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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
37/*
38$Log$
b9d0a01d 39Revision 1.1.6.1 2002/06/10 14:57:41 hristov
40Merged with v3-08-02
41
42Revision 1.2 2002/04/17 12:48:54 morsch
43const added.
44
d5b6b483 45Revision 1.1 2001/12/04 18:06:39 morsch
46AliGenSTRANGElib.cxx first commit.
47
87f8f72e 48*/
49
50#include "TMath.h"
51#include "TRandom.h"
52
53#include "AliGenSTRANGElib.h"
54
55ClassImp(AliGenSTRANGElib)
56
57//=============================================================
58//
59 Double_t AliGenSTRANGElib::PtScal(Double_t pt, Int_t np)
60{
61// Mt-scaling
62// Function for the calculation of the Pt distribution for a
63// given particle np, from the pion Pt distribution using the
64// mt scaling. This function was taken from AliGenMUONlib
65// aliroot version 3.01, and was extended for hyperons.
66// np = 1=>Pions 2=>Kaons 3=>Etas 4=>Omegas 5=>ETA' 6=>PHI
67// 7=>BARYONS-BARYONBARS
68// 8=>Lambda-antiLambda
69// 9=>Xi-antiXi
70// 10=>Omega-antiOmega
71
72 // MASS SCALING RESPECT TO PIONS
73 // MASS 1=>PI, 2=>K, 3=>ETA,4=>OMEGA,5=>ETA',6=>PHI
74 const Double_t khm[10] = {0.1396, 0.494,0.547, 0.782, 0.957, 1.02,
75 // MASS 7=>BARYON-BARYONBAR
76 0.938,
77 // MASS 8=>Lambda-antiLambda
78 1.1157,
79 // MASS 9=>Xi-antiXi
80 1.3213,
81 // MASS 10=>Omega-antiOmega
82 1.6725};
83 // VALUE MESON/PI AT 5 GEV
84 const Double_t kfmax[10]={1., 1., 1., 1., 1., 1., 1., 1., 1., 1.};
85 np--;
86 Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
87 Double_t kfmax2=f5/kfmax[np];
88 // PIONS
89 Double_t ptpion=100.*PtPion(&pt, (Double_t*) 0);
90 Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/
91 (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ kfmax2;
92 return fmtscal*ptpion;
93}
94//=============================================================
95//
96 Double_t AliGenSTRANGElib::PtPion(Double_t *px, Double_t *)
97{
98// Pion transverse momentum distribtuion taken
99// from AliGenMUONlib class, version 3.01 of aliroot
100// PT-PARAMETERIZATION CDF, PRL 61(88) 1819
101// POWER LAW FOR PT > 500 MEV
102// MT SCALING BELOW (T=160 MEV)
103//
104 const Double_t kp0 = 1.3;
105 const Double_t kxn = 8.28;
106 const Double_t kxlim=0.5;
107 const Double_t kt=0.160;
108 const Double_t kxmpi=0.139;
109 const Double_t kb=1.;
110 Double_t y, y1, kxmpi2, ynorm, a;
111 Double_t x=*px;
112 //
113 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
114 kxmpi2=kxmpi*kxmpi;
115 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+kxmpi2)/kt));
116 a=ynorm/y1;
117 if (x > kxlim)
118 y=a*TMath::Power(kp0/(kp0+x),kxn);
119 else
120 y=kb*TMath::Exp(-sqrt(x*x+kxmpi2)/kt);
121 return y*x;
122}
123// End Scaling
124//============================================================================
125// K A O N
126 Double_t AliGenSTRANGElib::PtKaon( Double_t *px, Double_t *)
127{
128// kaon
129// pt-distribution
130//____________________________________________________________
131
132 return PtScal(*px,2); // 2==> Kaon in the PtScal function
133}
134
135 Double_t AliGenSTRANGElib::YKaon( Double_t *py, Double_t *)
136{
137// y-distribution
138//____________________________________________________________
139
140 const Double_t ka = 1000.;
141 const Double_t kdy = 4.;
142
143
144 Double_t y=TMath::Abs(*py);
145 //
146 Double_t ex = y*y/(2*kdy*kdy);
147 return ka*TMath::Exp(-ex);
148}
149
150 Int_t AliGenSTRANGElib::IpKaon(TRandom *ran)
151{
152// particle composition
153//
154
155 Float_t random = ran->Rndm();
156 Float_t random2 = ran->Rndm();
157 if (random2 < 0.5)
158 {
159 if (random < 0.5) {
160 return 321; // K+
161 } else {
162 return -321; // K-
163 }
164 }
165 else
166 {
167 if (random < 0.5) {
168 return 130; // K^0 short
169 } else {
170 return 310; // K^0 long
171 }
172 }
173}
174// End Kaons
175//============================================================================
176//============================================================================
177// P H I
178 Double_t AliGenSTRANGElib::PtPhi( Double_t *px, Double_t *)
179{
180// phi
181// pt-distribution
182//____________________________________________________________
183
184 return PtScal(*px,6); // 6==> Phi in the PtScal function
185}
186
187 Double_t AliGenSTRANGElib::YPhi( Double_t *py, Double_t *)
188{
189// y-distribution
190//____________________________________________________________
191
192 const Double_t ka = 1000.;
193 const Double_t kdy = 4.;
194
195
196 Double_t y=TMath::Abs(*py);
197 //
198 Double_t ex = y*y/(2*kdy*kdy);
199 return ka*TMath::Exp(-ex);
200}
201
202 Int_t AliGenSTRANGElib::IpPhi(TRandom *)
203{
204// particle composition
205//
206
207 return 333; // Phi
208}
209// End Phis
210//===================================================================
211//============================================================================
212// Lambda
213 Double_t AliGenSTRANGElib::PtLambda( Double_t *px, Double_t *)
214{
215// Lambda
216// pt-distribution
217//____________________________________________________________
218
219 return PtScal(*px,8); // 8==> Lambda-antiLambda in the PtScal function
220}
221
222 Double_t AliGenSTRANGElib::YLambda( Double_t *py, Double_t *)
223{
224// y-distribution
225//____________________________________________________________
226
227 const Double_t ka = 1000.;
228 const Double_t kdy = 4.;
229
230
231 Double_t y=TMath::Abs(*py);
232 //
233 Double_t ex = y*y/(2*kdy*kdy);
234 return ka*TMath::Exp(-ex);
235}
236
237 Int_t AliGenSTRANGElib::IpLambda(TRandom *)
238{
239// particle composition
240// generation of fixed type of particle
241//
242
243 return 3122; // Lambda
244}
245// End Lambda
246//============================================================================
247// XIminus
248 Double_t AliGenSTRANGElib::PtXiMinus( Double_t *px, Double_t *)
249{
250// Xi
251// pt-distribution
252//____________________________________________________________
253
254 return PtScal(*px,9); // 9==> Xi-antiXi in the PtScal function
255}
256
257 Double_t AliGenSTRANGElib::YXiMinus( Double_t *py, Double_t *)
258{
259// y-distribution
260//____________________________________________________________
261
262 const Double_t ka = 1000.;
263 const Double_t kdy = 4.;
264
265
266 Double_t y=TMath::Abs(*py);
267 //
268 Double_t ex = y*y/(2*kdy*kdy);
269 return ka*TMath::Exp(-ex);
270}
271
272 Int_t AliGenSTRANGElib::IpXiMinus(TRandom *)
273{
274// particle composition
275// generation of fixed type of particle
276//
277
278 return 3312; // Xi- (only)
279// return -3312; // Xi+
280}
281// End Ximinus
282//============================================================================
283// Omegaminus
284 Double_t AliGenSTRANGElib::PtOmegaMinus( Double_t *px, Double_t *)
285{
286// Omega
287// pt-distribution
288//____________________________________________________________
289
290 return PtScal(*px,10); // 10==> Omega-antiOmega in the PtScal function
291}
292
293 Double_t AliGenSTRANGElib::YOmegaMinus( Double_t *py, Double_t *)
294{
295// y-distribution
296//____________________________________________________________
297
298 const Double_t ka = 1000.;
299 const Double_t kdy = 4.;
300
301
302 Double_t y=TMath::Abs(*py);
303 //
304 Double_t ex = y*y/(2*kdy*kdy);
305 return ka*TMath::Exp(-ex);
306}
307
308 Int_t AliGenSTRANGElib::IpOmegaMinus(TRandom *)
309{
310// particle composition
311// generation of fixed type of particle
312//
313
314 return 3334; // Omega-
315}
316// End Omegaminus
317//============================================================================
318
319
320typedef Double_t (*GenFunc) (Double_t*, Double_t*);
d5b6b483 321 GenFunc AliGenSTRANGElib::GetPt(Int_t param, const char* tname) const
87f8f72e 322{
323// Return pinter to pT parameterisation
324 GenFunc func;
325
326 switch (param)
327 {
328 case kKaon:
329 func=PtKaon;
330 break;
331 case kPhi:
332 func=PtPhi;
333 break;
334 case kLambda:
335 func=PtLambda;
336 break;
337 case kXiMinus:
338 func=PtXiMinus;
339 break;
340 case kOmegaMinus:
341 func=PtOmegaMinus;
342 break;
343 default:
344 func=0;
345 printf("<AliGenSTRANGElib::GetPt> unknown parametrisationn");
346 }
347 return func;
348}
349
d5b6b483 350 GenFunc AliGenSTRANGElib::GetY(Int_t param, const char* tname) const
87f8f72e 351{
352// Return pointer to Y parameterisation
353 GenFunc func;
354 switch (param)
355 {
356 case kKaon:
357 func=YKaon;
358 break;
359 case kPhi:
360 func=YPhi;
361 break;
362 case kLambda:
363 func=YLambda;
364 break;
365 case kXiMinus:
366 func=YXiMinus;
367 break;
368 case kOmegaMinus:
369 func=YOmegaMinus;
370 break;
371 default:
372 func=0;
373 printf("<AliGenSTRANGElib::GetY> unknown parametrisationn");
374 }
375 return func;
376}
377typedef Int_t (*GenFuncIp) (TRandom *);
d5b6b483 378 GenFuncIp AliGenSTRANGElib::GetIp(Int_t param, const char* tname) const
87f8f72e 379{
380// Return pointer to particle composition
381 GenFuncIp func;
382 switch (param)
383 {
384 case kKaon:
385 func=IpKaon;
386 break;
387 case kPhi:
388 func=IpPhi;
389 break;
390 case kLambda:
391 func=IpLambda;
392 break;
393 case kXiMinus:
394 func=IpXiMinus;
395 break;
396 case kOmegaMinus:
397 func=IpOmegaMinus;
398 break;
399 default:
400 func=0;
401 printf("<AliGenSTRANGElib::GetIp> unknown parametrisationn");
402 }
403 return func;
404}
405