MixBoostEvtVtxGenerator.cc

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/*
________________________________________________________________________

 MixBoostEvtVtxGenerator

 Smear vertex according to the Beta function on the transverse plane
 and a Gaussian on the z axis. It allows the beam to have a crossing
 angle (slopes dxdz and dydz).

 Based on GaussEvtVtxGenerator
 implemented by Francisco Yumiceva (yumiceva@fnal.gov)

 FERMILAB
 2006
________________________________________________________________________
*/

//lingshan: add beta for z-axis boost

//#include "IOMC/EventVertexGenerators/interface/BetafuncEvtVtxGenerator.h"

#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Utilities/interface/Exception.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"

#include "FWCore/Framework/interface/EDProducer.h"
#include "FWCore/Utilities/interface/InputTag.h"

#include "SimDataFormats/CrossingFrame/interface/MixCollection.h"
#include "SimDataFormats/GeneratorProducts/interface/HepMCProduct.h"
#include "DataFormats/VertexReco/interface/Vertex.h"
#include "DataFormats/VertexReco/interface/VertexFwd.h"

#include "CLHEP/Units/GlobalSystemOfUnits.h"
#include "CLHEP/Units/GlobalPhysicalConstants.h"
//#include "CLHEP/Vector/ThreeVector.h"
#include "HepMC/SimpleVector.h"
#include "TMatrixD.h"

#include <iostream>

using namespace edm;
using namespace std;
using namespace CLHEP;

class RandGaussQ;
class FourVector;

class MixBoostEvtVtxGenerator : public edm::EDProducer {
public:
  MixBoostEvtVtxGenerator(const edm::ParameterSet& p);
  MixBoostEvtVtxGenerator(const MixBoostEvtVtxGenerator& p) = delete;
  MixBoostEvtVtxGenerator& operator=(const MixBoostEvtVtxGenerator& rhs) = delete;
  ~MixBoostEvtVtxGenerator() override;

  void produce(edm::Event&, const edm::EventSetup&) override;
  virtual TMatrixD* GetInvLorentzBoost();
  virtual HepMC::FourVector* getVertex(edm::Event&);
  virtual HepMC::FourVector* getRecVertex(edm::Event&);

  void sigmaZ(double s = 1.0);

  void X0(double m = 0) { fX0 = m; }
  void Y0(double m = 0) { fY0 = m; }
  void Z0(double m = 0) { fZ0 = m; }

  void Phi(double m = 0) { phi_ = m; }
  void Alpha(double m = 0) { alpha_ = m; }
  void Beta(double m = 0) { beta_ = m; }

  void betastar(double m = 0) { fbetastar = m; }
  void emittance(double m = 0) { femittance = m; }

  double BetaFunction(double z, double z0);

private:
  double alpha_, phi_;
  //TMatrixD boost_;
  double beta_;
  double fX0, fY0, fZ0;
  double fSigmaZ;
  //double fdxdz, fdydz;
  double fbetastar, femittance;
  double falpha;

  HepMC::FourVector* fVertex;
  TMatrixD* boost_;
  double fTimeOffset;

  edm::EDGetTokenT<reco::VertexCollection> vtxLabel;
  edm::EDGetTokenT<HepMCProduct> signalLabel;
  edm::EDGetTokenT<CrossingFrame<HepMCProduct> > mixLabel;
  bool useRecVertex;
  std::vector<double> vtxOffset;
};

MixBoostEvtVtxGenerator::MixBoostEvtVtxGenerator(const edm::ParameterSet& pset)
    : fVertex(nullptr),
      boost_(nullptr),
      fTimeOffset(0),
      vtxLabel(mayConsume<reco::VertexCollection>(pset.getParameter<edm::InputTag>("vtxLabel"))),
      signalLabel(consumes<HepMCProduct>(pset.getParameter<edm::InputTag>("signalLabel"))),
      mixLabel(consumes<CrossingFrame<HepMCProduct> >(pset.getParameter<edm::InputTag>("mixLabel"))),
      useRecVertex(pset.exists("useRecVertex") ? pset.getParameter<bool>("useRecVertex") : false) {
  beta_ = pset.getParameter<double>("Beta");
  alpha_ = 0;
  phi_ = 0;
  if (pset.exists("Alpha")) {
    alpha_ = pset.getParameter<double>("Alpha") * radian;
    phi_ = pset.getParameter<double>("Phi") * radian;
  }

  vtxOffset.resize(3);
  if (pset.exists("vtxOffset"))
    vtxOffset = pset.getParameter<std::vector<double> >("vtxOffset");

  produces<edm::HepMCProduct>();
}

MixBoostEvtVtxGenerator::~MixBoostEvtVtxGenerator() {
  if (fVertex != nullptr)
    delete fVertex;
  if (boost_ != nullptr)
    delete boost_;
}

double MixBoostEvtVtxGenerator::BetaFunction(double z, double z0) {
  return sqrt(femittance * (fbetastar + (((z - z0) * (z - z0)) / fbetastar)));
}

void MixBoostEvtVtxGenerator::sigmaZ(double s) {
  if (s >= 0) {
    fSigmaZ = s;
  } else {
    throw cms::Exception("LogicError") << "Error in MixBoostEvtVtxGenerator::sigmaZ: "
                                       << "Illegal resolution in Z (negative)";
  }
}

TMatrixD* MixBoostEvtVtxGenerator::GetInvLorentzBoost() {
  //alpha_ = 0;
  //phi_ = 142.e-6;
  //    if (boost_ != 0 ) return boost_;

  //boost_.ResizeTo(4,4);
  //boost_ = new TMatrixD(4,4);
  TMatrixD tmpboost(4, 4);
  TMatrixD tmpboostZ(4, 4);
  TMatrixD tmpboostXYZ(4, 4);

  //if ( (alpha_ == 0) && (phi_==0) ) { boost_->Zero(); return boost_; }

  // Lorentz boost to frame where the collision is head-on
  // phi is the half crossing angle in the plane ZS
  // alpha is the angle to the S axis from the X axis in the XY plane

  tmpboost(0, 0) = 1. / cos(phi_);
  tmpboost(0, 1) = -cos(alpha_) * sin(phi_);
  tmpboost(0, 2) = -tan(phi_) * sin(phi_);
  tmpboost(0, 3) = -sin(alpha_) * sin(phi_);
  tmpboost(1, 0) = -cos(alpha_) * tan(phi_);
  tmpboost(1, 1) = 1.;
  tmpboost(1, 2) = cos(alpha_) * tan(phi_);
  tmpboost(1, 3) = 0.;
  tmpboost(2, 0) = 0.;
  tmpboost(2, 1) = -cos(alpha_) * sin(phi_);
  tmpboost(2, 2) = cos(phi_);
  tmpboost(2, 3) = -sin(alpha_) * sin(phi_);
  tmpboost(3, 0) = -sin(alpha_) * tan(phi_);
  tmpboost(3, 1) = 0.;
  tmpboost(3, 2) = sin(alpha_) * tan(phi_);
  tmpboost(3, 3) = 1.;
  //cout<<"beta "<<beta_;
  double gama = 1.0 / sqrt(1 - beta_ * beta_);
  tmpboostZ(0, 0) = gama;
  tmpboostZ(0, 1) = 0.;
  tmpboostZ(0, 2) = -1.0 * beta_ * gama;
  tmpboostZ(0, 3) = 0.;
  tmpboostZ(1, 0) = 0.;
  tmpboostZ(1, 1) = 1.;
  tmpboostZ(1, 2) = 0.;
  tmpboostZ(1, 3) = 0.;
  tmpboostZ(2, 0) = -1.0 * beta_ * gama;
  tmpboostZ(2, 1) = 0.;
  tmpboostZ(2, 2) = gama;
  tmpboostZ(2, 3) = 0.;
  tmpboostZ(3, 0) = 0.;
  tmpboostZ(3, 1) = 0.;
  tmpboostZ(3, 2) = 0.;
  tmpboostZ(3, 3) = 1.;

  tmpboostXYZ = tmpboostZ * tmpboost;
  tmpboostXYZ.Invert();

  //cout<<"Boosting with beta : "<<beta_<<endl;

  boost_ = new TMatrixD(tmpboostXYZ);
  boost_->Print();

  return boost_;
}

HepMC::FourVector* MixBoostEvtVtxGenerator::getVertex(Event& evt) {
  const HepMC::GenEvent* inev = nullptr;

  Handle<CrossingFrame<HepMCProduct> > cf;
  evt.getByToken(mixLabel, cf);
  MixCollection<HepMCProduct> mix(cf.product());

  const HepMCProduct& bkg = mix.getObject(1);
  if (!(bkg.isVtxGenApplied())) {
    throw cms::Exception("MatchVtx") << "Input background does not have smeared vertex!" << endl;
  } else {
    inev = bkg.GetEvent();
  }

  HepMC::GenVertex* genvtx = inev->signal_process_vertex();
  if (!genvtx) {
    cout << "No Signal Process Vertex!" << endl;
    HepMC::GenEvent::particle_const_iterator pt = inev->particles_begin();
    HepMC::GenEvent::particle_const_iterator ptend = inev->particles_end();
    while (!genvtx || (genvtx->particles_in_size() == 1 && pt != ptend)) {
      if (!genvtx)
        cout << "No Gen Vertex!" << endl;
      if (pt == ptend)
        cout << "End reached!" << endl;
      genvtx = (*pt)->production_vertex();
      ++pt;
    }
  }
  double aX, aY, aZ, aT;

  aX = genvtx->position().x();
  aY = genvtx->position().y();
  aZ = genvtx->position().z();
  aT = genvtx->position().t();

  if (!fVertex)
    fVertex = new HepMC::FourVector();
  fVertex->set(aX, aY, aZ, aT);

  return fVertex;
}

HepMC::FourVector* MixBoostEvtVtxGenerator::getRecVertex(Event& evt) {
  Handle<reco::VertexCollection> input;
  evt.getByToken(vtxLabel, input);

  double aX, aY, aZ;

  aX = input->begin()->position().x() + vtxOffset[0];
  aY = input->begin()->position().y() + vtxOffset[1];
  aZ = input->begin()->position().z() + vtxOffset[2];

  if (!fVertex)
    fVertex = new HepMC::FourVector();
  fVertex->set(10.0 * aX, 10.0 * aY, 10.0 * aZ, 0.0);  // HepMC positions in mm (RECO in cm)

  return fVertex;
}

void MixBoostEvtVtxGenerator::produce(Event& evt, const EventSetup&) {
  Handle<HepMCProduct> HepUnsmearedMCEvt;
  evt.getByToken(signalLabel, HepUnsmearedMCEvt);

  // Copy the HepMC::GenEvent
  HepMC::GenEvent* genevt = new HepMC::GenEvent(*HepUnsmearedMCEvt->GetEvent());
  std::unique_ptr<edm::HepMCProduct> HepMCEvt(new edm::HepMCProduct(genevt));
  // generate new vertex & apply the shift
  //

  HepMCEvt->boostToLab(GetInvLorentzBoost(), "vertex");
  HepMCEvt->boostToLab(GetInvLorentzBoost(), "momentum");

  HepMCEvt->applyVtxGen(useRecVertex ? getRecVertex(evt) : getVertex(evt));

  evt.put(std::move(HepMCEvt));
  return;
}

#include "FWCore/Framework/interface/MakerMacros.h"
DEFINE_FWK_MODULE(MixBoostEvtVtxGenerator);