Rivet analyses

title: ALICE_2012_I1126966

Pion, Kaon, and Proton Production in Central Pb-Pb Collisions at 2.76 TeV

Experiment: ALICE (LHC)

Inspire ID: 1126966

Status: UNVALIDATED

Authors: - Cody B Duncan - Patrick Kirchgaesser - Johannes Bellm

References: - Phys.Rev.Lett. 109 (2012) 252301 - arXiv: 1208.1974

Beams: 1000822080 1000822080

Beam energies: (287040.0, 287040.0)GeV

Run details: - Analysis of various pT spectra in central Pb-Pb collisions at 2.76 TeV

Measurements of the transverse momentum distributions of charged pions, kaons and (anti)protons in Lead-Lead collisions at a centre-of-mass energy per nucleon of 2.76 TeV. The data, covering the PT range up to 4.5 GeV for protons, is restricted to the central rapidity range |y| < 0.5.

Source code:ALICE_2012_I1126966.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Analyses/AliceCommon.hh"

include "Rivet/Projections/CentralityProjection.hh"

namespace Rivet {

/// Pion, Kaon, and Proton Production in 0-5% /// central Pb--Pb Collisions at 2.76 TeV class ALICE_2012_I1126966 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ALICE_2012_I1126966);

/// Book histograms and initialise projections before the run
void init() {
  // Particles of interest.
  declare(ALICE::PrimaryParticles(Cuts::absrap < 0.5), "CFS");

  // The event trigger.
  declare(ALICE::V0AndTrigger(), "V0-AND");
  // The centrality projection.
  declareCentrality(ALICE::V0MMultiplicity(), "ALICE_2015_CENT_PBPB", "V0M", "V0M");

  // Invariant pT distributions.
  book(_histPtPi, "d01-x01-y01");        //pi+
  book(_histPtPibar, "d01-x01-y02");     // pi-
  book(_histPtKaon, "d02-x01-y01");      //K+
  book(_histPtKaonbar, "d02-x01-y02");   //K-
  book(_histPtProton, "d03-x01-y01");    //P+
  book(_histPtProtonbar, "d03-x01-y02"); //P-
  // Yield histograms.
  book(_histNpi, "d04-x01-y01");
  book(_histNpibar, "d04-x01-y02");
  book(_histNKaon, "d04-x01-y03");
  book(_histNKaonbar, "d04-x01-y04");
  book(_histNproton, "d04-x01-y05");
  book(_histNprotonbar, "d04-x01-y06");
  // Sum of weights of triggered events.
  book(sow, "sow");
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // Analysis only considers 0-5% central events
  if (apply<CentralityProjection>(event, "V0M")() > 5.0) vetoEvent;
  // Event trigger.
  if (!apply<ALICE::V0AndTrigger>(event, "V0-AND")()) vetoEvent;

  sow->fill();
  // ID particles counters for this event.
  int Npi = 0;
  int Npibar = 0;
  int NKaon = 0;
  int NKaonbar = 0;
  int Nproton = 0;
  int Nprotonbar = 0;

  for (const Particle& p : apply<ALICE::PrimaryParticles>(event, "CFS").particles()) {
    const double pWeight = 1.0 / p.pT() / 2. / M_PI;
    switch (p.pid()) {
      case 211: // pi+
        Npi++;
        _histPtPi->fill(p.pT() / GeV, pWeight);
        break;
      case -211: //pi-
        Npibar++;
        _histPtPibar->fill(p.pT() / GeV, pWeight);
        break;
      case 2212: // proton
        Nproton++;
        _histPtProton->fill(p.pT() / GeV, pWeight);
        break;
      case -2212: // p-bar
        Nprotonbar++;
        _histPtProtonbar->fill(p.pT() / GeV, pWeight);
        break;
      case 321: // K+
        NKaon++;
        _histPtKaon->fill(p.pT() / GeV, pWeight);
        break;
      case -321: // K-
        NKaonbar++;
        _histPtKaonbar->fill(p.pT() / GeV, pWeight);
        break;
    }
  } // Particle loop ends.

  // Fill yield histograms.
  _histNpi->fill(0.0, Npi);
  _histNpibar->fill(0.0, Npibar);
  _histNKaon->fill(0.0, NKaon);
  _histNKaonbar->fill(0.0, NKaonbar);
  _histNproton->fill(0.0, Nproton);
  _histNprotonbar->fill(0.0, Nprotonbar);
}


void finalize() {
  const double s = 1. / sow->sumW();
  _histPtPi->scaleW(s);
  _histPtPibar->scaleW(s);
  _histPtKaon->scaleW(s);
  _histPtKaonbar->scaleW(s);
  _histPtProton->scaleW(s);
  _histPtProtonbar->scaleW(s);
  _histNpi->scaleW(s);
  _histNpibar->scaleW(s);
  _histNKaon->scaleW(s);
  _histNKaonbar->scaleW(s);
  _histNproton->scaleW(s);
  _histNprotonbar->scaleW(s);
}

private:

// pT histograms
Histo1DPtr _histPtPi;
Histo1DPtr _histPtKaon;
Histo1DPtr _histPtProton;
Histo1DPtr _histPtPibar;
Histo1DPtr _histPtKaonbar;
Histo1DPtr _histPtProtonbar;
Histo1DPtr _histNpi;
Histo1DPtr _histNpibar;
Histo1DPtr _histNKaon;
Histo1DPtr _histNKaonbar;
Histo1DPtr _histNproton;
Histo1DPtr _histNprotonbar;
CounterPtr sow;

};

RIVET_DECLARE_PLUGIN(ALICE_2012_I1126966);

} ```