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Raphael did some modifications to AliGenMUONLMR in order to make it more robust.
[u/mrichter/AliRoot.git] / EVGEN / AliGenMUONLMR.cxx
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368fc61e 1//#include <TClonesArray.h>
2
3#include <TDatabasePDG.h>
4#include <TFile.h>
5#include "AliConst.h"
6#include "AliGenMUONLMR.h"
7#include "AliMC.h"
8#include "AliRun.h"
c279681a 9#include "AliLog.h"
368fc61e 10#include "AliGenEventHeader.h"
11
12ClassImp(AliGenMUONLMR)
13
c279681a 14AliGenMUONLMR::AliGenMUONLMR () : AliGenMC(),
35e2c739 15 fNMuMin(2),
c279681a 16 fCMSEnergy(kNCMSEnergies),
35e2c739 17 fGenSingleProc(-1),
18 fCosTheta(0x0),
19 fRhoLineShape(0x0),
20 fHMultMu(0x0),
21 fHNProc(0x0) {
368fc61e 22 //
23 // default constructor
24 //
c279681a 25 for (int i=0; i<fgkNpart; i++) {
26 fPDG[i] = 0;
27 fScaleMult[i] = 1.;
28 fPt[i] = NULL;
29 fY[i] = NULL;
30 fMult[i] = NULL;
31 fDecay[i] = NULL;
32 fParticle[i] = NULL;
33 }
34for (int i=0; i<3; i++) fDalitz[i] = NULL;
35for (int i=0; i<3; i++) fMu[i] = NULL;
36
37}
35e2c739 38
c279681a 39//-----------------------------------------------------------
368fc61e 40
c279681a 41void AliGenMUONLMR::SetCMSEnergy(CMSEnergies energy){
42 fCMSEnergy = energy;
43 // initialize pt and y distributions according to a fit to
44 // Pythia simulation at sqrt(s) = 7 TeV
45 for (Int_t ipart=0; ipart < fgkNpart; ipart++) fScaleMult[ipart] = 1;
46 fScaleMult[kPionLMR] = 0; // set pion multiplicity to zero
47 fScaleMult[kKaonLMR] = 0; // set kaon multiplicity to zero
48 const char* fdname[2] = {"fDecPion","fDecKaon"};
49 Double_t ctau[2] = {7.8045, 3.712};
50 Int_t pdg[7] = {211, 321, 221, 113, 223, 333, 331};
51 const char* fptname[7] = {"fPtPion","fPtKaon","fPtEta","fPtRho","fPtOmega","fPtPhi","fPtEtaPrime"};
52 const char* fyname[7] = {"fYPion","fYKaon","fYEta","fYRho","fYOmega","fYPhi","fYEtaPrime"};
53 const char* fnname[7] = {"fMultPion","fMultKaon","fMultEta","fMultRho","fMultOmega","fMultPhi","fMultEtaPrime"};
54 Double_t ptparam[7][9];
55 Double_t yparam[7][9];
56 Double_t nparam[7][9];
57
58 // parameters for 7 TeV generation
59 if (fCMSEnergy==kCMS7000GeV) {
60 AliInfo ("Using pp parameterization at 7 TeV\n");
61 Double_t ptparam7000[7][9] = {{1,0.427,2.52,0,0,0,0,0,0}, // pions from Pythia
62 {1,0.58,2.57,0,0,0,0,0,0}, // kaons from Pythia
63 {1,0.641,2.62,0,0,0,0,0,0}, // eta from Pythia
64 {1,1.44,3.16,0,0,0,0,0,0}, // rho+omega from ALICE muon
65 {1,1.44,3.16,0,0,0,0,0,0}, // rho+omega from ALICE muon
66 {1,1.16,2.74,0,0,0,0,0,0}, // phi from ALICE muon
67 {1,0.72,2.5,0,0,0,0,0,0}}; // etaPrime from Pythia
68
69 Double_t yparam7000[7][9] = {{1,0.8251,3.657,0,0,0,0,0,0}, // pions from pythia
70 {1,1.83,2.698,0,0,0,0,0,0}, // kaons from pythia
71 {1,1.169,3.282,0,0,0,0,0,0}, // eta from pythia
72 {1,1.234,3.264,0,0,0,0,0,0}, // rho from pythia
73 {1,1.311,3.223,0,0,0,0,0,0}, // omega from pythia
74 {1,2.388,2.129,0,0,0,0,0,0}, // phi from pythia
75 {1,1.13,3.3,0,0,0,0,0,0}}; // eta prime from pythia
76
77 // multiplicity parameters from pythia
78 Double_t nparam7000[7][9] = {{353.582, 6.76263, 1.66979, 998.445, 9.73281, 12.6704, 175.187, 29.08, 40.2531},
79 {1.e4, 0.2841, 0,0,0,0,0,0,0},
80 {1.e4, 0.2647, 0,0,0,0,0,0,0},
81 {7055, 0.1786, 0,0,0,0,0,0,0},
82 {7500, 0.1896, 0,0,0,0,0,0,0},
83 {5.e4, 1.167, 0,0,0,0,0,0,0},
84 {2.9e4, 0.714, 0,0,0,0,0,0,0}};
85
86 for (Int_t i=0; i<fgkNpart; i++) {
87 for (Int_t j=0; j<9; j++) {
88 ptparam[i][j] = ptparam7000[i][j];
89 yparam[i][j] = yparam7000[i][j];
90 nparam[i][j] = nparam7000[i][j];
91 }
92 }
93 }
94
95 // parameters for 2.76 generation
96 // pt params has been determined as <pt>ALICE_2.76 = <pt>ALICE_7 * <pt>PYTHIA_2.76 / <pt>PYTHIA_7
97 else if (fCMSEnergy==kCMS2760GeV){
98 AliInfo ("Using pp parameterization at 2.76 TeV\n");
99 Double_t yparam2760[7][9] = {{1,0.8251,3.657,0,0,0,0,0,0}, // pions from pythia
100 {1,1.83,2.698,0,0,0,0,0,0}, // kaons from pythia
101 {1,0.011,3.474,0,0,0,0,0,0}, // eta from pythia
102 {1,-0.01,3.409,0,0,0,0,0,0}, // rho from pythia
103 {1,-0.037,3.294,0,0,0,0,0,0}, // omega from pythia
104 {1,-0.016,2.717,0,0,0,0,0,0}, // phi from pythia
105 {1,-0.010,3.312,0,0,0,0,0,0}}; // eta prime from pythia
106
107 Double_t ptparam2760[7][9] = {{1,0.1665,8.878,0,0,0,0,0,0}, // pions from Pythia
108 {1,0.1657,8.591,0,0,0,0,0,0}, // kaons from Pythia
109 {1,0.641,2.62,0,0,0,0,0,0}, // eta from ALICE 7 TeV
110 {1,1.3551,3.16,0,0,0,0,0,0}, // rho with <pt> scaled
111 {1,1.3551,3.16,0,0,0,0,0,0}, // omega with <pt> scaled
112 {1,1.0811,2.74,0,0,0,0,0,0}, // phi with <pt> scaled
113 {1,0.72,2.5,0,0,0,0,0,0}}; // etaPrime from ALICE 7 TeV
114
115 Double_t nparam2760[7][9] = {{9752,-2.693,3.023,9.5e9,-84.68,16.75,-14.06,635.3,-423.2}, // pions
116 {1.e5, 1.538, 0,0,0,0,0,0,0}, // kaons
117 {1.e4, 0.351, 0,0,0,0,0,0,0}, // eta
118 {1.e4, 0.2471, 0,0,0,0,0,0,0}, // rho
119 {1.e4, 0.2583, 0,0,0,0,0,0,0}, // omega
120 {1.e5, 1.393, 0,0,0,0,0,0,0}, // phi
121 {1.e4, 0.9005, 0,0,0,0,0,0,0}}; // etaPrime
122
123 for (Int_t i=0; i<fgkNpart; i++) {
124 for (Int_t j=0; j<9; j++) {
125 ptparam[i][j] = ptparam2760[i][j];
126 yparam[i][j] = yparam2760[i][j];
127 nparam[i][j] = nparam2760[i][j];
128 }
129 }
130 } else
131 AliFatal("Energy not correctly defined");
132
133 for (Int_t i=0; i<fgkNpart; i++) {
134 fPDG[i] = pdg[i];
135 if (i!=0) {
136 fMult[i] = new TF1(fnname[i],"[0]*exp(-[1]*x)",0,30);
137 fMult[i]->SetParameters(nparam[i][0],nparam[i][1]);
138 }
139 else {
140 fMult[i] = new TF1(fnname[i],"gaus(0)+gaus(3)+gaus(6)",0,150);
141 for (Int_t j=0; j<9; j++) fMult[i]->SetParameter(j,nparam[i][j]);
142 }
143
144 fPt[i] = new TF1(fptname[i],AliGenMUONLMR::PtDistr,0,20,3);
145 fPt[i]->SetParameters(ptparam[i][0], ptparam[i][1], ptparam[i][2]);
146 fY[i] = new TF1(fyname[i],AliGenMUONLMR::YDistr,-10,10,3);
147 fY[i]->SetParameters(yparam[i][0], yparam[i][1], yparam[i][2]);
368fc61e 148 }
c279681a 149
150 for(Int_t i = 0; i<2; i++){
151 fDecay[i] = new TF1(fdname[i],"exp(-x/[0])",0,150);
152 fDecay[i]->SetParameter(0,ctau[i]);
368fc61e 153 }
c279681a 154
155 for (Int_t ipart = 0; ipart < fgkNpart; ipart++) {
156 fParticle[ipart] = new TParticle();
157 fParticle[ipart]->SetPdgCode(fPDG[ipart]);
158 }
159
160 TDatabasePDG *pdgdb = TDatabasePDG::Instance();
161 Double_t mumass = pdgdb->GetParticle(13)->Mass();
162 fMu[0] = new TParticle();
163 fMu[0]->SetPdgCode(-13);
164 fMu[0]->SetCalcMass(mumass);
165 fMu[1] = new TParticle();
166 fMu[1]->SetPdgCode(13);
167 fMu[1]->SetCalcMass(mumass);
168
169 // function for polarized theta distributions
170 fCosTheta = new TF1 ("fCosTheta","1+[0]*x*x",-1,1);
171 fCosTheta->SetParameter(0,1);
172
173 // Dalitz decays
174 Int_t nbins = 1000;
175 Double_t xmin = 0, xmax = 2;
176 fDalitz[0] = new TH1F("hDalitzEta","",nbins,xmin,xmax);
177 fDalitz[1] = new TH1F("hDalitzOmega","",nbins,xmin,xmax);
178 fDalitz[2] = new TH1F("hDalitzEtaPrime","",nbins,xmin,xmax);
179
180 Double_t meta = pdgdb->GetParticle("eta")->Mass();
181 Double_t momega = pdgdb->GetParticle("omega")->Mass();
182 Double_t metaPrime = pdgdb->GetParticle("eta'")->Mass();
183 Double_t mpi0 = pdgdb->GetParticle("pi0")->Mass();
184 Double_t md3 = 0, mres = 0;
185
186 for (Int_t index = 0; index < 3; index++) {
187 if (index == 0) {
188 mres = meta;
189 md3 = 0;
190 }
191 else if (index == 1) {
192 mres = momega;
193 md3 = mpi0;
194 }
195 else if (index == 2) {
196 mres = metaPrime;
197 md3 = 0;
198 }
199 Double_t delta = md3 * md3 / (mres * mres);
200 Double_t epsilon = mumass * mumass / (mres * mres);
201 nbins = fDalitz[index]->GetNbinsX();
202 xmin = fDalitz[index]->GetXaxis()->GetXmin();
203 Double_t deltax = fDalitz[index]->GetBinWidth(1);
204 Double_t xd = xmin - deltax/2.;
205 for (Int_t ibin = 0; ibin< nbins; ibin++) {
206 Double_t dalval = 0;
207 xd += deltax;
208 if (xd > 4. *epsilon) {
209 Double_t bracket = TMath::Power(1. + xd/(1. - delta),2)
210 - 4. * xd / ((1. - delta) * (1. - delta));
211 if (bracket > 0) {
212 dalval = TMath::Power(bracket,1.5) /xd *
213 TMath::Sqrt(1 - 4 * epsilon / xd) * (1 + 2 * epsilon / xd) *
214 FormFactor(xd * mres * mres, index);
215 fDalitz[index]->Fill(xd,dalval);
216 }
217 }
218 }
219 }
220
221 fRhoLineShape = new TF1("fRhoLineShape",RhoLineShapeNew,0,2,2);
222 fHMultMu = new TH1D("fHMultMu","Muon multiplicity",20,-0.5,19.5);
223 fHNProc = new TH1D("fHNProc","Number of gen. evts. per process in 4 pi",9,-0.5,8.5);
224
368fc61e 225}
35e2c739 226//-----------------------------------------------------------
227
228AliGenMUONLMR::AliGenMUONLMR (AliGenMUONLMR &gen) : AliGenMC(),
229 fNMuMin(gen.fNMuMin),
c279681a 230 fCMSEnergy(gen.fCMSEnergy),
231 fGenSingleProc(gen.fGenSingleProc),
35e2c739 232 fCosTheta(gen.fCosTheta),
233 fRhoLineShape(gen.fRhoLineShape),
234 fHMultMu(gen.fHMultMu),
235 fHNProc(gen.fHNProc) {
236 for (Int_t i=0; i < fgkNpart; i++) {
237 fPDG[i] = gen.fPDG[i];
238 fScaleMult[i] = gen.fScaleMult[i];
239 fPt[i] = (TF1*) gen.fPt[i]->Clone();
240 fY[i] = (TF1*) gen.fY[i]->Clone();
241 fMult[i] = (TF1*) gen.fMult[i]->Clone();
242 fParticle[i] = (TParticle*) gen.fParticle[i]->Clone();
243 }
244
245 for(Int_t i = 0; i<2; i++) fDecay[i] = (TF1*) gen.fDecay[i]->Clone();
246 for(Int_t i = 0; i<3; i++) fDalitz[i] = (TH1F*) gen.fDalitz[i]->Clone();
247 for(Int_t i = 0; i<2; i++) fMu[i] = (TParticle*) gen.fMu[i]->Clone();
248}
249
250//-----------------------------------------------------------
251
252AliGenMUONLMR& AliGenMUONLMR::operator=(const AliGenMUONLMR &gen) {
c279681a 253 // Assignment operator
a59583d3 254 if (this!=&gen) {
255 fNMuMin = gen.fNMuMin;
c279681a 256 fCMSEnergy = gen.fCMSEnergy;
a59583d3 257 fGenSingleProc = gen.fGenSingleProc;
258 fCosTheta = (TF1*) gen.fCosTheta->Clone();
259 fRhoLineShape = (TF1*) gen.fRhoLineShape->Clone();
260 fHMultMu = (TH1D*) gen.fHMultMu->Clone();
261 fHNProc = (TH1D*) gen.fHNProc->Clone();
262
263 for (Int_t i=0; i < fgkNpart; i++) {
264 fPDG[i] = gen.fPDG[i];
265 fScaleMult[i] = gen.fScaleMult[i];
266 fPt[i] = (TF1*) gen.fPt[i]->Clone();
267 fY[i] = (TF1*) gen.fY[i]->Clone();
268 fMult[i] = (TF1*) gen.fMult[i]->Clone();
269 fParticle[i] = (TParticle*) gen.fParticle[i]->Clone();
270 }
271
272 for(Int_t i = 0; i<2; i++) fDecay[i] = (TF1*) gen.fDecay[i]->Clone();
273 for(Int_t i = 0; i<3; i++) fDalitz[i] = (TH1F*) gen.fDalitz[i]->Clone();
274 for(Int_t i = 0; i<2; i++) fMu[i] = (TParticle*) gen.fMu[i]->Clone();
35e2c739 275 }
35e2c739 276 return *this;
277}
278
279
368fc61e 280//-----------------------------------------------------------
281
282AliGenMUONLMR::~AliGenMUONLMR()
283{
284 // Default destructor
285 for (Int_t i=0; i<7; i++) {
286 delete fPt[i];
287 delete fY[i];
288 delete fMult[i];
289 delete fParticle[i];
290 }
291
292 for (Int_t i=0; i<2; i++) {
293 delete fDecay[i];
294 delete fMu[i];
295 }
296
297 for (Int_t i=0; i<3; i++) delete fDalitz[i];
298
299 delete fCosTheta; fCosTheta = 0;
300 delete fRhoLineShape; fRhoLineShape = 0;
301 delete fHMultMu; fHMultMu = 0;
302 delete fHNProc; fHNProc = 0;
303}
304
305//-----------------------------------------------------------
306
307void AliGenMUONLMR::FinishRun(){
308 // save some histograms to an output file
309 Int_t nbins = fHNProc->GetNbinsX();
c279681a 310 for (Int_t ibin=1; ibin <= nbins; ibin++) AliInfo (Form("ibin = %d nEvProc = %g",
311 ibin,fHNProc->GetBinContent(ibin)));
368fc61e 312 TFile *fout = new TFile("AliGenMUONLMR_histos.root","recreate");
313 fHMultMu->Write();
314 fHNProc->Write();
315 fout->Close();
316}
317
318//-----------------------------------------------------------
319
35e2c739 320Double_t AliGenMUONLMR::YDistr(Double_t *px, Double_t *par){
368fc61e 321 // function for rapidity distribution: plateau at par[0] +
322 // gaussian tails centered at par[1] and with par[2]=sigma
323 Double_t x = TMath::Abs(px[0]);
324 Double_t func = 0;
325 if (x<par[1]) func = par[0];
326 else {
327 Double_t z = (x-par[1])/(par[2]);
328 func = par[0] * TMath::Exp(-0.5 * z * z);
329 }
330 return func;
331}
332
333//-----------------------------------------------------------
334
35e2c739 335Double_t AliGenMUONLMR::PtDistr(Double_t *px, Double_t *par){
368fc61e 336 // pt distribution: power law
337 Double_t x = px[0];
338 Double_t func = par[0] * x / TMath::Power((1+(x/par[1])*(x/par[1])),par[2]);
339 return func;
340}
341
342//-----------------------------------------------------------
343
344void AliGenMUONLMR::Generate() {
345 //
346 // generate the low mass resonances and their decays according to
347 // the multiplicity parameterized by pythia and BR from PDG
348 // rapidity distributions parametrized from pythia
349 // pt distributions from data (or pythia for etaprime)
350 //
351 Double_t pxPushed[100], pyPushed[100], pzPushed[100], ePushed[100];
352 Int_t nmuons = -1, npartPushed = 0, pdgPushed[100];
353 Double_t polar[3]= {0,0,0}; // Polarisation of the parent particle (for GEANT tracking)
354 Double_t origin0[3]; // Origin of the generated parent particle (for GEANT tracking)
355 // Calculating vertex position per event
356 for (Int_t j=0;j<3;j++) origin0[j]=fOrigin[j];
357 if(fVertexSmear==kPerEvent) {
358 Vertex();
359 for (Int_t j=0;j<3;j++) origin0[j]=fVertex[j];
360 }
361
368fc61e 362 TParticle *mother;
363 TDatabasePDG* pdg = TDatabasePDG::Instance();
364
365 Double_t pt, y, phi, mass, px, py, pz, ene, mt;
366
367 const Int_t nproc = 9;
368 Int_t idRes[nproc] = {kEtaLMR, kEtaLMR, kRhoLMR, kOmegaLMR, kOmegaLMR, kPhiLMR, kEtaPrimeLMR, kPionLMR, kKaonLMR};
35e2c739 369 Double_t BR[nproc] = {5.8e-6, 3.1e-4, 4.55e-5, 7.28e-5, 1.3e-4, 2.86e-4, 1.04e-4, 1, 0.6344};
368fc61e 370 // Double_t BR[nproc] = {1, 1, 1, 1, 1, 1, 1, 1, 1};
371 Int_t idDec[nproc] = {0, 1, 0, 0, 1, 0, 1, 2, 2}; // 0:2body, 1:Dalitz, 2:pi/K
372 Int_t mult[nproc] = {0,0,0,0,0,0,0,0,0};
373
374 while (nmuons < fNMuMin) {
375
376 nmuons = 0;
377 npartPushed = 0;
378 for (Int_t iproc=0; iproc<nproc; iproc++) {
379 if (fGenSingleProc == -1) {
380 mult[iproc] = Int_t(fMult[idRes[iproc]]->GetRandom()*fScaleMult[idRes[iproc]]);
381 }
382 else {
383 if (iproc==fGenSingleProc) {
384 mult[iproc] = 1;
385 BR[iproc] = 1;
386 }
387 else {
388 mult[iproc] = 0;
389 BR[iproc] = 0;
390 }
391 }
392 }
393
394 if (fGenSingleProc == -1) {
395 mult[1] = mult[0];
396 mult[4] = mult[3];
397 }
398
399 for (Int_t iproc = 0; iproc < nproc; iproc++) {
400// printf ("Multiplicity for process %d is %d\n",iproc,mult[iproc]);
401 for (Int_t imult=0; imult<mult[iproc]; imult++) {
402 if (gRandom->Rndm() < BR[iproc]) {
403 fHNProc->Fill(iproc);
404 Int_t ipart = idRes[iproc];
405 pt = fPt[ipart]->GetRandom();
406 y = fY[ipart]->GetRandom();
407 phi = gRandom->Rndm() * 2 * TMath::Pi();
408 mass = pdg->GetParticle(fPDG[ipart])->Mass();
409 px = pt * TMath::Cos(phi);
410 py = pt * TMath::Sin(phi);
411 mt = TMath::Sqrt(pt * pt + mass * mass);
412 pz = mt * TMath::SinH(y);
413 ene = mt * TMath::CosH(y);
414
415 mother = fParticle[ipart];
416 mother->SetMomentum(px,py,pz,ene);
417 mother->SetCalcMass(mass);
418 if (!KinematicSelection(mother,0)) continue;
419
420 Bool_t hasDecayed = kTRUE;
421 if (idDec[iproc] == 0) Decay2Body(mother);
422 else if (idDec[iproc] == 1) DalitzDecay(mother);
423 else DecayPiK(mother,hasDecayed);
424 if (!hasDecayed) continue;
425 Bool_t isMu0Acc = KinematicSelection(fMu[0],1);
426 Bool_t isMu1Acc = KinematicSelection(fMu[1],1);
427 Bool_t isMuFromPiKAcc = kTRUE;
428
429 if (idDec[iproc] == 2) isMuFromPiKAcc = (mother->GetPdgCode()>0) ? isMu0Acc : isMu1Acc;
430 // mother
431 if ((idDec[iproc] < 2 && (isMu0Acc || isMu1Acc)) ||
432 (idDec[iproc] == 2 && isMuFromPiKAcc)) {
433 pdgPushed[npartPushed] = mother->GetPdgCode();
434 pxPushed[npartPushed] = mother->Px();
435 pyPushed[npartPushed] = mother->Py();
436 pzPushed[npartPushed] = mother->Pz();
437 ePushed[npartPushed] = mother->Energy();
438 npartPushed++;
439 if (isMu0Acc && (idDec[iproc] < 2 || mother->GetPdgCode() > 0)) {
440 pdgPushed[npartPushed] = fMu[0]->GetPdgCode();
441 pxPushed[npartPushed] = fMu[0]->Px();
442 pyPushed[npartPushed] = fMu[0]->Py();
443 pzPushed[npartPushed] = fMu[0]->Pz();
444 ePushed[npartPushed] = fMu[0]->Energy();
445 npartPushed++;
446 nmuons++;
447 }
448
449 if (isMu1Acc && (idDec[iproc] < 2 || mother->GetPdgCode() < 0)) {
450 pdgPushed[npartPushed] = fMu[1]->GetPdgCode();
451 pxPushed[npartPushed] = fMu[1]->Px();
452 pyPushed[npartPushed] = fMu[1]->Py();
453 pzPushed[npartPushed] = fMu[1]->Pz();
454 ePushed[npartPushed] = fMu[1]->Energy();
455 npartPushed++;
456 nmuons++;
457 }
458 }
459 } // end if BR
460 } // end loop on multiplicity
461 } // end loop on process
462 fHMultMu->Fill(nmuons);
463 } // keep on generating until at least a muon is created in the event
464
465 Int_t ntmother = 0, ntchild =0;
466 for (Int_t ipart = 0; ipart < npartPushed; ipart++) {
467 if (TMath::Abs(pdgPushed[ipart]) != 13) { // particle is not a muon, hence it's a mother
468 PushTrack(0,-1,pdgPushed[ipart],
469 pxPushed[ipart],pyPushed[ipart],pzPushed[ipart],ePushed[ipart],
35e2c739 470 origin0[0],origin0[1],origin0[2],0.,
368fc61e 471 polar[0],polar[1],polar[2],
472 kPPrimary,ntmother,1,11);
473 KeepTrack(ntmother);
474 }
475 else {
476 PushTrack(1,ntmother,pdgPushed[ipart],
477 pxPushed[ipart],pyPushed[ipart],pzPushed[ipart],ePushed[ipart],
35e2c739 478 origin0[0],origin0[1],origin0[2],0.,
368fc61e 479 polar[0],polar[1],polar[2],
480 kPDecay,ntchild,1,1);
481 KeepTrack(ntchild);
482 }
483 }
484 SetHighWaterMark(ntchild);
485 AliGenEventHeader* header = new AliGenEventHeader("LMR");
486 header->SetPrimaryVertex(fVertex);
487 header->SetNProduced(fNprimaries);
488 AddHeader(header);
489}
490
491//------------------------------------------------------------------
492
35e2c739 493void AliGenMUONLMR::Decay2Body(TParticle *mother){
368fc61e 494 // performs decay in two muons of the low mass resonances
495 Double_t md1 = fMu[0]->GetMass();
496 Int_t pdg = mother->GetPdgCode();
497 Double_t mres =0;
498 // if mother is a rho, extract the mass from its line shape
499 // otherwise consider the resonance mass
500 if (pdg == 113) mres = fRhoLineShape->GetRandom();
501 else mres = mother->GetCalcMass();
502 // while (mres < md1 + md2) mres = fDsigmaDm[res]->GetRandom();
503 // energies and momenta in rest frame
504 Double_t e1 = mres / 2.;
505 Double_t p1 = TMath::Sqrt((e1 + md1)*(e1 - md1));
506 // orientation in decaying particle rest frame
507 Double_t costheta = gRandom->Rndm() * 2 - 1;
508 Double_t sintheta = TMath::Sqrt((1. + costheta)*(1. - costheta));
509 Double_t phi = 2. * TMath::Pi() * gRandom->Rndm();
510 Double_t px1 = p1 * sintheta * TMath::Cos(phi);
511 Double_t py1 = p1 * sintheta * TMath::Sin(phi);
512 Double_t pz1 = p1 * costheta;
513
514 // boost muons into lab frame
515
516 TLorentzVector vmother, v1, v2;
517 // TLorentzVector boosted1, boosted2;
518 vmother.SetPxPyPzE(mother->Px(),mother->Py(),mother->Pz(),mother->Energy());
519 v1.SetPxPyPzE(px1,py1,pz1,e1);
520 v2.SetPxPyPzE(-px1,-py1,-pz1,e1);
521
522 TVector3 betaParent = (1./vmother.E())*vmother.Vect(); // beta = p/E
523 v1.Boost(betaParent);
524 v2.Boost(betaParent);
525
526// TLorentzVector vtot = v1 + v2;
527// printf ("mother: %g %g %g %g\n",vmother.Px(), vmother.Py(), vmother.Pz(), vmother.E());
528// printf ("vtot : %g %g %g %g\n",vtot.Px(), vtot.Py(), vtot.Pz(), vtot.E());
529
530 fMu[0]->SetMomentum(v1.Px(),v1.Py(),v1.Pz(),v1.E());
531 fMu[1]->SetMomentum(v2.Px(),v2.Py(),v2.Pz(),v2.E());
532}
533
534//------------------------------------------------------------------
535
536void AliGenMUONLMR::DecayPiK(TParticle *mother, Bool_t &hasDecayed){
537 // performs decays of pions and kaons
538 Double_t md1 = fMu[0]->GetMass();
539 // extract the mass from the resonance's line shape
540 Double_t mres = mother->GetMass();
541 // choose the pi/k sign, assuming 50% probabilities for both signs
542 Int_t sign = (gRandom->Rndm() > 0.5) ? 1 : -1;
543 mother->SetPdgCode(sign * TMath::Abs(mother->GetPdgCode()));
544
545 // energies and momenta in rest frame
546 Double_t e1 = (mres*mres + md1*md1)/(2*mres);
547 Double_t p1 = TMath::Sqrt((e1 + md1)*(e1 - md1));
548 // orientation in decaying particle rest frame
549 Double_t costheta = gRandom->Rndm() * 2 - 1;
550 Double_t sintheta = TMath::Sqrt((1. + costheta)*(1. - costheta));
551 Double_t phi = 2. * TMath::Pi() * gRandom->Rndm();
552 Double_t px1 = p1 * sintheta * TMath::Cos(phi);
553 Double_t py1 = p1 * sintheta * TMath::Sin(phi);
554 Double_t pz1 = p1 * costheta;
555
556 // boost muons into lab frame
557 TLorentzVector vmother, v1;
558 vmother.SetPxPyPzE(mother->Px(),mother->Py(),mother->Pz(),mother->Energy());
559 v1.SetPxPyPzE(px1,py1,pz1,e1);
560
561 TVector3 betaParent = (1./vmother.E())*vmother.Vect(); // beta = p/E
562 v1.Boost(betaParent);
563 if (mother->GetPdgCode()>0) fMu[0]->SetMomentum(v1.Px(),v1.Py(),v1.Pz(),v1.E());
564 else fMu[1]->SetMomentum(v1.Px(),v1.Py(),v1.Pz(),v1.E());
565
a59583d3 566 Int_t idmother = 0;
35e2c739 567 if (TMath::Abs(mother->GetPdgCode())== 211) idmother = 0;
568 if (TMath::Abs(mother->GetPdgCode())== 321) idmother = 1;
368fc61e 569 Double_t gammaRes = mother->Energy()/mres;
570 Double_t zResCM = fDecay[idmother]->GetRandom();
571 Double_t zResLab = gammaRes*zResCM;
572 if(zResLab > 0.938) hasDecayed = 0; // 0.938: distance from IP to absorber + lambda_i
573 else hasDecayed = 1;
368fc61e 574}
575
576//-------------------------------------------------------------------
577
35e2c739 578void AliGenMUONLMR::DalitzDecay(TParticle *mother){
368fc61e 579 //
580 // perform dalitz decays of eta, omega and etaprime
581 //
582 //in the rest frame of the virtual photon:
583 Double_t mres = mother->GetCalcMass();
584 Double_t mumass = fMu[0]->GetMass();
585 Double_t md3 = 0; // unless differently specified, third particle is a photon
586 if (mother->GetPdgCode() == 223) md3 = 0.134977; // if mother is an omega, third particle is a pi0
a59583d3 587 Int_t index = 0;
35e2c739 588 if (mother->GetPdgCode() == 221) index = 0; // eta
589 else if (mother->GetPdgCode() == 223) index = 1; // omega
590 else if (mother->GetPdgCode() == 331) index = 2; // etaPrime
368fc61e 591 Int_t flag = 0;
592 Double_t xd=0, mvirt2=0;
593 Double_t countIt = 0;
594 while (flag==0) {
595 xd = fDalitz[index]->GetRandom();
596 mvirt2 = xd * mres * mres; // mass of virtual photon
597 // check kinematics
598 if (mres - md3 > TMath::Sqrt(mvirt2) && TMath::Sqrt(mvirt2)/2. > mumass) flag=1;
599 if (++countIt>1E11) {
600 mvirt2 = mres * mres * 0.998;
601 break;
602 }
603 }
604
605 //
606 // Generate muons in virtual photon rest frame.
607 // z axis is the virt. photon direction (before boost)
608 //
609
610 Double_t e1 = TMath::Sqrt(mvirt2)/2.; // energy of mu1 in the virtual photon frame
611 Double_t psquare = (e1 + mumass)*(e1 - mumass);
612 if (psquare<0) {
c279681a 613 AliError(Form("sqrt of psquare = %f put to 0\n",psquare));
368fc61e 614 psquare = 0;
615 }
616 Double_t p1 = TMath::Sqrt(psquare);
617 //theta angle between the pos. muon and the virtual photon
618 Double_t costheta = fCosTheta->GetRandom();
619 if (costheta>1) costheta = 1;
620 if (costheta<-1) costheta = -1;
621 Double_t sintheta = TMath::Sqrt((1. + costheta)*(1. - costheta));
622 Double_t phi = 2 * TMath::Pi() * gRandom->Rndm();
623 Double_t sinphi = TMath::Sin(phi);
624 Double_t cosphi = TMath::Cos(phi);
625
626 // fill 4-vectors of leptons in the virtual photon frame
627
628 Double_t px1 = p1*sintheta*cosphi;
629 Double_t py1 = p1*sintheta*sinphi;
630 Double_t pz1 = p1*costheta;
631 Double_t px2 = -p1*sintheta*cosphi;
632 Double_t py2 = -p1*sintheta*sinphi;
633 Double_t pz2 = -p1*costheta;
634 Double_t e2 = e1;
635
636 fMu[0]->SetMomentum(px1,py1,pz1,e1);
637 fMu[1]->SetMomentum(px2,py2,pz2,e2);
638
639 // calculate components of non-dilepton in CMS of parent resonance
640
641 Double_t e3 = (mres * mres + md3 * md3 - mvirt2) / (2.*mres);
642 Double_t psquare3 = (e3 + md3)*(e3 - md3);
643 if (psquare3<0) {
c279681a 644 AliError(Form("Sqrt of psquare3 = %f put to 0\n",psquare3));
368fc61e 645 psquare3 = 0;
646 }
647 Double_t p3 = TMath::Sqrt(psquare3);
648 Double_t costheta2 = 2.* gRandom->Rndm() - 1.; // angle between virtual photon and resonance
649 if (costheta2>1) costheta2 = 1;
650 if (costheta2<-1) costheta2 = -1;
651 Double_t sintheta2 = TMath::Sqrt((1. + costheta2)*(1. - costheta2));
652 Double_t phi2 = 2 * TMath::Pi() * gRandom->Rndm();
653 Double_t sinphi2 = TMath::Sin(phi2);
654 Double_t cosphi2 = TMath::Cos(phi2);
655 Double_t px3 = p3*sintheta2*cosphi2;
656 Double_t py3 = p3*sintheta2*sinphi2;
657 Double_t pz3 = p3*costheta2;
658 TLorentzVector v3(px3,py3,pz3,e3);
659
660 sintheta2 = -sintheta2;
661 cosphi2 = -cosphi2;
662 sinphi2 = -sinphi2;
663
664 Double_t px1new = px1*costheta2*cosphi2 - py1*sinphi2 + pz1*sintheta2*cosphi2;
665 Double_t py1new = px1*costheta2*sinphi2 + py1*cosphi2 + pz1*sintheta2*sinphi2;
666 Double_t pz1new =-px1*sintheta2 + pz1*costheta2;
667 Double_t px2new = px2*costheta2*cosphi2 - py2*sinphi2 + pz2*sintheta2*cosphi2;
668 Double_t py2new = px2*costheta2*sinphi2 + py2*cosphi2 + pz2*sintheta2*sinphi2;
669 Double_t pz2new =-px2*sintheta2 + pz2*costheta2;
670
671 fMu[0]->SetMomentum(px1new,py1new,pz1new,e1);
672 fMu[1]->SetMomentum(px2new,py2new,pz2new,e2);
673
674 Double_t evirt = mres - e3;
675 Double_t pxvirt = -px3;
676 Double_t pyvirt = -py3;
677 Double_t pzvirt = -pz3;
678 TLorentzVector vvirt(pxvirt,pyvirt,pzvirt,evirt);
679 TVector3 betaVirt = (1./evirt) * vvirt.Vect(); // virtual photon beta in res frame
680
681 TLorentzVector v1(px1,py1,pz1,e1);
682 TLorentzVector v2(px2,py2,pz2,e2);
683
684 // boost the muons in the frame where the resonance is at rest
685
686 v1.Boost(betaVirt);
687 v2.Boost(betaVirt);
688
689 // boost muons and third particle in lab frame
690
691 TLorentzVector vmother(mother->Px(), mother->Py(), mother->Pz(), mother->Energy());
692 TVector3 resBetaLab = (1./vmother.E())*vmother.Vect(); // eta beta in lab frame
693 v1.Boost(resBetaLab);
694 v2.Boost(resBetaLab);
695 v3.Boost(resBetaLab);
696 vvirt.Boost(resBetaLab);
697
698 fMu[0]->SetMomentum(v1.Px(),v1.Py(),v1.Pz(),v1.E());
699 fMu[1]->SetMomentum(v2.Px(),v2.Py(),v2.Pz(),v2.E());
700// part3->SetMomentum(v3.Px(),v3.Py(),v3.Pz(),v3.E());
701
702// TLorentzVector vtot = v1 + v2 + v3;
703// TLorentzVector vdimu = v1 + v2;
704// printf ("mother: %g %g %g %g\n",vmother.Px(), vmother.Py(), vmother.Pz(), vmother.E());
705// printf ("vtot : %g %g %g %g\n",vtot.Px(), vtot.Py(), vtot.Pz(), vtot.E());
706// printf ("vvirt : %g %g %g %g\n",vvirt.Px(), vvirt.Py(), vvirt.Pz(), vvirt.E());
707// printf ("vdimu : %g %g %g %g\n",vdimu.Px(), vdimu.Py(), vdimu.Pz(), vdimu.E());
708
709}
710
711//------------------------------------------------------------------
712
713Double_t AliGenMUONLMR::FormFactor(Double_t q2, Int_t decay){
714 // Calculates the form factor for Dalitz decays A->B+l+l
715 // Returns: |F(q^2)|^2
716 //
717 // References: L.G. Landsberg, Physics Reports 128 No.6 (1985) 301-376.
718
719 Double_t ff2, mass2;
720 Double_t n2, n4, m2;
721 // Lepton-G
722
723 Double_t lambda2inv = 0;
724 switch (decay) {
725 case 0: // eta -> mu mu gamma
726 // eta -> l+ l- gamma: pole approximation
727 lambda2inv = 1.95;
728 mass2 = fParticle[kEtaLMR]->GetMass() * fParticle[kEtaLMR]->GetMass();
729 if (q2 < mass2) ff2 = TMath::Power(1./(1.-lambda2inv*q2),2);
730 else ff2 = 0;
731 break;
732 case 1: // omega -> mu mu pi0
733 // omega -> l+ l- pi0: pole approximation
734 mass2 = fParticle[kOmegaLMR]->GetMass() * fParticle[kOmegaLMR]->GetMass();
735 lambda2inv = 2.26;
736 if (q2 < mass2) ff2 = TMath::Power(1./(1.-lambda2inv*q2),2);
737 else ff2 = 0;
738 break;
739 case 2: // etaPrime -> mu mu gamma
740 mass2 = fParticle[kEtaPrimeLMR]->GetMass() * fParticle[kEtaPrimeLMR]->GetMass();
741 // eta' -> l+ l- gamma: Breit-Wigner fitted to data
742 n2 = 0.764 * 0.764;
743 n4 = n2 * n2;
744 m2 = 0.1020 * 0.1020;
745 if (q2 < mass2) ff2 = n4 / (TMath::Power(n2-q2,2) + m2 * n2);
746 else ff2 = 0;
747 break;
748 default:
c279681a 749 AliError ("FormFactor: Decay not found");
368fc61e 750 return 0;
751 break;
752 }
753 return ff2;
754}
755
756//____________________________________________________________
757
35e2c739 758Double_t AliGenMUONLMR::RhoLineShapeNew(Double_t *x, Double_t */*para*/){
368fc61e 759 //new parameterization implemented by Hiroyuki Sako (GSI)
760 Double_t mass = *x;
761 double r, GammaTot;
762 Double_t mRho = TDatabasePDG::Instance()->GetParticle("rho0")->Mass();
763 Double_t mPi = TDatabasePDG::Instance()->GetParticle("pi0")->Mass();
764 Double_t mMu = TDatabasePDG::Instance()->GetParticle("mu-")->Mass();
765 Double_t Gamma0 = TDatabasePDG::Instance()->GetParticle("rho0")->Width();
766
767 const double Norm = 0.0744416*1.01;
35e2c739 768
368fc61e 769 // 0.0744416 at m = 0.72297
770 // is the max number with Norm=1 (for rho)
771
772 double mThreshold = 2.*mPi;
773
774 const double T = 0.170; // Assumption of pi+ temperature [GeV/c^2]
775 //const double T = 0.11; // Taken from fit to pi+ temperature [GeV/c^2]
776 // with Reference: LEBC-EHS collab., Z. Phys. C 50 (1991) 405
777
778 if (mass < mThreshold) {
779 r = 0.;
780 return r;
781 }
782
783 double k = sqrt(0.25*mass*mass-(mThreshold/2)*(mThreshold/2));
784 double k0 = sqrt(0.25*mRho*mRho-(mThreshold/2)*(mThreshold/2));
785
786 GammaTot = (k/k0)*(k/k0)*(k/k0)*(mRho/mass)*(mRho/mass)*Gamma0;
787
788 double FormFactor2 = 1/((mass*mass-mRho*mRho)*(mass*mass-mRho*mRho)+
789 mass*mass*GammaTot*GammaTot);
790
791 r = pow(mass,1.5)*pow((1-mThreshold*mThreshold/(mass*mass)),1.5)*
792 ((mass*mass+2*mMu*mMu)/(mass*mass))*(pow((mass*mass-4*mMu*mMu),0.5)/mass)*FormFactor2
793 *exp(-mass/T)/Norm;
794
795 return r;
796}
c279681a 797