Rivet analyses

Pseudorapidity distribution of charged hadrons in proton–proton collisions at $\sqrt{s} = 13$ TeV

Experiment: CMS (LHC)

Inspire ID: 1384119

Status: VALIDATED

Authors: - Hannes Jung

References: - arXiv: 1507.05915

Beams: p+ p+

Beam energies: (6500.0, 6500.0)GeV

Run details: - $\sqrt{s}=13$ TeV, pp inelastic events, no pT cut on partons

The pseudorapidity distribution of charged hadrons in pp collisions at $\sqrt{s} =13$ TeV is measured using a data sample obtained with the CMS detector, operated at zero magnetic field, at the CERN LHC. The yield of primary charged long-lived hadrons produced in inelastic pp collisions is determined in the central region of the CMS pixel detector (|eta| < 2) using both hit pairs and reconstructed tracks.

Source code:CMS_2015_I1384119.cc

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

namespace Rivet {


  class CMS_2015_I1384119 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2015_I1384119);


    /// Book histograms and initialise projections before the run
    void init() {
      const FinalState fsa(Cuts::abseta < 20);
      declare(fsa, "FSA");
      const ChargedFinalState cfs(Cuts::abseta < 2);
      declare(cfs, "CFS");

      book(_hist_dNch_dEta_inel ,1, 1, 1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // Apply inelastic selection (veto pp -> pp elastic events)
      const FinalState& fsa = apply<FinalState>(event, "FSA");
      if (fsa.size() <= 2) vetoEvent;

      const ChargedFinalState& cfs = apply<ChargedFinalState>(event, "CFS");
      for (const Particle& p : cfs.particles()) {
        const int id = p.abspid();
        // continue if particle is a proton, a kaon or a pion
        if (id == 211 || id == 321 || id == 2212) ///< @todo Use PID:: ID constants
          _hist_dNch_dEta_inel->fill(p.eta(), 1.0);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_hist_dNch_dEta_inel,  1/sumOfWeights());
    }


  private:

    /// Histograms
    Histo1DPtr _hist_dNch_dEta_inel;

  };


  RIVET_DECLARE_PLUGIN(CMS_2015_I1384119);

}