1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
18 #include "AliPythia.h"
19 #include "AliPythiaRndm.h"
20 #include "../FASTSIM/AliFastGlauber.h"
21 #include "../FASTSIM/AliQuenchingWeights.h"
27 # define pyclus pyclus_
28 # define pycell pycell_
29 # define pyshow pyshow_
30 # define pyrobo pyrobo_
31 # define pyquen pyquen_
32 # define pyevnw pyevnw_
35 # define pyclus PYCLUS
36 # define pycell PYCELL
37 # define pyrobo PYROBO
38 # define pyquen PYQUEN
39 # define pyevnw PYEVNW
40 # define type_of_call _stdcall
43 extern "C" void type_of_call pyclus(Int_t & );
44 extern "C" void type_of_call pycell(Int_t & );
45 extern "C" void type_of_call pyshow(Int_t &, Int_t &, Double_t &);
46 extern "C" void type_of_call pyrobo(Int_t &, Int_t &, Double_t &, Double_t &, Double_t &, Double_t &, Double_t &);
47 extern "C" void type_of_call pyquen(Double_t &, Int_t &, Double_t &);
48 extern "C" void type_of_call pyevnw();
50 //_____________________________________________________________________________
52 AliPythia* AliPythia::fgAliPythia=NULL;
54 AliPythia::AliPythia()
56 // Default Constructor
59 if (!AliPythiaRndm::GetPythiaRandom())
60 AliPythiaRndm::SetPythiaRandom(GetRandom());
62 fQuenchingWeights = 0;
65 void AliPythia::ProcInit(Process_t process, Float_t energy, StrucFunc_t strucfunc)
67 // Initialise the process to generate
68 if (!AliPythiaRndm::GetPythiaRandom())
69 AliPythiaRndm::SetPythiaRandom(GetRandom());
73 fStrucFunc = strucfunc;
74 //...Switch off decay of pi0, K0S, Lambda, Sigma+-, Xi0-, Omega-.
75 SetMDCY(Pycomp(111) ,1,0);
76 SetMDCY(Pycomp(310) ,1,0);
77 SetMDCY(Pycomp(3122),1,0);
78 SetMDCY(Pycomp(3112),1,0);
79 SetMDCY(Pycomp(3212),1,0);
80 SetMDCY(Pycomp(3222),1,0);
81 SetMDCY(Pycomp(3312),1,0);
82 SetMDCY(Pycomp(3322),1,0);
83 SetMDCY(Pycomp(3334),1,0);
84 // select structure function
86 SetMSTP(51,strucfunc);
88 // Pythia initialisation for selected processes//
92 for (Int_t i=1; i<= 200; i++) {
95 // select charm production
98 case kPyOldUEQ2ordered: //Old underlying events with Q2 ordered QCD processes
99 // Multiple interactions on.
101 // Double Gaussian matter distribution.
107 // Reference energy for pT0 and energy rescaling pace.
110 // String drawing almost completely minimizes string length.
113 // ISR and FSR activity.
119 case kPyOldUEQ2ordered2:
120 // Old underlying events with Q2 ordered QCD processes
121 // Multiple interactions on.
123 // Double Gaussian matter distribution.
129 // Reference energy for pT0 and energy rescaling pace.
131 SetPARP(90,0.16); // here is the difference with kPyOldUEQ2ordered
132 // String drawing almost completely minimizes string length.
135 // ISR and FSR activity.
142 // Old production mechanism: Old Popcorn
145 // (D=2) Like MSTJ(12)=2 but added prod ofthe 1er rank baryon
147 // (D=1)see can be used to form baryons (BARYON JUNCTION)
149 SetMSTP(51,kCTEQ5L);// CTEQ 5L ! CTEQ5L pdf
150 SetMSTP(81,1); // Multiple Interactions ON
151 SetMSTP(82,4); // Double Gaussian Model
152 SetPARP(82,1.8); // [GeV] PT_min at Ref. energy
153 SetPARP(89,1000.); // [GeV] Ref. energy
154 SetPARP(90,0.16); // 2*epsilon (exponent in power law)
155 SetPARP(83,0.5); // Core density in proton matter dist. (def.value)
156 SetPARP(84,0.5); // Core radius
157 SetPARP(85,0.33); // Regulates gluon prod. mechanism
158 SetPARP(86,0.66); // Regulates gluon prod. mechanism
159 SetPARP(67,1); // Regulate gluon prod. mechanism
163 // heavy quark masses
195 case kPyCharmUnforced:
204 case kPyBeautyUnforced:
214 // Minimum Bias pp-Collisions
217 // select Pythia min. bias model
219 SetMSUB(92,1); // single diffraction AB-->XB
220 SetMSUB(93,1); // single diffraction AB-->AX
221 SetMSUB(94,1); // double diffraction
222 SetMSUB(95,1); // low pt production
228 SetMSTP(51, kCTEQ5L); // CTEQ5L pdf
229 SetMSTP(81,1); // Multiple Interactions ON
230 SetMSTP(82,4); // Double Gaussian Model
232 SetPARP(82,1.8); // [GeV] PT_min at Ref. energy
233 SetPARP(89,1000.); // [GeV] Ref. energy
234 SetPARP(90,0.16); // 2*epsilon (exponent in power law)
235 SetPARP(83,0.5); // Core density in proton matter distribution (def.value)
236 SetPARP(84,0.5); // Core radius
237 SetPARP(85,0.33); // Regulates gluon prod. mechanism
238 SetPARP(86,0.66); // Regulates gluon prod. mechanism
239 SetPARP(67,1); // Regulates Initial State Radiation
242 // Minimum Bias pp-Collisions
245 // select Pythia min. bias model
247 SetMSUB(95,1); // low pt production
253 SetMSTP(51,kCTEQ5L); // CTEQ5L pdf
254 SetMSTP(81,1); // Multiple Interactions ON
255 SetMSTP(82,4); // Double Gaussian Model
257 SetPARP(82,1.8); // [GeV] PT_min at Ref. energy
258 SetPARP(89,1000.); // [GeV] Ref. energy
259 SetPARP(90,0.16); // 2*epsilon (exponent in power law)
260 SetPARP(83,0.5); // Core density in proton matter distribution (def.value)
261 SetPARP(84,0.5); // Core radius
262 SetPARP(85,0.33); // Regulates gluon prod. mechanism
263 SetPARP(86,0.66); // Regulates gluon prod. mechanism
264 SetPARP(67,1); // Regulates Initial State Radiation
271 // Pythia Tune A (CDF)
273 SetPARP(67,4.); // Regulates Initial State Radiation
274 SetMSTP(82,4); // Double Gaussian Model
275 SetPARP(82,2.0); // [GeV] PT_min at Ref. energy
276 SetPARP(84,0.4); // Core radius
277 SetPARP(85,0.90) ; // Regulates gluon prod. mechanism
278 SetPARP(86,0.95); // Regulates gluon prod. mechanism
279 SetPARP(89,1800.); // [GeV] Ref. energy
280 SetPARP(90,0.25); // 2*epsilon (exponent in power law)
285 case kPyCharmPbPbMNR:
287 // Tuning of Pythia parameters aimed to get a resonable agreement
288 // between with the NLO calculation by Mangano, Nason, Ridolfi for the
289 // c-cbar single inclusive and double differential distributions.
290 // This parameter settings are meant to work with Pb-Pb collisions
291 // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
292 // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
293 // has to be set to 2.1GeV. Example in ConfigCharmPPR.C.
298 // No multiple interactions
303 // Initial/final parton shower on (Pythia default)
323 case kPyDPlusPbPbMNR:
324 // Tuning of Pythia parameters aimed to get a resonable agreement
325 // between with the NLO calculation by Mangano, Nason, Ridolfi for the
326 // c-cbar single inclusive and double differential distributions.
327 // This parameter settings are meant to work with Pb-Pb collisions
328 // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
329 // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
330 // has to be set to 2.1GeV. Example in ConfigCharmPPR.C.
335 // No multiple interactions
340 // Initial/final parton shower on (Pythia default)
362 // Tuning of Pythia parameters aimed to get a resonable agreement
363 // between with the NLO calculation by Mangano, Nason, Ridolfi for the
364 // c-cbar single inclusive and double differential distributions.
365 // This parameter settings are meant to work with p-Pb collisions
366 // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
367 // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
368 // has to be set to 2.1GeV. Example in ConfigCharmPPR.C.
373 // No multiple interactions
378 // Initial/final parton shower on (Pythia default)
399 // Tuning of Pythia parameters aimed to get a resonable agreement
400 // between with the NLO calculation by Mangano, Nason, Ridolfi for the
401 // c-cbar single inclusive and double differential distributions.
402 // This parameter settings are meant to work with p-Pb collisions
403 // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
404 // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
405 // has to be set to 2.1GeV. Example in ConfigCharmPPR.C.
410 // No multiple interactions
415 // Initial/final parton shower on (Pythia default)
437 // Tuning of Pythia parameters aimed to get a resonable agreement
438 // between with the NLO calculation by Mangano, Nason, Ridolfi for the
439 // c-cbar single inclusive and double differential distributions.
440 // This parameter settings are meant to work with pp collisions
441 // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
442 // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
443 // has to be set to 2.1GeV. Example in ConfigCharmPPR.C.
448 // No multiple interactions
453 // Initial/final parton shower on (Pythia default)
474 // Tuning of Pythia parameters aimed to get a resonable agreement
475 // between with the NLO calculation by Mangano, Nason, Ridolfi for the
476 // c-cbar single inclusive and double differential distributions.
477 // This parameter settings are meant to work with pp collisions
478 // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
479 // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
480 // has to be set to 2.1GeV. Example in ConfigCharmPPR.C.
485 // No multiple interactions
490 // Initial/final parton shower on (Pythia default)
510 case kPyBeautyPbPbMNR:
511 // Tuning of Pythia parameters aimed to get a resonable agreement
512 // between with the NLO calculation by Mangano, Nason, Ridolfi for the
513 // b-bbar single inclusive and double differential distributions.
514 // This parameter settings are meant to work with Pb-Pb collisions
515 // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
516 // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
517 // has to be set to 2.75GeV. Example in ConfigBeautyPPR.C.
522 // No multiple interactions
527 // Initial/final parton shower on (Pythia default)
549 case kPyBeautypPbMNR:
550 // Tuning of Pythia parameters aimed to get a resonable agreement
551 // between with the NLO calculation by Mangano, Nason, Ridolfi for the
552 // b-bbar single inclusive and double differential distributions.
553 // This parameter settings are meant to work with p-Pb collisions
554 // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
555 // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
556 // has to be set to 2.75GeV. Example in ConfigBeautyPPR.C.
561 // No multiple interactions
566 // Initial/final parton shower on (Pythia default)
589 // Tuning of Pythia parameters aimed to get a resonable agreement
590 // between with the NLO calculation by Mangano, Nason, Ridolfi for the
591 // b-bbar single inclusive and double differential distributions.
592 // This parameter settings are meant to work with pp collisions
593 // (AliGenPythia::SetNuclei) and with kCTEQ4L PDFs.
594 // To get a good agreement the minimum ptHard (AliGenPythia::SetPtHard)
595 // has to be set to 2.75GeV. Example in ConfigBeautyPPR.C.
600 // No multiple interactions
605 // Initial/final parton shower on (Pythia default)
630 //Inclusive production of W+/-
636 // //f fbar -> gamma W+
643 // Initial/final parton shower on (Pythia default)
644 // With parton showers on we are generating "W inclusive process"
645 SetMSTP(61,1); //Initial QCD & QED showers on
646 SetMSTP(71,1); //Final QCD & QED showers on
652 //Inclusive production of Z
657 // // f fbar -> g Z/gamma
659 // // f fbar -> gamma Z/gamma
661 // // f g -> f Z/gamma
663 // // f gamma -> f Z/gamma
666 //only Z included, not gamma
669 // Initial/final parton shower on (Pythia default)
670 // With parton showers on we are generating "Z inclusive process"
671 SetMSTP(61,1); //Initial QCD & QED showers on
672 SetMSTP(71,1); //Final QCD & QED showers on
679 SetMSTP(41,1); // all resonance decays switched on
681 Initialize("CMS","p","p",fEcms);
685 Int_t AliPythia::CheckedLuComp(Int_t kf)
687 // Check Lund particle code (for debugging)
689 printf("\n Lucomp kf,kc %d %d",kf,kc);
693 void AliPythia::SetNuclei(Int_t a1, Int_t a2)
695 // Treat protons as inside nuclei with mass numbers a1 and a2
696 // The MSTP array in the PYPARS common block is used to enable and
697 // select the nuclear structure functions.
698 // MSTP(52) : (D=1) choice of proton and nuclear structure-function library
699 // =1: internal PYTHIA acording to MSTP(51)
700 // =2: PDFLIB proton s.f., with MSTP(51) = 1000xNGROUP+NSET
701 // If the following mass number both not equal zero, nuclear corrections of the stf are used.
702 // MSTP(192) : Mass number of nucleus side 1
703 // MSTP(193) : Mass number of nucleus side 2
710 AliPythia* AliPythia::Instance()
712 // Set random number generator
716 fgAliPythia = new AliPythia();
721 void AliPythia::PrintParticles()
723 // Print list of particl properties
725 char* name = new char[16];
726 for (Int_t kf=0; kf<1000000; kf++) {
727 for (Int_t c = 1; c > -2; c-=2) {
728 Int_t kc = Pycomp(c*kf);
730 Float_t mass = GetPMAS(kc,1);
731 Float_t width = GetPMAS(kc,2);
732 Float_t tau = GetPMAS(kc,4);
738 printf("\n mass, width, tau: %6d %s %10.3f %10.3e %10.3e",
739 c*kf, name, mass, width, tau);
743 printf("\n Number of particles %d \n \n", np);
746 void AliPythia::ResetDecayTable()
748 // Set default values for pythia decay switches
750 for (i = 1; i < 501; i++) SetMDCY(i,1,fDefMDCY[i]);
751 for (i = 1; i < 2001; i++) SetMDME(i,1,fDefMDME[i]);
754 void AliPythia::SetDecayTable()
756 // Set default values for pythia decay switches
759 for (i = 1; i < 501; i++) fDefMDCY[i] = GetMDCY(i,1);
760 for (i = 1; i < 2001; i++) fDefMDME[i] = GetMDME(i,1);
763 void AliPythia::Pyclus(Int_t& njet)
765 // Call Pythia clustering algorithm
770 void AliPythia::Pycell(Int_t& njet)
772 // Call Pythia jet reconstruction algorithm
777 void AliPythia::Pyshow(Int_t ip1, Int_t ip2, Double_t qmax)
779 // Call Pythia jet reconstruction algorithm
781 pyshow(ip1, ip2, qmax);
784 void AliPythia::Pyrobo(Int_t imi, Int_t ima, Double_t the, Double_t phi, Double_t bex, Double_t bey, Double_t bez)
786 pyrobo(imi, ima, the, phi, bex, bey, bez);
791 void AliPythia::InitQuenching(Float_t cMin, Float_t cMax, Float_t k, Int_t iECMethod)
794 // (1) The quenching model using quenching weights according to C. Salgado and U. Wiedemann
795 // (2) The nuclear geometry using the Glauber Model
799 fGlauber = new AliFastGlauber();
801 fGlauber->SetCentralityClass(cMin, cMax);
803 fQuenchingWeights = new AliQuenchingWeights();
804 fQuenchingWeights->InitMult();
805 fQuenchingWeights->SetK(k);
806 fQuenchingWeights->SetECMethod(AliQuenchingWeights::kECMethod(iECMethod));
810 void AliPythia::Quench()
814 // Simple Jet Quenching routine:
815 // =============================
816 // The jet formed by all final state partons radiated by the parton created
817 // in the hard collisions is quenched by a factor (1-z) using light cone variables in
818 // the initial parton reference frame:
819 // (E + p_z)new = (1-z) (E + p_z)old
824 // The lost momentum is first balanced by one gluon with virtuality > 0.
825 // Subsequently the gluon splits to yield two gluons with E = p.
829 static Float_t eMean = 0.;
830 static Int_t icall = 0;
835 Int_t klast[4] = {-1, -1, -1, -1};
837 Int_t numpart = fPyjets->N;
838 Double_t px = 0., py = 0., pz = 0., e = 0., m = 0., p = 0., pt = 0., theta = 0., phi = 0.;
839 Double_t pxq[4], pyq[4], pzq[4], eq[4], yq[4], mq[4], pq[4], phiq[4], thetaq[4], ptq[4];
847 // Sore information about Primary partons
850 // 0, 1 partons from hard scattering
851 // 2, 3 partons from initial state radiation
853 for (Int_t i = 2; i <= 7; i++) {
855 // Skip gluons that participate in hard scattering
856 if (i == 4 || i == 5) continue;
857 // Gluons from hard Scattering
858 if (i == 6 || i == 7) {
860 pxq[j] = fPyjets->P[0][i];
861 pyq[j] = fPyjets->P[1][i];
862 pzq[j] = fPyjets->P[2][i];
863 eq[j] = fPyjets->P[3][i];
864 mq[j] = fPyjets->P[4][i];
866 // Gluons from initial state radiation
868 // Obtain 4-momentum vector from difference between original parton and parton after gluon
869 // radiation. Energy is calculated independently because initial state radition does not
870 // conserve strictly momentum and energy for each partonic system independently.
872 // Not very clean. Should be improved !
876 pxq[j] = fPyjets->P[0][i] - fPyjets->P[0][i+2];
877 pyq[j] = fPyjets->P[1][i] - fPyjets->P[1][i+2];
878 pzq[j] = fPyjets->P[2][i] - fPyjets->P[2][i+2];
879 mq[j] = fPyjets->P[4][i];
880 eq[j] = TMath::Sqrt(pxq[j] * pxq[j] + pyq[j] * pyq[j] + pzq[j] * pzq[j] + mq[j] * mq[j]);
883 // Calculate some kinematic variables
885 yq[j] = 0.5 * TMath::Log((eq[j] + pzq[j] + 1.e-14) / (eq[j] - pzq[j] + 1.e-14));
886 pq[j] = TMath::Sqrt(pxq[j] * pxq[j] + pyq[j] * pyq[j] + pzq[j] * pzq[j]);
887 phiq[j] = TMath::Pi()+TMath::ATan2(-pyq[j], -pxq[j]);
888 ptq[j] = TMath::Sqrt(pxq[j] * pxq[j] + pyq[j] * pyq[j]);
889 thetaq[j] = TMath::ATan2(ptq[j], pzq[j]);
890 qPdg[j] = fPyjets->K[1][i];
896 fGlauber->GetI0I1ForPythiaAndXY(4, phiq, int0, int1, fXJet, fYJet, 15.);
898 for (Int_t j = 0; j < 4; j++) {
900 // Quench only central jets and with E > 10.
904 Int_t itype = (qPdg[j] == 21) ? 2 : 1;
905 Double_t eloss = fQuenchingWeights->GetELossRandomKFast(itype, int0[j], int1[j], eq[j]);
907 if (TMath::Abs(yq[j]) > 2.5 || eq[j] < 10.) {
910 if (eq[j] > 40. && TMath::Abs(yq[j]) < 0.5) {
916 Double_t l = fQuenchingWeights->CalcLk(int0[j], int1[j]);
917 wjtKick[j] = TMath::Sqrt(l * fQuenchingWeights->CalcQk(int0[j], int1[j]));
919 // Fractional energy loss
920 fZQuench[j] = eloss / eq[j];
922 // Avoid complete loss
924 if (fZQuench[j] == 1.) fZQuench[j] = 0.95;
926 // Some debug printing
929 // printf("Initial parton # %3d, Type %3d Energy %10.3f Phi %10.3f Length %10.3f Loss %10.3f Kick %10.3f Mean: %10.3f %10.3f\n",
930 // j, itype, eq[j], phiq[j], l, eloss, wjtKick[j], eMean / Float_t(icall+1), yq[j]);
932 // fZQuench[j] = 0.8;
933 // while (fZQuench[j] >= 0.95) fZQuench[j] = gRandom->Exp(0.2);
936 quenched[j] = (fZQuench[j] > 0.01);
941 Double_t pNew[1000][4];
948 for (Int_t isys = 0; isys < 4; isys++) {
949 // Skip to next system if not quenched.
950 if (!quenched[isys]) continue;
952 nGluon[isys] = 1 + Int_t(fZQuench[isys] / (1. - fZQuench[isys]));
953 if (nGluon[isys] > 6) nGluon[isys] = 6;
954 zquench[isys] = 1. - TMath::Power(1. - fZQuench[isys], 1./Double_t(nGluon[isys]));
955 wjtKick[isys] = wjtKick[isys] / TMath::Sqrt(Double_t(nGluon[isys]));
961 Double_t pg[4] = {0., 0., 0., 0.};
964 // Loop on radiation events
966 for (Int_t iglu = 0; iglu < nGluon[isys]; iglu++) {
969 for (Int_t k = 0; k < 4; k++)
976 for (Int_t i = 0; i < numpart; i++)
978 imo = fPyjets->K[2][i];
979 kst = fPyjets->K[0][i];
980 pdg = fPyjets->K[1][i];
984 // Quarks and gluons only
985 if (pdg != 21 && TMath::Abs(pdg) > 6) continue;
986 // Particles from hard scattering only
988 if (imo > 8 && imo < 1000) imo = fPyjets->K[2][imo - 1];
989 Int_t imom = imo % 1000;
990 if ((isys == 0 || isys == 1) && ((imom != (isys + 7)))) continue;
991 if ((isys == 2 || isys == 3) && ((imom != (isys + 1)))) continue;
994 // Skip comment lines
995 if (kst != 1 && kst != 2) continue;
998 px = fPyjets->P[0][i];
999 py = fPyjets->P[1][i];
1000 pz = fPyjets->P[2][i];
1001 e = fPyjets->P[3][i];
1002 m = fPyjets->P[4][i];
1003 pt = TMath::Sqrt(px * px + py * py);
1004 p = TMath::Sqrt(px * px + py * py + pz * pz);
1005 phi = TMath::Pi() + TMath::ATan2(-py, -px);
1006 theta = TMath::ATan2(pt, pz);
1009 // Save 4-momentum sum for balancing
1020 // Fractional energy loss
1021 Double_t z = zquench[index];
1024 // Don't fully quench radiated gluons
1027 // This small factor makes sure that the gluons are not too close in phase space to avoid recombination
1032 // printf("z: %d %f\n", imo, z);
1039 // Transform into frame in which initial parton is along z-axis
1041 TVector3 v(px, py, pz);
1042 v.RotateZ(-phiq[index]); v.RotateY(-thetaq[index]);
1043 Double_t pxs = v.X(); Double_t pys = v.Y(); Double_t pl = v.Z();
1045 Double_t jt = TMath::Sqrt(pxs * pxs + pys * pys);
1046 Double_t mt2 = jt * jt + m * m;
1049 // Kinematic limit on z
1051 if (m > 0.) zmax = 1. - m / TMath::Sqrt(m * m + jt * jt);
1053 // Change light-cone kinematics rel. to initial parton
1055 Double_t eppzOld = e + pl;
1056 Double_t empzOld = e - pl;
1058 Double_t eppzNew = (1. - z) * eppzOld;
1059 Double_t empzNew = empzOld - mt2 * z / eppzOld;
1060 Double_t eNew = 0.5 * (eppzNew + empzNew);
1061 Double_t plNew = 0.5 * (eppzNew - empzNew);
1065 // if mt very small (or sometimes even < 0 for numerical reasons) set it to 0
1066 Double_t mt2New = eppzNew * empzNew;
1067 if (mt2New < 1.e-8) mt2New = 0.;
1069 if (m * m > mt2New) {
1071 // This should not happen
1073 Fatal("Quench()", "This should never happen %e %e %e!", m, eppzNew, empzNew);
1076 jtNew = TMath::Sqrt(mt2New - m * m);
1079 // If pT is to small (probably a leading massive particle) we scale only the energy
1080 // This can cause negative masses of the radiated gluon
1081 // Let's hope for the best ...
1083 eNew = TMath::Sqrt(plNew * plNew + mt2);
1087 // Calculate new px, py
1089 Double_t pxNew = jtNew / jt * pxs;
1090 Double_t pyNew = jtNew / jt * pys;
1092 // Double_t dpx = pxs - pxNew;
1093 // Double_t dpy = pys - pyNew;
1094 // Double_t dpz = pl - plNew;
1095 // Double_t de = e - eNew;
1096 // Double_t dmass2 = de * de - dpx * dpx - dpy * dpy - dpz * dpz;
1097 // printf("New mass (1) %e %e %e %e %e %e %e \n", dmass2, jt, jtNew, pl, plNew, e, eNew);
1098 // printf("New mass (2) %e %e \n", pxNew, pyNew);
1102 TVector3 w(pxNew, pyNew, plNew);
1103 w.RotateY(thetaq[index]); w.RotateZ(phiq[index]);
1104 pxNew = w.X(); pyNew = w.Y(); plNew = w.Z();
1106 p1[index][0] += pxNew;
1107 p1[index][1] += pyNew;
1108 p1[index][2] += plNew;
1109 p1[index][3] += eNew;
1111 // Updated 4-momentum vectors
1113 pNew[icount][0] = pxNew;
1114 pNew[icount][1] = pyNew;
1115 pNew[icount][2] = plNew;
1116 pNew[icount][3] = eNew;
1121 // Check if there was phase-space for quenching
1124 if (icount == 0) quenched[isys] = kFALSE;
1125 if (!quenched[isys]) break;
1127 for (Int_t j = 0; j < 4; j++)
1129 p2[isys][j] = p0[isys][j] - p1[isys][j];
1131 p2[isys][4] = p2[isys][3] * p2[isys][3] - p2[isys][0] * p2[isys][0] - p2[isys][1] * p2[isys][1] - p2[isys][2] * p2[isys][2];
1132 if (p2[isys][4] > 0.) {
1133 p2[isys][4] = TMath::Sqrt(p2[isys][4]);
1136 printf("Warning negative mass squared in system %d %f ! \n", isys, zquench[isys]);
1137 printf("4-Momentum: %10.3e %10.3e %10.3e %10.3e %10.3e \n", p2[isys][0], p2[isys][1], p2[isys][2], p2[isys][3], p2[isys][4]);
1138 if (p2[isys][4] < -0.01) {
1139 printf("Negative mass squared !\n");
1140 // Here we have to put the gluon back to mass shell
1141 // This will lead to a small energy imbalance
1143 p2[isys][3] = TMath::Sqrt(p2[isys][0] * p2[isys][0] + p2[isys][1] * p2[isys][1] + p2[isys][2] * p2[isys][2]);
1152 printf("zHeavy lowered to %f\n", zHeavy);
1153 if (zHeavy < 0.01) {
1154 printf("No success ! \n");
1156 quenched[isys] = kFALSE;
1160 } // iteration on z (while)
1162 // Update event record
1163 for (Int_t k = 0; k < icount; k++) {
1164 // printf("%6d %6d %10.3e %10.3e %10.3e %10.3e\n", k, kNew[k], pNew[k][0],pNew[k][1], pNew[k][2], pNew[k][3] );
1165 fPyjets->P[0][kNew[k]] = pNew[k][0];
1166 fPyjets->P[1][kNew[k]] = pNew[k][1];
1167 fPyjets->P[2][kNew[k]] = pNew[k][2];
1168 fPyjets->P[3][kNew[k]] = pNew[k][3];
1175 if (!quenched[isys]) continue;
1177 // Last parton from shower i
1178 Int_t in = klast[isys];
1180 // Continue if no parton in shower i selected
1181 if (in == -1) continue;
1183 // If this is the second initial parton and it is behind the first move pointer by previous ish
1184 if (isys == 1 && klast[1] > klast[0]) in += ish;
1189 // How many additional gluons will be generated
1191 if (p2[isys][4] > 0.05) ish = 2;
1193 // Position of gluons
1195 if (iglu == 0) igMin = iGlu;
1198 (fPyjets->N) += ish;
1201 fPyjets->P[0][iGlu] = p2[isys][0];
1202 fPyjets->P[1][iGlu] = p2[isys][1];
1203 fPyjets->P[2][iGlu] = p2[isys][2];
1204 fPyjets->P[3][iGlu] = p2[isys][3];
1205 fPyjets->P[4][iGlu] = p2[isys][4];
1207 fPyjets->K[0][iGlu] = 1;
1208 if (iglu == nGluon[isys] - 1) fPyjets->K[0][iGlu] = 1;
1209 fPyjets->K[1][iGlu] = 21;
1210 fPyjets->K[2][iGlu] = fPyjets->K[2][in] + 1000;
1211 fPyjets->K[3][iGlu] = -1;
1212 fPyjets->K[4][iGlu] = -1;
1214 pg[0] += p2[isys][0];
1215 pg[1] += p2[isys][1];
1216 pg[2] += p2[isys][2];
1217 pg[3] += p2[isys][3];
1220 // Split gluon in rest frame.
1222 Double_t bx = p2[isys][0] / p2[isys][3];
1223 Double_t by = p2[isys][1] / p2[isys][3];
1224 Double_t bz = p2[isys][2] / p2[isys][3];
1225 Double_t pst = p2[isys][4] / 2.;
1227 // Isotropic decay ????
1228 Double_t cost = 2. * gRandom->Rndm() - 1.;
1229 Double_t sint = TMath::Sqrt(1. - cost * cost);
1230 Double_t phi = 2. * TMath::Pi() * gRandom->Rndm();
1232 Double_t pz1 = pst * cost;
1233 Double_t pz2 = -pst * cost;
1234 Double_t pt1 = pst * sint;
1235 Double_t pt2 = -pst * sint;
1236 Double_t px1 = pt1 * TMath::Cos(phi);
1237 Double_t py1 = pt1 * TMath::Sin(phi);
1238 Double_t px2 = pt2 * TMath::Cos(phi);
1239 Double_t py2 = pt2 * TMath::Sin(phi);
1241 fPyjets->P[0][iGlu] = px1;
1242 fPyjets->P[1][iGlu] = py1;
1243 fPyjets->P[2][iGlu] = pz1;
1244 fPyjets->P[3][iGlu] = pst;
1245 fPyjets->P[4][iGlu] = 0.;
1247 fPyjets->K[0][iGlu] = 1 ;
1248 fPyjets->K[1][iGlu] = 21;
1249 fPyjets->K[2][iGlu] = fPyjets->K[2][in] + 1000;
1250 fPyjets->K[3][iGlu] = -1;
1251 fPyjets->K[4][iGlu] = -1;
1253 fPyjets->P[0][iGlu+1] = px2;
1254 fPyjets->P[1][iGlu+1] = py2;
1255 fPyjets->P[2][iGlu+1] = pz2;
1256 fPyjets->P[3][iGlu+1] = pst;
1257 fPyjets->P[4][iGlu+1] = 0.;
1259 fPyjets->K[0][iGlu+1] = 1;
1260 if (iglu == nGluon[isys] - 1) fPyjets->K[0][iGlu+1] = 1;
1261 fPyjets->K[1][iGlu+1] = 21;
1262 fPyjets->K[2][iGlu+1] = fPyjets->K[2][in] + 1000;
1263 fPyjets->K[3][iGlu+1] = -1;
1264 fPyjets->K[4][iGlu+1] = -1;
1270 Pyrobo(iGlu + 1, iGlu + 2, 0., 0., bx, by, bz);
1273 for (Int_t ig = iGlu; ig < iGlu+ish; ig++) {
1274 Double_t px, py, pz;
1275 px = fPyjets->P[0][ig];
1276 py = fPyjets->P[1][ig];
1277 pz = fPyjets->P[2][ig];
1278 TVector3 v(px, py, pz);
1279 v.RotateZ(-phiq[isys]);
1280 v.RotateY(-thetaq[isys]);
1281 Double_t pxs = v.X(); Double_t pys = v.Y(); Double_t pzs = v.Z();
1282 Double_t r = AliPythiaRndm::GetPythiaRandom()->Rndm();
1283 Double_t jtKick = 0.3 * TMath::Sqrt(-TMath::Log(r));
1284 if (ish == 2) jtKick = wjtKick[i] * TMath::Sqrt(-TMath::Log(r)) / TMath::Sqrt(2.);
1285 Double_t phiKick = 2. * TMath::Pi() * AliPythiaRndm::GetPythiaRandom()->Rndm();
1286 pxs += jtKick * TMath::Cos(phiKick);
1287 pys += jtKick * TMath::Sin(phiKick);
1288 TVector3 w(pxs, pys, pzs);
1289 w.RotateY(thetaq[isys]);
1290 w.RotateZ(phiq[isys]);
1291 fPyjets->P[0][ig] = w.X();
1292 fPyjets->P[1][ig] = w.Y();
1293 fPyjets->P[2][ig] = w.Z();
1294 fPyjets->P[2][ig] = w.Mag();
1300 // Check energy conservation
1304 Double_t es = 14000.;
1306 for (Int_t i = 0; i < numpart; i++)
1308 kst = fPyjets->K[0][i];
1309 if (kst != 1 && kst != 2) continue;
1310 pxs += fPyjets->P[0][i];
1311 pys += fPyjets->P[1][i];
1312 pzs += fPyjets->P[2][i];
1313 es -= fPyjets->P[3][i];
1315 if (TMath::Abs(pxs) > 1.e-2 ||
1316 TMath::Abs(pys) > 1.e-2 ||
1317 TMath::Abs(pzs) > 1.e-1) {
1318 printf("%e %e %e %e\n", pxs, pys, pzs, es);
1319 // Fatal("Quench()", "4-Momentum non-conservation");
1322 } // end quenching loop (systems)
1324 for (Int_t i = 0; i < numpart; i++)
1326 imo = fPyjets->K[2][i];
1328 fPyjets->K[2][i] = fPyjets->K[2][i] % 1000;
1335 void AliPythia::Pyquen(Double_t a, Int_t ibf, Double_t b)
1337 // Igor Lokthine's quenching routine
1341 void AliPythia::Pyevnw()
1343 // New multiple interaction scenario
1347 void AliPythia::GetQuenchingParameters(Double_t& xp, Double_t& yp, Double_t z[4])
1349 // Return event specific quenching parameters
1352 for (Int_t i = 0; i < 4; i++) z[i] = fZQuench[i];