Rivet analyses

Inclusive production of protons, anti-protons and neutrons in p+p collisions at 158 GeV/c beam momentum

Experiment: NA49 (SPS)

Inspire ID: 818217

Status: UNVALIDATED

Authors: - Viktar Kireyeu

References: - https://link.springer.com/article/10.1140/epjc/s10052-009-1172-2

Beams: p+ p+

Beam energies: (8.7, 8.7)GeV

Run details: - pp collisions at 17.3~GeV. Minimum bias events.

Production of p, p̄ and neutrons in fixed target, $p_{} = $158 GeV/c. The elastic trigger is implemented by looking for elastic final states with only 2 particles, instead of attempting to reproduce the experimental trigger, which cannot be directly unfolded.

Source code:NA49_2009_I818217.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Particle.hh"
#include "Rivet/Projections/FinalState.hh"

namespace Rivet {


  class NA49_2009_I818217 : public Analysis {
  public:

    /// @name Constructors etc.
    /// @{
    /// Constructor
    NA49_2009_I818217()
        : Analysis("NA49_2009_I818217") { }

    void init() {
      declare(FinalState(), "FS");
      book(_h_dndxf, 1, 1, 1);
      book(_p_mptxf, 2, 1, 1);
      book(_h_dndy, 3, 1, 1);
      book(_c_ninel, "nInelastic");
    }

    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");
      const size_t numParticles = fs.particles().size();
      const float SRT = event.sqrtS();

      // Inelastic events selection
      if (numParticles <= 2) {
        MSG_DEBUG("Elastic event");
        vetoEvent;
      }
      _c_ninel->fill();

      // Plot distributions
      for (const Particle& p : fs.particles()) {
        if (p.pid() == PID::PROTON) {
          double xF = p.pz() / (SRT / 2.);
          _h_dndxf->fill(xF);
          _h_dndy->fill(p.rapidity());
          _p_mptxf->fill(xF, p.pt());
        }
      }
    }

    void finalize() {
      scale(_h_dndxf, 1. / *_c_ninel);                            // Scale by the number of inelastic events
      for (auto& b : _h_dndxf->bins()) b.scaleW(1. / b.xWidth()); // Scale by the bin width (dxF)

      scale(_h_dndy, 1. / *_c_ninel);
      for (auto& by : _h_dndy->bins()) by.scaleW(1. / by.xWidth());
    }

  private:

    CounterPtr _c_ninel;   // Counter of inelastic events
    Histo1DPtr _h_dndxf;   // dn/dxf histogram
    Histo1DPtr _h_dndy;    // dn/dy histogram
    Profile1DPtr _p_mptxf; // mean pT vs xF profile
  };

  RIVET_DECLARE_PLUGIN(NA49_2009_I818217);
}