Rivet analyses

Charged particle ⟨p⟂⟩ vs. Nch in pp collisions at 900 GeV

Experiment: ALICE (LHC)

Inspire ID: 860416

Status: VALIDATED

Authors: - Holger Schulz - Jan Fiete Grosse-Oetringhaus

References: - Phys.Lett.B693:53-68,2010 - arXiv: 1007.0719

Beams: p+ p+

Beam energies: (450.0, 450.0)GeV

Run details: - Diffractive events need to be switched on

ALICE measurement of ⟨p⟂⟩ vs. Nch and invariant particle yield (as function of p⟂) in proton-proton collisions at $\sqrt{s} = 900~\GeV$.

Source code:ALICE_2010_I860416.cc

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

namespace Rivet {


  class ALICE_2010_I860416 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(ALICE_2010_I860416);


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

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

      ChargedFinalState cfs((Cuts::etaIn(-0.8, 0.8) && Cuts::pT >= 0.15));
      declare(cfs, "CFS");

      book(_h_pT, 4, 1, 1);

      book(_h_pT_Nch_015, 11, 1, 1);
      book(_h_pT_Nch_05,  12, 1, 1);

      book(_Nevt_after_cuts,"Nevt_after_cuts");

    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const ChargedFinalState& charged = apply<ChargedFinalState>(event, "CFS");

      _Nevt_after_cuts->fill();

      // Get number of particles that fulfill certain pT requirements
      int Nch_015 = 0;
      int Nch_05  = 0;
      for (const Particle& p : charged.particles()) {
        double pT = p.pT()/GeV;
        if (pT < 4.0) Nch_015++;
        if (pT > 0.5  && pT < 4.0) Nch_05++;
      }

      // Now we can fill histograms
      for (const Particle& p : charged.particles()) {
        double pT = p.pT()/GeV;
        if (pT < 4.0) _h_pT_Nch_015 ->fill(Nch_015, pT);
        if (pT > 0.5  && pT < 4.0) _h_pT_Nch_05  ->fill(Nch_05,  pT);

      // To get the Yield, fill appropriate weight 1/(2PI * pT * d eta)
        _h_pT->fill(pT, 1.0 /(TWOPI*pT*1.6) );
      }

    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_h_pT, 1.0/ *_Nevt_after_cuts);
    }

    /// @}


  private:

    /// @name Histograms
    /// @{
    Histo1DPtr _h_pT;
    Profile1DPtr _h_pT_Nch_015;
    Profile1DPtr _h_pT_Nch_05;
    CounterPtr _Nevt_after_cuts;
    /// @}

  };



  RIVET_DECLARE_ALIASED_PLUGIN(ALICE_2010_I860416, ALICE_2010_S8706239);

}

Aliases: - ALICE_2010_S8706239