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