]> git.uio.no Git - u/mrichter/AliRoot.git/blame - EVGEN/AliGenCorrHF.cxx
git://git.uio.no / u / mrichter / AliRoot.git / blame
? search:
summary | shortlog | log | commit | commitdiff | tree
blob | blame (incremental) | history | HEAD
New generator for the krypton runs of TPC (Marek)
[u/mrichter/AliRoot.git] / EVGEN / AliGenCorrHF.cxx
CommitLineData
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
23// Pythia6.124 using 100K events generated with kCharmppMNRwmi & kBeautyppMNRwmi
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
27//
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>
2c890605 96
97#include "AliGenCorrHF.h"
98#include "AliLog.h"
99#include "AliConst.h"
100#include "AliDecayer.h"
101#include "AliMC.h"
102#include "AliRun.h"
103
104ClassImp(AliGenCorrHF)
105
106 //Begin_Html
107 /*
108 <img src="picts/AliGenCorrHF.gif">
109 */
110 //End_Html
111
112Double_t AliGenCorrHF::fgdph[19] = {0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180};
113Double_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};
114Double_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};
115Int_t AliGenCorrHF::fgnptbins = 12;
116Double_t AliGenCorrHF::fgptbmin[12] = {0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 9};
117Double_t AliGenCorrHF::fgptbmax[12] = {0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 9, 100};
118
119Double_t* AliGenCorrHF::fgIntegral = 0;
120
121//____________________________________________________________
122 AliGenCorrHF::AliGenCorrHF():
123 fFileName(0),
124 fFile(0),
125 fQuark(0),
126 fBias(0.),
127 fTrials(0),
128 fDecayer(0)
129{
130// Default constructor
131}
132
133//____________________________________________________________
134AliGenCorrHF::AliGenCorrHF(Int_t npart, Int_t param):
135 AliGenMC(npart),
136 fFileName(0),
137 fFile(0),
138 fQuark(param),
139 fBias(0.),
140 fTrials(0),
141 // fDecayer(new AliDecayerPythia())
142 fDecayer(0)
143{
144// Constructor using number of particles, quark type & default InputFile
145//
146 if (fQuark != 5) fQuark = 4;
147 fFileName = "$ALICE_ROOT/EVGEN/dataCorrHF/CharmppMNRwmiCorr100K.root";
148 if (fQuark == 5) fFileName = "$ALICE_ROOT/EVGEN/dataCorrHF/BeautyppMNRwmiCorr100K.root";
149
150 fName = "Default";
151 fTitle= "Generator for correlated pairs of HF hadrons";
152
153 fChildSelect.Set(5);
154 for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
155 SetForceDecay();
156 SetCutOnChild();
157 SetChildMomentumRange();
158 SetChildPtRange();
159 SetChildPhiRange();
160 SetChildThetaRange();
161}
162
163//___________________________________________________________________
164AliGenCorrHF::AliGenCorrHF(char* tname, Int_t npart, Int_t param):
165 AliGenMC(npart),
166 fFileName(tname),
167 fFile(0),
168 fQuark(param),
169 fBias(0.),
170 fTrials(0),
171 // fDecayer(new AliDecayerPythia())
172 fDecayer(0)
173{
174// Constructor using number of particles, quark type & user-defined InputFile
175//
176 if (fQuark != 5) fQuark = 4;
177 fName = "UserDefined";
178 fTitle= "Generator for correlated pairs of HF hadrons";
179
180 fChildSelect.Set(5);
181 for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
182 SetForceDecay();
183 SetCutOnChild();
184 SetChildMomentumRange();
185 SetChildPtRange();
186 SetChildPhiRange();
187 SetChildThetaRange();
188}
189
2c890605 190//____________________________________________________________
191AliGenCorrHF::~AliGenCorrHF()
192{
193// Destructor
194 delete fFile;
195}
196
197//____________________________________________________________
198void AliGenCorrHF::Init()
199{
200// Initialisation
201
202 AliInfo(Form(" QQbar kinematics and fragm. functions from: %s",fFileName.Data() ));
203 fFile = TFile::Open(fFileName.Data());
204 if(!fFile->IsOpen()){
205 AliError(Form("Could not open file %s",fFileName.Data() ));
206 }
207
208 ComputeIntegral(fFile);
209
210 fParentWeight = 1./fNpart; // fNpart is number of HF-hadron pairs
211
212// particle decay related initialization
213
214 if (gMC) fDecayer = gMC->GetDecayer();
215 fDecayer->SetForceDecay(fForceDecay);
216 fDecayer->Init();
217
218//
219 AliGenMC::Init();
220}
221
222//____________________________________________________________
223void AliGenCorrHF::Generate()
224{
225//
226// Generate fNpart of correlated HF hadron pairs per event
227// in the the desired theta and momentum windows (phi = 0 - 2pi).
228// Gaussian smearing on the vertex is done if selected.
229// The decay of heavy hadrons is done using lujet,
230// and the childern particle are tracked by GEANT
231// However, light mesons are directly tracked by GEANT
232// setting fForceDecay = nodecay (SetForceDecay(nodecay))
233//
234
235
236 Float_t polar[3]= {0,0,0}; // Polarisation of the parent particle (for GEANT tracking)
237 Float_t origin0[3]; // Origin of the generated parent particle (for GEANT tracking)
238 Float_t pt, pl, ptot; // Transverse, logitudinal and total momenta of the parent particle
239 Float_t phi, theta; // Phi and theta spherical angles of the parent particle momentum
240 Float_t p[3], pc[3], och[3];// Momentum, polarisation and origin of the children particles from lujet
241
242
243 Double_t dphi=0, ptq[2], yq[2], pth[2], plh[2], ph[2], phih[2];
244 Int_t i, j, ipair, ihadron[2];
245 for (i=0; i<2; i++) {
246 ptq[i] =0;
247 yq[i] =0;
248 pth[i] =0;
249 plh[i] =0;
250 ihadron[i] =0;
251 }
252
253 static TClonesArray *particles;
254 //
255 if(!particles) particles = new TClonesArray("TParticle",1000);
256
257 TDatabasePDG* pDataBase = TDatabasePDG::Instance();
258
259// Calculating vertex position per event
260 for (j=0;j<3;j++) origin0[j]=fOrigin[j];
261 if(fVertexSmear==kPerEvent) {
262 Vertex();
263 for (j=0;j<3;j++) origin0[j]=fVertex[j];
264 }
265
266 Float_t wgtp, wgtch, random[6];
267 Int_t ipap = 0;
268 Int_t nt = 0;
269
270// Generating fNpart HF-hadron pairs per event
271 while(ipap<fNpart) {
272
273 while(1) {
274
275 GetQuarkPair(fFile, fgIntegral, yq[0], yq[1], ptq[0], ptq[1], dphi);
276
277 GetHadronPair(fFile, fQuark, yq[0], yq[1], ptq[0], ptq[1], ihadron[0], ihadron[1], plh[0], plh[1], pth[0], pth[1]);
278
279// Here we assume that |phi_H1 - phi_H2| = |phi_Q1 - phi_Q2| = dphi
280// which is a good approximation for heavy flavors in Pythia
281
282 /* // doesn't work if PhiMax < k2PI or PhiMin > 0, since dphi = 0 - 180
283 phih[0] = fPhiMin + Rndm()*(fPhiMax-fPhiMin);
284 phih[1] = phih[0] + dphi*kDegrad;
285 if (phih[0] > fPhiMax/2.) phih[1] = phih[0] - dphi*kDegrad;
286 */
287 phih[0] = Rndm()*k2PI;
288 phih[1] = phih[0] + dphi*kDegrad;
289 if (phih[0] > TMath::Pi()) phih[1] = phih[0] - dphi*kDegrad;
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// Common origin for particles of the HF-hadron pair
304 if(fVertexSmear==kPerTrack) {
305 Rndm(random,6);
306 for (j=0;j<3;j++) {
307 origin0[j]=
308 fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
309 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
310 }
311 }
312
313 Int_t np1=0, kf1[100], select1[100], iparent1[100], trackIt1[100];
314 Float_t wgtch1=0, p1[3], pc1[100][3], och1[100][3];
315
316 for (j=0; j<3; j++) p1[j] = 0;
317 for (i=0; i<100; i++) {
318 kf1[i] = 0;
319 select1[i] = 0;
320 iparent1[i] = 0;
321 trackIt1[i] = 0;
322 for (j=0; j<3; j++) {
323 pc1[i][j] = 0;
324 och1[i][j] = 0;
325 }
326 }
327
328//
329// Loop over particles of the HF-hadron pair
330 Int_t nhadron = 0;
331 for (ipair=0;ipair<2;ipair++) {
332 phi = phih[ipair];
333 pl = plh[ipair];
334 pt = pth[ipair];
335 ptot = ph[ipair];
336//
337// particle type
338 Int_t iPart = ihadron[ipair];
339 Float_t am = pDataBase->GetParticle(iPart)->Mass();
340 fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
341
342 wgtp = fParentWeight;
343 wgtch = fChildWeight;
344
345//
346 p[0]=pt*TMath::Cos(phi);
347 p[1]=pt*TMath::Sin(phi);
348 p[2]=pl;
349
350// Looking at fForceDecay :
351// if fForceDecay != none Primary particle decays using
352// AliPythia and children are tracked by GEANT
353//
354// if fForceDecay == none Primary particle is tracked by GEANT
355// (In the latest, make sure that GEANT actually does all the decays you want)
356//
357
358 if (fForceDecay != kNoDecay) {
359// Using lujet to decay particle
360 Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
361 TLorentzVector pmom(p[0], p[1], p[2], energy);
362 fDecayer->Decay(iPart,&pmom);
363//
364// select decay particles
365 Int_t np=fDecayer->ImportParticles(particles);
366
367// Selecting GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
368 if (fGeometryAcceptance)
369 if (!CheckAcceptanceGeometry(np,particles)) break;
370 Int_t ncsel=0;
371 Int_t* pParent = new Int_t[np];
372 Int_t* pSelected = new Int_t[np];
373 Int_t* trackIt = new Int_t[np];
374
375 for (i=0; i<np; i++) {
376 pSelected[i] = 0;
377 pParent[i] = -1;
378 }
379
380 if (np >1) {
381 TParticle* iparticle = (TParticle *) particles->At(0);
382 for (i=1; i<np; i++) {
383 trackIt[i] = 1;
384 iparticle = (TParticle *) particles->At(i);
385 Int_t kf = iparticle->GetPdgCode();
386 Int_t ks = iparticle->GetStatusCode();
387
388// particles with long life-time (c tau > .3 mum)
389 if (ks != 1) {
390 Double_t lifeTime = fDecayer->GetLifetime(kf);
391 if (lifeTime <= (Double_t) fMaxLifeTime) {
392 trackIt[i] = 0;
393 pSelected[i] = 1;
394 }
395 } // ks==1 ?
396//
397// children, discard neutrinos
398 if (TMath::Abs(kf) == 12 || TMath::Abs(kf) == 14) continue;
399 if (trackIt[i])
400 {
401 if (fCutOnChild) {
402 pc[0]=iparticle->Px();
403 pc[1]=iparticle->Py();
404 pc[2]=iparticle->Pz();
405 Bool_t childok = KinematicSelection(iparticle, 1);
406 if(childok) {
407 pSelected[i] = 1;
408 ncsel++;
409 } else {
410 ncsel=-1;
411 break;
412 } // child kine cuts
413 } else {
414 pSelected[i] = 1;
415 ncsel++;
416 } // if child selection
417 } // select muon
418 } // decay particle loop
419 } // if decay products
420
421 Int_t iparent;
422 if ((fCutOnChild && ncsel >0) || !fCutOnChild){
423
424 nhadron++;
425//
426// Parents and Decay Products
427 if (ipair == 0) {
428 np1 = np;
429 wgtch1 = wgtch;
430 p1[0] = p[0]; p1[1] = p[1]; p1[2] = p[2];
431 } else {
432 ipap++;
433 PushTrack(0, -1, ihadron[0], p1, origin0, polar, 0,
434 kPPrimary, nt, wgtp);
435 KeepTrack(nt);
436 for (i = 1; i < np1; i++) {
437 if (select1[i]) {
438 for (j=0; j<3; j++) {
439 och[j] = och1[i][j];
440 pc[j] = pc1[i][j];
441 }
442 PushTrack(fTrackIt*trackIt1[i], iparent1[i], kf1[i], pc, och,
443 polar, 0, kPDecay, nt, wgtch1);
444 KeepTrack(nt);
445 }
446 }
447 PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
448 KeepTrack(nt);
449 }
450 pParent[0] = nt;
451//
452// Decay Products
453 Int_t ntcount = 0;
454 for (i = 1; i < np; i++) {
455 if (pSelected[i]) {
456 TParticle* iparticle = (TParticle *) particles->At(i);
457 Int_t kf = iparticle->GetPdgCode();
458 Int_t ipa = iparticle->GetFirstMother()-1;
459
460 och[0] = origin0[0]+iparticle->Vx()/10;
461 och[1] = origin0[1]+iparticle->Vy()/10;
462 och[2] = origin0[2]+iparticle->Vz()/10;
463 pc[0] = iparticle->Px();
464 pc[1] = iparticle->Py();
465 pc[2] = iparticle->Pz();
466
467 if (ipa > -1) {
468 iparent = pParent[ipa];
469 } else {
470 iparent = -1;
471 }
472
473 if (ipair == 0) {
474 kf1[i] = kf;
475 select1[i] = pSelected[i];
476 iparent1[i] = iparent;
477 trackIt1[i] = trackIt[i];
478 for (j=0; j<3; j++) {
479 och1[i][j] = och[j];
480 pc1[i][j] = pc[j];
481 }
482 ntcount++;
483 } else {
484 PushTrack(fTrackIt*trackIt[i], iparent, kf, pc, och,
485 polar, 0, kPDecay, nt, wgtch);
486 KeepTrack(nt);
487 }
488 pParent[i] = nt + ntcount;
489 } // Selected
490 } // Particle loop
491 } // Decays by Lujet
492 particles->Clear();
493 if (pParent) delete[] pParent;
494 if (pSelected) delete[] pSelected;
495 if (trackIt) delete[] trackIt;
496 } // kinematic selection
497 else // nodecay option, so parent will be tracked by GEANT
498 {
499 nhadron++;
500 if (ipair == 0) {
501 p1[0] = p[0]; p1[1] = p[1]; p1[2] = p[2];
502 } else {
503 ipap++;
504 gAlice->GetMCApp()->
505 PushTrack(fTrackIt,-1,ihadron[0],p1,origin0,polar,0,kPPrimary,nt,wgtp);
506 gAlice->GetMCApp()->
507 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
508 }
509 }
510 if (nhadron == 0) break;
511 } // ipair loop
512 if (nhadron != 2) continue;
513 break;
514 } // while(1)
515 nt++;
516 } // while(ipa<fNpart) --> event loop
517
518 SetHighWaterMark(nt);
519}
520
2c890605 521//____________________________________________________________________________________
522Int_t AliGenCorrHF::IpCharm(TRandom* ran)
523{
524// Composition of lower state charm hadrons, containing a c-quark
525 Float_t random;
526 Int_t ip; // +- 411,421,431,4122,4132,4232,4332
527 random = ran->Rndm();
528// Rates from Pythia6.214 using 100Kevents with kPyCharmppMNRwmi at 14 TeV.
529
530 if (random < 0.6027) {
531 ip=421;
532 } else if (random < 0.7962) {
533 ip=411;
534 } else if (random < 0.9127) {
535 ip=431;
536 } else if (random < 0.9899) {
537 ip=4122;
538 } else if (random < 0.9948) {
539 ip=4132;
540 } else if (random < 0.9999) {
541 ip=4232;
542 } else {
543 ip=4332;
544 }
545
546 return ip;
547}
548
549Int_t AliGenCorrHF::IpBeauty(TRandom* ran)
550{
551// Composition of lower state beauty hadrons, containing a b-quark
552 Float_t random;
553 Int_t ip; // +- 511,521,531,5122,5132,5232,5332
554 random = ran->Rndm();
555// Rates from Pythia6.214 using 100Kevents with kPyBeautyppMNRwmi at 14 TeV.
556 // B-Bbar mixing will be done by Pythia at the decay point
557 if (random < 0.3965) {
558 ip=-511;
559 } else if (random < 0.7930) {
560 ip=-521;
561 } else if (random < 0.9112) {
562 ip=-531;
563 } else if (random < 0.9887) {
564 ip=5122;
565 } else if (random < 0.9943) {
566 ip=5132;
567 } else if (random < 0.9999) {
568 ip=5232;
569 } else {
570 ip=5332;
571 }
572
573 return ip;
574}
575
576//____________________________________________________________________________________
577Double_t AliGenCorrHF::ComputeIntegral(TFile* fG) // needed by GetQuarkPair
578{
579 // Read QQbar kinematical 5D grid's cell occupancy weights
580 Int_t* cell = new Int_t[6]; // cell[6]={wght,iy1,iy2,ipt1,ipt2,idph}
581 TTree* tG = (TTree*) fG->Get("tGqq");
582 tG->GetBranch("cell")->SetAddress(cell);
583 Int_t nbins = tG->GetEntries();
584
585 // delete previously computed integral (if any)
586 if(fgIntegral) delete [] fgIntegral;
587
588 fgIntegral = new Double_t[nbins+1];
589 fgIntegral[0] = 0;
590 Int_t bin;
591 for(bin=0;bin<nbins;bin++) {
592 tG->GetEvent(bin);
593 fgIntegral[bin+1] = fgIntegral[bin] + cell[0];
594 }
595 // Normalize integral to 1
596 if (fgIntegral[nbins] == 0 ) {
597 return 0;
598 }
599 for (bin=1;bin<=nbins;bin++) fgIntegral[bin] /= fgIntegral[nbins];
600
601 return fgIntegral[nbins];
602}
603
604//____________________________________________________________________________________
605void AliGenCorrHF::GetQuarkPair(TFile* fG, Double_t* fInt, Double_t &y1, Double_t &y2, Double_t &pt1, Double_t &pt2, Double_t &dphi)
606 // modification of ROOT's TH3::GetRandom3 for 5D
607{
608 // Read QQbar kinematical 5D grid's cell coordinates
609 Int_t* cell = new Int_t[6]; // cell[6]={wght,iy1,iy2,ipt1,ipt2,idph}
610 TTree* tG = (TTree*) fG->Get("tGqq");
611 tG->GetBranch("cell")->SetAddress(cell);
612 Int_t nbins = tG->GetEntries();
613 Double_t rand[6];
614 gRandom->RndmArray(6,rand);
615 Int_t ibin = TMath::BinarySearch(nbins,fInt,rand[0]);
616 tG->GetEvent(ibin);
617 y1 = fgy[cell[1]] + (fgy[cell[1]+1]-fgy[cell[1]])*rand[1];
618 y2 = fgy[cell[2]] + (fgy[cell[2]+1]-fgy[cell[2]])*rand[2];
619 pt1 = fgpt[cell[3]] + (fgpt[cell[3]+1]-fgpt[cell[3]])*rand[3];
620 pt2 = fgpt[cell[4]] + (fgpt[cell[4]+1]-fgpt[cell[4]])*rand[4];
621 dphi = fgdph[cell[5]]+ (fgdph[cell[5]+1]-fgdph[cell[5]])*rand[5];
622}
623
624//____________________________________________________________________________________
625void 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)
626{
627 // Generate a hadron pair
628 Int_t (*fIpParaFunc )(TRandom*);//Pointer to particle type parametrisation function
629 fIpParaFunc = IpCharm;
630 Double_t mq = 1.2; // c & b quark masses (used in AliPythia)
631 if (idq == 5) {
632 fIpParaFunc = IpBeauty;
633 mq = 4.75;
634 }
635 Double_t z11, z12, z21, z22, pz1, pz2, e1, e2, mh, ptemp, rand[2];
636 char tag[100];
637 TH2F *h2h[12], *h2s[12]; // hard & soft Fragmentation Functions
638 for (Int_t ipt = 0; ipt<fgnptbins; ipt++) {
639 sprintf(tag,"h2h_pt%d",ipt);
640 h2h[ipt] = (TH2F*) fG->Get(tag);
641 sprintf(tag,"h2s_pt%d",ipt);
642 h2s[ipt] = (TH2F*) fG->Get(tag);
643 }
644
645 if (y1*y2 < 0) {
646 for (Int_t ipt = 0; ipt<fgnptbins; ipt++) {
647 if(pt1 >= fgptbmin[ipt] && pt1 < fgptbmax[ipt])
648 h2h[ipt]->GetRandom2(z11, z21);
649 if(pt2 >= fgptbmin[ipt] && pt2 < fgptbmax[ipt])
650 h2h[ipt]->GetRandom2(z12, z22);
651 }
652 }
653 else {
654 if (TMath::Abs(y1) > TMath::Abs(y2)) {
655 for (Int_t ipt = 0; ipt<fgnptbins; ipt++) {
656 if(pt1 >= fgptbmin[ipt] && pt1 < fgptbmax[ipt])
657 h2h[ipt]->GetRandom2(z11, z21);
658 if(pt2 >= fgptbmin[ipt] && pt2 < fgptbmax[ipt])
659 h2s[ipt]->GetRandom2(z12, z22);
660 }
661 }
662 else {
663 for (Int_t ipt = 0; ipt<fgnptbins; ipt++) {
664 if(pt1 >= fgptbmin[ipt] && pt1 < fgptbmax[ipt])
665 h2s[ipt]->GetRandom2(z11, z21);
666 if(pt2 >= fgptbmin[ipt] && pt2 < fgptbmax[ipt])
667 h2h[ipt]->GetRandom2(z12, z22);
668 }
669 }
670 }
671 gRandom->RndmArray(2,rand);
672 ptemp = TMath::Sqrt(pt1*pt1 + mq*mq);
673 pz1 = ptemp*TMath::SinH(y1);
674 e1 = ptemp*TMath::CosH(y1);
675 ptemp = TMath::Sqrt(pt2*pt2 + mq*mq);
676 pz2 = ptemp*TMath::SinH(y2);
677 e2 = ptemp*TMath::CosH(y2);
678
679 id3 = fIpParaFunc(gRandom);
680 mh = TDatabasePDG::Instance()->GetParticle(id3)->Mass();
681 ptemp = z11*z21*(e1*e1-pz1*pz1) - mh*mh;
682 pt3 = (idq-3)*rand[0]; // some smearing at low pt, try better
683 if (ptemp > 0) pt3 = TMath::Sqrt(ptemp);
684 if (pz1 > 0) pz3 = (z11*(e1 + pz1) - z21*(e1 - pz1)) / 2;
685 else pz3 = (z21*(e1 + pz1) - z11*(e1 - pz1)) / 2;
686 e1 = TMath::Sqrt(pz3*pz3 + pt3*pt3 + mh*mh);
687
688 id4 = - fIpParaFunc(gRandom);
689 mh = TDatabasePDG::Instance()->GetParticle(id4)->Mass();
690 ptemp = z12*z22*(e2*e2-pz2*pz2) - mh*mh;
691 pt4 = (idq-3)*rand[1]; // some smearing at low pt, try better
692 if (ptemp > 0) pt4 = TMath::Sqrt(ptemp);
693 if (pz2 > 0) pz4 = (z12*(e2 + pz2) - z22*(e2 - pz2)) / 2;
694 else pz4 = (z22*(e2 + pz2) - z12*(e2 - pz2)) / 2;
695 e2 = TMath::Sqrt(pz4*pz4 + pt4*pt4 + mh*mh);
696
697 // small corr. instead of using Frag. Func. depending on yQ (in addition to ptQ)
698 Float_t ycorr = 0.2, y3, y4;
699 gRandom->RndmArray(2,rand);
700 y3 = 0.5 * TMath::Log((e1 + pz3 + 1.e-13)/(e1 - pz3 + 1.e-13));
701 y4 = 0.5 * TMath::Log((e2 + pz4 + 1.e-13)/(e2 - pz4 + 1.e-13));
702 if(TMath::Abs(y3)<ycorr && TMath::Abs(y4)<ycorr && rand[0]>0.5) {
703 ptemp = TMath::Sqrt(e1*e1 - pz3*pz3);
704 y3 = 4*(1 - 2*rand[1]);
705 pz3 = ptemp*TMath::SinH(y3);
706 pz4 = pz3;
707 }
708}