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[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
39#include "TMath.h"
40#include "TRandom.h"
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
62 // MASS 1=>PI, 2=>K, 3=>ETA,4=>OMEGA,5=>ETA',6=>PHI
13313168 63 const Double_t khm[11] = {0.1396, 0.494,0.547, 0.782, 0.957, 1.02,
87f8f72e 64 // MASS 7=>BARYON-BARYONBAR
65 0.938,
66 // MASS 8=>Lambda-antiLambda
67 1.1157,
68 // MASS 9=>Xi-antiXi
69 1.3213,
70 // MASS 10=>Omega-antiOmega
13313168 71 1.6725,
72 // MASS 11=>Lambda(1520)
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 np--;
77 Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
78 Double_t kfmax2=f5/kfmax[np];
79 // PIONS
80 Double_t ptpion=100.*PtPion(&pt, (Double_t*) 0);
81 Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/
82 (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ kfmax2;
83 return fmtscal*ptpion;
84}
85//=============================================================
86//
87 Double_t AliGenSTRANGElib::PtPion(Double_t *px, Double_t *)
88{
89// Pion transverse momentum distribtuion taken
90// from AliGenMUONlib class, version 3.01 of aliroot
91// PT-PARAMETERIZATION CDF, PRL 61(88) 1819
92// POWER LAW FOR PT > 500 MEV
93// MT SCALING BELOW (T=160 MEV)
94//
95 const Double_t kp0 = 1.3;
96 const Double_t kxn = 8.28;
97 const Double_t kxlim=0.5;
98 const Double_t kt=0.160;
99 const Double_t kxmpi=0.139;
100 const Double_t kb=1.;
101 Double_t y, y1, kxmpi2, ynorm, a;
102 Double_t x=*px;
103 //
104 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
105 kxmpi2=kxmpi*kxmpi;
106 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+kxmpi2)/kt));
107 a=ynorm/y1;
108 if (x > kxlim)
109 y=a*TMath::Power(kp0/(kp0+x),kxn);
110 else
111 y=kb*TMath::Exp(-sqrt(x*x+kxmpi2)/kt);
112 return y*x;
113}
114// End Scaling
115//============================================================================
116// K A O N
117 Double_t AliGenSTRANGElib::PtKaon( Double_t *px, Double_t *)
118{
119// kaon
120// pt-distribution
121//____________________________________________________________
122
123 return PtScal(*px,2); // 2==> Kaon in the PtScal function
124}
125
126 Double_t AliGenSTRANGElib::YKaon( Double_t *py, Double_t *)
127{
128// y-distribution
129//____________________________________________________________
130
131 const Double_t ka = 1000.;
132 const Double_t kdy = 4.;
133
134
135 Double_t y=TMath::Abs(*py);
136 //
137 Double_t ex = y*y/(2*kdy*kdy);
138 return ka*TMath::Exp(-ex);
139}
140
141 Int_t AliGenSTRANGElib::IpKaon(TRandom *ran)
142{
143// particle composition
144//
145
146 Float_t random = ran->Rndm();
147 Float_t random2 = ran->Rndm();
148 if (random2 < 0.5)
149 {
150 if (random < 0.5) {
151 return 321; // K+
152 } else {
153 return -321; // K-
154 }
155 }
156 else
157 {
158 if (random < 0.5) {
159 return 130; // K^0 short
160 } else {
161 return 310; // K^0 long
162 }
163 }
164}
165// End Kaons
166//============================================================================
167//============================================================================
168// P H I
169 Double_t AliGenSTRANGElib::PtPhi( Double_t *px, Double_t *)
170{
171// phi
172// pt-distribution
173//____________________________________________________________
174
175 return PtScal(*px,6); // 6==> Phi in the PtScal function
176}
177
178 Double_t AliGenSTRANGElib::YPhi( Double_t *py, Double_t *)
179{
180// y-distribution
181//____________________________________________________________
182
183 const Double_t ka = 1000.;
184 const Double_t kdy = 4.;
185
186
187 Double_t y=TMath::Abs(*py);
188 //
189 Double_t ex = y*y/(2*kdy*kdy);
190 return ka*TMath::Exp(-ex);
191}
192
193 Int_t AliGenSTRANGElib::IpPhi(TRandom *)
194{
195// particle composition
196//
197
198 return 333; // Phi
199}
200// End Phis
201//===================================================================
202//============================================================================
203// Lambda
204 Double_t AliGenSTRANGElib::PtLambda( Double_t *px, Double_t *)
205{
206// Lambda
207// pt-distribution
208//____________________________________________________________
209
210 return PtScal(*px,8); // 8==> Lambda-antiLambda in the PtScal function
211}
212
213 Double_t AliGenSTRANGElib::YLambda( Double_t *py, Double_t *)
214{
215// y-distribution
216//____________________________________________________________
217
218 const Double_t ka = 1000.;
219 const Double_t kdy = 4.;
220
221
222 Double_t y=TMath::Abs(*py);
223 //
224 Double_t ex = y*y/(2*kdy*kdy);
225 return ka*TMath::Exp(-ex);
226}
227
48b91885 228 Int_t AliGenSTRANGElib::IpLambda(TRandom *ran)
87f8f72e 229{
230// particle composition
231// generation of fixed type of particle
232//
48b91885 233 Float_t random = ran->Rndm();
234 if (random < 0.5) {
235 return 3122; // Lambda
236 } else {
237 return -3122; // Anti-Lambda
238 }
87f8f72e 239}
240// End Lambda
241//============================================================================
242// XIminus
243 Double_t AliGenSTRANGElib::PtXiMinus( Double_t *px, Double_t *)
244{
245// Xi
246// pt-distribution
247//____________________________________________________________
248
249 return PtScal(*px,9); // 9==> Xi-antiXi in the PtScal function
250}
251
252 Double_t AliGenSTRANGElib::YXiMinus( Double_t *py, Double_t *)
253{
254// y-distribution
255//____________________________________________________________
256
257 const Double_t ka = 1000.;
258 const Double_t kdy = 4.;
259
260
261 Double_t y=TMath::Abs(*py);
262 //
263 Double_t ex = y*y/(2*kdy*kdy);
264 return ka*TMath::Exp(-ex);
265}
266
48b91885 267 Int_t AliGenSTRANGElib::IpXiMinus(TRandom *ran)
87f8f72e 268{
269// particle composition
270// generation of fixed type of particle
271//
48b91885 272 Float_t random = ran->Rndm();
273 if (random < 0.5) {
274 return 3312; // Xi-
275 } else {
276 return -3312; // Xi+
277 }
87f8f72e 278}
279// End Ximinus
280//============================================================================
281// Omegaminus
282 Double_t AliGenSTRANGElib::PtOmegaMinus( Double_t *px, Double_t *)
283{
284// Omega
285// pt-distribution
286//____________________________________________________________
287
288 return PtScal(*px,10); // 10==> Omega-antiOmega in the PtScal function
289}
290
291 Double_t AliGenSTRANGElib::YOmegaMinus( Double_t *py, Double_t *)
292{
293// y-distribution
294//____________________________________________________________
295
296 const Double_t ka = 1000.;
297 const Double_t kdy = 4.;
298
299
300 Double_t y=TMath::Abs(*py);
301 //
302 Double_t ex = y*y/(2*kdy*kdy);
303 return ka*TMath::Exp(-ex);
304}
305
48b91885 306 Int_t AliGenSTRANGElib::IpOmegaMinus(TRandom * ran)
87f8f72e 307{
308// particle composition
309// generation of fixed type of particle
310//
311
48b91885 312 Float_t random = ran->Rndm();
313 if (random < 0.5) {
314 return 3334; // Omega-
315 } else {
316 return -3334; // Omega+
317 }
87f8f72e 318}
319// End Omegaminus
320//============================================================================
13313168 321// Lambda(1520)
322Double_t AliGenSTRANGElib::PtLambda1520( Double_t *px, Double_t *)
323{
324// Lambda(1520)
325// pt-distribution
326//____________________________________________________________
327
328 return PtScal(*px,11); // 11=> Lambda(1520) in the PtScal function
329}
87f8f72e 330
13313168 331Double_t AliGenSTRANGElib::YLambda1520( Double_t *py, Double_t *)
332{
333// y-distribution
334//____________________________________________________________
335
336 const Double_t ka = 1000.;
337 const Double_t kdy = 4.;
338
339
340 Double_t y=TMath::Abs(*py);
341 //
342 Double_t ex = y*y/(2*kdy*kdy);
343 return ka*TMath::Exp(-ex);
344}
345
346Int_t AliGenSTRANGElib::IpLambda1520(TRandom * ran)
347{
348// particle composition
349// generation of fixed type of particle
350//
351
352 Float_t random = ran->Rndm();
353 if (random < 0.5) {
354 return 3124; // Lambda(1520)
355 } else {
356 return -3124; // antiLambda(1520)
357 }
358}
359// End Lambda(1520)
360//============================================================================
87f8f72e 361
362typedef Double_t (*GenFunc) (Double_t*, Double_t*);
198bb1c7 363 GenFunc AliGenSTRANGElib::GetPt(Int_t param, const char* /*tname*/) const
87f8f72e 364{
365// Return pinter to pT parameterisation
366 GenFunc func;
367
368 switch (param)
369 {
370 case kKaon:
371 func=PtKaon;
372 break;
373 case kPhi:
374 func=PtPhi;
375 break;
376 case kLambda:
377 func=PtLambda;
378 break;
379 case kXiMinus:
380 func=PtXiMinus;
381 break;
382 case kOmegaMinus:
383 func=PtOmegaMinus;
384 break;
13313168 385 case kLambda1520:
386 func=PtLambda1520;
387 break;
87f8f72e 388 default:
389 func=0;
390 printf("<AliGenSTRANGElib::GetPt> unknown parametrisationn");
391 }
392 return func;
393}
394
198bb1c7 395 GenFunc AliGenSTRANGElib::GetY(Int_t param, const char* /*tname*/) const
87f8f72e 396{
397// Return pointer to Y parameterisation
398 GenFunc func;
399 switch (param)
400 {
401 case kKaon:
402 func=YKaon;
403 break;
404 case kPhi:
405 func=YPhi;
406 break;
407 case kLambda:
408 func=YLambda;
409 break;
410 case kXiMinus:
411 func=YXiMinus;
412 break;
413 case kOmegaMinus:
414 func=YOmegaMinus;
415 break;
13313168 416 case kLambda1520:
417 func=YLambda1520;
418 break;
87f8f72e 419 default:
420 func=0;
421 printf("<AliGenSTRANGElib::GetY> unknown parametrisationn");
422 }
423 return func;
424}
425typedef Int_t (*GenFuncIp) (TRandom *);
198bb1c7 426 GenFuncIp AliGenSTRANGElib::GetIp(Int_t param, const char* /*tname*/) const
87f8f72e 427{
428// Return pointer to particle composition
429 GenFuncIp func;
430 switch (param)
431 {
432 case kKaon:
433 func=IpKaon;
434 break;
435 case kPhi:
436 func=IpPhi;
437 break;
438 case kLambda:
439 func=IpLambda;
440 break;
441 case kXiMinus:
442 func=IpXiMinus;
443 break;
444 case kOmegaMinus:
445 func=IpOmegaMinus;
446 break;
13313168 447 case kLambda1520:
448 func=IpLambda1520;
449 break;
87f8f72e 450 default:
451 func=0;
452 printf("<AliGenSTRANGElib::GetIp> unknown parametrisationn");
453 }
454 return func;
455}
456