1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
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
23 // AliGenParam(npar, param, AliGenSTRANGElib::GetPt(param),
24 // AliGenSTRANGElib::GetY(param),
25 // AliGenSTRANGElib::GetIp(param) )
26 // param represents the particle to be simulated.
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
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 //======================================================================
43 #include "AliGenSTRANGElib.h"
45 ClassImp(AliGenSTRANGElib)
47 //=============================================================
49 Double_t AliGenSTRANGElib::PtScal(Double_t pt, Int_t np)
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
60 // 10=>Omega-antiOmega
62 // MASS SCALING RESPECT TO PIONS
63 // MASS 1=>PI, 2=>K, 3=>ETA,4=>OMEGA,5=>ETA',6=>PHI
64 const Double_t khm[11] = {0.1396, 0.494,0.547, 0.782, 0.957, 1.02,
65 // MASS 7=>BARYON-BARYONBAR
67 // MASS 8=>Lambda-antiLambda
71 // MASS 10=>Omega-antiOmega
73 // MASS 11=>Lambda(1520)
75 // VALUE MESON/PI AT 5 GEV
76 const Double_t kfmax[11]={1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1.};
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];
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;
86 //=============================================================
88 Double_t AliGenSTRANGElib::PtPion(const Double_t *px, const Double_t *)
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)
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;
105 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
107 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+kxmpi2)/kt));
110 y=a*TMath::Power(kp0/(kp0+x),kxn);
112 y=kb*TMath::Exp(-sqrt(x*x+kxmpi2)/kt);
116 //============================================================================
118 Double_t AliGenSTRANGElib::PtKaon( const Double_t *px, const Double_t *)
122 //____________________________________________________________
124 return PtScal(*px,2); // 2==> Kaon in the PtScal function
127 Double_t AliGenSTRANGElib::YKaon( const Double_t *py, const Double_t *)
130 //____________________________________________________________
132 const Double_t ka = 1000.;
133 const Double_t kdy = 4.;
136 Double_t y=TMath::Abs(*py);
138 Double_t ex = y*y/(2*kdy*kdy);
139 return ka*TMath::Exp(-ex);
142 Int_t AliGenSTRANGElib::IpKaon(TRandom *ran)
144 // particle composition
147 Float_t random = ran->Rndm();
148 Float_t random2 = ran->Rndm();
160 return 130; // K^0 short
162 return 310; // K^0 long
167 //============================================================================
168 //============================================================================
170 Double_t AliGenSTRANGElib::PtPhi( const Double_t *px, const Double_t *)
174 //____________________________________________________________
176 return PtScal(*px,6); // 6==> Phi in the PtScal function
179 Double_t AliGenSTRANGElib::YPhi( const Double_t *py, const Double_t *)
182 //____________________________________________________________
184 const Double_t ka = 1000.;
185 const Double_t kdy = 4.;
188 Double_t y=TMath::Abs(*py);
190 Double_t ex = y*y/(2*kdy*kdy);
191 return ka*TMath::Exp(-ex);
194 Int_t AliGenSTRANGElib::IpPhi(TRandom *)
196 // particle composition
202 //===================================================================
203 //============================================================================
205 Double_t AliGenSTRANGElib::PtLambda( const Double_t *px, const Double_t *)
209 //____________________________________________________________
211 return PtScal(*px,8); // 8==> Lambda-antiLambda in the PtScal function
214 Double_t AliGenSTRANGElib::YLambda( const Double_t *py, const Double_t *)
217 //____________________________________________________________
219 const Double_t ka = 1000.;
220 const Double_t kdy = 4.;
223 Double_t y=TMath::Abs(*py);
225 Double_t ex = y*y/(2*kdy*kdy);
226 return ka*TMath::Exp(-ex);
229 Int_t AliGenSTRANGElib::IpLambda(TRandom *ran)
231 // particle composition
232 // generation of fixed type of particle
234 Float_t random = ran->Rndm();
236 return 3122; // Lambda
238 return -3122; // Anti-Lambda
242 //============================================================================
244 Double_t AliGenSTRANGElib::PtXiMinus( const Double_t *px, const Double_t *)
248 //____________________________________________________________
250 return PtScal(*px,9); // 9==> Xi-antiXi in the PtScal function
253 Double_t AliGenSTRANGElib::YXiMinus( const Double_t *py, const Double_t *)
256 //____________________________________________________________
258 const Double_t ka = 1000.;
259 const Double_t kdy = 4.;
262 Double_t y=TMath::Abs(*py);
264 Double_t ex = y*y/(2*kdy*kdy);
265 return ka*TMath::Exp(-ex);
268 Int_t AliGenSTRANGElib::IpXiMinus(TRandom *ran)
270 // particle composition
271 // generation of fixed type of particle
273 Float_t random = ran->Rndm();
281 //============================================================================
283 Double_t AliGenSTRANGElib::PtOmegaMinus( const Double_t *px, const Double_t *)
287 //____________________________________________________________
289 return PtScal(*px,10); // 10==> Omega-antiOmega in the PtScal function
292 Double_t AliGenSTRANGElib::YOmegaMinus( const Double_t *py, const Double_t *)
295 //____________________________________________________________
297 const Double_t ka = 1000.;
298 const Double_t kdy = 4.;
301 Double_t y=TMath::Abs(*py);
303 Double_t ex = y*y/(2*kdy*kdy);
304 return ka*TMath::Exp(-ex);
307 Int_t AliGenSTRANGElib::IpOmegaMinus(TRandom * ran)
309 // particle composition
310 // generation of fixed type of particle
313 Float_t random = ran->Rndm();
315 return 3334; // Omega-
317 return -3334; // Omega+
321 //============================================================================
323 Double_t AliGenSTRANGElib::PtLambda1520( const Double_t *px, const Double_t *)
327 //____________________________________________________________
329 return PtScal(*px,11); // 11=> Lambda(1520) in the PtScal function
332 Double_t AliGenSTRANGElib::YLambda1520( const Double_t *py, const Double_t *)
335 //____________________________________________________________
337 const Double_t ka = 1000.;
338 const Double_t kdy = 4.;
341 Double_t y=TMath::Abs(*py);
343 Double_t ex = y*y/(2*kdy*kdy);
344 return ka*TMath::Exp(-ex);
347 Int_t AliGenSTRANGElib::IpLambda1520(TRandom * ran)
349 // particle composition
350 // generation of fixed type of particle
353 Float_t random = ran->Rndm();
355 return 3124; // Lambda(1520)
357 return -3124; // antiLambda(1520)
361 //============================================================================
363 typedef Double_t (*GenFunc) (const Double_t*, const Double_t*);
364 GenFunc AliGenSTRANGElib::GetPt(Int_t param, const char* /*tname*/) const
366 // Return pinter to pT parameterisation
391 printf("<AliGenSTRANGElib::GetPt> unknown parametrisationn");
396 GenFunc AliGenSTRANGElib::GetY(Int_t param, const char* /*tname*/) const
398 // Return pointer to Y parameterisation
422 printf("<AliGenSTRANGElib::GetY> unknown parametrisationn");
426 typedef Int_t (*GenFuncIp) (TRandom *);
427 GenFuncIp AliGenSTRANGElib::GetIp(Int_t param, const char* /*tname*/) const
429 // Return pointer to particle composition
453 printf("<AliGenSTRANGElib::GetIp> unknown parametrisationn");