StRoot: StHbtMaker/ThCorrFctn/StHbtFsiQuantStat.cxx Source File

00001 /***************************************************************************
00002  *
00003  * $Id: 
00004  *
00005  * Author: Laurent Conin, Fabrice Retiere, Subatech, France
00006  ***************************************************************************
00007  *
00008  * Description: Calculate the quantum statistic only
00009  *
00010  ***************************************************************************
00011  *
00012  * $Log: 
00013  *
00014  **************************************************************************/
00015 
00016 
00017 #include "StHbtMaker/Base/StHbtThPair.hh"
00018 #include "StHbtMaker/ThCorrFctn/StHbtFsiQuantStat.h"
00019 #include "StarClassLibrary/PhysicalConstants.h"
00020 #include "StHbtMaker/Infrastructure/StHbtTypes.hh"
00021 
00022 #ifdef __ROOT__
00023 ClassImp(StHbtFsiQuantStat)
00024 #endif
00025 double StHbtFsiQuantStat::GetWeight(const StHbtThPair* aThPair){
00026   
00027   if (aThPair->GetPid1()==aThPair->GetPid2()){
00028     int tSpin=abs(aThPair->GetPid1())%10;  // tSpin=2J+1
00029     if (tSpin==0) return 1;  // non identified particle
00030     double tSpinFactor=-::pow(-1.,tSpin)/tSpin;  //for non polarised particle
00031     StHbtLorentzVector q= *(aThPair->GetRealMomentum1())-
00032       *(aThPair->GetRealMomentum2());
00033     StHbtLorentzVector r=*(aThPair->GetEmPoint1())-
00034       *(aThPair->GetEmPoint2());
00035     double wei=(1.+tSpinFactor*cos((double)(q*r)*fermi/hbarc));
00036     return wei;
00037   } else {
00038     return 1;
00039   }
00040 }
00041 
00042 //inline double StHbtFsiQuantStat::GetWeightDen() {return mWeightDen;}
00043