AliGenCorrHF generator for correlated heavy flavor. (Smbat Grigoryan)
authormorsch <morsch@f7af4fe6-9843-0410-8265-dc069ae4e863>
Mon, 18 Dec 2006 17:32:38 +0000 (17:32 +0000)
committermorsch <morsch@f7af4fe6-9843-0410-8265-dc069ae4e863>
Mon, 18 Dec 2006 17:32:38 +0000 (17:32 +0000)
EVGEN/AliGenCorrHF.cxx [new file with mode: 0644]
EVGEN/AliGenCorrHF.h [new file with mode: 0644]
EVGEN/EVGENLinkDef.h
EVGEN/libEVGEN.pkg

diff --git a/EVGEN/AliGenCorrHF.cxx b/EVGEN/AliGenCorrHF.cxx
new file mode 100644 (file)
index 0000000..626b3f9
--- /dev/null
@@ -0,0 +1,729 @@
+/**************************************************************************
+ * 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.                  *
+ **************************************************************************/
+
+/* $Id$ */
+
+// Class to generate correlated Heavy Flavor hadron pairs (one or several pairs
+// per event) using paramtrized kinematics of quark pairs from some generator
+// and quark fragmentation functions.
+// Is a generalisation of AliGenParam class for correlated pairs of hadrons.
+// In this version quark pairs and fragmentation functions are obtained from
+// Pythia6.124 using 100K events generated with kCharmppMNRwmi & kBeautyppMNRwmi 
+// in pp collisions at 14 TeV.
+// Decays are performed by Pythia. Used AliRoot version: v4-04-Release
+// Author: S. Grigoryan, LPC Clermont-Fd & YerPhI, Smbat.Grigoryan@cern.ch
+//
+//-------------------------------------------------------------------------
+// How it works (for the given flavor):
+//
+// 1) Reads QQbar kinematical grid from the Input file and generates
+// quark pairs according to the weights of the cells.
+// It is a 5D grid in y1,y2,pt1,pt2 and deltaphi, with occupancy weights
+// of the cells obtained from Pythia (see details in GetQuarkPair).
+// 2) Reads "soft" and "hard" fragmentation functions (12 2D-histograms each,
+// for 12 pt bins) from the Input file, applies to quarks and produces hadrons
+// (only lower states, with proportions of species obtained from Pythia).
+// Fragmentation functions are the same for all hadron species and depend
+// on 2 variables - light cone energy-momentum fractions:
+//     z1=(E_H + Pz_H)/(E_Q + Pz_Q),  z2=(E_H - Pz_H)/(E_Q - Pz_Q).
+// "soft" & "hard" FFs correspond to "slower" & "faster" quark of a pair 
+// (see details in GetHadronPair).
+// 3) Decays the hadrons and saves all the particles in the event stack in the
+// following order: HF hadron from Q, then its decay products, then HF hadron
+// from Qbar, then its decay productes, then next HF hadon pair (if any) 
+// in the same way, etc... 
+// 4) It is fast, e.g., generates the same number of events with a beauty pair 
+//  ~15 times faster than AliGenPythia with kBeautyppMNRwmi (w/o tracking)
+//
+// An Input file for each quark flavor is included in EVGEN/dataCorrHF/
+// One can use also user-defined Input files.
+//
+// More details could be found in my presentation at DiMuonNet Workshop, Dec 2006: 
+// http://www-dapnia.cea.fr/Sphn/Alice/DiMuonNet
+// and will be published in an Internal Note. 
+//
+//-------------------------------------------------------------------------
+// How to use it:
+//
+// add the following typical lines in Config.C
+/*
+  if (!strcmp(option,"corr")) {
+    // Example for correlated charm or beauty hadron pair production 
+
+    // AliGenCorrHF *gener = new AliGenCorrHF(1, 4);  // for charm, 1 pair per event
+    AliGenCorrHF *gener = new AliGenCorrHF(1, 5);  // for beauty, 1 pair per event
+
+    gener->SetMomentumRange(0,9999);
+    gener->SetCutOnChild(0);        // 1/0 means cuts on children enable/disable
+    gener->SetChildThetaRange(171.0,178.0);
+    gener->SetOrigin(0,0,0);          //vertex position    
+    gener->SetSigma(0,0,0);           //Sigma in (X,Y,Z) (cm) on IP position
+    gener->SetForceDecay(kSemiMuonic);
+    gener->SetTrackingFlag(0);
+    gener->Init();
+}
+*/
+// and in aliroot do e.g. gAlice->Run(10,"Config.C") to produce 10 events.
+// One can include AliGenCorrHF in an AliGenCocktail generator.
+//--------------------------------------------------------------------------
+
+#include <TFile.h>
+#include <TTree.h>
+#include <TH2F.h>
+#include <TMath.h>
+#include <TRandom.h>
+#include <TROOT.h>
+#include <TLorentzVector.h>
+#include <TParticle.h>
+#include <TParticlePDG.h>
+#include <TDatabasePDG.h>
+#include <TVirtualMC.h>
+#include <TCanvas.h>
+#include <Riostream.h>
+
+#include "AliGenCorrHF.h"
+#include "AliLog.h"
+#include "AliConst.h"
+#include "AliDecayer.h"
+#include "AliMC.h"
+#include "AliRun.h"
+
+ClassImp(AliGenCorrHF)
+
+  //Begin_Html
+  /*
+    <img src="picts/AliGenCorrHF.gif">
+  */
+  //End_Html
+
+Double_t AliGenCorrHF::fgdph[19] = {0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180};
+Double_t AliGenCorrHF::fgy[31] = {-10,-7, -6.5, -6, -5.5, -5, -4.5, -4, -3.5, -3, -2.5, -2,- 1.5, -1, -0.5, 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 10};
+Double_t AliGenCorrHF::fgpt[33] = {0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.6, 7.2, 7.8, 8.4, 9, 9.6, 10.3, 11.1, 12, 13.1, 14.3, 15.6, 17.1, 19, 21, 24, 28, 35, 50, 100};
+Int_t AliGenCorrHF::fgnptbins = 12;
+Double_t AliGenCorrHF::fgptbmin[12] = {0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 9};
+Double_t AliGenCorrHF::fgptbmax[12] = {0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 9, 100};
+
+Double_t* AliGenCorrHF::fgIntegral = 0;
+
+//____________________________________________________________
+    AliGenCorrHF::AliGenCorrHF():
+       fFileName(0),
+       fFile(0),
+       fQuark(0),
+       fBias(0.),
+       fTrials(0),
+       fDecayer(0)
+{
+// Default constructor
+}
+
+//____________________________________________________________
+AliGenCorrHF::AliGenCorrHF(Int_t npart, Int_t param):
+    AliGenMC(npart),
+    fFileName(0),
+    fFile(0),
+    fQuark(param),
+    fBias(0.),
+    fTrials(0),
+    //    fDecayer(new AliDecayerPythia())
+    fDecayer(0)
+{
+// Constructor using number of particles, quark type & default InputFile
+//
+    if (fQuark != 5) fQuark = 4;
+    fFileName = "$ALICE_ROOT/EVGEN/dataCorrHF/CharmppMNRwmiCorr100K.root";
+    if (fQuark == 5) fFileName = "$ALICE_ROOT/EVGEN/dataCorrHF/BeautyppMNRwmiCorr100K.root";
+
+    fName = "Default";
+    fTitle= "Generator for correlated pairs of HF hadrons";
+      
+    fChildSelect.Set(5);
+    for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
+    SetForceDecay();
+    SetCutOnChild();
+    SetChildMomentumRange();
+    SetChildPtRange();
+    SetChildPhiRange();
+    SetChildThetaRange(); 
+}
+
+//___________________________________________________________________
+AliGenCorrHF::AliGenCorrHF(char* tname, Int_t npart, Int_t param):
+    AliGenMC(npart),
+    fFileName(tname),
+    fFile(0),
+    fQuark(param),
+    fBias(0.),
+    fTrials(0),
+    //    fDecayer(new AliDecayerPythia())
+    fDecayer(0)
+{
+// Constructor using number of particles, quark type & user-defined InputFile
+//
+    if (fQuark != 5) fQuark = 4;
+    fName = "UserDefined";
+    fTitle= "Generator for correlated pairs of HF hadrons";
+      
+    fChildSelect.Set(5);
+    for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
+    SetForceDecay();
+    SetCutOnChild();
+    SetChildMomentumRange();
+    SetChildPtRange();
+    SetChildPhiRange();
+    SetChildThetaRange(); 
+}
+
+//____________________________________________________________
+AliGenCorrHF::AliGenCorrHF(const AliGenCorrHF & CorrHF)
+    :AliGenMC(CorrHF), 
+     fFileName(0),
+     fFile(0),
+     fQuark(0),
+     fBias(0.),
+     fTrials(0),
+     fDecayer(0)
+{
+// Copy constructor
+    CorrHF.Copy(*this);
+}
+
+//____________________________________________________________
+AliGenCorrHF::~AliGenCorrHF()
+{
+// Destructor
+  delete fFile;
+}
+
+//____________________________________________________________
+void AliGenCorrHF::Init()
+{
+// Initialisation
+
+  AliInfo(Form(" QQbar kinematics and fragm. functions from:  %s",fFileName.Data() )); 
+    fFile = TFile::Open(fFileName.Data());
+    if(!fFile->IsOpen()){
+      AliError(Form("Could not open file %s",fFileName.Data() ));
+    }
+
+    ComputeIntegral(fFile);
+
+    fParentWeight = 1./fNpart;   // fNpart is number of HF-hadron pairs
+
+// particle decay related initialization
+
+    if (gMC) fDecayer = gMC->GetDecayer();
+    fDecayer->SetForceDecay(fForceDecay);
+    fDecayer->Init();
+
+//
+    AliGenMC::Init();
+}
+
+//____________________________________________________________
+void AliGenCorrHF::Generate()
+{
+//
+// Generate fNpart of correlated HF hadron pairs per event
+// in the the desired theta and momentum windows (phi = 0 - 2pi). 
+// Gaussian smearing on the vertex is done if selected. 
+// The decay of heavy hadrons is done using lujet, 
+//    and the childern particle are tracked by GEANT
+// However, light mesons are directly tracked by GEANT 
+// setting fForceDecay = nodecay (SetForceDecay(nodecay)) 
+//
+
+
+  Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
+  Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
+  Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
+  Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
+  Float_t p[3], pc[3], och[3];// Momentum, polarisation and origin of the children particles from lujet
+
+
+  Double_t dphi=0, ptq[2], yq[2], pth[2], plh[2], ph[2], phih[2];
+  Int_t i, j, ipair, ihadron[2];
+  for (i=0; i<2; i++) { 
+    ptq[i] =0; 
+    yq[i]  =0; 
+    pth[i] =0; 
+    plh[i] =0; 
+    ihadron[i] =0; 
+  }
+
+  static TClonesArray *particles;
+  //
+  if(!particles) particles = new TClonesArray("TParticle",1000);
+  
+  TDatabasePDG* pDataBase = TDatabasePDG::Instance();
+// Calculating vertex position per event
+  for (j=0;j<3;j++) origin0[j]=fOrigin[j];
+  if(fVertexSmear==kPerEvent) {
+      Vertex();
+      for (j=0;j<3;j++) origin0[j]=fVertex[j];
+  }
+  
+  Float_t wgtp, wgtch, random[6];
+  Int_t ipap = 0;
+  Int_t nt   = 0;
+
+// Generating fNpart HF-hadron pairs per event
+  while(ipap<fNpart) {
+
+    while(1) {
+
+      GetQuarkPair(fFile, fgIntegral, yq[0], yq[1], ptq[0], ptq[1], dphi);
+
+      GetHadronPair(fFile, fQuark, yq[0], yq[1], ptq[0], ptq[1], ihadron[0], ihadron[1], plh[0], plh[1], pth[0], pth[1]);
+
+// Here we assume that  |phi_H1 - phi_H2| = |phi_Q1 - phi_Q2| = dphi
+// which is a good approximation for heavy flavors in Pythia
+
+      /* // doesn't work if PhiMax < k2PI or PhiMin > 0, since dphi = 0 - 180 
+      phih[0] = fPhiMin + Rndm()*(fPhiMax-fPhiMin);
+      phih[1] = phih[0] + dphi*kDegrad;
+      if (phih[0] > fPhiMax/2.) phih[1] = phih[0] - dphi*kDegrad;
+      */
+      phih[0] = Rndm()*k2PI;
+      phih[1] = phih[0] + dphi*kDegrad; 
+      if (phih[0] > TMath::Pi()) phih[1] = phih[0] - dphi*kDegrad;
+
+// Cut on theta
+      theta=TMath::ATan2(pth[0],plh[0]);
+      if(theta<fThetaMin || theta>fThetaMax) continue;
+      theta=TMath::ATan2(pth[1],plh[1]);
+      if(theta<fThetaMin || theta>fThetaMax) continue;
+
+// Cut on momentum
+      ph[0]=TMath::Sqrt(pth[0]*pth[0]+plh[0]*plh[0]);
+      if (ph[0]<fPMin || ph[0]>fPMax) continue;
+      ph[1]=TMath::Sqrt(pth[1]*pth[1]+plh[1]*plh[1]);
+      if (ph[1]<fPMin || ph[1]>fPMax) continue;
+
+// Common origin for particles of the HF-hadron pair
+      if(fVertexSmear==kPerTrack) {
+         Rndm(random,6);
+         for (j=0;j<3;j++) {
+             origin0[j]=
+               fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
+               TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
+         }
+      }
+
+      Int_t np1=0, kf1[100], select1[100], iparent1[100], trackIt1[100];
+      Float_t  wgtch1=0, p1[3], pc1[100][3], och1[100][3];
+
+      for (j=0; j<3; j++)   p1[j] = 0;
+      for (i=0; i<100; i++) {
+       kf1[i]      = 0;  
+       select1[i]  = 0;  
+       iparent1[i] = 0;  
+       trackIt1[i] = 0;
+       for (j=0; j<3; j++) {
+         pc1[i][j]  = 0;
+         och1[i][j] = 0;
+       }
+      }
+
+//
+// Loop over particles of the HF-hadron pair
+      Int_t nhadron = 0;
+      for (ipair=0;ipair<2;ipair++) {
+       phi  = phih[ipair];
+       pl   = plh[ipair];
+       pt   = pth[ipair];
+       ptot = ph[ipair];
+//
+// particle type 
+         Int_t iPart = ihadron[ipair];
+         Float_t am  = pDataBase->GetParticle(iPart)->Mass();
+          fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
+
+          wgtp  = fParentWeight;
+         wgtch = fChildWeight;
+
+//
+         p[0]=pt*TMath::Cos(phi);
+         p[1]=pt*TMath::Sin(phi);
+         p[2]=pl;
+         
+// Looking at fForceDecay : 
+// if fForceDecay != none Primary particle decays using 
+// AliPythia and children are tracked by GEANT
+//
+// if fForceDecay == none Primary particle is tracked by GEANT 
+// (In the latest, make sure that GEANT actually does all the decays you want)   
+//
+
+         if (fForceDecay != kNoDecay) {
+// Using lujet to decay particle
+             Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
+             TLorentzVector pmom(p[0], p[1], p[2], energy);
+             fDecayer->Decay(iPart,&pmom);
+//
+// select decay particles
+             Int_t np=fDecayer->ImportParticles(particles);
+
+//  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
+             if (fGeometryAcceptance)
+               if (!CheckAcceptanceGeometry(np,particles)) break;
+             Int_t ncsel=0;
+             Int_t* pParent    = new Int_t[np];
+             Int_t* pSelected  = new Int_t[np];
+             Int_t* trackIt    = new Int_t[np];
+
+             for (i=0; i<np; i++) {
+                 pSelected[i] =  0;
+                 pParent[i]   = -1;
+             }
+             
+             if (np >1) {
+                 TParticle* iparticle =  (TParticle *) particles->At(0);
+                 for (i=1; i<np; i++) {
+                     trackIt[i] = 1;
+                     iparticle = (TParticle *) particles->At(i);
+                     Int_t kf = iparticle->GetPdgCode();
+                     Int_t ks = iparticle->GetStatusCode();
+
+// particles with long life-time (c tau > .3 mum)
+                     if (ks != 1) { 
+                         Double_t lifeTime = fDecayer->GetLifetime(kf);
+                         if (lifeTime <= (Double_t) fMaxLifeTime) {
+                             trackIt[i]     = 0;
+                             pSelected[i]   = 1;
+                         }
+                     } // ks==1 ?
+//
+// children, discard neutrinos
+                     if (TMath::Abs(kf) == 12 || TMath::Abs(kf) == 14) continue;
+                     if (trackIt[i])
+                     {
+                         if (fCutOnChild) {
+                             pc[0]=iparticle->Px();
+                             pc[1]=iparticle->Py();
+                             pc[2]=iparticle->Pz();
+                             Bool_t  childok = KinematicSelection(iparticle, 1);
+                             if(childok) {
+                                 pSelected[i]  = 1;
+                                 ncsel++;
+                             } else {
+                                 ncsel=-1;
+                                 break;
+                             } // child kine cuts
+                         } else {
+                             pSelected[i]  = 1;
+                             ncsel++;
+                         } // if child selection
+                     } // select muon
+                 } // decay particle loop
+             } // if decay products
+             
+             Int_t iparent;
+             if ((fCutOnChild && ncsel >0) || !fCutOnChild){
+
+                 nhadron++;
+//
+// Parents and Decay Products
+                 if (ipair == 0) {
+                     np1    = np;
+                     wgtch1 = wgtch;
+                     p1[0] = p[0]; p1[1] = p[1]; p1[2] = p[2];
+                 } else {
+                     ipap++;
+                     PushTrack(0, -1, ihadron[0], p1, origin0, polar, 0, 
+                               kPPrimary, nt, wgtp);
+                     KeepTrack(nt);
+                     for (i = 1; i < np1; i++) {
+                       if (select1[i]) {
+                         for (j=0; j<3; j++) {
+                             och[j] = och1[i][j];
+                             pc[j]  = pc1[i][j];
+                         }
+                         PushTrack(fTrackIt*trackIt1[i], iparent1[i], kf1[i], pc, och,
+                                   polar, 0, kPDecay, nt, wgtch1);
+                         KeepTrack(nt);
+                         }
+                     }
+                     PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
+                     KeepTrack(nt);
+                 } 
+                 pParent[0] = nt;
+//
+// Decay Products
+                 Int_t ntcount = 0;
+                 for (i = 1; i < np; i++) {
+                   if (pSelected[i]) {
+                         TParticle* iparticle = (TParticle *) particles->At(i);
+                         Int_t kf  = iparticle->GetPdgCode();
+                         Int_t ipa = iparticle->GetFirstMother()-1;
+
+                         och[0] = origin0[0]+iparticle->Vx()/10;
+                         och[1] = origin0[1]+iparticle->Vy()/10;
+                         och[2] = origin0[2]+iparticle->Vz()/10;
+                         pc[0]  = iparticle->Px();
+                         pc[1]  = iparticle->Py();
+                         pc[2]  = iparticle->Pz();
+                         
+                         if (ipa > -1) {
+                             iparent = pParent[ipa];
+                         } else {
+                             iparent = -1;
+                         }
+
+                         if (ipair == 0) {
+                             kf1[i]      = kf;  
+                             select1[i]  = pSelected[i];
+                             iparent1[i] = iparent;
+                             trackIt1[i] = trackIt[i];
+                             for (j=0; j<3; j++) {
+                                 och1[i][j] = och[j];
+                                 pc1[i][j]  = pc[j];
+                             }
+                             ntcount++;
+                         } else {
+                           PushTrack(fTrackIt*trackIt[i], iparent, kf, pc, och,
+                                     polar, 0, kPDecay, nt, wgtch);
+                           KeepTrack(nt); 
+                         } 
+                         pParent[i] = nt + ntcount;
+                   } // Selected
+                 } // Particle loop 
+             }  // Decays by Lujet
+             particles->Clear();
+             if (pParent)    delete[] pParent;
+             if (pSelected)  delete[] pSelected;          
+             if (trackIt)    delete[] trackIt;
+         } // kinematic selection
+         else  // nodecay option, so parent will be tracked by GEANT
+         {
+           nhadron++;
+           if (ipair == 0) {
+               p1[0] = p[0]; p1[1] = p[1]; p1[2] = p[2];
+           } else {
+               ipap++;
+               gAlice->GetMCApp()->
+               PushTrack(fTrackIt,-1,ihadron[0],p1,origin0,polar,0,kPPrimary,nt,wgtp);
+               gAlice->GetMCApp()->
+               PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
+           }
+         }
+         if (nhadron == 0) break;
+      } // ipair loop
+      if (nhadron != 2) continue;
+      break;
+    } // while(1)
+    nt++;
+  } // while(ipa<fNpart) --> event loop
+
+  SetHighWaterMark(nt);
+}
+
+//____________________________________________________________________________________
+AliGenCorrHF& AliGenCorrHF::operator=(const  AliGenCorrHF& rhs)
+{
+// Assignment operator
+    rhs.Copy(*this);
+    return *this;
+}
+
+//____________________________________________________________________________________
+Int_t AliGenCorrHF::IpCharm(TRandom* ran)
+{  
+// Composition of lower state charm hadrons, containing a c-quark
+    Float_t random;
+    Int_t ip;            // +- 411,421,431,4122,4132,4232,4332
+    random = ran->Rndm();
+//  Rates from Pythia6.214 using 100Kevents with kPyCharmppMNRwmi at 14 TeV.   
+  
+    if (random < 0.6027) {                       
+        ip=421;
+    } else if (random < 0.7962) {
+        ip=411;
+    } else if (random < 0.9127) {
+        ip=431;        
+    } else if (random < 0.9899) {
+        ip=4122;        
+    } else if (random < 0.9948) {
+        ip=4132;        
+    } else if (random < 0.9999) {
+        ip=4232;        
+    } else {
+        ip=4332;
+    }
+    
+    return ip;
+}
+
+Int_t AliGenCorrHF::IpBeauty(TRandom* ran)
+{  
+// Composition of lower state beauty hadrons, containing a b-quark
+    Float_t random;
+    Int_t ip;            // +- 511,521,531,5122,5132,5232,5332
+    random = ran->Rndm(); 
+//  Rates from Pythia6.214 using 100Kevents with kPyBeautyppMNRwmi at 14 TeV.   
+                        // B-Bbar mixing will be done by Pythia at the decay point
+ if (random < 0.3965) {                       
+        ip=-511;
+    } else if (random < 0.7930) {
+        ip=-521;
+    } else if (random < 0.9112) {
+        ip=-531;        
+    } else if (random < 0.9887) {
+        ip=5122;        
+    } else if (random < 0.9943) {
+        ip=5132;        
+    } else if (random < 0.9999) {
+        ip=5232;        
+    } else {
+        ip=5332;
+    }
+    
+  return ip;
+}
+
+//____________________________________________________________________________________
+Double_t AliGenCorrHF::ComputeIntegral(TFile* fG)       // needed by GetQuarkPair
+{
+   // Read QQbar kinematical 5D grid's cell occupancy weights
+   Int_t* cell = new Int_t[6];           // cell[6]={wght,iy1,iy2,ipt1,ipt2,idph}
+   TTree* tG = (TTree*) fG->Get("tGqq");
+   tG->GetBranch("cell")->SetAddress(cell);
+   Int_t nbins = tG->GetEntries();
+
+   //   delete previously computed integral (if any)
+   if(fgIntegral) delete [] fgIntegral;
+
+   fgIntegral = new Double_t[nbins+1];
+   fgIntegral[0] = 0;
+   Int_t bin;
+   for(bin=0;bin<nbins;bin++) {
+     tG->GetEvent(bin);
+     fgIntegral[bin+1] = fgIntegral[bin] + cell[0];
+   }
+   //   Normalize integral to 1
+   if (fgIntegral[nbins] == 0 ) {
+      return 0;
+   }
+   for (bin=1;bin<=nbins;bin++)  fgIntegral[bin] /= fgIntegral[nbins];
+
+   return fgIntegral[nbins];
+}
+
+//____________________________________________________________________________________
+void AliGenCorrHF::GetQuarkPair(TFile* fG, Double_t* fInt, Double_t &y1, Double_t &y2, Double_t &pt1, Double_t &pt2, Double_t &dphi)              
+                                 // modification of ROOT's TH3::GetRandom3 for 5D
+{
+   // Read QQbar kinematical 5D grid's cell coordinates
+   Int_t* cell = new Int_t[6];           // cell[6]={wght,iy1,iy2,ipt1,ipt2,idph}
+   TTree* tG = (TTree*) fG->Get("tGqq");
+   tG->GetBranch("cell")->SetAddress(cell);
+   Int_t nbins = tG->GetEntries();
+   Double_t rand[6];
+   gRandom->RndmArray(6,rand);
+   Int_t ibin = TMath::BinarySearch(nbins,fInt,rand[0]);
+   tG->GetEvent(ibin);
+   y1   = fgy[cell[1]]  + (fgy[cell[1]+1]-fgy[cell[1]])*rand[1];
+   y2   = fgy[cell[2]]  + (fgy[cell[2]+1]-fgy[cell[2]])*rand[2];
+   pt1  = fgpt[cell[3]] + (fgpt[cell[3]+1]-fgpt[cell[3]])*rand[3];
+   pt2  = fgpt[cell[4]] + (fgpt[cell[4]+1]-fgpt[cell[4]])*rand[4];
+   dphi = fgdph[cell[5]]+ (fgdph[cell[5]+1]-fgdph[cell[5]])*rand[5];
+}
+
+//____________________________________________________________________________________
+void AliGenCorrHF::GetHadronPair(TFile* fG, Int_t idq, Double_t y1, Double_t y2, Double_t pt1, Double_t pt2, Int_t &id3, Int_t &id4, Double_t &pz3, Double_t &pz4, Double_t &pt3, Double_t &pt4) 
+{
+    // Generate a hadron pair
+    Int_t (*fIpParaFunc )(TRandom*);//Pointer to particle type parametrisation function
+    fIpParaFunc = IpCharm;
+    Double_t mq = 1.2;              // c & b quark masses (used in AliPythia)
+    if (idq == 5) {
+      fIpParaFunc = IpBeauty;
+      mq = 4.75;
+    }
+    Double_t z11, z12, z21, z22, pz1, pz2, e1, e2, mh, ptemp, rand[2];
+    char tag[100]; 
+    TH2F *h2h[12], *h2s[12];      // hard & soft Fragmentation Functions
+    for (Int_t ipt = 0; ipt<fgnptbins; ipt++) { 
+      sprintf(tag,"h2h_pt%d",ipt); 
+      h2h[ipt] = (TH2F*) fG->Get(tag); 
+      sprintf(tag,"h2s_pt%d",ipt); 
+      h2s[ipt] = (TH2F*) fG->Get(tag); 
+    }
+
+       if (y1*y2 < 0) {
+        for (Int_t ipt = 0; ipt<fgnptbins; ipt++) { 
+          if(pt1 >= fgptbmin[ipt] && pt1 < fgptbmax[ipt]) 
+            h2h[ipt]->GetRandom2(z11, z21);
+          if(pt2 >= fgptbmin[ipt] && pt2 < fgptbmax[ipt]) 
+            h2h[ipt]->GetRandom2(z12, z22); 
+        }
+       }
+       else {
+        if (TMath::Abs(y1) > TMath::Abs(y2)) {
+          for (Int_t ipt = 0; ipt<fgnptbins; ipt++) { 
+            if(pt1 >= fgptbmin[ipt] && pt1 < fgptbmax[ipt]) 
+              h2h[ipt]->GetRandom2(z11, z21);
+            if(pt2 >= fgptbmin[ipt] && pt2 < fgptbmax[ipt]) 
+              h2s[ipt]->GetRandom2(z12, z22); 
+          }
+        }
+        else {
+          for (Int_t ipt = 0; ipt<fgnptbins; ipt++) { 
+            if(pt1 >= fgptbmin[ipt] && pt1 < fgptbmax[ipt]) 
+              h2s[ipt]->GetRandom2(z11, z21);
+            if(pt2 >= fgptbmin[ipt] && pt2 < fgptbmax[ipt]) 
+              h2h[ipt]->GetRandom2(z12, z22); 
+          }
+        }
+       }
+      gRandom->RndmArray(2,rand);
+      ptemp = TMath::Sqrt(pt1*pt1 + mq*mq);
+      pz1   = ptemp*TMath::SinH(y1); 
+      e1    = ptemp*TMath::CosH(y1); 
+      ptemp = TMath::Sqrt(pt2*pt2 + mq*mq);
+      pz2   = ptemp*TMath::SinH(y2); 
+      e2    = ptemp*TMath::CosH(y2); 
+
+      id3   = fIpParaFunc(gRandom);
+      mh    = TDatabasePDG::Instance()->GetParticle(id3)->Mass();
+      ptemp = z11*z21*(e1*e1-pz1*pz1) - mh*mh;
+      pt3   = (idq-3)*rand[0];                // some smearing at low pt, try better
+      if (ptemp > 0) pt3 = TMath::Sqrt(ptemp);
+      if (pz1 > 0)   pz3 = (z11*(e1 + pz1) - z21*(e1 - pz1)) / 2;
+      else           pz3 = (z21*(e1 + pz1) - z11*(e1 - pz1)) / 2;
+      e1 = TMath::Sqrt(pz3*pz3 + pt3*pt3 + mh*mh);
+
+      id4   = - fIpParaFunc(gRandom);
+      mh    = TDatabasePDG::Instance()->GetParticle(id4)->Mass();
+      ptemp = z12*z22*(e2*e2-pz2*pz2) - mh*mh;
+      pt4   = (idq-3)*rand[1];                // some smearing at low pt, try better
+      if (ptemp > 0) pt4 = TMath::Sqrt(ptemp);
+      if (pz2 > 0)   pz4 = (z12*(e2 + pz2) - z22*(e2 - pz2)) / 2;
+      else           pz4 = (z22*(e2 + pz2) - z12*(e2 - pz2)) / 2;
+      e2 = TMath::Sqrt(pz4*pz4 + pt4*pt4 + mh*mh);
+
+      // small corr. instead of using Frag. Func. depending on yQ (in addition to ptQ)
+      Float_t ycorr = 0.2, y3, y4;
+      gRandom->RndmArray(2,rand);
+      y3 = 0.5 * TMath::Log((e1 + pz3 + 1.e-13)/(e1 - pz3 + 1.e-13));
+      y4 = 0.5 * TMath::Log((e2 + pz4 + 1.e-13)/(e2 - pz4 + 1.e-13));
+      if(TMath::Abs(y3)<ycorr && TMath::Abs(y4)<ycorr && rand[0]>0.5) {
+       ptemp = TMath::Sqrt(e1*e1 - pz3*pz3);
+       y3  = 4*(1 - 2*rand[1]);
+       pz3 = ptemp*TMath::SinH(y3);
+       pz4 = pz3;
+      }
+}
diff --git a/EVGEN/AliGenCorrHF.h b/EVGEN/AliGenCorrHF.h
new file mode 100644 (file)
index 0000000..e3fec0e
--- /dev/null
@@ -0,0 +1,82 @@
+#ifndef ALIGENCORRHF_H
+#define ALIGENCORRHF_H
+/* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
+ * See cxx source for full Copyright notice                               */
+
+/* $Id$ */
+
+//
+// Class to generate correlated Heavy Flavor hadron pairs using paramtrized
+// kinematics of quark pairs from some generator and quark fragmentation functions.
+// Is a generalisation of AliGenParam class for correlated pairs of hadrons.
+// Author: S. Grigoryan, LPC Clermont-Fd & YerPhI, Smbat.Grigoryan@cern.ch
+//
+
+#include "AliGenMC.h"
+
+class AliPythia;
+class TParticle;
+class TRandom;
+class TFile;
+class TString;
+
+//-------------------------------------------------------------
+class AliGenCorrHF : public AliGenMC
+{
+ public:
+    AliGenCorrHF();
+    AliGenCorrHF(Int_t npart, Int_t param);
+    AliGenCorrHF(char* tname, Int_t npart, Int_t param);
+    AliGenCorrHF(const AliGenCorrHF &CorrHF);
+     
+    virtual ~AliGenCorrHF();
+    virtual void Generate();
+    virtual void Init();
+    // force decay type
+    virtual void SetDecayer(AliDecayer* decayer) {fDecayer = decayer;}
+
+    AliGenCorrHF & operator=(const AliGenCorrHF & rhs);
+
+    // Particle type parametrisation functions, needed by GetHadronPair
+    static Int_t IpCharm(TRandom* ran);
+    static Int_t IpBeauty(TRandom* ran);
+
+    // Computation of cumulative sums of cell wght-s, needed by GetQuarkPair
+    static Double_t ComputeIntegral(TFile* fG);
+
+    // fG - input file w QQbar kinematical grid (TTree) and fragm. functions (24 TH2-s)
+    static void GetQuarkPair(TFile* fG, Double_t* fInt, Double_t &y1, Double_t &y2, Double_t &pt1, Double_t &pt2, Double_t &dphi);              
+    static void GetHadronPair(TFile* fG, Int_t idq, Double_t y1, Double_t y2, Double_t pt1, Double_t pt2, Int_t &id3, Int_t &id4, Double_t &pz3, Double_t &pz4, Double_t &pt3, Double_t &pt4); 
+
+ protected:
+    TString     fFileName;    // Name of the input file
+    TFile*      fFile;        //! Pointer to input file
+    Int_t       fQuark;       // Quark type 
+    Float_t     fBias;        // Biasing factor
+    Int_t       fTrials;      // Number of trials
+    AliDecayer* fDecayer;     //! Pointer to pythia object for decays
+
+ private:
+    static Double_t* fgIntegral; //! Pointer to array of cumulative sums of wght-s
+    static Int_t  fgnptbins;             // =12 Number of bins for the fragm. 
+                                         //   function dependence on quark pt
+    // Number of the grid bins in deltaphi, y and pt:  18, 30 and 32
+    static Double_t fgdph[19];           // deltaphi bin coordinates  
+    static Double_t fgy[31];             // y bin coordinates
+    static Double_t fgpt[33];            // pt bin coordinates
+    static Double_t fgptbmin[12];        // min & max coordinates of pt bins for
+    static Double_t fgptbmax[12];        // the fragm. function
+    
+    ClassDef(AliGenCorrHF,1)  // Generator using parameterized QQbar & fragm. functions
+};
+#endif
+
+
+
+
+
+
+
+
+
+
index ecc1c13..7638660 100644 (file)
 #pragma link C++ class  AliGenCocktailEventHeader+;
 #pragma link C++ class  AliGenReaderEMD+;
 #pragma link C++ class  AliDecayerPolarized+;
+#pragma link C++ class  AliGenCorrHF+;
 #endif
-
-
-
-
-
-
index 498db17..cb1bbf1 100644 (file)
@@ -17,7 +17,7 @@ SRCS          = AliGenHIJINGpara.cxx AliGenBox.cxx AliGenFixed.cxx \
                AliGenGeVSimEventHeader.cxx\
                AliSlowNucleonModel.cxx AliSlowNucleonModelExp.cxx \
                AliGenMUONCocktail.cxx AliGenMUONCocktailpp.cxx AliGenHBTosl.cxx AliGenCocktailEventHeader.cxx \
-               AliGenReaderEMD.cxx AliDecayerPolarized.cxx
+               AliGenReaderEMD.cxx AliDecayerPolarized.cxx AliGenCorrHF.cxx
 
 # Headerfiles for this particular package (Path respect to own directory)
 HDRS= $(SRCS:.cxx=.h)