Rivet analyses

title: ATLAS_2011_I896268

Measurement of $J/\psi$ production

Experiment: ATLAS (LHC)

Inspire ID: 896268

Status: VALIDATED

Authors: none listed

References: - Expt page: ATLAS-BPHY-2010-01 - arXiv: 1104.3038

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - pp to hadrons including both prompt J/Psi production and the production in B decays

The inclusive $J/\psi$ production cross-section and fraction of $J/\psi$ mesons produced in B-hadron decays are measured in proton-proton collisions at $\sqrt{s} = 7$ TeV with the ATLAS detector at the LHC, as a function of the transverse momentum and rapidity of the J/psi, using 2.3$\textrm{pb}^{-1}$ of integrated luminosity. The cross section is measured from a minimum $p_T$ of 1 GeV to a maximum of 70 GeV and for rapidities within $|y| < 2.4$ giving the widest reach of any measurement of $J/\psi$ production to date.

Source code:ATLAS_2011_I896268.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// J/psi production at ATLAS class ATLAS_2011_I896268 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2011_I896268);


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

void init() {
  declare(UnstableParticles(), "UFS");
  book(_nonPrRapHigh, 14, 1, 1);
  book(_nonPrRapMedHigh, 13, 1, 1);
  book(_nonPrRapMedLow, 12, 1, 1);
  book(_nonPrRapLow, 11, 1, 1);
  book(_PrRapHigh, 18, 1, 1);
  book(_PrRapMedHigh, 17, 1, 1);
  book(_PrRapMedLow, 16, 1, 1);
  book(_PrRapLow, 15, 1, 1);
  book(_IncRapHigh, 20, 1, 1);
  book(_IncRapMedHigh, 21, 1, 1);
  book(_IncRapMedLow, 22, 1, 1);
  book(_IncRapLow, 23, 1, 1);
}


void analyze(const Event& e) {

  // Final state of unstable particles to get particle spectra
  const UnstableParticles& ufs = apply<UnstableParticles>(e, "UFS");

  for (const Particle& p : ufs.particles()) {
    if (p.abspid() != 443) continue;
    ConstGenVertexPtr gv = p.genParticle()->production_vertex();
    bool nonPrompt = false;
    if (gv) {
      for (ConstGenParticlePtr pi : HepMCUtils::particles(gv, Relatives::ANCESTORS)) {
        const PdgId pid2 = pi->pdg_id();
        if (PID::isHadron(pid2) && PID::hasBottom(pid2)) {
          nonPrompt = true;
          break;
        }
      }
    }
    double absrap = p.absrap();
    double xp = p.perp();

    if (absrap <= 2.4 and absrap > 2.) {
      if (nonPrompt)
        _nonPrRapHigh->fill(xp);
      else if (!nonPrompt)
        _PrRapHigh->fill(xp);
      _IncRapHigh->fill(xp);
    }
    else if (absrap <= 2. and absrap > 1.5) {
      if (nonPrompt)
        _nonPrRapMedHigh->fill(xp);
      else if (!nonPrompt)
        _PrRapMedHigh->fill(xp);
      _IncRapMedHigh->fill(xp);
    }
    else if (absrap <= 1.5 and absrap > 0.75) {
      if (nonPrompt)
        _nonPrRapMedLow->fill(xp);
      else if (!nonPrompt)
        _PrRapMedLow->fill(xp);
      _IncRapMedLow->fill(xp);
    }

    else if (absrap <= 0.75) {
      if (nonPrompt)
        _nonPrRapLow->fill(xp);
      else if (!nonPrompt)
        _PrRapLow->fill(xp);
      _IncRapLow->fill(xp);
    }
  }
}


/// Finalize
void finalize() {
  double factor = crossSection() / nanobarn * 0.0593;

  scale(_PrRapHigh, factor / sumOfWeights());
  scale(_PrRapMedHigh, factor / sumOfWeights());
  scale(_PrRapMedLow, factor / sumOfWeights());
  scale(_PrRapLow, factor / sumOfWeights());

  scale(_nonPrRapHigh, factor / sumOfWeights());
  scale(_nonPrRapMedHigh, factor / sumOfWeights());
  scale(_nonPrRapMedLow, factor / sumOfWeights());
  scale(_nonPrRapLow, factor / sumOfWeights());

  scale(_IncRapHigh, 1000. * factor / sumOfWeights());
  scale(_IncRapMedHigh, 1000. * factor / sumOfWeights());
  scale(_IncRapMedLow, 1000. * factor / sumOfWeights());
  scale(_IncRapLow, 1000. * factor / sumOfWeights());
}

/// @}

private:

Histo1DPtr _nonPrRapHigh;
Histo1DPtr _nonPrRapMedHigh;
Histo1DPtr _nonPrRapMedLow;
Histo1DPtr _nonPrRapLow;

Histo1DPtr _PrRapHigh;
Histo1DPtr _PrRapMedHigh;
Histo1DPtr _PrRapMedLow;
Histo1DPtr _PrRapLow;

Histo1DPtr _IncRapHigh;
Histo1DPtr _IncRapMedHigh;
Histo1DPtr _IncRapMedLow;
Histo1DPtr _IncRapLow;

};

RIVET_DECLARE_ALIASED_PLUGIN(ATLAS_2011_I896268, ATLAS_2011_S9035664);

} ```

Aliases: - ATLAS_2011_S9035664