EmbeddingLHEProducer.cc

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// -*- C++ -*-
//
// Package:    test/EmbeddingLHEProducer
// Class:      EmbeddingLHEProducer
//
//
// Original Author:  Stefan Wayand
//         Created:  Wed, 13 Jan 2016 08:15:01 GMT
//
//


// system include files
#include <algorithm>
#include <iostream>
#include <iterator>
#include <fstream>
#include <string>
#include <memory>
#include "TLorentzVector.h"

// user include files
#include "FWCore/Framework/interface/Frameworkfwd.h"
#include "FWCore/Framework/interface/one/EDProducer.h"

#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Framework/interface/Run.h"
#include "FWCore/Framework/interface/MakerMacros.h"

#include "FWCore/ParameterSet/interface/ParameterSet.h"

#include "DataFormats/VertexReco/interface/Vertex.h"
#include "DataFormats/VertexReco/interface/VertexFwd.h"
#include "DataFormats/PatCandidates/interface/Muon.h"
#include "DataFormats/Math/interface/LorentzVector.h"

#include "SimDataFormats/GeneratorProducts/interface/LesHouches.h"
#include "SimDataFormats/GeneratorProducts/interface/LHECommonBlocks.h"
#include "SimDataFormats/GeneratorProducts/interface/LHERunInfoProduct.h"
#include "SimDataFormats/GeneratorProducts/interface/LHEEventProduct.h"
#include "SimDataFormats/GeneratorProducts/interface/LHEXMLStringProduct.h"

#include "GeneratorInterface/LHEInterface/interface/LHERunInfo.h"
#include "GeneratorInterface/LHEInterface/interface/LHEEvent.h"
#include "GeneratorInterface/LHEInterface/interface/LHEReader.h"

#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/ServiceRegistry/interface/Service.h"
#include "FWCore/Utilities/interface/RandomNumberGenerator.h"
#include "FWCore/Utilities/interface/StreamID.h"
#include "CLHEP/Random/RandExponential.h"



//
// class declaration
//

namespace CLHEP{
  class HepRandomEngine;
}




class EmbeddingLHEProducer : public edm::one::EDProducer<edm::BeginRunProducer,
                                                        edm::EndRunProducer> {
   public:
      explicit EmbeddingLHEProducer(const edm::ParameterSet&);
      ~EmbeddingLHEProducer() override;

      static void fillDescriptions(edm::ConfigurationDescriptions& descriptions);

   private:
      void beginJob() override;
      void produce(edm::Event&, const edm::EventSetup&) override;
      void endJob() override;

      void beginRunProduce(edm::Run& run, edm::EventSetup const& es) override;
      void endRunProduce(edm::Run&, edm::EventSetup const&) override;

      void fill_lhe_from_mumu(TLorentzVector &positiveLepton, TLorentzVector &negativeLepton, lhef::HEPEUP &outlhe, CLHEP::HepRandomEngine* engine);
      void fill_lhe_with_particle(lhef::HEPEUP &outlhe, TLorentzVector &particle, int pdgid, double spin, double ctau);

      void transform_mumu_to_tautau(TLorentzVector &positiveLepton, TLorentzVector &negativeLepton);
      const reco::Candidate* find_original_muon(const reco::Candidate* muon);
      void assign_4vector(TLorentzVector &Lepton, const pat::Muon* muon, std::string FSRmode);
      void mirror(TLorentzVector &positiveLepton, TLorentzVector &negativeLepton);
      void rotate180(TLorentzVector &positiveLepton, TLorentzVector &negativeLepton);

      LHERunInfoProduct::Header give_slha();

      edm::EDGetTokenT<edm::View<pat::Muon>> muonsCollection_;
      edm::EDGetTokenT<reco::VertexCollection> vertexCollection_;
      int particleToEmbed_;
      bool mirror_,rotate180_;
      const double tauMass_ = 1.77682;
      const double elMass_ = 0.00051;
      const int embeddingParticles[3] {11,13,15};

      std::ofstream file;
      bool write_lheout;

      // instead of reconstruted 4vectors of muons generated are taken to study FSR. Possible modes:
      // afterFSR - muons without FSR photons taken into account
      // beforeFSR - muons with FSR photons taken into account
      std::string studyFSRmode_;
};

//
// constructors and destructor
//
EmbeddingLHEProducer::EmbeddingLHEProducer(const edm::ParameterSet& iConfig)
{
   //register your products
   produces<LHEEventProduct>();
   produces<LHERunInfoProduct, edm::Transition::BeginRun>();
   produces<math::XYZTLorentzVectorD>("vertexPosition");

   muonsCollection_ = consumes<edm::View<pat::Muon>>(iConfig.getParameter<edm::InputTag>("src"));
   vertexCollection_ = consumes<reco::VertexCollection>(iConfig.getParameter<edm::InputTag>("vertices"));
   particleToEmbed_ = iConfig.getParameter<int>("particleToEmbed");
   mirror_ = iConfig.getParameter<bool>("mirror");
   rotate180_ = iConfig.getParameter<bool>("rotate180");
   studyFSRmode_ = iConfig.getUntrackedParameter<std::string>("studyFSRmode","");

   write_lheout=false;
   std::string lhe_ouputfile = iConfig.getUntrackedParameter<std::string>("lhe_outputfilename","");
   if (lhe_ouputfile !=""){
     write_lheout=true;
     file.open(lhe_ouputfile, std::fstream::out | std::fstream::trunc);
   }

   //check if particle can be embedded
    if (std::find(std::begin(embeddingParticles), std::end(embeddingParticles),
      particleToEmbed_) == std::end(embeddingParticles)) {
      throw cms::Exception("Configuration")
        << "The given particle to embed is not in the list of allowed particles.";
    }

   edm::Service<edm::RandomNumberGenerator> rng;
   if ( ! rng.isAvailable()) {
     throw cms::Exception("Configuration")
       << "The EmbeddingLHEProducer requires the RandomNumberGeneratorService\n"
          "which is not present in the configuration file. \n"
          "You must add the service\n"
          "in the configuration file or remove the modules that require it.";
    }


}


EmbeddingLHEProducer::~EmbeddingLHEProducer()
{
}


//
// member functions
//

// ------------ method called to produce the data  ------------
void
EmbeddingLHEProducer::produce(edm::Event& iEvent, const edm::EventSetup& iSetup)
{
    using namespace edm;

    edm::Service<edm::RandomNumberGenerator> rng;
    CLHEP::HepRandomEngine* engine = &rng->getEngine(iEvent.streamID());


    edm::Handle< edm::View<pat::Muon> > muonHandle;
    iEvent.getByToken(muonsCollection_, muonHandle);
    edm::View<pat::Muon> coll_muons = *muonHandle;

    Handle<std::vector<reco::Vertex>> coll_vertices;
    iEvent.getByToken(vertexCollection_ , coll_vertices);

    TLorentzVector positiveLepton, negativeLepton;
    bool mu_plus_found = false;
    bool mu_minus_found = false;
    lhef::HEPEUP hepeup;
    hepeup.IDPRUP = 0;
    hepeup.XWGTUP = 1;
    hepeup.SCALUP = -1;
    hepeup.AQEDUP = -1;
    hepeup.AQCDUP = -1;
    // Assuming Pt-Order
    for (edm::View<pat::Muon>::const_iterator muon=  coll_muons.begin(); muon!= coll_muons.end();  ++muon)
    {
      if (muon->charge() == 1 && !mu_plus_found)
      {
        assign_4vector(positiveLepton, &(*muon), studyFSRmode_);
        mu_plus_found = true;
      }
      else if (muon->charge() == -1 && !mu_minus_found)
      {
        assign_4vector(negativeLepton, &(*muon), studyFSRmode_);
        mu_minus_found = true;
      }
      else if (mu_minus_found && mu_plus_found) break;
    }
    mirror(positiveLepton,negativeLepton); // if no mirror, function does nothing.
    rotate180(positiveLepton,negativeLepton); // if no rotate180, function does nothing
    transform_mumu_to_tautau(positiveLepton,negativeLepton); // if MuonEmbedding, function does nothing.
    fill_lhe_from_mumu(positiveLepton,negativeLepton,hepeup,engine);

    double originalXWGTUP_ = 1.;
    std::unique_ptr<LHEEventProduct> product( new LHEEventProduct(hepeup,originalXWGTUP_) );

    if (write_lheout) std::copy(product->begin(), product->end(), std::ostream_iterator<std::string>(file));

    iEvent.put(std::move(product));
    // Saving vertex position
    std::unique_ptr<math::XYZTLorentzVectorD> vertex_position (new math::XYZTLorentzVectorD(coll_vertices->at(0).x(),coll_vertices->at(0).y(),coll_vertices->at(0).z(),0.0));
    iEvent.put(std::move(vertex_position), "vertexPosition");

}

// ------------ method called once each job just before starting event loop  ------------
void
EmbeddingLHEProducer::beginJob()
{
}

// ------------ method called once each job just after ending the event loop  ------------
void
EmbeddingLHEProducer::endJob() {
}

// ------------ method called when starting to processes a run  ------------

void
EmbeddingLHEProducer::beginRunProduce(edm::Run &run, edm::EventSetup const&)
{
    // fill HEPRUP common block and store in edm::Run
    lhef::HEPRUP heprup;

    // set number of processes: 1 for Z to tau tau
    heprup.resize(1);

    //Process independent information

    //beam particles ID (two protons)
    //heprup.IDBMUP.first = 2212;
    //heprup.IDBMUP.second = 2212;

    //beam particles energies (both 6.5 GeV)
    //heprup.EBMUP.first = 6500.;
    //heprup.EBMUP.second = 6500.;

    //take default pdf group for both beamparticles
    //heprup.PDFGUP.first = -1;
    //heprup.PDFGUP.second = -1;

    //take certan pdf set ID (same as in officially produced DYJets LHE files)
    //heprup.PDFSUP.first = -1;
    //heprup.PDFSUP.second = -1;

    //master switch for event weight iterpretation (same as in officially produced DYJets LHE files)
    heprup.IDWTUP = 3;

    //Information for first process (Z to tau tau), for now only placeholder:
    heprup.XSECUP[0] = 1.;
    heprup.XERRUP[0] = 0;
    heprup.XMAXUP[0] = 1;
    heprup.LPRUP[0]= 1;


    std::unique_ptr<LHERunInfoProduct> runInfo(new LHERunInfoProduct(heprup));
    runInfo->addHeader(give_slha());


    if (write_lheout)std::copy(runInfo->begin(), runInfo->end(),std::ostream_iterator<std::string>(file));
    run.put(std::move(runInfo));


}


void
EmbeddingLHEProducer::endRunProduce(edm::Run& run, edm::EventSetup const& es)
{
    if (write_lheout) {
      file << LHERunInfoProduct::endOfFile();
      file.close();
    }
}

void
EmbeddingLHEProducer::fill_lhe_from_mumu(TLorentzVector &positiveLepton, TLorentzVector &negativeLepton, lhef::HEPEUP &outlhe, CLHEP::HepRandomEngine* engine)
{

    TLorentzVector Z = positiveLepton + negativeLepton;
    int leptonPDGID = particleToEmbed_;

   // double tau_ctau = 0.00871100; //cm
    double tau_ctau0 = 8.71100e-02; // mm (for Pythia)
    double tau_ctau_p = tau_ctau0 * CLHEP::RandExponential::shoot(engine); // return -std::log(HepRandom::getTheEngine()->flat());
    // replaces tau = process[iNow].tau0() * rndmPtr->exp(); from pythia8212/src/ProcessContainer.cc which is not initialized for ProcessLevel:all = off mode (no beam particle mode)
    double tau_ctau_n = tau_ctau0 * CLHEP::RandExponential::shoot(engine);
    //std::cout<<"tau_ctau P: "<<tau_ctau_p<<" tau_ctau N:  "<<tau_ctau_n<<std::endl;

    fill_lhe_with_particle(outlhe, Z,23,9.0, 0);
    fill_lhe_with_particle(outlhe, positiveLepton,-leptonPDGID,1.0, tau_ctau_p);
    fill_lhe_with_particle(outlhe, negativeLepton,leptonPDGID,-1.0, tau_ctau_n);

    return;
}

void EmbeddingLHEProducer::fill_lhe_with_particle(lhef::HEPEUP &outlhe, TLorentzVector &particle, int pdgid, double spin, double ctau)
{
    // Pay attention to different index conventions:
    // 'particleindex' follows usual C++ index conventions starting at 0 for a list.
    // 'motherindex' follows the LHE index conventions: 0 is for 'not defined', so the listing starts at 1.
    // That means: LHE index 1 == C++ index 0.
    int particleindex = outlhe.NUP;
    outlhe.resize(outlhe.NUP+1);

    outlhe.PUP[particleindex][0] = particle.Px();
    outlhe.PUP[particleindex][1] = particle.Py();
    outlhe.PUP[particleindex][2] = particle.Pz();
    outlhe.PUP[particleindex][3] = particle.E();
    outlhe.PUP[particleindex][4] = particle.M();
    outlhe.IDUP[particleindex] = pdgid;
    outlhe.SPINUP[particleindex] = spin;
    outlhe.VTIMUP[particleindex] = ctau;

    outlhe.ICOLUP[particleindex].first = 0;
    outlhe.ICOLUP[particleindex].second = 0;

    if (std::abs(pdgid) == 23){
      outlhe.MOTHUP[particleindex].first = 0; // No Mother
      outlhe.MOTHUP[particleindex].second = 0;
      outlhe.ISTUP[particleindex] = 2; // status

    }

    if (std::find(std::begin(embeddingParticles), std::end(embeddingParticles),
     std::abs(pdgid)) != std::end(embeddingParticles)) {
      outlhe.MOTHUP[particleindex].first = 1;  // Mother is the Z (first partile)
      outlhe.MOTHUP[particleindex].second = 1; // Mother is the Z (first partile)

      outlhe.ISTUP[particleindex] = 1;//status
    }

    return;
}




void EmbeddingLHEProducer::transform_mumu_to_tautau(TLorentzVector &positiveLepton, TLorentzVector &negativeLepton)
{
    // No corrections applied for muon embedding
    double lep_mass;
    if (particleToEmbed_ == 11) {
      lep_mass = elMass_;
    } else if (particleToEmbed_ == 15) {
      lep_mass = tauMass_;
    } else {
      return;
    }

    TLorentzVector Z = positiveLepton + negativeLepton;

    TVector3 boost_from_Z_to_LAB = Z.BoostVector();
    TVector3 boost_from_LAB_to_Z = -Z.BoostVector();

    // Boosting the two leptons to Z restframe, then both are back to back. This means, same 3-momentum squared
    positiveLepton.Boost(boost_from_LAB_to_Z);
    negativeLepton.Boost(boost_from_LAB_to_Z);

    // Energy of tau = 0.5*Z-mass
    double lep_mass_squared = lep_mass*lep_mass;
    double lep_energy_squared = 0.25*Z.M2();
    double lep_3momentum_squared = lep_energy_squared - lep_mass_squared;
    if (lep_3momentum_squared < 0)
    {
        edm::LogWarning("TauEmbedding") << "3-Momentum squared is negative";
        return;
    }

    //Computing scale, applying it on the 3-momenta and building new 4 momenta of the taus
    double scale = std::sqrt(lep_3momentum_squared/positiveLepton.Vect().Mag2());
    positiveLepton.SetPxPyPzE(scale*positiveLepton.Px(),scale*positiveLepton.Py(),scale*positiveLepton.Pz(),std::sqrt(lep_energy_squared));
    negativeLepton.SetPxPyPzE(scale*negativeLepton.Px(),scale*negativeLepton.Py(),scale*negativeLepton.Pz(),std::sqrt(lep_energy_squared));

    //Boosting the new taus back to LAB frame
    positiveLepton.Boost(boost_from_Z_to_LAB);
    negativeLepton.Boost(boost_from_Z_to_LAB);

    return;
}

void EmbeddingLHEProducer::assign_4vector(TLorentzVector &Lepton, const pat::Muon* muon, std::string FSRmode)
{
    if("afterFSR" == FSRmode && muon->genParticle() != nullptr)
    {
        const reco::GenParticle* afterFSRMuon = muon->genParticle();
        Lepton.SetPxPyPzE(afterFSRMuon->p4().px(),afterFSRMuon->p4().py(),afterFSRMuon->p4().pz(), afterFSRMuon->p4().e());
    }
    else if ("beforeFSR" == FSRmode && muon->genParticle() != nullptr)
    {
        const reco::Candidate* beforeFSRMuon = find_original_muon(muon->genParticle());
        Lepton.SetPxPyPzE(beforeFSRMuon->p4().px(),beforeFSRMuon->p4().py(),beforeFSRMuon->p4().pz(), beforeFSRMuon->p4().e());
    }
    else
    {
        Lepton.SetPxPyPzE(muon->p4().px(),muon->p4().py(),muon->p4().pz(), muon->p4().e());
    }
    return;
}

const reco::Candidate* EmbeddingLHEProducer::find_original_muon(const reco::Candidate* muon)
{
    if(muon->mother(0) == nullptr) return muon;
    if(muon->pdgId() == muon->mother(0)->pdgId()) return find_original_muon(muon->mother(0));
    else return muon;
}

void EmbeddingLHEProducer::rotate180(TLorentzVector &positiveLepton, TLorentzVector &negativeLepton)
{
    if (!rotate180_) return;
    edm::LogInfo("TauEmbedding") << "Applying 180<C2><B0> rotation" ;
    // By construction, the 3-momenta of mu-, mu+ and Z are in one plane.
    // That means, one vector for perpendicular projection can be used for both leptons.
    TLorentzVector Z = positiveLepton + negativeLepton;

    edm::LogInfo("TauEmbedding") << "MuMinus before. Pt: " << negativeLepton.Pt() << " Eta: " << negativeLepton.Eta() << " Phi: " << negativeLepton.Phi() << " Mass: " << negativeLepton.M();

    TVector3 Z3 = Z.Vect();
    TVector3 positiveLepton3 = positiveLepton.Vect();
    TVector3 negativeLepton3 = negativeLepton.Vect();

    TVector3 p3_perp = positiveLepton3 - positiveLepton3.Dot(Z3)/Z3.Dot(Z3)*Z3;
    p3_perp = p3_perp.Unit();

    positiveLepton3 -= 2*positiveLepton3.Dot(p3_perp)*p3_perp;
    negativeLepton3 -= 2*negativeLepton3.Dot(p3_perp)*p3_perp;

    positiveLepton.SetVect(positiveLepton3);
    negativeLepton.SetVect(negativeLepton3);

    edm::LogInfo("TauEmbedding") << "MuMinus after. Pt: " << negativeLepton.Pt() << " Eta: " << negativeLepton.Eta() << " Phi: " << negativeLepton.Phi() << " Mass: " << negativeLepton.M();

    return;
}

void EmbeddingLHEProducer::mirror(TLorentzVector &positiveLepton, TLorentzVector &negativeLepton)
{
    if(!mirror_) return;
    edm::LogInfo("TauEmbedding")<< "Applying mirroring" ;
    TLorentzVector Z = positiveLepton + negativeLepton;

    edm::LogInfo("TauEmbedding") << "MuMinus before. Pt: " << negativeLepton.Pt() << " Eta: " << negativeLepton.Eta() << " Phi: " << negativeLepton.Phi() << " Mass: " << negativeLepton.M() ;

    TVector3 Z3 = Z.Vect();
    TVector3 positiveLepton3 = positiveLepton.Vect();
    TVector3 negativeLepton3 = negativeLepton.Vect();

    TVector3 beam(0.,0.,1.);
    TVector3 perpToZandBeam = Z3.Cross(beam).Unit();

    positiveLepton3 -= 2*positiveLepton3.Dot(perpToZandBeam)*perpToZandBeam;
    negativeLepton3 -= 2*negativeLepton3.Dot(perpToZandBeam)*perpToZandBeam;

    positiveLepton.SetVect(positiveLepton3);
    negativeLepton.SetVect(negativeLepton3);

    edm::LogInfo("TauEmbedding") << "MuMinus after. Pt: " << negativeLepton.Pt() << " Eta: " << negativeLepton.Eta() << " Phi: " << negativeLepton.Phi() << " Mass: " << negativeLepton.M() ;

    return;
}


LHERunInfoProduct::Header EmbeddingLHEProducer::give_slha(){
  LHERunInfoProduct::Header slhah("slha");

  slhah.addLine("######################################################################\n");
  slhah.addLine("## PARAM_CARD AUTOMATICALY GENERATED BY MG5 FOLLOWING UFO MODEL   ####\n");
  slhah.addLine("######################################################################\n");
  slhah.addLine("##                                                                  ##\n");
  slhah.addLine("##  Width set on Auto will be computed following the information    ##\n");
  slhah.addLine("##        present in the decay.py files of the model.               ##\n");
  slhah.addLine("##        See  arXiv:1402.1178 for more details.                    ##\n");
  slhah.addLine("##                                                                  ##\n");
  slhah.addLine("######################################################################\n");
  slhah.addLine("\n");
  slhah.addLine("###################################\n");
  slhah.addLine("## INFORMATION FOR MASS\n");
  slhah.addLine("###################################\n");
  slhah.addLine("Block mass \n");
  slhah.addLine("    6 1.730000e+02 # MT \n");
  slhah.addLine("   15 1.777000e+00 # MTA \n");
  slhah.addLine("   23 9.118800e+01 # MZ \n");
  slhah.addLine("   25 1.250000e+02 # MH \n");
  slhah.addLine("## Dependent parameters, given by model restrictions.\n");
  slhah.addLine("## Those values should be edited following the \n");
  slhah.addLine("## analytical expression. MG5 ignores those values \n");
  slhah.addLine("## but they are important for interfacing the output of MG5\n");
  slhah.addLine("## to external program such as Pythia.\n");
  slhah.addLine("  1 0.000000 # d : 0.0 \n");
  slhah.addLine("  2 0.000000 # u : 0.0 \n");
  slhah.addLine("  3 0.000000 # s : 0.0 \n");
  slhah.addLine("  4 0.000000 # c : 0.0 \n");
  slhah.addLine("  5 0.000000 # b : 0.0 \n");
  slhah.addLine("  11 0.000000 # e- : 0.0 \n");
  slhah.addLine("  12 0.000000 # ve : 0.0 \n");
  slhah.addLine("  13 0.000000 # mu- : 0.0 \n");
  slhah.addLine("  14 0.000000 # vm : 0.0 \n");
  slhah.addLine("  16 0.000000 # vt : 0.0 \n");
  slhah.addLine("  21 0.000000 # g : 0.0 \n");
  slhah.addLine("  22 0.000000 # a : 0.0 \n");
  slhah.addLine("  24 80.419002 # w+ : cmath.sqrt(MZ__exp__2/2. + cmath.sqrt(MZ__exp__4/4. - (aEW*cmath.pi*MZ__exp__2)/(Gf*sqrt__2))) \n");
  slhah.addLine("\n");
  slhah.addLine("###################################\n");
  slhah.addLine("## INFORMATION FOR SMINPUTS\n");
  slhah.addLine("###################################\n");
  slhah.addLine("Block sminputs \n");
  slhah.addLine("    1 1.325070e+02 # aEWM1 \n");
  slhah.addLine("    2 1.166390e-05 # Gf \n");
  slhah.addLine("    3 1.180000e-01 # aS \n");
  slhah.addLine("\n");
  slhah.addLine("###################################\n");
  slhah.addLine("## INFORMATION FOR WOLFENSTEIN\n");
  slhah.addLine("###################################\n");
  slhah.addLine("Block wolfenstein \n");
  slhah.addLine("    1 2.253000e-01 # lamWS \n");
  slhah.addLine("    2 8.080000e-01 # AWS \n");
  slhah.addLine("    3 1.320000e-01 # rhoWS \n");
  slhah.addLine("    4 3.410000e-01 # etaWS \n");
  slhah.addLine("\n");
  slhah.addLine("###################################\n");
  slhah.addLine("## INFORMATION FOR YUKAWA\n");
  slhah.addLine("###################################\n");
  slhah.addLine("Block yukawa \n");
  slhah.addLine("    6 1.730000e+02 # ymt \n");
  slhah.addLine("   15 1.777000e+00 # ymtau \n");
  slhah.addLine("\n");
  slhah.addLine("###################################\n");
  slhah.addLine("## INFORMATION FOR DECAY\n");
  slhah.addLine("###################################\n");
  slhah.addLine("DECAY   6 1.491500e+00 # WT \n");
  slhah.addLine("DECAY  15 2.270000e-12 # WTau \n");
  slhah.addLine("DECAY  23 2.441404e+00 # WZ \n");
  slhah.addLine("DECAY  24 2.047600e+00 # WW \n");
  slhah.addLine("DECAY  25 6.382339e-03 # WH \n");
  slhah.addLine("## Dependent parameters, given by model restrictions.\n");
  slhah.addLine("## Those values should be edited following the \n");
  slhah.addLine("## analytical expression. MG5 ignores those values \n");
  slhah.addLine("## but they are important for interfacing the output of MG5\n");
  slhah.addLine("## to external program such as Pythia.\n");
  slhah.addLine("DECAY  1 0.000000 # d : 0.0 \n");
  slhah.addLine("DECAY  2 0.000000 # u : 0.0 \n");
  slhah.addLine("DECAY  3 0.000000 # s : 0.0 \n");
  slhah.addLine("DECAY  4 0.000000 # c : 0.0 \n");
  slhah.addLine("DECAY  5 0.000000 # b : 0.0 \n");
  slhah.addLine("DECAY  11 0.000000 # e- : 0.0 \n");
  slhah.addLine("DECAY  12 0.000000 # ve : 0.0 \n");
  slhah.addLine("DECAY  13 0.000000 # mu- : 0.0 \n");
  slhah.addLine("DECAY  14 0.000000 # vm : 0.0 \n");
  slhah.addLine("DECAY  16 0.000000 # vt : 0.0 \n");
  slhah.addLine("DECAY  21 0.000000 # g : 0.0 \n");
  slhah.addLine("DECAY  22 0.000000 # a : 0.0\n");

  return slhah;
}



// ------------ method fills 'descriptions' with the allowed parameters for the module  ------------
void
EmbeddingLHEProducer::fillDescriptions(edm::ConfigurationDescriptions& descriptions) {
  //The following says we do not know what parameters are allowed so do no validation
  // Please change this to state exactly what you do use, even if it is no parameters
  edm::ParameterSetDescription desc;
  desc.setUnknown();
  descriptions.addDefault(desc);
}

//define this as a plug-in
DEFINE_FWK_MODULE(EmbeddingLHEProducer);