Rivet analyses

title: H1_1996_I421105

Inclusive D0 and D*+- production in deep inelastic e p scattering at HERA

Experiment: H1 (HERA)

Inspire ID: 421105

Status: VALIDATED

Authors: - Muhammad Ibrahim Abdulhamid - Hannes Jung

References: - Z.Phys.C 72 (1996) 593 - DOI: 10.1007/s002880050281,10.1007/BF02909190 - arXiv: hep-ex/9607012 - DESY-96-138

Beams: e- p+, p+ e-

Beam energies: (27.6, 820.0); (820.0, 27.6)GeV

Run details: - Charm production in DIS with Q2> 10 and 0.01 < y < 0.7

First results on inclusive D0 and D* production in deep inelastic ep scattering are reported using data collected by the H1 experiment at HERA in 1994.

Source code:H1_1996_I421105.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DISKinematics.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Inclusive D0 and D*+- production in deep inelastic e p scattering at HERA (H1) class H1_1996_I421105 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(H1_1996_I421105);


/// @name Analysis methods
///@{

/// Book histograms and initialise projections before the run
void init() {

  // Declare projections
  declare(DISKinematics(), "Kinematics");
  declare(UnstableParticles(), "UFS");
  declare(FinalState(Cuts::abseta < 4.9), "FS");

  // Book histograms from reference data using HEPData ID (digits in "d01-x01-y01")
  book(_h["p_tD*_norm"], 4, 1, 1);
  book(_h["p_tD*"], 4, 1, 2);
  book(_h["p_tD0_norm"], 5, 1, 1);
  book(_h["p_tD0"], 5, 1, 2);
  book(_h["xD_D*_norm"], 6, 1, 1);
  book(_h["xD_D*"], 6, 1, 2);
  book(_h["xD_D0_norm"], 7, 1, 1);
  book(_h["xD_D0"], 7, 1, 2);
}


/// Perform the per-event analysis
void analyze(const Event& event) {

  /// @todo Do the event by event analysis here
  const DISKinematics& dk = apply<DISKinematics>(event, "Kinematics");
  const LorentzTransform hcmboost = dk.boostHCM();

  // Get the DIS kinematics
  double y = dk.y();
  double W2 = dk.W2() / GeV2;
  double Q2 = dk.Q2() / GeV;

  bool cut;
  cut = Q2 > 10 && Q2 < 100 && y > 0.01 && y < 0.7;

  if (!cut) vetoEvent;
  bool etacut;
  for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
    etacut = abs(p.momentum().eta()) < 1.5;
    const FourMomentum hcmMom = hcmboost.transform(p.momentum());
    double p_D;
    double x_D = 0;
    p_D = std::sqrt(hcmMom.px() * hcmMom.px() + hcmMom.py() * hcmMom.py() + hcmMom.pz() * hcmMom.pz());
    x_D = 2. * p_D / sqrt(W2);
    if (p.abspid() == 421) {
      _h["p_tD0"]->fill(p.momentum().pT() / GeV);
      _h["p_tD0_norm"]->fill(p.momentum().pT() / GeV);
      if (etacut) _h["xD_D0"]->fill(x_D);
      if (etacut) _h["xD_D0_norm"]->fill(x_D);
    }

    if (p.abspid() == 413) {
      _h["p_tD*"]->fill(p.momentum().pT() / GeV);
      _h["p_tD*_norm"]->fill(p.momentum().pT() / GeV);
      // x_D is defined for the D0
      if (etacut) _h["xD_D*"]->fill(x_D);
      if (etacut) _h["xD_D*_norm"]->fill(x_D);
    }
  }
}
/// Normalise histograms etc., after the run
void finalize() {


  scale(_h["p_tD*"], crossSection() / nanobarn / sumW());
  scale(_h["p_tD0"], crossSection() / nanobarn / sumW());
  normalize(_h["p_tD*_norm"]);
  normalize(_h["p_tD0_norm"]);

  scale(_h["xD_D*"], crossSection() / nanobarn / sumW());
  scale(_h["xD_D0"], crossSection() / nanobarn / sumW());
  normalize(_h["xD_D*_norm"]);
  normalize(_h["xD_D0_norm"]);
}

///@}


/// @name Histograms
///@{
map<string, Histo1DPtr> _h;
///@}

};

RIVET_DECLARE_PLUGIN(H1_1996_I421105);

} ```