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E735_1998_S3905616

Charged particle multiplicity in $p\bar{p}$ collisions at $\sqrt{s} = 1.8\;\text{TeV}$
Experiment: E735 (Tevatron)
Inspire ID: 480349
Status: VALIDATED
Authors:
  • Holger Schulz
  • Andy Buckley
References:
  • Phys.Lett.B435:453-457,1998
Beams: p- p+
Beam energies: (900.0, 900.0) GeV
Run details:
  • QCD events, diffractive processes need to be switched on in order to fill the low multiplicity regions. The measurement was done in $|\eta| \lesssim 3.25$ and was extrapolated to full phase space. However, the method of extrapolation remains unclear.

A measurement of the charged multiplicity distribution at $\sqrt{s} = 1.8\;\text{TeV}$. The analysis is reproduced to the best of abilities. There is no theory curve in the paper to compare to.

Source code: E735_1998_S3905616.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"

#include "Rivet/Projections/TriggerCDFRun0Run1.hh"
#include "Rivet/Projections/TriggerUA5.hh"

namespace Rivet {


  /// @brief E735 charged multiplicity in NSD-triggered events
  class E735_1998_S3905616 : public Analysis {
  public:

    /// Constructor
    E735_1998_S3905616() : Analysis("E735_1998_S3905616") {
      _sumWTrig = 0;
    }


    /// @name Analysis methods
    //@{

    void init() {
      // Projections
      declare(TriggerUA5(), "Trigger");
      declare(ChargedFinalState(), "FS");

      // Histo
      _hist_multiplicity = bookHisto1D(1, 1, 1);
    }


    void analyze(const Event& event) {
      const bool trigger = apply<TriggerUA5>(event, "Trigger").nsdDecision();
      if (!trigger) vetoEvent;
      const double weight = event.weight();
      _sumWTrig += weight;

      const ChargedFinalState& fs = apply<ChargedFinalState>(event, "FS");
      const size_t numParticles = fs.particles().size();
      _hist_multiplicity->fill(numParticles, weight);
    }


    void finalize() {
      scale(_hist_multiplicity, 1/_sumWTrig);
    }

    //@}


  private:

    /// @name Weight counter
    //@{
    double _sumWTrig;
    //@}

    /// @name Histograms
    //@{
    Histo1DPtr _hist_multiplicity;
    //@}

  };



  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(E735_1998_S3905616);

}