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 //======================================================================
39 Revision 1.1.6.1 2002/06/10 14:57:41 hristov
42 Revision 1.2 2002/04/17 12:48:54 morsch
45 Revision 1.1 2001/12/04 18:06:39 morsch
46 AliGenSTRANGElib.cxx first commit.
53 #include "AliGenSTRANGElib.h"
55 ClassImp(AliGenSTRANGElib)
57 //=============================================================
59 Double_t AliGenSTRANGElib::PtScal(Double_t pt, Int_t np)
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
70 // 10=>Omega-antiOmega
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
77 // MASS 8=>Lambda-antiLambda
81 // MASS 10=>Omega-antiOmega
83 // VALUE MESON/PI AT 5 GEV
84 const Double_t kfmax[10]={1., 1., 1., 1., 1., 1., 1., 1., 1., 1.};
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];
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;
94 //=============================================================
96 Double_t AliGenSTRANGElib::PtPion(Double_t *px, Double_t *)
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)
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;
113 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
115 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+kxmpi2)/kt));
118 y=a*TMath::Power(kp0/(kp0+x),kxn);
120 y=kb*TMath::Exp(-sqrt(x*x+kxmpi2)/kt);
124 //============================================================================
126 Double_t AliGenSTRANGElib::PtKaon( Double_t *px, Double_t *)
130 //____________________________________________________________
132 return PtScal(*px,2); // 2==> Kaon in the PtScal function
135 Double_t AliGenSTRANGElib::YKaon( Double_t *py, Double_t *)
138 //____________________________________________________________
140 const Double_t ka = 1000.;
141 const Double_t kdy = 4.;
144 Double_t y=TMath::Abs(*py);
146 Double_t ex = y*y/(2*kdy*kdy);
147 return ka*TMath::Exp(-ex);
150 Int_t AliGenSTRANGElib::IpKaon(TRandom *ran)
152 // particle composition
155 Float_t random = ran->Rndm();
156 Float_t random2 = ran->Rndm();
168 return 130; // K^0 short
170 return 310; // K^0 long
175 //============================================================================
176 //============================================================================
178 Double_t AliGenSTRANGElib::PtPhi( Double_t *px, Double_t *)
182 //____________________________________________________________
184 return PtScal(*px,6); // 6==> Phi in the PtScal function
187 Double_t AliGenSTRANGElib::YPhi( Double_t *py, Double_t *)
190 //____________________________________________________________
192 const Double_t ka = 1000.;
193 const Double_t kdy = 4.;
196 Double_t y=TMath::Abs(*py);
198 Double_t ex = y*y/(2*kdy*kdy);
199 return ka*TMath::Exp(-ex);
202 Int_t AliGenSTRANGElib::IpPhi(TRandom *)
204 // particle composition
210 //===================================================================
211 //============================================================================
213 Double_t AliGenSTRANGElib::PtLambda( Double_t *px, Double_t *)
217 //____________________________________________________________
219 return PtScal(*px,8); // 8==> Lambda-antiLambda in the PtScal function
222 Double_t AliGenSTRANGElib::YLambda( Double_t *py, Double_t *)
225 //____________________________________________________________
227 const Double_t ka = 1000.;
228 const Double_t kdy = 4.;
231 Double_t y=TMath::Abs(*py);
233 Double_t ex = y*y/(2*kdy*kdy);
234 return ka*TMath::Exp(-ex);
237 Int_t AliGenSTRANGElib::IpLambda(TRandom *)
239 // particle composition
240 // generation of fixed type of particle
243 return 3122; // Lambda
246 //============================================================================
248 Double_t AliGenSTRANGElib::PtXiMinus( Double_t *px, Double_t *)
252 //____________________________________________________________
254 return PtScal(*px,9); // 9==> Xi-antiXi in the PtScal function
257 Double_t AliGenSTRANGElib::YXiMinus( Double_t *py, Double_t *)
260 //____________________________________________________________
262 const Double_t ka = 1000.;
263 const Double_t kdy = 4.;
266 Double_t y=TMath::Abs(*py);
268 Double_t ex = y*y/(2*kdy*kdy);
269 return ka*TMath::Exp(-ex);
272 Int_t AliGenSTRANGElib::IpXiMinus(TRandom *)
274 // particle composition
275 // generation of fixed type of particle
278 return 3312; // Xi- (only)
279 // return -3312; // Xi+
282 //============================================================================
284 Double_t AliGenSTRANGElib::PtOmegaMinus( Double_t *px, Double_t *)
288 //____________________________________________________________
290 return PtScal(*px,10); // 10==> Omega-antiOmega in the PtScal function
293 Double_t AliGenSTRANGElib::YOmegaMinus( Double_t *py, Double_t *)
296 //____________________________________________________________
298 const Double_t ka = 1000.;
299 const Double_t kdy = 4.;
302 Double_t y=TMath::Abs(*py);
304 Double_t ex = y*y/(2*kdy*kdy);
305 return ka*TMath::Exp(-ex);
308 Int_t AliGenSTRANGElib::IpOmegaMinus(TRandom *)
310 // particle composition
311 // generation of fixed type of particle
314 return 3334; // Omega-
317 //============================================================================
320 typedef Double_t (*GenFunc) (Double_t*, Double_t*);
321 GenFunc AliGenSTRANGElib::GetPt(Int_t param, const char* tname) const
323 // Return pinter to pT parameterisation
345 printf("<AliGenSTRANGElib::GetPt> unknown parametrisationn");
350 GenFunc AliGenSTRANGElib::GetY(Int_t param, const char* tname) const
352 // Return pointer to Y parameterisation
373 printf("<AliGenSTRANGElib::GetY> unknown parametrisationn");
377 typedef Int_t (*GenFuncIp) (TRandom *);
378 GenFuncIp AliGenSTRANGElib::GetIp(Int_t param, const char* tname) const
380 // Return pointer to particle composition
401 printf("<AliGenSTRANGElib::GetIp> unknown parametrisationn");