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