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),
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);
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.;
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 )
}
+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)
{
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;
}
/* $Id$ */
//---------------------------------------------------------------------------------------------------
-////
-//// 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)
+//
+//---------------------------------------------------------------------------------------------------
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;