Added a new function to the AliDecayerExdous class for JPsi. And additionally I found...
authormorsch <andreas.morsch@cern.ch>
Thu, 5 Jun 2014 13:37:01 +0000 (15:37 +0200)
committermorsch <andreas.morsch@cern.ch>
Thu, 5 Jun 2014 13:37:01 +0000 (15:37 +0200)
Irem Erdemir <irem.erdemir@cern.ch>

EVGEN/AliDecayerExodus.cxx
EVGEN/AliDecayerExodus.h
PYTHIA6/AliDecayerPythia.cxx

index f0d98c4..866a8f5 100644 (file)
 
 ClassImp(AliDecayerExodus)
 
+//---------------------------------------------------------------------------------------------------
+//                                 
+// Generate electron-pair mass distributions for Dalitz decays according
+// to the Kroll-Wada parametrization: N. Kroll, W. Wada: Phys. Rev 98(1955)1355
+// and generate electron-pair mass distributions for resonances according
+// to the Gounaris-Sakurai parametrization: G.J. Gounaris, J.J. Sakurai: Phys.Rev.Lett. 21(1968)244 
+//
+// For the electromagnetic form factor the parameterization from
+// Lepton-G is used: L.G. Landsberg et al.: Phys. Rep. 128(1985)301
+//
+// Ralf Averbeck (R.Averbeck@gsi.de) 
+// Irem Erdemir  (irem.erdemir@cern.ch)
+//
+//---------------------------------------------------------------------------------------------------
+
+
 AliDecayerExodus::AliDecayerExodus():
     AliDecayer(),
     fEPMassPion(0),
@@ -276,7 +292,7 @@ void AliDecayerExodus::Init()
      weight_rho     = (Float_t)GounarisSakurai(mass_bin,vmass_rho,vwidth_rho,emass);
      weight_omega   = (Float_t)GounarisSakurai(mass_bin,vmass_omega,vwidth_omega,emass);
      weight_phi     = (Float_t)GounarisSakurai(mass_bin,vmass_phi,vwidth_phi,emass); 
-     weight_jpsi    = (Float_t)GounarisSakurai(mass_bin,vmass_jpsi,vwidth_jpsi,emass);
+     weight_jpsi    = (Float_t)Lorentz(mass_bin,vmass_jpsi,vwidth_jpsi);
 
      // Fill histograms of electron pair masses from resonance decays
      fEPMassRho  ->AddBinContent(ibin,weight_rho);
@@ -290,6 +306,7 @@ void AliDecayerExodus::Init()
 Double_t AliDecayerExodus::GounarisSakurai(Float_t mass, Double_t vmass, Double_t vwidth, Double_t emass)
 {
 // Invariant mass distributions of electron pairs from resonance decays
+// of rho, omega and phi
 // using Gounaris-Sakurai function
 
   Double_t corr = 0.;
@@ -297,10 +314,10 @@ Double_t AliDecayerExodus::GounarisSakurai(Float_t mass, Double_t vmass, Double_
   Double_t weight = 0.;
 
   Double_t pimass = 0.13956995;
+  corr = vwidth*(vmass/mass)*exp(1.5*log((mass*mass/4.0-pimass*pimass)
+         /(vmass*vmass/4.0-pimass*pimass)));
 
-  corr = vwidth*(vmass/mass)
-         * exp(1.5*log((mass*mass/4.0-pimass*pimass)
-          /(vmass*vmass/4.0-pimass*pimass)));
   epsilon = (emass/mass)*(emass/mass);
        
   if ( 1.0-4.0*epsilon>=0.0 )
@@ -313,6 +330,20 @@ Double_t AliDecayerExodus::GounarisSakurai(Float_t mass, Double_t vmass, Double_
 }
 
 
+Double_t AliDecayerExodus::Lorentz(Float_t mass, Double_t vmass, Double_t vwidth)
+{
+// Invariant mass distributions of electron pairs from resonance decay
+// of jpsi (and it can also be used for other particles except rho, omega and phi) 
+// using Lorentz function
+
+  Double_t weight;
+  
+  weight = (vwidth*vwidth/4.0)/(vwidth*vwidth/4.0+(vmass-mass)*(vmass-mass));
+
+  return weight;
+
+}
+
 void AliDecayerExodus::Decay(Int_t idpart, TLorentzVector* pparent)
 {
  
@@ -910,7 +941,15 @@ void AliDecayerExodus::Decay(Int_t idpart, TLorentzVector* pparent)
         mp_jpsi = pparent->M();
         }
      else{
-     mp_jpsi = 3.096;
+      /*Double_t x_jpsi=pparent->Px(); 
+      Double_t y_jpsi=pparent->Py(); 
+      Double_t z_jpsi=pparent->Pz();
+      Double_t t_jpsi=pparent->E();
+      Double_t p_jpsi=x_jpsi*x_jpsi+y_jpsi*y_jpsi+z_jpsi*z_jpsi;
+      Double_t Q2_jpsi= abs((t_jpsi*t_jpsi)-(p_jpsi*p_jpsi));
+      mp_jpsi = sqrt(Q2_jpsi);*/
+       
+      mp_jpsi = 3.096;
 
      }
     
index 3ba2857..615c3ad 100644 (file)
@@ -7,17 +7,19 @@
 /* $Id$ */
 
 //---------------------------------------------------------------------------------------------------
-////
-//// Generate electron-pair mass distributions for Dalitz decays according
-//// to the Kroll-Wada parametrization: N. Kroll, W. Wada: Phys. Rev 98(1955)1355
-//// and
-//// Generate electron-pair mass distributions for resonances according
-//// to the Gounaris-Sakurai parametrization: G.J. Gounaris, J.J. Sakurai: Phys.Rev.Lett. 21(1968)244 
-////
-//// For the electromagnetic form factor the parameterization from
-//// Lepton-G is used: L.G. Landsberg et al.: Phys. Rep. 128(1985)301
-////
-////-------------------------------------------------------------------------------------------------
+//                                 
+// Generate electron-pair mass distributions for Dalitz decays according
+// to the Kroll-Wada parametrization: N. Kroll, W. Wada: Phys. Rev 98(1955)1355
+// and generate electron-pair mass distributions for resonances according
+// to the Gounaris-Sakurai parametrization: G.J. Gounaris, J.J. Sakurai: Phys.Rev.Lett. 21(1968)244 
+//
+// For the electromagnetic form factor the parameterization from
+// Lepton-G is used: L.G. Landsberg et al.: Phys. Rep. 128(1985)301
+//
+// Ralf Averbeck (R.Averbeck@gsi.de) 
+// Irem Erdemir  (irem.erdemir@cern.ch)
+//
+//---------------------------------------------------------------------------------------------------
 
 
 
@@ -91,6 +93,7 @@ class AliDecayerExodus : public AliDecayer
 
  private:
     Double_t GounarisSakurai(Float_t mass, Double_t vmass, Double_t vwidth, Double_t emass);
+    Double_t Lorentz(Float_t mass, Double_t vmass, Double_t vwidth); 
     virtual void    Rot(Double_t pin[3], Double_t pout[3],
                         Double_t costheta, Double_t sintheta,
                         Double_t cosphi, Double_t sinphi) const;
index 0b9be55..7b2b325 100644 (file)
@@ -62,6 +62,7 @@ AliDecayerPythia::AliDecayerPythia():
     fHeavyFlavour(kTRUE),
     fLongLived(kFALSE),
     fPatchOmegaDalitz(0),
+    fDecayerExodus(0),
     fPi0(1)
 {
 // Default Constructor
@@ -76,6 +77,7 @@ AliDecayerPythia::AliDecayerPythia(const AliDecayerPythia &decayer):
     fHeavyFlavour(kTRUE),
     fLongLived(kFALSE),
     fPatchOmegaDalitz(0),
+    fDecayerExodus(0),
     fPi0(1)
 {
     // Copy Constructor