargCM.Z() << endl;
// TLorentzVector QuantumZ = ( pProjCM*( VectorMeson.Dot(pTargCM) ) - pTargCM*( VectorMeson.Dot(pProjCM) ) ).Unit();
TLorentzVector QuantumZ = ( pProjCM*( VectorMeson.Dot(pTargCM) ) - pTargCM*( VectorMeson.Dot(pProjCM) ) );
// QuantumZ *= ( 1./QuantumZ.Mag2() );
Double_t xQuantumY = pProjCM.Pz()*pTargCM.E()*VectorMeson.Py()-pProjCM.E()*pTargCM.Pz()*VectorMeson.Py();
Double_t yQuantumY = -pProjCM.Pz()*pTargCM.E()*VectorMeson.Px()+pProjCM.E()*pTargCM.Pz()*VectorMeson.Px();
TLorentzVector QuantumYnotnormalised(xQuantumY, yQuantumY, 0., 0.);
// TLorentzVector QuantumY = QuantumYnotnormalised.Unit();
TLorentzVector QuantumY = QuantumYnotnormalised;
// QuantumY *= ( 1./QuantumY.Mag2() );
// TLorentzVector QuantumX = ( QuantumY.Dot(QuantumZ) ).Unit();
// TLorentzVector QuantumX = ( QuantumY.Dot(QuantumZ) );
// QuantumX *= ( 1./QuantumX.Mag2() );
TLorentzVector QuantumX = VectorMeson - pProjCM*(VectorMeson.Mag2()/( 2*(VectorMeson.Dot(pProjCM)) )) - pTargCM*(VectorMeson.Mag2()/( 2*(VectorMeson.Dot(pTargCM)) ));
// QuantumX *= ( 1./QuantumX.Mag2() );
TLorentzVector DifferenceMuons = muonPositive - muonNegative;
Double_t xFinalVector = QuantumX.Dot(DifferenceMuons);
Double_t yFinalVector = QuantumY.Dot(DifferenceMuons);
Double_t zFinalVector = QuantumZ.Dot(DifferenceMuons);
TVector3 FinalVector( xFinalVector, yFinalVector, zFinalVector );
Double_t CosThetaQuantumCS = ( FinalVector.Unit() ).Z();
Double_t SinThetaQuantumCS = TMath::Sqrt( 1 - CosThetaQuantumCS*CosThetaQuantumCS );
Double_t PhiQuantumCS = TMath::ASin( ( (FinalVector.Unit()).Y() )/ SinThetaQuantumCS );
return CosThetaQuantumCS;
}
//_____________________________________________________________________________
Double_t AliAnalysisTaskUPCforwardMC::PhiQuantumTomogrCS( TLorentzVector muonPositive,
TLorentzVector muonNegative,
TLorentzVector possibleJPsi )
{
/* - Quantum Tomography for CS.
-
*/
/* - Half of the energy per pair of the colliding nucleons.
-
*/
Double_t HalfSqrtSnn = 2510.;
Double_t MassOfLead208 = 193.6823;
Double_t MomentumBeam = TMath::Sqrt( HalfSqrtSnn*HalfSqrtSnn*208*208 - MassOfLead208*MassOfLead208 );
/* - Fill the Lorentz vector for projectile and target.
- For the moment we do not consider the crossing angle.
- Projectile runs towards the MUON arm.
-
*/
TLorentzVector pProjCM(0.,0., -MomentumBeam, HalfSqrtSnn*208); // projectile
TLorentzVector pTargCM(0.,0., MomentumBeam, HalfSqrtSnn*208); // target
TLorentzVector VectorMeson = possibleJPsi;
// TLorentzVector QuantumZ = ( pProjCM*( VectorMeson.Dot(pTargCM) ) - pTargCM*( VectorMeson.Dot(pProjCM) ) ).Unit();
TLorentzVector QuantumZ = ( pProjCM*( VectorMeson.Dot(pTargCM) ) - pTargCM*( VectorMeson.Dot(pProjCM) ) );
// QuantumZ *= ( 1./QuantumZ.Mag2() );
Double_t xQuantumY = -pProjCM.Pz()*pTargCM.E()*VectorMeson.Py()+pProjCM.E()*pTargCM.Pz()*VectorMeson.Py();
Double_t yQuantumY = pProjCM.Pz()*pTargCM.E()*VectorMeson.Px()+pProjCM.E()*pTargCM.Pz()*VectorMeson.Px();
TLorentzVector QuantumYnotnormalised(xQuantumY, yQuantumY, 0., 0.);
// TLorentzVector QuantumY = QuantumYnotnormalised.Unit();
TLorentzVector QuantumY = QuantumYnotnormalised;
// QuantumY *= ( 1./QuantumY.Mag2() );
// TLorentzVector QuantumX = ( QuantumY.Dot(QuantumZ) ).Unit();
// TLorentzVector QuantumX = ( QuantumY.Dot(QuantumZ) );
// QuantumX *= ( 1./QuantumX.Mag2() );
TLorentzVector QuantumX = VectorMeson - pProjCM*(VectorMeson.Mag2()/( 2*(VectorMeson.Dot(pProjCM)) )) - pTargCM*(VectorMeson.Mag2()/( 2*(VectorMeson.Dot(pTargCM)) ));
// QuantumX *= ( 1./QuantumX.Mag2() );
TLorentzVector DifferenceMuons = muonPositive - muonNegative;
Double_t xFinalVector = QuantumX.Dot(DifferenceMuons);
Double_t yFinalVector = QuantumY.Dot(DifferenceMuons);
Double_t zFinalVector = QuantumZ.Dot(DifferenceMuons);
TVector3 FinalVector( xFinalVector, yFinalVector, zFinalVector );
Double_t CosThetaQuantumCS = ( FinalVector.Unit() ).Z();
Double_t SinThetaQuantumCS = TMath::Sqrt( 1 - CosThetaQuantumCS*CosThetaQuantumCS );
Double_t PhiQuantumCS = TMath::ASin( ( (FinalVector.Unit()).Y() )/ SinThetaQuantumCS );
return PhiQuantumCS;
}
//_____________________________________________________________________________