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add calculation and histograms for MC cross section
[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
0d19baad 14 AliGenMUONLMR::AliGenMUONLMR () : AliGenMC(),
15 fNMuMin(2),
16 fCMSEnergy(kNCMSEnergies),
17 fGenSingleProc(-1),
18 fYCM(0),
19 fCosTheta(0x0),
20 fRhoLineShape(0x0),
21 fHMultMu(0x0),
22 fHNProc(0x0) {
23 //
24 // default constructor
25 //
26 for (int i=0; i<fgkNpart; i++) {
27 fPDG[i] = 0;
28 fScaleMult[i] = 1.;
29 fPt[i] = NULL;
30 fY[i] = NULL;
31 fMult[i] = NULL;
0d19baad 32 fParticle[i] = NULL;
33 }
14467d5d 34 for (int i=0; i<2; i++) {
35 fMu[i] = NULL;
36 fDecay[i] = NULL;
37 }
38
39 for (int i=0; i<3; i++) {
40 fDalitz[i] = NULL;
41 }
42
0d19baad 43 }
35e2c739 44
c279681a 45//-----------------------------------------------------------
368fc61e 46
c279681a 47void AliGenMUONLMR::SetCMSEnergy(CMSEnergies energy){
0d19baad 48 fCMSEnergy = energy;
49 // initialize pt and y distributions according to a fit to
50 // Pythia simulation at sqrt(s) = 7 TeV
51 for (Int_t ipart=0; ipart < fgkNpart; ipart++) fScaleMult[ipart] = 1;
52 fScaleMult[kPionLMR] = 0; // set pion multiplicity to zero
53 fScaleMult[kKaonLMR] = 0; // set kaon multiplicity to zero
54 const char* fdname[2] = {"fDecPion","fDecKaon"};
55 Double_t ctau[2] = {7.8045, 3.712};
56 Int_t pdg[7] = {211, 321, 221, 113, 223, 333, 331};
57 const char* fptname[7] = {"fPtPion","fPtKaon","fPtEta","fPtRho","fPtOmega","fPtPhi","fPtEtaPrime"};
58 const char* fyname[7] = {"fYPion","fYKaon","fYEta","fYRho","fYOmega","fYPhi","fYEtaPrime"};
59 const char* fnname[7] = {"fMultPion","fMultKaon","fMultEta","fMultRho","fMultOmega","fMultPhi","fMultEtaPrime"};
60 Double_t ptparam[7][9];
61 Double_t yparam[7][9];
62 Double_t nparam[7][9];
c279681a 63
0d19baad 64 // parameters for 7 TeV generation
65 if (fCMSEnergy==kCMS7000GeV) {
66 AliInfo ("Using pp parameterization at 7 TeV\n");
67 Double_t ptparam7000[7][9] = {{1,0.427,2.52,0,0,0,0,0,0}, // pions from Pythia
68 {1,0.58,2.57,0,0,0,0,0,0}, // kaons from Pythia
69 {1,0.641,2.62,0,0,0,0,0,0}, // eta from Pythia
70 {1,1.44,3.16,0,0,0,0,0,0}, // rho+omega from ALICE muon
71 {1,1.44,3.16,0,0,0,0,0,0}, // rho+omega from ALICE muon
72 {1,1.16,2.74,0,0,0,0,0,0}, // phi from ALICE muon
73 {1,0.72,2.5,0,0,0,0,0,0}}; // etaPrime from Pythia
c279681a 74
0d19baad 75 Double_t yparam7000[7][9] = {{1,0.8251,3.657,0,0,0,0,0,0}, // pions from pythia
76 {1,1.83,2.698,0,0,0,0,0,0}, // kaons from pythia
77 {1,1.169,3.282,0,0,0,0,0,0}, // eta from pythia
78 {1,1.234,3.264,0,0,0,0,0,0}, // rho from pythia
79 {1,1.311,3.223,0,0,0,0,0,0}, // omega from pythia
80 {1,2.388,2.129,0,0,0,0,0,0}, // phi from pythia
81 {1,1.13,3.3,0,0,0,0,0,0}}; // eta prime from pythia
c279681a 82
0d19baad 83 // multiplicity parameters from pythia
84 Double_t nparam7000[7][9] = {{353.582, 6.76263, 1.66979, 998.445, 9.73281, 12.6704, 175.187, 29.08, 40.2531},
85 {1.e4, 0.2841, 0,0,0,0,0,0,0},
86 {1.e4, 0.2647, 0,0,0,0,0,0,0},
87 {7055, 0.1786, 0,0,0,0,0,0,0},
88 {7500, 0.1896, 0,0,0,0,0,0,0},
89 {5.e4, 1.167, 0,0,0,0,0,0,0},
90 {2.9e4, 0.714, 0,0,0,0,0,0,0}};
c279681a 91
0d19baad 92 for (Int_t i=0; i<fgkNpart; i++) {
93 for (Int_t j=0; j<9; j++) {
94 ptparam[i][j] = ptparam7000[i][j];
95 yparam[i][j] = yparam7000[i][j];
96 nparam[i][j] = nparam7000[i][j];
97 }
98 }
99 }
100 if (fCMSEnergy==kCMS5020GeVpPb || fCMSEnergy==kCMS5020GeVPbp) {
101 AliInfo ("Using pPb parameterization at 5.02 TeV\n");
102 Double_t ptparam5020[7][9] = {{1,0.427,2.52,0,0,0,0,0,0}, // pions from Pythia at 7 TeV
103 {1,0.58,2.57,0,0,0,0,0,0}, // kaons from Pythia at 7 TeV
104 {1,0.665,2.796,0,0,0,0,0,0}, // eta from Pythia at 5.02 TeV
105 {1,1.66,3.12,0,0,0,0,0,0}, // rho+omega from ALICE muon
106 {1,1.66,3.12,0,0,0,0,0,0}, // rho+omega from ALICE muon
107 {1,2.03,3.13,0,0,0,0,0,0}, // phi from ALICE muon
108 {1,0.767,2.713,0,0,0,0,0,0}}; // etaPrime from Pythia at 5.02 TeV
c279681a 109
0d19baad 110 Double_t yparam5020[7][9] = {{1,0.8251,3.657,0,0,0,0,0,0}, // pions from pythia at 7 TeV
111 {1,1.83,2.698,0,0,0,0,0,0}, // kaons from pythia at 7 TeV
112 {1,1.169,3.282,0,0,0,0,0,0}, // eta from pythia at 7 TeV
113 {1,1.234,3.264,0,0,0,0,0,0}, // rho from pythia at 7 TeV
114 {1,1.311,3.223,0,0,0,0,0,0}, // omega from pythia at 7 TeV
115 {1,2.388,2.129,0,0,0,0,0,0}, // phi from pythia at 7 TeV
116 {1,1.13,3.3,0,0,0,0,0,0}}; // eta prime from pythia at 7 TeV
c279681a 117
0d19baad 118 // multiplicity parameters from pythia at 7 TeV
119 Double_t nparam5020[7][9] = {{353.582, 6.76263, 1.66979, 998.445, 9.73281, 12.6704, 175.187, 29.08, 40.2531},
120 {1.e4, 0.2841, 0,0,0,0,0,0,0},
121 {1.e4, 0.2647, 0,0,0,0,0,0,0},
122 {7055, 0.1786, 0,0,0,0,0,0,0},
123 {7500, 0.1896, 0,0,0,0,0,0,0},
124 {5.e4, 1.167, 0,0,0,0,0,0,0},
125 {2.9e4, 0.714, 0,0,0,0,0,0,0}};
c279681a 126
c279681a 127 for (Int_t i=0; i<fgkNpart; i++) {
0d19baad 128 for (Int_t j=0; j<9; j++) {
129 ptparam[i][j] = ptparam5020[i][j];
130 yparam[i][j] = yparam5020[i][j];
131 nparam[i][j] = nparam5020[i][j];
132 }
133 }
134 if (fCMSEnergy==kCMS5020GeVpPb) fYCM = -0.4654;
135 else fYCM = 0.4654;
136 }
137 else if (fCMSEnergy==kCMS2760GeV){
138 // parameters for 2.76 generation
139 // pt params has been determined as <pt>ALICE_2.76 = <pt>ALICE_7 * <pt>PYTHIA_2.76 / <pt>PYTHIA_7
140 AliInfo ("Using pp parameterization at 2.76 TeV\n");
141 Double_t yparam2760[7][9] = {{1,0.8251,3.657,0,0,0,0,0,0}, // pions from pythia
142 {1,1.83,2.698,0,0,0,0,0,0}, // kaons from pythia
143 {1,0.011,3.474,0,0,0,0,0,0}, // eta from pythia
144 {1,-0.01,3.409,0,0,0,0,0,0}, // rho from pythia
145 {1,-0.037,3.294,0,0,0,0,0,0}, // omega from pythia
146 {1,-0.016,2.717,0,0,0,0,0,0}, // phi from pythia
147 {1,-0.010,3.312,0,0,0,0,0,0}}; // eta prime from pythia
c279681a 148
0d19baad 149 Double_t ptparam2760[7][9] = {{1,0.1665,8.878,0,0,0,0,0,0}, // pions from Pythia
150 {1,0.1657,8.591,0,0,0,0,0,0}, // kaons from Pythia
151 {1,0.641,2.62,0,0,0,0,0,0}, // eta from ALICE 7 TeV
152 {1,1.3551,3.16,0,0,0,0,0,0}, // rho with <pt> scaled
153 {1,1.3551,3.16,0,0,0,0,0,0}, // omega with <pt> scaled
154 {1,1.0811,2.74,0,0,0,0,0,0}, // phi with <pt> scaled
155 {1,0.72,2.5,0,0,0,0,0,0}}; // etaPrime from ALICE 7 TeV
156
157 Double_t nparam2760[7][9] = {{9752,-2.693,3.023,9.5e9,-84.68,16.75,-14.06,635.3,-423.2}, // pions
158 {1.e5, 1.538, 0,0,0,0,0,0,0}, // kaons
159 {1.e4, 0.351, 0,0,0,0,0,0,0}, // eta
160 {1.e4, 0.2471, 0,0,0,0,0,0,0}, // rho
161 {1.e4, 0.2583, 0,0,0,0,0,0,0}, // omega
162 {1.e5, 1.393, 0,0,0,0,0,0,0}, // phi
163 {1.e4, 0.9005, 0,0,0,0,0,0,0}}; // etaPrime
164
165 for (Int_t i=0; i<fgkNpart; i++) {
166 for (Int_t j=0; j<9; j++) {
167 ptparam[i][j] = ptparam2760[i][j];
168 yparam[i][j] = yparam2760[i][j];
169 nparam[i][j] = nparam2760[i][j];
170 }
368fc61e 171 }
0d19baad 172 }
173 else AliFatal("Energy not correctly defined");
c279681a 174
0d19baad 175 for (Int_t i=0; i<fgkNpart; i++) {
176 fPDG[i] = pdg[i];
177 if (i!=0) {
178 fMult[i] = new TF1(fnname[i],"[0]*exp(-[1]*x)",0,30);
179 fMult[i]->SetParameters(nparam[i][0],nparam[i][1]);
180 }
181 else {
182 fMult[i] = new TF1(fnname[i],"gaus(0)+gaus(3)+gaus(6)",0,150);
183 for (Int_t j=0; j<9; j++) fMult[i]->SetParameter(j,nparam[i][j]);
184 }
185
186 fPt[i] = new TF1(fptname[i],AliGenMUONLMR::PtDistr,0,20,3);
187 fPt[i]->SetParameters(ptparam[i][0], ptparam[i][1], ptparam[i][2]);
188 fY[i] = new TF1(fyname[i],AliGenMUONLMR::YDistr,-10,10,4);
189 fY[i]->SetParameters(yparam[i][0], yparam[i][1], yparam[i][2],fYCM);
190 }
c279681a 191
0d19baad 192 for(Int_t i = 0; i<2; i++){
193 fDecay[i] = new TF1(fdname[i],"exp(-x/[0])",0,150);
194 fDecay[i]->SetParameter(0,ctau[i]);
195 }
196
197 for (Int_t ipart = 0; ipart < fgkNpart; ipart++) {
198 fParticle[ipart] = new TParticle();
199 fParticle[ipart]->SetPdgCode(fPDG[ipart]);
200 }
c279681a 201
0d19baad 202 TDatabasePDG *pdgdb = TDatabasePDG::Instance();
203 Double_t mumass = pdgdb->GetParticle(13)->Mass();
204 fMu[0] = new TParticle();
205 fMu[0]->SetPdgCode(-13);
206 fMu[0]->SetCalcMass(mumass);
207 fMu[1] = new TParticle();
208 fMu[1]->SetPdgCode(13);
209 fMu[1]->SetCalcMass(mumass);
c279681a 210
0d19baad 211 // function for polarized theta distributions
212 fCosTheta = new TF1 ("fCosTheta","1+[0]*x*x",-1,1);
213 fCosTheta->SetParameter(0,1);
c279681a 214
0d19baad 215 // Dalitz decays
216 Int_t nbins = 1000;
217 Double_t xmin = 0, xmax = 2;
218 fDalitz[0] = new TH1F("hDalitzEta","",nbins,xmin,xmax);
219 fDalitz[1] = new TH1F("hDalitzOmega","",nbins,xmin,xmax);
220 fDalitz[2] = new TH1F("hDalitzEtaPrime","",nbins,xmin,xmax);
c279681a 221
0d19baad 222 Double_t meta = pdgdb->GetParticle("eta")->Mass();
223 Double_t momega = pdgdb->GetParticle("omega")->Mass();
224 Double_t metaPrime = pdgdb->GetParticle("eta'")->Mass();
225 Double_t mpi0 = pdgdb->GetParticle("pi0")->Mass();
226 Double_t md3 = 0, mres = 0;
c279681a 227
0d19baad 228 for (Int_t index = 0; index < 3; index++) {
229 if (index == 0) {
230 mres = meta;
231 md3 = 0;
232 }
233 else if (index == 1) {
234 mres = momega;
235 md3 = mpi0;
236 }
237 else if (index == 2) {
238 mres = metaPrime;
239 md3 = 0;
240 }
241 Double_t delta = md3 * md3 / (mres * mres);
242 Double_t epsilon = mumass * mumass / (mres * mres);
243 nbins = fDalitz[index]->GetNbinsX();
244 xmin = fDalitz[index]->GetXaxis()->GetXmin();
245 Double_t deltax = fDalitz[index]->GetBinWidth(1);
246 Double_t xd = xmin - deltax/2.;
247 for (Int_t ibin = 0; ibin< nbins; ibin++) {
248 Double_t dalval = 0;
249 xd += deltax;
250 if (xd > 4. *epsilon) {
251 Double_t bracket = TMath::Power(1. + xd/(1. - delta),2)
252 - 4. * xd / ((1. - delta) * (1. - delta));
253 if (bracket > 0) {
254 dalval = TMath::Power(bracket,1.5) /xd *
255 TMath::Sqrt(1 - 4 * epsilon / xd) * (1 + 2 * epsilon / xd) *
256 FormFactor(xd * mres * mres, index);
257 fDalitz[index]->Fill(xd,dalval);
c279681a 258 }
0d19baad 259 }
260 }
261 }
c279681a 262
0d19baad 263 fRhoLineShape = new TF1("fRhoLineShape",RhoLineShapeNew,0,2,2);
264 fHMultMu = new TH1D("fHMultMu","Muon multiplicity",20,-0.5,19.5);
265 fHNProc = new TH1D("fHNProc","Number of gen. evts. per process in 4 pi",9,-0.5,8.5);
c279681a 266
368fc61e 267}
35e2c739 268//-----------------------------------------------------------
269
270AliGenMUONLMR::AliGenMUONLMR (AliGenMUONLMR &gen) : AliGenMC(),
271 fNMuMin(gen.fNMuMin),
0d19baad 272 fCMSEnergy(gen.fCMSEnergy),
273 fGenSingleProc(gen.fGenSingleProc),
274 fYCM(gen.fYCM),
35e2c739 275 fCosTheta(gen.fCosTheta),
276 fRhoLineShape(gen.fRhoLineShape),
277 fHMultMu(gen.fHMultMu),
278 fHNProc(gen.fHNProc) {
279 for (Int_t i=0; i < fgkNpart; i++) {
280 fPDG[i] = gen.fPDG[i];
281 fScaleMult[i] = gen.fScaleMult[i];
282 fPt[i] = (TF1*) gen.fPt[i]->Clone();
283 fY[i] = (TF1*) gen.fY[i]->Clone();
284 fMult[i] = (TF1*) gen.fMult[i]->Clone();
285 fParticle[i] = (TParticle*) gen.fParticle[i]->Clone();
286 }
287
288 for(Int_t i = 0; i<2; i++) fDecay[i] = (TF1*) gen.fDecay[i]->Clone();
289 for(Int_t i = 0; i<3; i++) fDalitz[i] = (TH1F*) gen.fDalitz[i]->Clone();
290 for(Int_t i = 0; i<2; i++) fMu[i] = (TParticle*) gen.fMu[i]->Clone();
291}
292
293//-----------------------------------------------------------
294
295AliGenMUONLMR& AliGenMUONLMR::operator=(const AliGenMUONLMR &gen) {
0d19baad 296 // Assignment operator
a59583d3 297 if (this!=&gen) {
298 fNMuMin = gen.fNMuMin;
0d19baad 299 fCMSEnergy = gen.fCMSEnergy;
a59583d3 300 fGenSingleProc = gen.fGenSingleProc;
0d19baad 301 fYCM = gen.fYCM;
a59583d3 302 fCosTheta = (TF1*) gen.fCosTheta->Clone();
303 fRhoLineShape = (TF1*) gen.fRhoLineShape->Clone();
304 fHMultMu = (TH1D*) gen.fHMultMu->Clone();
305 fHNProc = (TH1D*) gen.fHNProc->Clone();
306
307 for (Int_t i=0; i < fgkNpart; i++) {
308 fPDG[i] = gen.fPDG[i];
309 fScaleMult[i] = gen.fScaleMult[i];
310 fPt[i] = (TF1*) gen.fPt[i]->Clone();
311 fY[i] = (TF1*) gen.fY[i]->Clone();
312 fMult[i] = (TF1*) gen.fMult[i]->Clone();
313 fParticle[i] = (TParticle*) gen.fParticle[i]->Clone();
314 }
315
316 for(Int_t i = 0; i<2; i++) fDecay[i] = (TF1*) gen.fDecay[i]->Clone();
317 for(Int_t i = 0; i<3; i++) fDalitz[i] = (TH1F*) gen.fDalitz[i]->Clone();
318 for(Int_t i = 0; i<2; i++) fMu[i] = (TParticle*) gen.fMu[i]->Clone();
35e2c739 319 }
35e2c739 320 return *this;
321}
322
323
368fc61e 324//-----------------------------------------------------------
325
326AliGenMUONLMR::~AliGenMUONLMR()
327{
328 // Default destructor
329 for (Int_t i=0; i<7; i++) {
330 delete fPt[i];
331 delete fY[i];
332 delete fMult[i];
333 delete fParticle[i];
334 }
335
336 for (Int_t i=0; i<2; i++) {
337 delete fDecay[i];
338 delete fMu[i];
339 }
340
341 for (Int_t i=0; i<3; i++) delete fDalitz[i];
342
343 delete fCosTheta; fCosTheta = 0;
344 delete fRhoLineShape; fRhoLineShape = 0;
345 delete fHMultMu; fHMultMu = 0;
346 delete fHNProc; fHNProc = 0;
347}
348
349//-----------------------------------------------------------
350
351void AliGenMUONLMR::FinishRun(){
352 // save some histograms to an output file
353 Int_t nbins = fHNProc->GetNbinsX();
c279681a 354 for (Int_t ibin=1; ibin <= nbins; ibin++) AliInfo (Form("ibin = %d nEvProc = %g",
0d19baad 355 ibin,fHNProc->GetBinContent(ibin)));
356 TFile *fout = new TFile("AliGenMUONLMR_histos.root","recreate");
368fc61e 357 fHMultMu->Write();
358 fHNProc->Write();
359 fout->Close();
360}
361
362//-----------------------------------------------------------
363
35e2c739 364Double_t AliGenMUONLMR::YDistr(Double_t *px, Double_t *par){
368fc61e 365 // function for rapidity distribution: plateau at par[0] +
366 // gaussian tails centered at par[1] and with par[2]=sigma
0d19baad 367 Double_t ylab = px[0];
368 Double_t y0 = par[3]; // center of mass rapidity
368fc61e 369 Double_t func = 0;
0d19baad 370 if (ylab<y0+par[1] && ylab>y0-par[1]) func = par[0];
371 else if (ylab>y0+par[1]) {
372 Double_t z = (ylab-(par[1]+y0) )/(par[2]);
373 func = par[0] * TMath::Exp(-0.5 * z * z);
374 }
375 else {
376 Double_t z = (ylab-(-par[1]+y0) )/(par[2]);
368fc61e 377 func = par[0] * TMath::Exp(-0.5 * z * z);
378 }
379 return func;
380}
381
382//-----------------------------------------------------------
383
35e2c739 384Double_t AliGenMUONLMR::PtDistr(Double_t *px, Double_t *par){
368fc61e 385 // pt distribution: power law
386 Double_t x = px[0];
387 Double_t func = par[0] * x / TMath::Power((1+(x/par[1])*(x/par[1])),par[2]);
388 return func;
389}
390
391//-----------------------------------------------------------
392
393void AliGenMUONLMR::Generate() {
394 //
395 // generate the low mass resonances and their decays according to
396 // the multiplicity parameterized by pythia and BR from PDG
397 // rapidity distributions parametrized from pythia
398 // pt distributions from data (or pythia for etaprime)
399 //
400 Double_t pxPushed[100], pyPushed[100], pzPushed[100], ePushed[100];
401 Int_t nmuons = -1, npartPushed = 0, pdgPushed[100];
402 Double_t polar[3]= {0,0,0}; // Polarisation of the parent particle (for GEANT tracking)
403 Double_t origin0[3]; // Origin of the generated parent particle (for GEANT tracking)
404 // Calculating vertex position per event
405 for (Int_t j=0;j<3;j++) origin0[j]=fOrigin[j];
406 if(fVertexSmear==kPerEvent) {
407 Vertex();
408 for (Int_t j=0;j<3;j++) origin0[j]=fVertex[j];
409 }
410
368fc61e 411 TParticle *mother;
412 TDatabasePDG* pdg = TDatabasePDG::Instance();
413
414 Double_t pt, y, phi, mass, px, py, pz, ene, mt;
415
416 const Int_t nproc = 9;
417 Int_t idRes[nproc] = {kEtaLMR, kEtaLMR, kRhoLMR, kOmegaLMR, kOmegaLMR, kPhiLMR, kEtaPrimeLMR, kPionLMR, kKaonLMR};
35e2c739 418 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 419 // Double_t BR[nproc] = {1, 1, 1, 1, 1, 1, 1, 1, 1};
420 Int_t idDec[nproc] = {0, 1, 0, 0, 1, 0, 1, 2, 2}; // 0:2body, 1:Dalitz, 2:pi/K
421 Int_t mult[nproc] = {0,0,0,0,0,0,0,0,0};
422
423 while (nmuons < fNMuMin) {
424
425 nmuons = 0;
426 npartPushed = 0;
427 for (Int_t iproc=0; iproc<nproc; iproc++) {
428 if (fGenSingleProc == -1) {
429 mult[iproc] = Int_t(fMult[idRes[iproc]]->GetRandom()*fScaleMult[idRes[iproc]]);
430 }
431 else {
432 if (iproc==fGenSingleProc) {
433 mult[iproc] = 1;
434 BR[iproc] = 1;
435 }
436 else {
437 mult[iproc] = 0;
438 BR[iproc] = 0;
439 }
440 }
441 }
442
443 if (fGenSingleProc == -1) {
444 mult[1] = mult[0];
445 mult[4] = mult[3];
446 }
447
448 for (Int_t iproc = 0; iproc < nproc; iproc++) {
0d19baad 449 // printf ("Multiplicity for process %d is %d\n",iproc,mult[iproc]);
368fc61e 450 for (Int_t imult=0; imult<mult[iproc]; imult++) {
451 if (gRandom->Rndm() < BR[iproc]) {
452 fHNProc->Fill(iproc);
453 Int_t ipart = idRes[iproc];
454 pt = fPt[ipart]->GetRandom();
455 y = fY[ipart]->GetRandom();
456 phi = gRandom->Rndm() * 2 * TMath::Pi();
457 mass = pdg->GetParticle(fPDG[ipart])->Mass();
458 px = pt * TMath::Cos(phi);
459 py = pt * TMath::Sin(phi);
460 mt = TMath::Sqrt(pt * pt + mass * mass);
461 pz = mt * TMath::SinH(y);
462 ene = mt * TMath::CosH(y);
463
464 mother = fParticle[ipart];
465 mother->SetMomentum(px,py,pz,ene);
466 mother->SetCalcMass(mass);
467 if (!KinematicSelection(mother,0)) continue;
468
469 Bool_t hasDecayed = kTRUE;
470 if (idDec[iproc] == 0) Decay2Body(mother);
471 else if (idDec[iproc] == 1) DalitzDecay(mother);
472 else DecayPiK(mother,hasDecayed);
473 if (!hasDecayed) continue;
474 Bool_t isMu0Acc = KinematicSelection(fMu[0],1);
475 Bool_t isMu1Acc = KinematicSelection(fMu[1],1);
476 Bool_t isMuFromPiKAcc = kTRUE;
477
478 if (idDec[iproc] == 2) isMuFromPiKAcc = (mother->GetPdgCode()>0) ? isMu0Acc : isMu1Acc;
479 // mother
480 if ((idDec[iproc] < 2 && (isMu0Acc || isMu1Acc)) ||
481 (idDec[iproc] == 2 && isMuFromPiKAcc)) {
482 pdgPushed[npartPushed] = mother->GetPdgCode();
483 pxPushed[npartPushed] = mother->Px();
484 pyPushed[npartPushed] = mother->Py();
485 pzPushed[npartPushed] = mother->Pz();
486 ePushed[npartPushed] = mother->Energy();
487 npartPushed++;
488 if (isMu0Acc && (idDec[iproc] < 2 || mother->GetPdgCode() > 0)) {
489 pdgPushed[npartPushed] = fMu[0]->GetPdgCode();
490 pxPushed[npartPushed] = fMu[0]->Px();
491 pyPushed[npartPushed] = fMu[0]->Py();
492 pzPushed[npartPushed] = fMu[0]->Pz();
493 ePushed[npartPushed] = fMu[0]->Energy();
494 npartPushed++;
495 nmuons++;
496 }
497
498 if (isMu1Acc && (idDec[iproc] < 2 || mother->GetPdgCode() < 0)) {
499 pdgPushed[npartPushed] = fMu[1]->GetPdgCode();
500 pxPushed[npartPushed] = fMu[1]->Px();
501 pyPushed[npartPushed] = fMu[1]->Py();
502 pzPushed[npartPushed] = fMu[1]->Pz();
503 ePushed[npartPushed] = fMu[1]->Energy();
504 npartPushed++;
505 nmuons++;
506 }
507 }
508 } // end if BR
509 } // end loop on multiplicity
510 } // end loop on process
511 fHMultMu->Fill(nmuons);
512 } // keep on generating until at least a muon is created in the event
513
514 Int_t ntmother = 0, ntchild =0;
515 for (Int_t ipart = 0; ipart < npartPushed; ipart++) {
516 if (TMath::Abs(pdgPushed[ipart]) != 13) { // particle is not a muon, hence it's a mother
517 PushTrack(0,-1,pdgPushed[ipart],
518 pxPushed[ipart],pyPushed[ipart],pzPushed[ipart],ePushed[ipart],
35e2c739 519 origin0[0],origin0[1],origin0[2],0.,
368fc61e 520 polar[0],polar[1],polar[2],
521 kPPrimary,ntmother,1,11);
522 KeepTrack(ntmother);
523 }
524 else {
525 PushTrack(1,ntmother,pdgPushed[ipart],
526 pxPushed[ipart],pyPushed[ipart],pzPushed[ipart],ePushed[ipart],
35e2c739 527 origin0[0],origin0[1],origin0[2],0.,
368fc61e 528 polar[0],polar[1],polar[2],
529 kPDecay,ntchild,1,1);
530 KeepTrack(ntchild);
531 }
532 }
533 SetHighWaterMark(ntchild);
534 AliGenEventHeader* header = new AliGenEventHeader("LMR");
535 header->SetPrimaryVertex(fVertex);
536 header->SetNProduced(fNprimaries);
537 AddHeader(header);
538}
539
540//------------------------------------------------------------------
541
35e2c739 542void AliGenMUONLMR::Decay2Body(TParticle *mother){
368fc61e 543 // performs decay in two muons of the low mass resonances
544 Double_t md1 = fMu[0]->GetMass();
545 Int_t pdg = mother->GetPdgCode();
546 Double_t mres =0;
547 // if mother is a rho, extract the mass from its line shape
548 // otherwise consider the resonance mass
549 if (pdg == 113) mres = fRhoLineShape->GetRandom();
550 else mres = mother->GetCalcMass();
551 // while (mres < md1 + md2) mres = fDsigmaDm[res]->GetRandom();
552 // energies and momenta in rest frame
553 Double_t e1 = mres / 2.;
554 Double_t p1 = TMath::Sqrt((e1 + md1)*(e1 - md1));
555 // orientation in decaying particle rest frame
556 Double_t costheta = gRandom->Rndm() * 2 - 1;
557 Double_t sintheta = TMath::Sqrt((1. + costheta)*(1. - costheta));
558 Double_t phi = 2. * TMath::Pi() * gRandom->Rndm();
559 Double_t px1 = p1 * sintheta * TMath::Cos(phi);
560 Double_t py1 = p1 * sintheta * TMath::Sin(phi);
561 Double_t pz1 = p1 * costheta;
562
563 // boost muons into lab frame
564
565 TLorentzVector vmother, v1, v2;
566 // TLorentzVector boosted1, boosted2;
567 vmother.SetPxPyPzE(mother->Px(),mother->Py(),mother->Pz(),mother->Energy());
568 v1.SetPxPyPzE(px1,py1,pz1,e1);
569 v2.SetPxPyPzE(-px1,-py1,-pz1,e1);
570
571 TVector3 betaParent = (1./vmother.E())*vmother.Vect(); // beta = p/E
572 v1.Boost(betaParent);
573 v2.Boost(betaParent);
574
0d19baad 575 // TLorentzVector vtot = v1 + v2;
576 // printf ("mother: %g %g %g %g\n",vmother.Px(), vmother.Py(), vmother.Pz(), vmother.E());
577 // printf ("vtot : %g %g %g %g\n",vtot.Px(), vtot.Py(), vtot.Pz(), vtot.E());
368fc61e 578
579 fMu[0]->SetMomentum(v1.Px(),v1.Py(),v1.Pz(),v1.E());
580 fMu[1]->SetMomentum(v2.Px(),v2.Py(),v2.Pz(),v2.E());
581}
582
583//------------------------------------------------------------------
584
585void AliGenMUONLMR::DecayPiK(TParticle *mother, Bool_t &hasDecayed){
586 // performs decays of pions and kaons
587 Double_t md1 = fMu[0]->GetMass();
588 // extract the mass from the resonance's line shape
589 Double_t mres = mother->GetMass();
590 // choose the pi/k sign, assuming 50% probabilities for both signs
591 Int_t sign = (gRandom->Rndm() > 0.5) ? 1 : -1;
592 mother->SetPdgCode(sign * TMath::Abs(mother->GetPdgCode()));
593
594 // energies and momenta in rest frame
595 Double_t e1 = (mres*mres + md1*md1)/(2*mres);
596 Double_t p1 = TMath::Sqrt((e1 + md1)*(e1 - md1));
597 // orientation in decaying particle rest frame
598 Double_t costheta = gRandom->Rndm() * 2 - 1;
599 Double_t sintheta = TMath::Sqrt((1. + costheta)*(1. - costheta));
600 Double_t phi = 2. * TMath::Pi() * gRandom->Rndm();
601 Double_t px1 = p1 * sintheta * TMath::Cos(phi);
602 Double_t py1 = p1 * sintheta * TMath::Sin(phi);
603 Double_t pz1 = p1 * costheta;
604
605 // boost muons into lab frame
606 TLorentzVector vmother, v1;
607 vmother.SetPxPyPzE(mother->Px(),mother->Py(),mother->Pz(),mother->Energy());
608 v1.SetPxPyPzE(px1,py1,pz1,e1);
609
610 TVector3 betaParent = (1./vmother.E())*vmother.Vect(); // beta = p/E
611 v1.Boost(betaParent);
612 if (mother->GetPdgCode()>0) fMu[0]->SetMomentum(v1.Px(),v1.Py(),v1.Pz(),v1.E());
613 else fMu[1]->SetMomentum(v1.Px(),v1.Py(),v1.Pz(),v1.E());
614
a59583d3 615 Int_t idmother = 0;
35e2c739 616 if (TMath::Abs(mother->GetPdgCode())== 211) idmother = 0;
617 if (TMath::Abs(mother->GetPdgCode())== 321) idmother = 1;
368fc61e 618 Double_t gammaRes = mother->Energy()/mres;
619 Double_t zResCM = fDecay[idmother]->GetRandom();
620 Double_t zResLab = gammaRes*zResCM;
621 if(zResLab > 0.938) hasDecayed = 0; // 0.938: distance from IP to absorber + lambda_i
622 else hasDecayed = 1;
368fc61e 623}
624
625//-------------------------------------------------------------------
626
35e2c739 627void AliGenMUONLMR::DalitzDecay(TParticle *mother){
368fc61e 628 //
629 // perform dalitz decays of eta, omega and etaprime
630 //
631 //in the rest frame of the virtual photon:
632 Double_t mres = mother->GetCalcMass();
633 Double_t mumass = fMu[0]->GetMass();
634 Double_t md3 = 0; // unless differently specified, third particle is a photon
635 if (mother->GetPdgCode() == 223) md3 = 0.134977; // if mother is an omega, third particle is a pi0
a59583d3 636 Int_t index = 0;
35e2c739 637 if (mother->GetPdgCode() == 221) index = 0; // eta
638 else if (mother->GetPdgCode() == 223) index = 1; // omega
639 else if (mother->GetPdgCode() == 331) index = 2; // etaPrime
368fc61e 640 Int_t flag = 0;
641 Double_t xd=0, mvirt2=0;
642 Double_t countIt = 0;
643 while (flag==0) {
644 xd = fDalitz[index]->GetRandom();
645 mvirt2 = xd * mres * mres; // mass of virtual photon
646 // check kinematics
647 if (mres - md3 > TMath::Sqrt(mvirt2) && TMath::Sqrt(mvirt2)/2. > mumass) flag=1;
648 if (++countIt>1E11) {
649 mvirt2 = mres * mres * 0.998;
650 break;
651 }
652 }
653
654 //
655 // Generate muons in virtual photon rest frame.
656 // z axis is the virt. photon direction (before boost)
657 //
658
659 Double_t e1 = TMath::Sqrt(mvirt2)/2.; // energy of mu1 in the virtual photon frame
660 Double_t psquare = (e1 + mumass)*(e1 - mumass);
661 if (psquare<0) {
c279681a 662 AliError(Form("sqrt of psquare = %f put to 0\n",psquare));
368fc61e 663 psquare = 0;
664 }
665 Double_t p1 = TMath::Sqrt(psquare);
666 //theta angle between the pos. muon and the virtual photon
667 Double_t costheta = fCosTheta->GetRandom();
668 if (costheta>1) costheta = 1;
669 if (costheta<-1) costheta = -1;
670 Double_t sintheta = TMath::Sqrt((1. + costheta)*(1. - costheta));
671 Double_t phi = 2 * TMath::Pi() * gRandom->Rndm();
672 Double_t sinphi = TMath::Sin(phi);
673 Double_t cosphi = TMath::Cos(phi);
674
675 // fill 4-vectors of leptons in the virtual photon frame
676
677 Double_t px1 = p1*sintheta*cosphi;
678 Double_t py1 = p1*sintheta*sinphi;
679 Double_t pz1 = p1*costheta;
680 Double_t px2 = -p1*sintheta*cosphi;
681 Double_t py2 = -p1*sintheta*sinphi;
682 Double_t pz2 = -p1*costheta;
683 Double_t e2 = e1;
684
685 fMu[0]->SetMomentum(px1,py1,pz1,e1);
686 fMu[1]->SetMomentum(px2,py2,pz2,e2);
687
688 // calculate components of non-dilepton in CMS of parent resonance
689
690 Double_t e3 = (mres * mres + md3 * md3 - mvirt2) / (2.*mres);
691 Double_t psquare3 = (e3 + md3)*(e3 - md3);
692 if (psquare3<0) {
c279681a 693 AliError(Form("Sqrt of psquare3 = %f put to 0\n",psquare3));
368fc61e 694 psquare3 = 0;
695 }
696 Double_t p3 = TMath::Sqrt(psquare3);
697 Double_t costheta2 = 2.* gRandom->Rndm() - 1.; // angle between virtual photon and resonance
698 if (costheta2>1) costheta2 = 1;
699 if (costheta2<-1) costheta2 = -1;
700 Double_t sintheta2 = TMath::Sqrt((1. + costheta2)*(1. - costheta2));
701 Double_t phi2 = 2 * TMath::Pi() * gRandom->Rndm();
702 Double_t sinphi2 = TMath::Sin(phi2);
703 Double_t cosphi2 = TMath::Cos(phi2);
704 Double_t px3 = p3*sintheta2*cosphi2;
705 Double_t py3 = p3*sintheta2*sinphi2;
706 Double_t pz3 = p3*costheta2;
707 TLorentzVector v3(px3,py3,pz3,e3);
708
709 sintheta2 = -sintheta2;
710 cosphi2 = -cosphi2;
711 sinphi2 = -sinphi2;
712
713 Double_t px1new = px1*costheta2*cosphi2 - py1*sinphi2 + pz1*sintheta2*cosphi2;
714 Double_t py1new = px1*costheta2*sinphi2 + py1*cosphi2 + pz1*sintheta2*sinphi2;
715 Double_t pz1new =-px1*sintheta2 + pz1*costheta2;
716 Double_t px2new = px2*costheta2*cosphi2 - py2*sinphi2 + pz2*sintheta2*cosphi2;
717 Double_t py2new = px2*costheta2*sinphi2 + py2*cosphi2 + pz2*sintheta2*sinphi2;
718 Double_t pz2new =-px2*sintheta2 + pz2*costheta2;
719
720 fMu[0]->SetMomentum(px1new,py1new,pz1new,e1);
721 fMu[1]->SetMomentum(px2new,py2new,pz2new,e2);
722
723 Double_t evirt = mres - e3;
724 Double_t pxvirt = -px3;
725 Double_t pyvirt = -py3;
726 Double_t pzvirt = -pz3;
727 TLorentzVector vvirt(pxvirt,pyvirt,pzvirt,evirt);
728 TVector3 betaVirt = (1./evirt) * vvirt.Vect(); // virtual photon beta in res frame
729
730 TLorentzVector v1(px1,py1,pz1,e1);
731 TLorentzVector v2(px2,py2,pz2,e2);
732
733 // boost the muons in the frame where the resonance is at rest
734
735 v1.Boost(betaVirt);
736 v2.Boost(betaVirt);
737
738 // boost muons and third particle in lab frame
739
740 TLorentzVector vmother(mother->Px(), mother->Py(), mother->Pz(), mother->Energy());
741 TVector3 resBetaLab = (1./vmother.E())*vmother.Vect(); // eta beta in lab frame
742 v1.Boost(resBetaLab);
743 v2.Boost(resBetaLab);
744 v3.Boost(resBetaLab);
745 vvirt.Boost(resBetaLab);
746
747 fMu[0]->SetMomentum(v1.Px(),v1.Py(),v1.Pz(),v1.E());
748 fMu[1]->SetMomentum(v2.Px(),v2.Py(),v2.Pz(),v2.E());
0d19baad 749 // part3->SetMomentum(v3.Px(),v3.Py(),v3.Pz(),v3.E());
368fc61e 750
0d19baad 751 // TLorentzVector vtot = v1 + v2 + v3;
752 // TLorentzVector vdimu = v1 + v2;
753 // printf ("mother: %g %g %g %g\n",vmother.Px(), vmother.Py(), vmother.Pz(), vmother.E());
754 // printf ("vtot : %g %g %g %g\n",vtot.Px(), vtot.Py(), vtot.Pz(), vtot.E());
755 // printf ("vvirt : %g %g %g %g\n",vvirt.Px(), vvirt.Py(), vvirt.Pz(), vvirt.E());
756 // printf ("vdimu : %g %g %g %g\n",vdimu.Px(), vdimu.Py(), vdimu.Pz(), vdimu.E());
368fc61e 757
758}
759
760//------------------------------------------------------------------
761
762Double_t AliGenMUONLMR::FormFactor(Double_t q2, Int_t decay){
763 // Calculates the form factor for Dalitz decays A->B+l+l
764 // Returns: |F(q^2)|^2
765 //
766 // References: L.G. Landsberg, Physics Reports 128 No.6 (1985) 301-376.
767
768 Double_t ff2, mass2;
769 Double_t n2, n4, m2;
770 // Lepton-G
771
772 Double_t lambda2inv = 0;
773 switch (decay) {
774 case 0: // eta -> mu mu gamma
0d19baad 775 // eta -> l+ l- gamma: pole approximation
368fc61e 776 lambda2inv = 1.95;
777 mass2 = fParticle[kEtaLMR]->GetMass() * fParticle[kEtaLMR]->GetMass();
778 if (q2 < mass2) ff2 = TMath::Power(1./(1.-lambda2inv*q2),2);
779 else ff2 = 0;
780 break;
781 case 1: // omega -> mu mu pi0
782 // omega -> l+ l- pi0: pole approximation
783 mass2 = fParticle[kOmegaLMR]->GetMass() * fParticle[kOmegaLMR]->GetMass();
784 lambda2inv = 2.26;
785 if (q2 < mass2) ff2 = TMath::Power(1./(1.-lambda2inv*q2),2);
786 else ff2 = 0;
787 break;
788 case 2: // etaPrime -> mu mu gamma
789 mass2 = fParticle[kEtaPrimeLMR]->GetMass() * fParticle[kEtaPrimeLMR]->GetMass();
790 // eta' -> l+ l- gamma: Breit-Wigner fitted to data
791 n2 = 0.764 * 0.764;
792 n4 = n2 * n2;
793 m2 = 0.1020 * 0.1020;
794 if (q2 < mass2) ff2 = n4 / (TMath::Power(n2-q2,2) + m2 * n2);
795 else ff2 = 0;
796 break;
797 default:
c279681a 798 AliError ("FormFactor: Decay not found");
368fc61e 799 return 0;
800 break;
801 }
802 return ff2;
803}
804
805//____________________________________________________________
806
35e2c739 807Double_t AliGenMUONLMR::RhoLineShapeNew(Double_t *x, Double_t */*para*/){
368fc61e 808 //new parameterization implemented by Hiroyuki Sako (GSI)
809 Double_t mass = *x;
810 double r, GammaTot;
811 Double_t mRho = TDatabasePDG::Instance()->GetParticle("rho0")->Mass();
812 Double_t mPi = TDatabasePDG::Instance()->GetParticle("pi0")->Mass();
813 Double_t mMu = TDatabasePDG::Instance()->GetParticle("mu-")->Mass();
814 Double_t Gamma0 = TDatabasePDG::Instance()->GetParticle("rho0")->Width();
815
816 const double Norm = 0.0744416*1.01;
35e2c739 817
368fc61e 818 // 0.0744416 at m = 0.72297
819 // is the max number with Norm=1 (for rho)
820
821 double mThreshold = 2.*mPi;
822
823 const double T = 0.170; // Assumption of pi+ temperature [GeV/c^2]
824 //const double T = 0.11; // Taken from fit to pi+ temperature [GeV/c^2]
825 // with Reference: LEBC-EHS collab., Z. Phys. C 50 (1991) 405
826
827 if (mass < mThreshold) {
828 r = 0.;
829 return r;
830 }
831
832 double k = sqrt(0.25*mass*mass-(mThreshold/2)*(mThreshold/2));
833 double k0 = sqrt(0.25*mRho*mRho-(mThreshold/2)*(mThreshold/2));
834
835 GammaTot = (k/k0)*(k/k0)*(k/k0)*(mRho/mass)*(mRho/mass)*Gamma0;
836
837 double FormFactor2 = 1/((mass*mass-mRho*mRho)*(mass*mass-mRho*mRho)+
838 mass*mass*GammaTot*GammaTot);
839
840 r = pow(mass,1.5)*pow((1-mThreshold*mThreshold/(mass*mass)),1.5)*
841 ((mass*mass+2*mMu*mMu)/(mass*mass))*(pow((mass*mass-4*mMu*mMu),0.5)/mass)*FormFactor2
842 *exp(-mass/T)/Norm;
843
844 return r;
845}
c279681a 846