Rivet analyses

title: STAR_2014_I1253360

The differential cross section within the pseudorapidity range $0.8 < \eta < 2.0$ in proton-proton collisions at $\sqrt{s} = 200$~GeV

Experiment: STAR (RHIC)

Inspire ID: 1253360

Status: VALIDATED

Authors: - Dmitry Kalinkin

References: - Phys. Rev. D 89, 012001 - DOI:10.1103/PhysRevD.89.012001 - arXiv: 1309.1800

Beams: p+ p+

Beam energies: (100.0, 100.0)GeV

Run details: none listed

The differencial inclusive cross section for pi0 production is measured at STAR using data from Run 6.

Source code:STAR_2014_I1253360.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief pi0 production cross section measured at STAR class STAR_2014_I1253360 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(STAR_2014_I1253360);

const double ETA_MIN = 0.8;
const double ETA_MAX = 2.0;
const double DELTA_ETA = ETA_MAX - ETA_MIN;

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

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

  // Initialise and register projections

  const UnstableParticles fs(Cuts::eta > ETA_MIN && Cuts::eta < ETA_MAX && Cuts::pid == 111);
  declare(fs, "fs");

  // Book histograms
  book(_h_pi0_pt, 8, 1, 1);
  _axis = YODA::Axis<double>({5., 6., 7., 8., 9., 10., 12., 16.});
}


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

  if (_edges.empty()) _edges = _h_pi0_pt->xEdges();

  const Particles& particles = apply<UnstableParticles>(event, "fs").particles();

  for (const Particle& p : particles) {
    discfill(p.pT() / GeV, 1 / (p.pT() / GeV));
  }
}

void discfill(const double value, double weight) {
  const size_t idx = _axis.index(value);
  string edge("OTHER");
  if (idx && idx <= _edges.size()) {
    edge = _edges[idx - 1];
    weight /= _axis.width(idx);
  }
  _h_pi0_pt->fill(edge, weight);
}

/// Normalise histograms etc., after the run
void finalize() {

  scale(_h_pi0_pt, crossSection() / millibarn / sumW() / (2 * pi) / DELTA_ETA);
}

///@}


/// @name Histograms
///@{
BinnedHistoPtr<string> _h_pi0_pt;
YODA::Axis<double> _axis;
vector<string> _edges;
///@}

};

RIVET_DECLARE_PLUGIN(STAR_2014_I1253360);

} ```