Rivet analyses

title: CMS_2022_I2142341

Measurement of differential fiducial Higgs boson production cross sections in $pp$collisions at $\sqrt{s} = 13$ TeV in the diphoton decay channel

Experiment: (LHC)

Inspire ID: 2142341

Status: VALIDATED

Authors: - Alessandro Tarabini - Massimiliano Galli

References: - JHEP 07 (2023) 091 - DOI:10.1007/JHEP07(2023)091 - arXiv: 2208.12279 - Expt page: CMS-HIG-19-016

Beams: p+ p+

Beam energies: (6500.0, 6500.0)GeV

Run details: - H->$\gamma\gamma$; ggH, VBF, VH, and ttH production modes are included

The cross section for Higgs boson production in pp collisions is measured using the $H\rightarrow \gamma\gamma$ decay mode. The measurements are performed using data collected by the CMS experiment at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $138\,\text{fb}^{-1}$. The original routine contained no diphoton mass cut, and this is the case by default. To turn on a cut on the diphoton mass between 105 and 160 GeV, making the cross section more "fiducial" and having negligible effect on real Higgs events, use the MASSCUT=TRUE option.

Source code:CMS_2022_I2142341.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Tools/RivetYODA.hh"

namespace Rivet {

/// @brief H->yy analysis at 13 TeV class CMS_2022_I2142341 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2022_I2142341);

void init() {

  _mode = 0;
  if (getOption("MASSCUT") == "TRUE") _mode = 1;

  //---All particle final state
  FinalState fs;
  declare(fs, "FS");

  //---Photons
  FinalState fs_photons(Cuts::abspid == PID::PHOTON);
  declare(fs_photons, "FS_PHOTONS");

  //---Jets
  FastJets fs_jets(fs, JetAlg::ANTIKT, 0.4);
  declare(fs_jets, "JETS");

  //---Histograms
  book(_h["pt_gg"], "d01-x01-y01");
  book(_h["njets_eta2p5"], "d03-x01-y01");
  book(_h["cos_theta_star"], "d05-x01-y01");
  book(_h["rapidity_gg"], "d07-x01-y01");
  book(_h["jet_pt_eta2p5"], "d09-x01-y01");
  book(_h["jet_rapidity_eta2p5"], "d11-x01-y01");
  book(_h["deltaphijj"], "d23-x01-y01");
  book(_h["deltaetajj"], "d29-x01-y01");
}

// cos theta star angle in the Collins Soper frame
double getCosThetaStar_CS(const FourMomentum& h1, const FourMomentum& h2) {
  FourMomentum hh = h1 + h2;
  LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(hh.betaVec());
  FourMomentum h1_boosted = boost.transform(h1);
  return abs(cos(h1_boosted.theta()));
}

void analyze(const Event& event) {
  Particles photons = apply<FinalState>(event, "FS_PHOTONS").particlesByPt();

  if (photons.size() < 2) vetoEvent;

  //---Isolate photons with ET_sum in cone
  Particles isolated_photons;
  Particles fs = apply<FinalState>(event, "FS").particlesByPt();
  for (const Particle& photon : photons) {
    FourMomentum mom_in_cone;
    for (const Particle& particle : fs) {
      if (deltaR(photon, particle) < 0.3 && photon.p() != particle.p())
        mom_in_cone += particle.momentum();
    }
    if (mom_in_cone.pt() < 10 * GeV && photon.abseta() < 2.5) isolated_photons.push_back(photon);
  }

  if (isolated_photons.size() < 2) vetoEvent;

  //---kinematic photon selection
  FourMomentum mom_PP = isolated_photons[0].mom() + isolated_photons[1].mom();
  if (isolated_photons[0].pT() < mom_PP.mass() / 3. || isolated_photons[1].pT() < mom_PP.mass() / 4.)
    vetoEvent;

  // optionally apply a fiducial mass cut.
  if ((_mode == 1) && (!inRange(mom_PP.mass() / GeV, 105., 160.))) vetoEvent;


  _h["pt_gg"]->fill(mom_PP.pt() / GeV);
  _h["rapidity_gg"]->fill(abs(mom_PP.rapidity()));
  _h["cos_theta_star"]->fill(getCosThetaStar_CS(isolated_photons[0].mom(), isolated_photons[1].mom()));

  //---jets
  auto jets_eta4p7 = apply<FastJets>(event, "JETS").jetsByPt(Cuts::abseta < 4.7 && Cuts::pt > 30 * GeV);
  Jets jets_eta4p7_npart;
  for (const Jet& j : jets_eta4p7) {
    if (j.constituents().size() > 5) jets_eta4p7_npart.push_back(j);
  }
  Particles selected_photons;
  selected_photons.push_back(isolated_photons[0]);
  selected_photons.push_back(isolated_photons[1]);
  idiscardIfAnyDeltaRLess(jets_eta4p7_npart, selected_photons, 0.4);
  if (jets_eta4p7_npart.size() > 1) {
    _h["deltaphijj"]->fill(deltaPhi(jets_eta4p7_npart[0], jets_eta4p7_npart[1]));
    _h["deltaetajj"]->fill(deltaEta(jets_eta4p7_npart[0], jets_eta4p7_npart[1]));
  }

  Jets jets_eta2p5;
  for (const Jet& j : jets_eta4p7_npart) {
    if (j.abseta() < 2.5) jets_eta2p5.push_back(j);
  }
  _h["njets_eta2p5"]->fill(jets_eta2p5.size());
  if (jets_eta2p5.size() > 0) {
    _h["jet_pt_eta2p5"]->fill(jets_eta2p5[0].pt() / GeV);
    _h["jet_rapidity_eta2p5"]->fill(abs(jets_eta2p5[0].rapidity()));
  }
}

void finalize() {
  scale(_h, crossSection() / femtobarn / sumOfWeights());
}

private:

map<string, Histo1DPtr> _h;
size_t _mode;

};

RIVET_DECLARE_PLUGIN(CMS_2022_I2142341);

} // namespace Rivet ```