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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>
40#include <TPDGCode.h>
41#include <TRandom.h>
87f8f72e 42
43#include "AliGenSTRANGElib.h"
44
45ClassImp(AliGenSTRANGElib)
46
47//=============================================================
48//
49 Double_t AliGenSTRANGElib::PtScal(Double_t pt, Int_t np)
50{
51// Mt-scaling
52// Function for the calculation of the Pt distribution for a
53// given particle np, from the pion Pt distribution using the
54// mt scaling. This function was taken from AliGenMUONlib
55// aliroot version 3.01, and was extended for hyperons.
56// np = 1=>Pions 2=>Kaons 3=>Etas 4=>Omegas 5=>ETA' 6=>PHI
57// 7=>BARYONS-BARYONBARS
58// 8=>Lambda-antiLambda
59// 9=>Xi-antiXi
60// 10=>Omega-antiOmega
61
62 // MASS SCALING RESPECT TO PIONS
63 // MASS 1=>PI, 2=>K, 3=>ETA,4=>OMEGA,5=>ETA',6=>PHI
13313168 64 const Double_t khm[11] = {0.1396, 0.494,0.547, 0.782, 0.957, 1.02,
87f8f72e 65 // MASS 7=>BARYON-BARYONBAR
66 0.938,
67 // MASS 8=>Lambda-antiLambda
68 1.1157,
69 // MASS 9=>Xi-antiXi
70 1.3213,
71 // MASS 10=>Omega-antiOmega
13313168 72 1.6725,
73 // MASS 11=>Lambda(1520)
74 1.5195};
87f8f72e 75 // VALUE MESON/PI AT 5 GEV
13313168 76 const Double_t kfmax[11]={1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1.};
87f8f72e 77 np--;
78 Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
79 Double_t kfmax2=f5/kfmax[np];
80 // PIONS
81 Double_t ptpion=100.*PtPion(&pt, (Double_t*) 0);
82 Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/
83 (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ kfmax2;
84 return fmtscal*ptpion;
85}
86//=============================================================
87//
75e0cc59 88 Double_t AliGenSTRANGElib::PtPion(const Double_t *px, const Double_t *)
87f8f72e 89{
90// Pion transverse momentum distribtuion taken
91// from AliGenMUONlib class, version 3.01 of aliroot
92// PT-PARAMETERIZATION CDF, PRL 61(88) 1819
93// POWER LAW FOR PT > 500 MEV
94// MT SCALING BELOW (T=160 MEV)
95//
96 const Double_t kp0 = 1.3;
97 const Double_t kxn = 8.28;
98 const Double_t kxlim=0.5;
99 const Double_t kt=0.160;
100 const Double_t kxmpi=0.139;
101 const Double_t kb=1.;
102 Double_t y, y1, kxmpi2, ynorm, a;
103 Double_t x=*px;
104 //
105 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
106 kxmpi2=kxmpi*kxmpi;
107 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+kxmpi2)/kt));
108 a=ynorm/y1;
109 if (x > kxlim)
110 y=a*TMath::Power(kp0/(kp0+x),kxn);
111 else
112 y=kb*TMath::Exp(-sqrt(x*x+kxmpi2)/kt);
113 return y*x;
114}
115// End Scaling
116//============================================================================
117// K A O N
75e0cc59 118 Double_t AliGenSTRANGElib::PtKaon( const Double_t *px, const Double_t *)
87f8f72e 119{
120// kaon
121// pt-distribution
122//____________________________________________________________
123
124 return PtScal(*px,2); // 2==> Kaon in the PtScal function
125}
126
75e0cc59 127 Double_t AliGenSTRANGElib::YKaon( const Double_t *py, const Double_t *)
87f8f72e 128{
129// y-distribution
130//____________________________________________________________
131
132 const Double_t ka = 1000.;
133 const Double_t kdy = 4.;
134
135
136 Double_t y=TMath::Abs(*py);
137 //
138 Double_t ex = y*y/(2*kdy*kdy);
139 return ka*TMath::Exp(-ex);
140}
141
142 Int_t AliGenSTRANGElib::IpKaon(TRandom *ran)
143{
144// particle composition
145//
146
147 Float_t random = ran->Rndm();
148 Float_t random2 = ran->Rndm();
149 if (random2 < 0.5)
150 {
151 if (random < 0.5) {
152 return 321; // K+
153 } else {
154 return -321; // K-
155 }
156 }
157 else
158 {
159 if (random < 0.5) {
160 return 130; // K^0 short
161 } else {
162 return 310; // K^0 long
163 }
164 }
165}
166// End Kaons
167//============================================================================
168//============================================================================
169// P H I
75e0cc59 170 Double_t AliGenSTRANGElib::PtPhi( const Double_t *px, const Double_t *)
87f8f72e 171{
172// phi
173// pt-distribution
174//____________________________________________________________
175
176 return PtScal(*px,6); // 6==> Phi in the PtScal function
177}
178
75e0cc59 179 Double_t AliGenSTRANGElib::YPhi( const Double_t *py, const Double_t *)
87f8f72e 180{
181// y-distribution
182//____________________________________________________________
183
184 const Double_t ka = 1000.;
185 const Double_t kdy = 4.;
186
187
188 Double_t y=TMath::Abs(*py);
189 //
190 Double_t ex = y*y/(2*kdy*kdy);
191 return ka*TMath::Exp(-ex);
192}
193
194 Int_t AliGenSTRANGElib::IpPhi(TRandom *)
195{
196// particle composition
197//
198
199 return 333; // Phi
200}
201// End Phis
202//===================================================================
203//============================================================================
204// Lambda
75e0cc59 205 Double_t AliGenSTRANGElib::PtLambda( const Double_t *px, const Double_t *)
87f8f72e 206{
207// Lambda
208// pt-distribution
209//____________________________________________________________
210
211 return PtScal(*px,8); // 8==> Lambda-antiLambda in the PtScal function
212}
213
75e0cc59 214 Double_t AliGenSTRANGElib::YLambda( const Double_t *py, const Double_t *)
87f8f72e 215{
216// y-distribution
217//____________________________________________________________
218
219 const Double_t ka = 1000.;
220 const Double_t kdy = 4.;
221
222
223 Double_t y=TMath::Abs(*py);
224 //
225 Double_t ex = y*y/(2*kdy*kdy);
226 return ka*TMath::Exp(-ex);
227}
228
48b91885 229 Int_t AliGenSTRANGElib::IpLambda(TRandom *ran)
87f8f72e 230{
231// particle composition
232// generation of fixed type of particle
233//
48b91885 234 Float_t random = ran->Rndm();
235 if (random < 0.5) {
236 return 3122; // Lambda
237 } else {
238 return -3122; // Anti-Lambda
239 }
87f8f72e 240}
241// End Lambda
242//============================================================================
243// XIminus
75e0cc59 244 Double_t AliGenSTRANGElib::PtXiMinus( const Double_t *px, const Double_t *)
87f8f72e 245{
246// Xi
247// pt-distribution
248//____________________________________________________________
249
250 return PtScal(*px,9); // 9==> Xi-antiXi in the PtScal function
251}
252
75e0cc59 253 Double_t AliGenSTRANGElib::YXiMinus( const Double_t *py, const Double_t *)
87f8f72e 254{
255// y-distribution
256//____________________________________________________________
257
258 const Double_t ka = 1000.;
259 const Double_t kdy = 4.;
260
261
262 Double_t y=TMath::Abs(*py);
263 //
264 Double_t ex = y*y/(2*kdy*kdy);
265 return ka*TMath::Exp(-ex);
266}
267
48b91885 268 Int_t AliGenSTRANGElib::IpXiMinus(TRandom *ran)
87f8f72e 269{
270// particle composition
271// generation of fixed type of particle
272//
48b91885 273 Float_t random = ran->Rndm();
274 if (random < 0.5) {
275 return 3312; // Xi-
276 } else {
277 return -3312; // Xi+
278 }
87f8f72e 279}
280// End Ximinus
281//============================================================================
282// Omegaminus
75e0cc59 283 Double_t AliGenSTRANGElib::PtOmegaMinus( const Double_t *px, const Double_t *)
87f8f72e 284{
285// Omega
286// pt-distribution
287//____________________________________________________________
288
289 return PtScal(*px,10); // 10==> Omega-antiOmega in the PtScal function
290}
291
75e0cc59 292 Double_t AliGenSTRANGElib::YOmegaMinus( const Double_t *py, const Double_t *)
87f8f72e 293{
294// y-distribution
295//____________________________________________________________
296
297 const Double_t ka = 1000.;
298 const Double_t kdy = 4.;
299
300
301 Double_t y=TMath::Abs(*py);
302 //
303 Double_t ex = y*y/(2*kdy*kdy);
304 return ka*TMath::Exp(-ex);
305}
306
48b91885 307 Int_t AliGenSTRANGElib::IpOmegaMinus(TRandom * ran)
87f8f72e 308{
309// particle composition
310// generation of fixed type of particle
311//
312
48b91885 313 Float_t random = ran->Rndm();
314 if (random < 0.5) {
315 return 3334; // Omega-
316 } else {
317 return -3334; // Omega+
318 }
87f8f72e 319}
320// End Omegaminus
321//============================================================================
13313168 322// Lambda(1520)
75e0cc59 323Double_t AliGenSTRANGElib::PtLambda1520( const Double_t *px, const Double_t *)
13313168 324{
325// Lambda(1520)
326// pt-distribution
327//____________________________________________________________
328
329 return PtScal(*px,11); // 11=> Lambda(1520) in the PtScal function
330}
87f8f72e 331
75e0cc59 332Double_t AliGenSTRANGElib::YLambda1520( const Double_t *py, const Double_t *)
13313168 333{
334// y-distribution
335//____________________________________________________________
336
337 const Double_t ka = 1000.;
338 const Double_t kdy = 4.;
339
340
341 Double_t y=TMath::Abs(*py);
342 //
343 Double_t ex = y*y/(2*kdy*kdy);
344 return ka*TMath::Exp(-ex);
345}
346
347Int_t AliGenSTRANGElib::IpLambda1520(TRandom * ran)
348{
349// particle composition
350// generation of fixed type of particle
351//
352
353 Float_t random = ran->Rndm();
354 if (random < 0.5) {
355 return 3124; // Lambda(1520)
356 } else {
357 return -3124; // antiLambda(1520)
358 }
359}
360// End Lambda(1520)
361//============================================================================
87f8f72e 362
75e0cc59 363typedef Double_t (*GenFunc) (const Double_t*, const Double_t*);
198bb1c7 364 GenFunc AliGenSTRANGElib::GetPt(Int_t param, const char* /*tname*/) const
87f8f72e 365{
366// Return pinter to pT parameterisation
367 GenFunc func;
368
369 switch (param)
370 {
371 case kKaon:
372 func=PtKaon;
373 break;
374 case kPhi:
375 func=PtPhi;
376 break;
377 case kLambda:
378 func=PtLambda;
379 break;
380 case kXiMinus:
381 func=PtXiMinus;
382 break;
383 case kOmegaMinus:
384 func=PtOmegaMinus;
385 break;
13313168 386 case kLambda1520:
387 func=PtLambda1520;
388 break;
87f8f72e 389 default:
390 func=0;
391 printf("<AliGenSTRANGElib::GetPt> unknown parametrisationn");
392 }
393 return func;
394}
395
198bb1c7 396 GenFunc AliGenSTRANGElib::GetY(Int_t param, const char* /*tname*/) const
87f8f72e 397{
398// Return pointer to Y parameterisation
399 GenFunc func;
400 switch (param)
401 {
402 case kKaon:
403 func=YKaon;
404 break;
405 case kPhi:
406 func=YPhi;
407 break;
408 case kLambda:
409 func=YLambda;
410 break;
411 case kXiMinus:
412 func=YXiMinus;
413 break;
414 case kOmegaMinus:
415 func=YOmegaMinus;
416 break;
13313168 417 case kLambda1520:
418 func=YLambda1520;
419 break;
87f8f72e 420 default:
421 func=0;
422 printf("<AliGenSTRANGElib::GetY> unknown parametrisationn");
423 }
424 return func;
425}
426typedef Int_t (*GenFuncIp) (TRandom *);
198bb1c7 427 GenFuncIp AliGenSTRANGElib::GetIp(Int_t param, const char* /*tname*/) const
87f8f72e 428{
429// Return pointer to particle composition
430 GenFuncIp func;
431 switch (param)
432 {
433 case kKaon:
434 func=IpKaon;
435 break;
436 case kPhi:
437 func=IpPhi;
438 break;
439 case kLambda:
440 func=IpLambda;
441 break;
442 case kXiMinus:
443 func=IpXiMinus;
444 break;
445 case kOmegaMinus:
446 func=IpOmegaMinus;
447 break;
13313168 448 case kLambda1520:
449 func=IpLambda1520;
450 break;
87f8f72e 451 default:
452 func=0;
453 printf("<AliGenSTRANGElib::GetIp> unknown parametrisationn");
454 }
455 return func;
456}
457