BOSS_7.0.2: /home/bes3soft/bes3soft/Boss/7.0.2/dist/7.0.2/Generator/Mcgpj/Mcgpj-00-01-04/src/code/src/TVCrossPart.C Source File

00001 #include "TVCrossPart.h"
00002 
00003 #include <iostream>
00004 double TVCrossPart::BornCrossSection(const double& theta){
00005   //save vacuum polarization status 
00006   bool tempVP = fZeroVP;
00007   // set zero vacuum polarization to calculate Born cross-section
00008   fZeroVP = true;
00009   Init();
00010 
00011   // integration in symmetric angle
00012   int NInt = 1<<14;
00013   double x, gsum = 0., h=-(cos(M_PI-theta)-cos(theta))/NInt;
00014   // simpson integration
00015   x = cos(M_PI-theta); fEvent->MakeEvent(x); gsum += BornShift(1,1,x);
00016   for(int i=1; i<NInt; i++){
00017     x += h; fEvent->MakeEvent(x); gsum += 2*(1+i%2)*BornShift(1,1,x);
00018   }
00019   x += h; fEvent->MakeEvent(x); gsum += BornShift(1,1,x);
00020 
00021   //restore vacuum polarization status
00022   fZeroVP = tempVP;
00023   Init();
00024 
00025   return gsum*h/3;
00026 }