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[u/mrichter/AliRoot.git] / EVGEN / AliGenCorrHF.cxx
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2c890605 1/**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
15
16/* $Id$ */
17
18// Class to generate correlated Heavy Flavor hadron pairs (one or several pairs
19// per event) using paramtrized kinematics of quark pairs from some generator
20// and quark fragmentation functions.
21// Is a generalisation of AliGenParam class for correlated pairs of hadrons.
22// In this version quark pairs and fragmentation functions are obtained from
b44c3901 23// Pythia6.124 using 100K events generated with kCharmppMNRwmi&kBeautyppMNRwmi
2c890605 24// in pp collisions at 14 TeV.
25// Decays are performed by Pythia. Used AliRoot version: v4-04-Release
26// Author: S. Grigoryan, LPC Clermont-Fd & YerPhI, Smbat.Grigoryan@cern.ch
b44c3901 27// July 07: added quarks in the stack (B. Vulpescu)
2c890605 28//-------------------------------------------------------------------------
29// How it works (for the given flavor):
30//
31// 1) Reads QQbar kinematical grid from the Input file and generates
32// quark pairs according to the weights of the cells.
33// It is a 5D grid in y1,y2,pt1,pt2 and deltaphi, with occupancy weights
34// of the cells obtained from Pythia (see details in GetQuarkPair).
35// 2) Reads "soft" and "hard" fragmentation functions (12 2D-histograms each,
36// for 12 pt bins) from the Input file, applies to quarks and produces hadrons
37// (only lower states, with proportions of species obtained from Pythia).
38// Fragmentation functions are the same for all hadron species and depend
39// on 2 variables - light cone energy-momentum fractions:
40// z1=(E_H + Pz_H)/(E_Q + Pz_Q), z2=(E_H - Pz_H)/(E_Q - Pz_Q).
41// "soft" & "hard" FFs correspond to "slower" & "faster" quark of a pair
42// (see details in GetHadronPair).
43// 3) Decays the hadrons and saves all the particles in the event stack in the
44// following order: HF hadron from Q, then its decay products, then HF hadron
45// from Qbar, then its decay productes, then next HF hadon pair (if any)
46// in the same way, etc...
47// 4) It is fast, e.g., generates the same number of events with a beauty pair
48// ~15 times faster than AliGenPythia with kBeautyppMNRwmi (w/o tracking)
49//
50// An Input file for each quark flavor is included in EVGEN/dataCorrHF/
51// One can use also user-defined Input files.
52//
53// More details could be found in my presentation at DiMuonNet Workshop, Dec 2006:
54// http://www-dapnia.cea.fr/Sphn/Alice/DiMuonNet
55// and will be published in an Internal Note.
56//
57//-------------------------------------------------------------------------
58// How to use it:
59//
60// add the following typical lines in Config.C
61/*
62 if (!strcmp(option,"corr")) {
63 // Example for correlated charm or beauty hadron pair production
64
65 // AliGenCorrHF *gener = new AliGenCorrHF(1, 4); // for charm, 1 pair per event
66 AliGenCorrHF *gener = new AliGenCorrHF(1, 5); // for beauty, 1 pair per event
67
68 gener->SetMomentumRange(0,9999);
69 gener->SetCutOnChild(0); // 1/0 means cuts on children enable/disable
70 gener->SetChildThetaRange(171.0,178.0);
71 gener->SetOrigin(0,0,0); //vertex position
72 gener->SetSigma(0,0,0); //Sigma in (X,Y,Z) (cm) on IP position
73 gener->SetForceDecay(kSemiMuonic);
74 gener->SetTrackingFlag(0);
75 gener->Init();
76}
77*/
78// and in aliroot do e.g. gAlice->Run(10,"Config.C") to produce 10 events.
79// One can include AliGenCorrHF in an AliGenCocktail generator.
80//--------------------------------------------------------------------------
81
7ca4655f 82#include <Riostream.h>
83#include <TCanvas.h>
84#include <TClonesArray.h>
85#include <TDatabasePDG.h>
2c890605 86#include <TFile.h>
2c890605 87#include <TH2F.h>
2c890605 88#include <TLorentzVector.h>
7ca4655f 89#include <TMath.h>
2c890605 90#include <TParticle.h>
91#include <TParticlePDG.h>
7ca4655f 92#include <TROOT.h>
93#include <TRandom.h>
94#include <TTree.h>
2c890605 95#include <TVirtualMC.h>
b44c3901 96#include <TVector3.h>
2c890605 97
98#include "AliGenCorrHF.h"
99#include "AliLog.h"
100#include "AliConst.h"
101#include "AliDecayer.h"
102#include "AliMC.h"
103#include "AliRun.h"
84555c93 104#include "AliGenEventHeader.h"
2c890605 105
106ClassImp(AliGenCorrHF)
107
108 //Begin_Html
109 /*
110 <img src="picts/AliGenCorrHF.gif">
111 */
112 //End_Html
113
114Double_t AliGenCorrHF::fgdph[19] = {0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180};
115Double_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};
116Double_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};
117Int_t AliGenCorrHF::fgnptbins = 12;
118Double_t AliGenCorrHF::fgptbmin[12] = {0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 9};
119Double_t AliGenCorrHF::fgptbmax[12] = {0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 9, 100};
120
121Double_t* AliGenCorrHF::fgIntegral = 0;
122
123//____________________________________________________________
124 AliGenCorrHF::AliGenCorrHF():
125 fFileName(0),
126 fFile(0),
127 fQuark(0),
128 fBias(0.),
129 fTrials(0),
130 fDecayer(0)
131{
132// Default constructor
133}
134
135//____________________________________________________________
136AliGenCorrHF::AliGenCorrHF(Int_t npart, Int_t param):
137 AliGenMC(npart),
138 fFileName(0),
139 fFile(0),
140 fQuark(param),
141 fBias(0.),
142 fTrials(0),
143 // fDecayer(new AliDecayerPythia())
144 fDecayer(0)
145{
146// Constructor using number of particles, quark type & default InputFile
147//
148 if (fQuark != 5) fQuark = 4;
149 fFileName = "$ALICE_ROOT/EVGEN/dataCorrHF/CharmppMNRwmiCorr100K.root";
150 if (fQuark == 5) fFileName = "$ALICE_ROOT/EVGEN/dataCorrHF/BeautyppMNRwmiCorr100K.root";
151
152 fName = "Default";
153 fTitle= "Generator for correlated pairs of HF hadrons";
154
155 fChildSelect.Set(5);
156 for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
157 SetForceDecay();
158 SetCutOnChild();
159 SetChildMomentumRange();
160 SetChildPtRange();
161 SetChildPhiRange();
162 SetChildThetaRange();
163}
164
165//___________________________________________________________________
166AliGenCorrHF::AliGenCorrHF(char* tname, Int_t npart, Int_t param):
167 AliGenMC(npart),
168 fFileName(tname),
169 fFile(0),
170 fQuark(param),
171 fBias(0.),
172 fTrials(0),
173 // fDecayer(new AliDecayerPythia())
174 fDecayer(0)
175{
176// Constructor using number of particles, quark type & user-defined InputFile
177//
178 if (fQuark != 5) fQuark = 4;
179 fName = "UserDefined";
180 fTitle= "Generator for correlated pairs of HF hadrons";
181
182 fChildSelect.Set(5);
183 for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
184 SetForceDecay();
185 SetCutOnChild();
186 SetChildMomentumRange();
187 SetChildPtRange();
188 SetChildPhiRange();
189 SetChildThetaRange();
190}
191
2c890605 192//____________________________________________________________
193AliGenCorrHF::~AliGenCorrHF()
194{
195// Destructor
196 delete fFile;
197}
198
199//____________________________________________________________
200void AliGenCorrHF::Init()
201{
202// Initialisation
203
204 AliInfo(Form(" QQbar kinematics and fragm. functions from: %s",fFileName.Data() ));
205 fFile = TFile::Open(fFileName.Data());
206 if(!fFile->IsOpen()){
207 AliError(Form("Could not open file %s",fFileName.Data() ));
208 }
209
210 ComputeIntegral(fFile);
b44c3901 211
2c890605 212 fParentWeight = 1./fNpart; // fNpart is number of HF-hadron pairs
213
214// particle decay related initialization
215
216 if (gMC) fDecayer = gMC->GetDecayer();
217 fDecayer->SetForceDecay(fForceDecay);
218 fDecayer->Init();
219
220//
221 AliGenMC::Init();
222}
2c890605 223//____________________________________________________________
224void AliGenCorrHF::Generate()
225{
226//
cb11fd27 227// Generate fNpart of correlated HF hadron pairs per event
228// in the the desired theta and momentum windows (phi = 0 - 2pi).
84555c93 229//
cb11fd27 230
84555c93 231// Reinitialize decayer
2c890605 232
84555c93 233 fDecayer->SetForceDecay(fForceDecay);
234 fDecayer->Init();
235
236 //
2c890605 237 Float_t polar[3]= {0,0,0}; // Polarisation of the parent particle (for GEANT tracking)
238 Float_t origin0[3]; // Origin of the generated parent particle (for GEANT tracking)
239 Float_t pt, pl, ptot; // Transverse, logitudinal and total momenta of the parent particle
240 Float_t phi, theta; // Phi and theta spherical angles of the parent particle momentum
241 Float_t p[3], pc[3], och[3];// Momentum, polarisation and origin of the children particles from lujet
84555c93 242 Int_t nt, i, j, ipa, ihadron[2], iquark[2];
243 Float_t wgtp, wgtch, random[6];
244 Float_t pq[2][3]; // Momenta of the two quarks
245 Int_t ntq[2] = {-1, -1};
cb11fd27 246 Double_t tanhy2, qm = 0;
2c890605 247
b44c3901 248 Double_t dphi=0, ptq[2], yq[2], pth[2], plh[2], ph[2], phih[2], phiq[2];
2c890605 249 for (i=0; i<2; i++) {
b44c3901 250 ptq[i] =0;
251 yq[i] =0;
252 pth[i] =0;
253 plh[i] =0;
254 phih[i] =0;
255 phiq[i] =0;
2c890605 256 ihadron[i] =0;
84555c93 257 iquark[i] =0;
2c890605 258 }
259
cb11fd27 260 // same quarks mass as in the fragmentation functions
261 if (fQuark == 4) qm = 1.20;
262 else qm = 4.75;
263
2c890605 264 static TClonesArray *particles;
265 //
266 if(!particles) particles = new TClonesArray("TParticle",1000);
267
84555c93 268 TDatabasePDG *pDataBase = TDatabasePDG::Instance();
269 //
270
271 // Calculating vertex position per event
2c890605 272 for (j=0;j<3;j++) origin0[j]=fOrigin[j];
273 if(fVertexSmear==kPerEvent) {
84555c93 274 Vertex();
275 for (j=0;j<3;j++) origin0[j]=fVertex[j];
2c890605 276 }
277
84555c93 278 ipa=0;
279
280 // Generating fNpart particles
281 fNprimaries = 0;
282
283 while (ipa<2*fNpart) {
284
285 GetQuarkPair(fFile, fgIntegral, yq[0], yq[1], ptq[0], ptq[1], dphi);
286
287 GetHadronPair(fFile, fQuark, yq[0], yq[1], ptq[0], ptq[1], ihadron[0], ihadron[1], plh[0], plh[1], pth[0], pth[1]);
288
289 // Cuts from AliGenerator
290
291 // Cut on theta
292 theta=TMath::ATan2(pth[0],plh[0]);
293 if(theta<fThetaMin || theta>fThetaMax) continue;
294 theta=TMath::ATan2(pth[1],plh[1]);
295 if(theta<fThetaMin || theta>fThetaMax) continue;
296
297 // Cut on momentum
298 ph[0]=TMath::Sqrt(pth[0]*pth[0]+plh[0]*plh[0]);
299 if (ph[0]<fPMin || ph[0]>fPMax) continue;
300 ph[1]=TMath::Sqrt(pth[1]*pth[1]+plh[1]*plh[1]);
301 if (ph[1]<fPMin || ph[1]>fPMax) continue;
302
303 // Add the quarks in the stack
304
305 phiq[0] = Rndm()*k2PI;
306 if (Rndm() < 0.5) {
b44c3901 307 phiq[1] = phiq[0] + dphi*kDegrad;
84555c93 308 } else {
309 phiq[1] = phiq[0] - dphi*kDegrad;
310 }
311 if (phiq[1] > k2PI) phiq[1] -= k2PI;
312 if (phiq[1] < 0 ) phiq[1] += k2PI;
313
314 // quarks pdg
315 iquark[0] = +fQuark;
316 iquark[1] = -fQuark;
317
318 // px and py
319 TVector2 qvect1 = TVector2();
320 TVector2 qvect2 = TVector2();
321 qvect1.SetMagPhi(ptq[0],phiq[0]);
322 qvect2.SetMagPhi(ptq[1],phiq[1]);
323 pq[0][0] = qvect1.Px();
324 pq[0][1] = qvect1.Py();
325 pq[1][0] = qvect2.Px();
326 pq[1][1] = qvect2.Py();
327
328 // pz
cb11fd27 329 tanhy2 = TMath::TanH(yq[0]);
330 tanhy2 *= tanhy2;
331 pq[0][2] = TMath::Sqrt((ptq[0]*ptq[0]+qm*qm)*tanhy2/(1-tanhy2));
332 pq[0][2] = TMath::Sign((Double_t)pq[0][2],yq[0]);
333 tanhy2 = TMath::TanH(yq[1]);
334 tanhy2 *= tanhy2;
335 pq[1][2] = TMath::Sqrt((ptq[1]*ptq[1]+qm*qm)*tanhy2/(1-tanhy2));
336 pq[1][2] = TMath::Sign((Double_t)pq[1][2],yq[1]);
84555c93 337
338 // Here we assume that |phi_H1 - phi_H2| = |phi_Q1 - phi_Q2| = dphi
339 // which is a good approximation for heavy flavors in Pythia
340 // ... moreover, same phi angles as for the quarks ...
341
342 phih[0] = phiq[0];
343 phih[1] = phiq[1];
b44c3901 344
84555c93 345 for (Int_t ihad = 0; ihad < 2; ihad++) {
346 while(1) {
347 //
348 // particle type
349 Int_t iPart = ihadron[ihad];
350 fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
351 wgtp=fParentWeight;
352 wgtch=fChildWeight;
353 TParticlePDG *particle = pDataBase->GetParticle(iPart);
354 Float_t am = particle->Mass();
355 phi = phih[ihad];
356 pt = pth[ihad];
357 pl = plh[ihad];
358 ptot=TMath::Sqrt(pt*pt+pl*pl);
359
360 p[0]=pt*TMath::Cos(phi);
361 p[1]=pt*TMath::Sin(phi);
362 p[2]=pl;
b44c3901 363
2c890605 364 if(fVertexSmear==kPerTrack) {
84555c93 365 Rndm(random,6);
366 for (j=0;j<3;j++) {
367 origin0[j]=
368 fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
369 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
2c890605 370 }
371 }
84555c93 372
373 // Looking at fForceDecay :
374 // if fForceDecay != none Primary particle decays using
375 // AliPythia and children are tracked by GEANT
376 //
377 // if fForceDecay == none Primary particle is tracked by GEANT
378 // (In the latest, make sure that GEANT actually does all the decays you want)
379 //
380
381 if (fForceDecay != kNoDecay) {
382 // Using lujet to decay particle
383 Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
384 TLorentzVector pmom(p[0], p[1], p[2], energy);
385 fDecayer->Decay(iPart,&pmom);
386 //
387 // select decay particles
388 Int_t np=fDecayer->ImportParticles(particles);
389
390 // Selecting GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
391 if (fGeometryAcceptance)
392 if (!CheckAcceptanceGeometry(np,particles)) continue;
393 Int_t ncsel=0;
394 Int_t* pFlag = new Int_t[np];
395 Int_t* pParent = new Int_t[np];
396 Int_t* pSelected = new Int_t[np];
397 Int_t* trackIt = new Int_t[np];
398
399 for (i=0; i<np; i++) {
400 pFlag[i] = 0;
401 pSelected[i] = 0;
402 pParent[i] = -1;
403 }
404
405 if (np >1) {
406 TParticle* iparticle = (TParticle *) particles->At(0);
407 Int_t ipF, ipL;
408 for (i = 1; i<np ; i++) {
409 trackIt[i] = 1;
410 iparticle = (TParticle *) particles->At(i);
411 Int_t kf = iparticle->GetPdgCode();
412 Int_t ks = iparticle->GetStatusCode();
413 // flagged particle
414
415 if (pFlag[i] == 1) {
416 ipF = iparticle->GetFirstDaughter();
417 ipL = iparticle->GetLastDaughter();
418 if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
419 continue;
420 }
421
422 // flag decay products of particles with long life-time (c tau > .3 mum)
423
424 if (ks != 1) {
425 //TParticlePDG *particle = pDataBase->GetParticle(kf);
426
427 Double_t lifeTime = fDecayer->GetLifetime(kf);
428 //Double_t mass = particle->Mass();
429 //Double_t width = particle->Width();
430 if (lifeTime > (Double_t) fMaxLifeTime) {
431 ipF = iparticle->GetFirstDaughter();
432 ipL = iparticle->GetLastDaughter();
433 if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
434 } else{
435 trackIt[i] = 0;
436 pSelected[i] = 1;
2c890605 437 }
84555c93 438 } // ks==1 ?
439 //
440 // children
441
f7b22746 442 if ((ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll) && trackIt[i])
84555c93 443 {
444 if (fCutOnChild) {
445 pc[0]=iparticle->Px();
446 pc[1]=iparticle->Py();
447 pc[2]=iparticle->Pz();
448 Bool_t childok = KinematicSelection(iparticle, 1);
449 if(childok) {
450 pSelected[i] = 1;
451 ncsel++;
452 } else {
453 ncsel=-1;
454 break;
455 } // child kine cuts
456 } else {
457 pSelected[i] = 1;
458 ncsel++;
459 } // if child selection
460 } // select muon
461 } // decay particle loop
462 } // if decay products
463
464 Int_t iparent;
465 if ((fCutOnChild && ncsel >0) || !fCutOnChild){
466 ipa++;
467 //
468 // Parent
469 // quark
470 PushTrack(0, -1, iquark[ihad], pq[ihad], origin0, polar, 0, kPPrimary, nt, wgtp);
471 KeepTrack(nt);
472 ntq[ihad] = nt;
84555c93 473 // hadron
474 PushTrack(0, ntq[ihad], iPart, p, origin0, polar, 0, kPDecay, nt, wgtp);
475 pParent[0] = nt;
476 KeepTrack(nt);
477 fNprimaries++;
84555c93 478
479 //
480 // Decay Products
481 //
482 for (i = 1; i < np; i++) {
483 if (pSelected[i]) {
484 TParticle* iparticle = (TParticle *) particles->At(i);
485 Int_t kf = iparticle->GetPdgCode();
7f11c778 486 Int_t jpa = iparticle->GetFirstMother()-1;
2c890605 487
84555c93 488 och[0] = origin0[0]+iparticle->Vx()/10;
489 och[1] = origin0[1]+iparticle->Vy()/10;
490 och[2] = origin0[2]+iparticle->Vz()/10;
491 pc[0] = iparticle->Px();
492 pc[1] = iparticle->Py();
493 pc[2] = iparticle->Pz();
2c890605 494
7f11c778 495 if (jpa > -1) {
496 iparent = pParent[jpa];
84555c93 497 } else {
498 iparent = -1;
499 }
500
501 PushTrack(fTrackIt*trackIt[i], iparent, kf,
502 pc, och, polar,
503 0, kPDecay, nt, wgtch);
84555c93 504 pParent[i] = nt;
505 KeepTrack(nt);
506 fNprimaries++;
507 } // Selected
508 } // Particle loop
509 } // Decays by Lujet
510 particles->Clear();
511 if (pFlag) delete[] pFlag;
512 if (pParent) delete[] pParent;
513 if (pSelected) delete[] pSelected;
514 if (trackIt) delete[] trackIt;
515 } // kinematic selection
516 else // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
517 {
518 gAlice->GetMCApp()->
519 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
520 ipa++;
521 fNprimaries++;
522 }
2c890605 523 break;
524 } // while(1)
84555c93 525 } // hadron pair loop
526 } // event loop
527
2c890605 528 SetHighWaterMark(nt);
84555c93 529
cb11fd27 530 AliGenEventHeader* header = new AliGenEventHeader("CorrHF");
84555c93 531 header->SetPrimaryVertex(fVertex);
532 header->SetNProduced(fNprimaries);
533 AddHeader(header);
2c890605 534
84555c93 535}
2c890605 536//____________________________________________________________________________________
537Int_t AliGenCorrHF::IpCharm(TRandom* ran)
538{
539// Composition of lower state charm hadrons, containing a c-quark
540 Float_t random;
541 Int_t ip; // +- 411,421,431,4122,4132,4232,4332
542 random = ran->Rndm();
543// Rates from Pythia6.214 using 100Kevents with kPyCharmppMNRwmi at 14 TeV.
544
545 if (random < 0.6027) {
546 ip=421;
547 } else if (random < 0.7962) {
548 ip=411;
549 } else if (random < 0.9127) {
550 ip=431;
551 } else if (random < 0.9899) {
552 ip=4122;
553 } else if (random < 0.9948) {
554 ip=4132;
555 } else if (random < 0.9999) {
556 ip=4232;
557 } else {
558 ip=4332;
559 }
560
561 return ip;
562}
563
564Int_t AliGenCorrHF::IpBeauty(TRandom* ran)
565{
566// Composition of lower state beauty hadrons, containing a b-quark
567 Float_t random;
568 Int_t ip; // +- 511,521,531,5122,5132,5232,5332
569 random = ran->Rndm();
570// Rates from Pythia6.214 using 100Kevents with kPyBeautyppMNRwmi at 14 TeV.
571 // B-Bbar mixing will be done by Pythia at the decay point
572 if (random < 0.3965) {
573 ip=-511;
574 } else if (random < 0.7930) {
575 ip=-521;
576 } else if (random < 0.9112) {
577 ip=-531;
578 } else if (random < 0.9887) {
579 ip=5122;
580 } else if (random < 0.9943) {
581 ip=5132;
582 } else if (random < 0.9999) {
583 ip=5232;
584 } else {
585 ip=5332;
586 }
587
588 return ip;
589}
590
591//____________________________________________________________________________________
592Double_t AliGenCorrHF::ComputeIntegral(TFile* fG) // needed by GetQuarkPair
593{
594 // Read QQbar kinematical 5D grid's cell occupancy weights
4c111067 595 Int_t cell[6]; // cell[6]={wght,iy1,iy2,ipt1,ipt2,idph}
2c890605 596 TTree* tG = (TTree*) fG->Get("tGqq");
4c111067 597 tG->GetBranch("cell")->SetAddress(&cell);
2c890605 598 Int_t nbins = tG->GetEntries();
599
600 // delete previously computed integral (if any)
601 if(fgIntegral) delete [] fgIntegral;
602
603 fgIntegral = new Double_t[nbins+1];
604 fgIntegral[0] = 0;
605 Int_t bin;
606 for(bin=0;bin<nbins;bin++) {
607 tG->GetEvent(bin);
608 fgIntegral[bin+1] = fgIntegral[bin] + cell[0];
609 }
610 // Normalize integral to 1
611 if (fgIntegral[nbins] == 0 ) {
612 return 0;
613 }
614 for (bin=1;bin<=nbins;bin++) fgIntegral[bin] /= fgIntegral[nbins];
615
616 return fgIntegral[nbins];
617}
618
619//____________________________________________________________________________________
620void AliGenCorrHF::GetQuarkPair(TFile* fG, Double_t* fInt, Double_t &y1, Double_t &y2, Double_t &pt1, Double_t &pt2, Double_t &dphi)
621 // modification of ROOT's TH3::GetRandom3 for 5D
622{
623 // Read QQbar kinematical 5D grid's cell coordinates
4c111067 624 Int_t cell[6]; // cell[6]={wght,iy1,iy2,ipt1,ipt2,idph}
2c890605 625 TTree* tG = (TTree*) fG->Get("tGqq");
4c111067 626 tG->GetBranch("cell")->SetAddress(&cell);
2c890605 627 Int_t nbins = tG->GetEntries();
628 Double_t rand[6];
629 gRandom->RndmArray(6,rand);
630 Int_t ibin = TMath::BinarySearch(nbins,fInt,rand[0]);
631 tG->GetEvent(ibin);
632 y1 = fgy[cell[1]] + (fgy[cell[1]+1]-fgy[cell[1]])*rand[1];
633 y2 = fgy[cell[2]] + (fgy[cell[2]+1]-fgy[cell[2]])*rand[2];
634 pt1 = fgpt[cell[3]] + (fgpt[cell[3]+1]-fgpt[cell[3]])*rand[3];
635 pt2 = fgpt[cell[4]] + (fgpt[cell[4]+1]-fgpt[cell[4]])*rand[4];
636 dphi = fgdph[cell[5]]+ (fgdph[cell[5]+1]-fgdph[cell[5]])*rand[5];
637}
638
639//____________________________________________________________________________________
640void 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)
641{
642 // Generate a hadron pair
643 Int_t (*fIpParaFunc )(TRandom*);//Pointer to particle type parametrisation function
644 fIpParaFunc = IpCharm;
645 Double_t mq = 1.2; // c & b quark masses (used in AliPythia)
646 if (idq == 5) {
647 fIpParaFunc = IpBeauty;
648 mq = 4.75;
649 }
650 Double_t z11, z12, z21, z22, pz1, pz2, e1, e2, mh, ptemp, rand[2];
651 char tag[100];
652 TH2F *h2h[12], *h2s[12]; // hard & soft Fragmentation Functions
653 for (Int_t ipt = 0; ipt<fgnptbins; ipt++) {
654 sprintf(tag,"h2h_pt%d",ipt);
655 h2h[ipt] = (TH2F*) fG->Get(tag);
656 sprintf(tag,"h2s_pt%d",ipt);
657 h2s[ipt] = (TH2F*) fG->Get(tag);
658 }
659
660 if (y1*y2 < 0) {
661 for (Int_t ipt = 0; ipt<fgnptbins; ipt++) {
662 if(pt1 >= fgptbmin[ipt] && pt1 < fgptbmax[ipt])
663 h2h[ipt]->GetRandom2(z11, z21);
664 if(pt2 >= fgptbmin[ipt] && pt2 < fgptbmax[ipt])
665 h2h[ipt]->GetRandom2(z12, z22);
666 }
667 }
668 else {
669 if (TMath::Abs(y1) > TMath::Abs(y2)) {
670 for (Int_t ipt = 0; ipt<fgnptbins; ipt++) {
671 if(pt1 >= fgptbmin[ipt] && pt1 < fgptbmax[ipt])
672 h2h[ipt]->GetRandom2(z11, z21);
673 if(pt2 >= fgptbmin[ipt] && pt2 < fgptbmax[ipt])
674 h2s[ipt]->GetRandom2(z12, z22);
675 }
676 }
677 else {
678 for (Int_t ipt = 0; ipt<fgnptbins; ipt++) {
679 if(pt1 >= fgptbmin[ipt] && pt1 < fgptbmax[ipt])
680 h2s[ipt]->GetRandom2(z11, z21);
681 if(pt2 >= fgptbmin[ipt] && pt2 < fgptbmax[ipt])
682 h2h[ipt]->GetRandom2(z12, z22);
683 }
684 }
685 }
686 gRandom->RndmArray(2,rand);
687 ptemp = TMath::Sqrt(pt1*pt1 + mq*mq);
688 pz1 = ptemp*TMath::SinH(y1);
689 e1 = ptemp*TMath::CosH(y1);
690 ptemp = TMath::Sqrt(pt2*pt2 + mq*mq);
691 pz2 = ptemp*TMath::SinH(y2);
692 e2 = ptemp*TMath::CosH(y2);
693
694 id3 = fIpParaFunc(gRandom);
695 mh = TDatabasePDG::Instance()->GetParticle(id3)->Mass();
696 ptemp = z11*z21*(e1*e1-pz1*pz1) - mh*mh;
697 pt3 = (idq-3)*rand[0]; // some smearing at low pt, try better
698 if (ptemp > 0) pt3 = TMath::Sqrt(ptemp);
699 if (pz1 > 0) pz3 = (z11*(e1 + pz1) - z21*(e1 - pz1)) / 2;
700 else pz3 = (z21*(e1 + pz1) - z11*(e1 - pz1)) / 2;
701 e1 = TMath::Sqrt(pz3*pz3 + pt3*pt3 + mh*mh);
702
703 id4 = - fIpParaFunc(gRandom);
704 mh = TDatabasePDG::Instance()->GetParticle(id4)->Mass();
705 ptemp = z12*z22*(e2*e2-pz2*pz2) - mh*mh;
706 pt4 = (idq-3)*rand[1]; // some smearing at low pt, try better
707 if (ptemp > 0) pt4 = TMath::Sqrt(ptemp);
708 if (pz2 > 0) pz4 = (z12*(e2 + pz2) - z22*(e2 - pz2)) / 2;
709 else pz4 = (z22*(e2 + pz2) - z12*(e2 - pz2)) / 2;
710 e2 = TMath::Sqrt(pz4*pz4 + pt4*pt4 + mh*mh);
711
712 // small corr. instead of using Frag. Func. depending on yQ (in addition to ptQ)
713 Float_t ycorr = 0.2, y3, y4;
714 gRandom->RndmArray(2,rand);
715 y3 = 0.5 * TMath::Log((e1 + pz3 + 1.e-13)/(e1 - pz3 + 1.e-13));
716 y4 = 0.5 * TMath::Log((e2 + pz4 + 1.e-13)/(e2 - pz4 + 1.e-13));
717 if(TMath::Abs(y3)<ycorr && TMath::Abs(y4)<ycorr && rand[0]>0.5) {
718 ptemp = TMath::Sqrt(e1*e1 - pz3*pz3);
719 y3 = 4*(1 - 2*rand[1]);
720 pz3 = ptemp*TMath::SinH(y3);
721 pz4 = pz3;
722 }
723}