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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 | ||
45 | ClassImp(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 | 323 | Double_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 | 332 | Double_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 | ||
347 | Int_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 | 363 | typedef 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 | } | |
426 | typedef 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 |