VetoedShower.cxx

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
#include "Pythia8_i/UserHooksFactory.h"
#include <stdexcept>
#include <iostream>
 
namespace Pythia8{
  class VetoedShower;
}
 
Pythia8_UserHooks::UserHooksFactory::Creator<Pythia8::VetoedShower> vetoedShowerCreator("VetoedShower");
 
namespace Pythia8{
 
 
  class VetoedShower : public UserHooks{
 
  public:
 
    VetoedShower(): m_pTVeto(0.),  m_doneISR(false){
      std::cout<<std::endl;
      std::cout<<"************************************************************************************************"<<std::endl;
      std::cout<<"Pythia8::VetoedShower: *** WARNING: THIS USER HOOK IS NOT VALIDATED FOR QCD JET PRODUCTION!! ***"<<std::endl;
      std::cout<<"************************************************************************************************"<<std::endl;
      std::cout<<std::endl;
    }
 
    ~VetoedShower(){}

    bool doVetoMPIStep(int, const Event&){
 
      m_pTVeto = infoPtr->QFac();
      m_doneISR = false;
 
//      std::cout<<" ******** veto scale = "<<m_pTVeto<<" *********"<<std::endl;
 
      return false;
    }

    bool doVetoISREmission(int, const Event &e, int){
      // Note ignoring new iSys param for now (addition required to fix compilation against >= 8.157
 
      if(m_doneISR) return false;
 
      int i = e.size() - 1;
 
      while(i != -1){
 
        if(e[i].isFinal() && e[i].status() == 43) break;
 
        --i;
 
        if(i == 0){
          e.list();
          throw std::runtime_error("Pythia8::VetoedShower::doVetoISREmission: Could not find ISR emission");
        }
      }
 
      //check the leg is connected to the hard system
      //coverity[NEGATIVE_RETURNS:FALSE]
      int iMother = e[i].mother1();
      if(e[iMother].status() != -41)
        throw std::runtime_error("Pythia8::VetoedShower::doVetoISREmission: Unexpected status code in ISR");
 
      iMother = e[iMother].daughter2();
      if(iMother != partonSystemsPtr->getInA(0) &&
         iMother != partonSystemsPtr->getInB(0)) return false;
 
      // Veto emission above the veto scale
      if(e[i].pT() > m_pTVeto) return true;
 
      m_doneISR = true;
      return false;
    }

    bool doVetoFSREmission(int, const Event &e, int, bool){
      // Note ignoring new iSys and isResonance params for now (addition required to fix compilation against >= 8.157
 
      int i = e.size() - 1;
 
      while(i != -1){
        if (e[i].isFinal() && e[i].status() == 51) break;
 
        --i;
 
        if(i == 0){
          e.list();
          throw std::runtime_error("Pythia8::VetoedShower::doVetoFSREmission: Could not find FSR emission");
        }
      }
 
      // Make sure radiation from the hard system
      //i cannot be negative here
      //coverity[NEGATIVE_RETURNS:FALSE]
      int  iMother = e[i].mother1();
      int  sysSize = partonSystemsPtr->sizeOut(0);
      bool hardSys = false;
 
      for (int j = 0; j < sysSize; ++j){
        int iOut = partonSystemsPtr->getOut(0, j);
        if (iOut == iMother) {
          hardSys = true;
          break;
        }
      }
 
      if (!hardSys) return false;
 
      // Veto if above the POWHEG scale
      if (e[i].pT() > m_pTVeto) return true;
 
      return false;
    }

    bool canVetoMPIStep(){return true;}
    int numberVetoMPIStep(){return 1;}
    bool canVetoISREmission(){return true;}
    bool canVetoFSREmission(){return true;}
 
  private:
 
    double m_pTVeto;
    bool m_doneISR;
  };
}