## main151

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    // main151.cc is a part of the PYTHIA event generator.
    // Copyright (C) 2025 Torbjorn Sjostrand.
    // PYTHIA is licenced under the GNU GPL v2 or later, see COPYING for details.
    // Please respect the MCnet Guidelines, see GUIDELINES for details.

    // Authors:
    //            Christian T. Preuss

    // Keywords:
    //            MC@NLO
    //            aMC@NLO
    //            MadGraph5_aMC@NLO

    // This is a simple program to demonstrate MC@NLO matching
    // with events MadGraph5_aMC@NLO.

    #include "Pythia8/Pythia.h"
    using namespace Pythia8;

    int main() {

      // Generator.
      Pythia pythia;
      pythia.readFile("main151.cmnd");
      // If Pythia fails to initialize, exit with error.
      if (!pythia.init()) return 1;

      // Number of events.
      int nEvent = pythia.mode("Main:numberOfEvents");

      // Histogram.
      Hist pTZ("pT Z", 50, 0., 200.);

      // Event loop.
      for (int iEvent = 0; iEvent < nEvent; ++iEvent) {
        if (!pythia.next()) continue;

        // Find the final copy of the W and its pT.
        int iZ = 0;
        for (int i = pythia.event.size() - 1; i > 0; --i)
          if (pythia.event[i].idAbs() == 23) {iZ = i; break;}
        pTZ.fill(pythia.event[iZ].pT());
      }

      // Print statistics and histogram.
      pythia.stat();
      cout << pTZ;

      // Done.
      return 0;
    }