ISRWeightProducer.cc

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#include <memory>

#include "FWCore/Framework/interface/Frameworkfwd.h"
#include "FWCore/Framework/interface/EDProducer.h"

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

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

#include "DataFormats/HepMCCandidate/interface/GenParticle.h"
#include "DataFormats/Candidate/interface/CompositeCandidate.h"
#include "CommonTools/CandUtils/interface/AddFourMomenta.h"
#include "CommonTools/CandUtils/interface/Booster.h"
#include <Math/VectorUtil.h>

//
// class declaration
//
class ISRWeightProducer : public edm::EDProducer {
public:
  explicit ISRWeightProducer(const edm::ParameterSet&);
  ~ISRWeightProducer() override;

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

  edm::EDGetTokenT<reco::GenParticleCollection> genToken_;
  std::vector<double> isrBinEdges_;
  std::vector<double> ptWeights_;
};

ISRWeightProducer::ISRWeightProducer(const edm::ParameterSet& pset) {
  genToken_ = consumes<reco::GenParticleCollection>(
      pset.getUntrackedParameter<edm::InputTag>("GenTag", edm::InputTag("genParticles")));

  // Pt bin edges
  std::vector<double> defPtEdges;
  defPtEdges.push_back(0.);
  defPtEdges.push_back(999999.);
  isrBinEdges_ = pset.getUntrackedParameter<std::vector<double> >("ISRBinEdges", defPtEdges);
  unsigned int ninputs_expected = isrBinEdges_.size() - 1;

  // Distortions in muon momentum
  std::vector<double> defWeights;
  defWeights.push_back(1.);
  ptWeights_ = pset.getUntrackedParameter<std::vector<double> >("PtWeights", defWeights);
  if (ptWeights_.size() == 1 && ninputs_expected > 1) {
    for (unsigned int i = 1; i < ninputs_expected; i++) {
      ptWeights_.push_back(ptWeights_[0]);
    }
  }

  produces<double>();
}

ISRWeightProducer::~ISRWeightProducer() {}

void ISRWeightProducer::beginJob() {}

void ISRWeightProducer::endJob() {}

void ISRWeightProducer::produce(edm::Event& iEvent, const edm::EventSetup&) {
  if (iEvent.isRealData())
    return;

  edm::Handle<reco::GenParticleCollection> genParticles;
  iEvent.getByToken(genToken_, genParticles);
  unsigned int gensize = genParticles->size();

  std::unique_ptr<double> weight(new double);

  // Set as default weight the asymptotic value at high pt (i.e. value of last bin)
  (*weight) = ptWeights_[ptWeights_.size() - 1];

  unsigned int nbins = isrBinEdges_.size() - 1;
  for (unsigned int i = 0; i < gensize; ++i) {
    const reco::GenParticle& part = (*genParticles)[i];
    int id = part.pdgId();
    if (id != 23 && abs(id) != 24)
      continue;
    int status = part.status();
    if (status != 3)
      continue;
    double pt = part.pt();
    if (pt > isrBinEdges_[0] && pt < isrBinEdges_[nbins]) {
      for (unsigned int j = 1; j <= nbins; ++j) {
        if (pt > isrBinEdges_[j])
          continue;
        (*weight) = ptWeights_[j - 1];
        break;
      }
    }
    break;
  }

  iEvent.put(std::move(weight));
}

DEFINE_FWK_MODULE(ISRWeightProducer);