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Merge branch 'master' of https://git.cern.ch/reps/AliRoot
[u/mrichter/AliRoot.git] / EVGEN / AliGenSTRANGElib.cxx
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87f8f72e 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
17//======================================================================
18// AliGenSTRANGElib class contains parameterizations of the
19// kaon, phi and hyperon (Lambda, Anti-Lambda, Xi, anti-Xi, Omega,
20// anti-Omega) for the PPR study of the strange particle production.
21// These parameterizations are used by the
22// AliGenParam class:
23// AliGenParam(npar, param, AliGenSTRANGElib::GetPt(param),
24// AliGenSTRANGElib::GetY(param),
25// AliGenSTRANGElib::GetIp(param) )
26// param represents the particle to be simulated.
27// ?????????
28// Pt distributions are calculated from the transverse mass scaling
29// with Pions, using the PtScal function taken from AliGenMUONlib
30// version aliroot 3.01
31//
32// Rocco CALIANDRO. Rosa Anna FINI, Tiziano VIRGILI
33// Rocco.Caliandro@cern.ch Rosanna.Fini@ba.infn.it,
34// Tiziano.Virgili@roma1.infn.it
35//======================================================================
36
ac3faee4 37/* $Id$ */
87f8f72e 38
7d245e03 39#include <TMath.h>
7d245e03 40#include <TRandom.h>
87f8f72e 41
42#include "AliGenSTRANGElib.h"
43
44ClassImp(AliGenSTRANGElib)
45
46//=============================================================
47//
48 Double_t AliGenSTRANGElib::PtScal(Double_t pt, Int_t np)
49{
50// Mt-scaling
51// Function for the calculation of the Pt distribution for a
52// given particle np, from the pion Pt distribution using the
53// mt scaling. This function was taken from AliGenMUONlib
54// aliroot version 3.01, and was extended for hyperons.
55// np = 1=>Pions 2=>Kaons 3=>Etas 4=>Omegas 5=>ETA' 6=>PHI
56// 7=>BARYONS-BARYONBARS
57// 8=>Lambda-antiLambda
58// 9=>Xi-antiXi
59// 10=>Omega-antiOmega
60
61 // MASS SCALING RESPECT TO PIONS
0db2f441 62 // MASS 0=>PI, 1=>K, 2=>ETA,3=>OMEGA,4=>ETA',5=>PHI
13313168 63 const Double_t khm[11] = {0.1396, 0.494,0.547, 0.782, 0.957, 1.02,
0db2f441 64 // MASS 6=>BARYON-BARYONBAR
87f8f72e 65 0.938,
0db2f441 66 // MASS 7=>Lambda-antiLambda
87f8f72e 67 1.1157,
0db2f441 68 // MASS 8=>Xi-antiXi
87f8f72e 69 1.3213,
0db2f441 70 // MASS 9=>Omega-antiOmega
13313168 71 1.6725,
0db2f441 72 // MASS 10=>Lambda(1520)
13313168 73 1.5195};
87f8f72e 74 // VALUE MESON/PI AT 5 GEV
13313168 75 const Double_t kfmax[11]={1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1.};
87f8f72e 76 Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
77 Double_t kfmax2=f5/kfmax[np];
78 // PIONS
79 Double_t ptpion=100.*PtPion(&pt, (Double_t*) 0);
80 Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/
81 (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ kfmax2;
82 return fmtscal*ptpion;
83}
84//=============================================================
85//
75e0cc59 86 Double_t AliGenSTRANGElib::PtPion(const Double_t *px, const Double_t *)
87f8f72e 87{
88// Pion transverse momentum distribtuion taken
89// from AliGenMUONlib class, version 3.01 of aliroot
90// PT-PARAMETERIZATION CDF, PRL 61(88) 1819
91// POWER LAW FOR PT > 500 MEV
92// MT SCALING BELOW (T=160 MEV)
93//
94 const Double_t kp0 = 1.3;
95 const Double_t kxn = 8.28;
96 const Double_t kxlim=0.5;
97 const Double_t kt=0.160;
98 const Double_t kxmpi=0.139;
99 const Double_t kb=1.;
100 Double_t y, y1, kxmpi2, ynorm, a;
101 Double_t x=*px;
102 //
103 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
104 kxmpi2=kxmpi*kxmpi;
105 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+kxmpi2)/kt));
106 a=ynorm/y1;
107 if (x > kxlim)
108 y=a*TMath::Power(kp0/(kp0+x),kxn);
109 else
110 y=kb*TMath::Exp(-sqrt(x*x+kxmpi2)/kt);
111 return y*x;
112}
113// End Scaling
114//============================================================================
115// K A O N
75e0cc59 116 Double_t AliGenSTRANGElib::PtKaon( const Double_t *px, const Double_t *)
87f8f72e 117{
118// kaon
119// pt-distribution
120//____________________________________________________________
121
0db2f441 122 return PtScal(*px,1); // 1==> Kaon in the PtScal function
87f8f72e 123}
124
75e0cc59 125 Double_t AliGenSTRANGElib::YKaon( const Double_t *py, const Double_t *)
87f8f72e 126{
127// y-distribution
128//____________________________________________________________
129
130 const Double_t ka = 1000.;
46ae38d0 131 const Double_t kdy = 4.*4;
87f8f72e 132
133
134 Double_t y=TMath::Abs(*py);
135 //
136 Double_t ex = y*y/(2*kdy*kdy);
137 return ka*TMath::Exp(-ex);
138}
139
140 Int_t AliGenSTRANGElib::IpKaon(TRandom *ran)
141{
142// particle composition
143//
144
145 Float_t random = ran->Rndm();
146 Float_t random2 = ran->Rndm();
147 if (random2 < 0.5)
148 {
149 if (random < 0.5) {
150 return 321; // K+
151 } else {
152 return -321; // K-
153 }
154 }
155 else
156 {
157 if (random < 0.5) {
158 return 130; // K^0 short
159 } else {
160 return 310; // K^0 long
161 }
162 }
163}
164// End Kaons
165//============================================================================
166//============================================================================
167// P H I
75e0cc59 168 Double_t AliGenSTRANGElib::PtPhi( const Double_t *px, const Double_t *)
87f8f72e 169{
170// phi
171// pt-distribution
172//____________________________________________________________
173
0db2f441 174 return PtScal(*px,5); // 5==> Phi in the PtScal function
87f8f72e 175}
176
75e0cc59 177 Double_t AliGenSTRANGElib::YPhi( const Double_t *py, const Double_t *)
87f8f72e 178{
179// y-distribution
180//____________________________________________________________
181
182 const Double_t ka = 1000.;
46ae38d0 183 const Double_t kdy = 4.*4;
87f8f72e 184
185
186 Double_t y=TMath::Abs(*py);
187 //
188 Double_t ex = y*y/(2*kdy*kdy);
189 return ka*TMath::Exp(-ex);
190}
191
192 Int_t AliGenSTRANGElib::IpPhi(TRandom *)
193{
194// particle composition
195//
196
197 return 333; // Phi
198}
199// End Phis
200//===================================================================
201//============================================================================
202// Lambda
75e0cc59 203 Double_t AliGenSTRANGElib::PtLambda( const Double_t *px, const Double_t *)
87f8f72e 204{
205// Lambda
206// pt-distribution
207//____________________________________________________________
208
0db2f441 209 return PtScal(*px,7); // 7==> Lambda-antiLambda in the PtScal function
87f8f72e 210}
211
75e0cc59 212 Double_t AliGenSTRANGElib::YLambda( const Double_t *py, const Double_t *)
87f8f72e 213{
214// y-distribution
215//____________________________________________________________
216
217 const Double_t ka = 1000.;
46ae38d0 218 const Double_t kdy = 4.*4;
87f8f72e 219
220
221 Double_t y=TMath::Abs(*py);
222 //
223 Double_t ex = y*y/(2*kdy*kdy);
224 return ka*TMath::Exp(-ex);
225}
226
48b91885 227 Int_t AliGenSTRANGElib::IpLambda(TRandom *ran)
87f8f72e 228{
229// particle composition
230// generation of fixed type of particle
231//
48b91885 232 Float_t random = ran->Rndm();
233 if (random < 0.5) {
234 return 3122; // Lambda
235 } else {
236 return -3122; // Anti-Lambda
237 }
87f8f72e 238}
239// End Lambda
240//============================================================================
241// XIminus
75e0cc59 242 Double_t AliGenSTRANGElib::PtXiMinus( const Double_t *px, const Double_t *)
87f8f72e 243{
244// Xi
245// pt-distribution
246//____________________________________________________________
247
0db2f441 248 return PtScal(*px,8); // 8==> Xi-antiXi in the PtScal function
87f8f72e 249}
250
75e0cc59 251 Double_t AliGenSTRANGElib::YXiMinus( const Double_t *py, const Double_t *)
87f8f72e 252{
253// y-distribution
254//____________________________________________________________
255
256 const Double_t ka = 1000.;
46ae38d0 257 const Double_t kdy = 4.*4;
87f8f72e 258
259
260 Double_t y=TMath::Abs(*py);
261 //
262 Double_t ex = y*y/(2*kdy*kdy);
263 return ka*TMath::Exp(-ex);
264}
265
48b91885 266 Int_t AliGenSTRANGElib::IpXiMinus(TRandom *ran)
87f8f72e 267{
268// particle composition
269// generation of fixed type of particle
270//
48b91885 271 Float_t random = ran->Rndm();
272 if (random < 0.5) {
273 return 3312; // Xi-
274 } else {
275 return -3312; // Xi+
276 }
87f8f72e 277}
278// End Ximinus
279//============================================================================
280// Omegaminus
75e0cc59 281 Double_t AliGenSTRANGElib::PtOmegaMinus( const Double_t *px, const Double_t *)
87f8f72e 282{
283// Omega
284// pt-distribution
285//____________________________________________________________
286
0db2f441 287 return PtScal(*px,9); // 9==> Omega-antiOmega in the PtScal function
87f8f72e 288}
289
75e0cc59 290 Double_t AliGenSTRANGElib::YOmegaMinus( const Double_t *py, const Double_t *)
87f8f72e 291{
292// y-distribution
293//____________________________________________________________
294
295 const Double_t ka = 1000.;
46ae38d0 296 const Double_t kdy = 4.*4;
87f8f72e 297
298
299 Double_t y=TMath::Abs(*py);
300 //
301 Double_t ex = y*y/(2*kdy*kdy);
302 return ka*TMath::Exp(-ex);
303}
304
48b91885 305 Int_t AliGenSTRANGElib::IpOmegaMinus(TRandom * ran)
87f8f72e 306{
307// particle composition
308// generation of fixed type of particle
309//
310
48b91885 311 Float_t random = ran->Rndm();
312 if (random < 0.5) {
313 return 3334; // Omega-
314 } else {
315 return -3334; // Omega+
316 }
87f8f72e 317}
318// End Omegaminus
319//============================================================================
13313168 320// Lambda(1520)
75e0cc59 321Double_t AliGenSTRANGElib::PtLambda1520( const Double_t *px, const Double_t *)
13313168 322{
323// Lambda(1520)
324// pt-distribution
325//____________________________________________________________
326
0db2f441 327 return PtScal(*px,10); // 10=> Lambda(1520) in the PtScal function
13313168 328}
87f8f72e 329
75e0cc59 330Double_t AliGenSTRANGElib::YLambda1520( const Double_t *py, const Double_t *)
13313168 331{
332// y-distribution
333//____________________________________________________________
334
335 const Double_t ka = 1000.;
336 const Double_t kdy = 4.;
337
338
339 Double_t y=TMath::Abs(*py);
340 //
341 Double_t ex = y*y/(2*kdy*kdy);
342 return ka*TMath::Exp(-ex);
343}
344
345Int_t AliGenSTRANGElib::IpLambda1520(TRandom * ran)
346{
347// particle composition
348// generation of fixed type of particle
349//
350
351 Float_t random = ran->Rndm();
352 if (random < 0.5) {
353 return 3124; // Lambda(1520)
354 } else {
355 return -3124; // antiLambda(1520)
356 }
357}
358// End Lambda(1520)
359//============================================================================
87f8f72e 360
75e0cc59 361typedef Double_t (*GenFunc) (const Double_t*, const Double_t*);
198bb1c7 362 GenFunc AliGenSTRANGElib::GetPt(Int_t param, const char* /*tname*/) const
87f8f72e 363{
364// Return pinter to pT parameterisation
365 GenFunc func;
366
367 switch (param)
368 {
369 case kKaon:
370 func=PtKaon;
371 break;
372 case kPhi:
373 func=PtPhi;
374 break;
375 case kLambda:
376 func=PtLambda;
377 break;
378 case kXiMinus:
379 func=PtXiMinus;
380 break;
381 case kOmegaMinus:
382 func=PtOmegaMinus;
383 break;
13313168 384 case kLambda1520:
385 func=PtLambda1520;
386 break;
87f8f72e 387 default:
388 func=0;
389 printf("<AliGenSTRANGElib::GetPt> unknown parametrisationn");
390 }
391 return func;
392}
393
198bb1c7 394 GenFunc AliGenSTRANGElib::GetY(Int_t param, const char* /*tname*/) const
87f8f72e 395{
396// Return pointer to Y parameterisation
397 GenFunc func;
398 switch (param)
399 {
400 case kKaon:
401 func=YKaon;
402 break;
403 case kPhi:
404 func=YPhi;
405 break;
406 case kLambda:
407 func=YLambda;
408 break;
409 case kXiMinus:
410 func=YXiMinus;
411 break;
412 case kOmegaMinus:
413 func=YOmegaMinus;
414 break;
13313168 415 case kLambda1520:
416 func=YLambda1520;
417 break;
87f8f72e 418 default:
419 func=0;
420 printf("<AliGenSTRANGElib::GetY> unknown parametrisationn");
421 }
422 return func;
423}
424typedef Int_t (*GenFuncIp) (TRandom *);
198bb1c7 425 GenFuncIp AliGenSTRANGElib::GetIp(Int_t param, const char* /*tname*/) const
87f8f72e 426{
427// Return pointer to particle composition
428 GenFuncIp func;
429 switch (param)
430 {
431 case kKaon:
432 func=IpKaon;
433 break;
434 case kPhi:
435 func=IpPhi;
436 break;
437 case kLambda:
438 func=IpLambda;
439 break;
440 case kXiMinus:
441 func=IpXiMinus;
442 break;
443 case kOmegaMinus:
444 func=IpOmegaMinus;
445 break;
13313168 446 case kLambda1520:
447 func=IpLambda1520;
448 break;
87f8f72e 449 default:
450 func=0;
451 printf("<AliGenSTRANGElib::GetIp> unknown parametrisationn");
452 }
453 return func;
454}
455