Rivet analyses

title: ATLAS_2015_I1360290

Charged particle spectra in Pb--Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV.

Experiment: ATLAS (LHC)

Inspire ID: 1360290

Status: UNVALIDATED

Authors: - Christian Bierlich

References: - Expt page: ATLAS-HION-2011-03 - JHEP 09 (2015) 050 - arXiv: 1504.04337

Beams: 1000822080 1000822080

Beam energies: (287040.0, 287040.0)GeV

Run details: - Pb--Pb minimum bias events. Centrality calibration from ATLAS_PBPB_CENTRALITY.

Invariant $p_\perp$ spectra of charged particles as function of centrality, in Pb--Pb collisions. Also measured is $\eta$ distributions at various $p_\perp$ intervals. Nuclear modification factors currently not implemented, but could be.

Source code:ATLAS_2015_I1360290.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Analyses/AtlasCommon.hh"

include "Rivet/Projections/ChargedFinalState.hh"

namespace Rivet {

/// @brief Add a short analysis description here class ATLAS_2015_I1360290 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2015_I1360290);


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

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

  // Initialise and register projections
  // Centrality projection.
  declareCentrality(ATLAS::SumET_PBPB_Centrality(), "ATLAS_PBPB_CENTRALITY", "sumETFwd", "sumETFwd");
  // Trigger projection.
  declare(ATLAS::MinBiasTrigger(), "Trigger");
  // The measured final state.
  declare(ChargedFinalState(Cuts::abseta < 2. && Cuts::pT > 0.5 * GeV && Cuts::pT < 150.0 * GeV), "CFS");

  taa = {26.3, 20.6, 14.4, 8.73, 5.05, 2.70, 1.34, 0.41};
  centData = {5., 10., 20., 30., 40., 50., 60., 80.};

  for (int i = 0, N = centData.size(); i < N; ++i) {
    // eta hists starts from table 55 ( first 1.7 < pT < 2.0)
    book(histEta1[centData[i]], 55 + i, 1, 1);
    // From table 64, 6.7 < pT < 7.7
    book(histEta2[centData[i]], 64 + i, 1, 1);
    // From table 73, 19.9 < pT < 22.8
    book(histEta3[centData[i]], 73 + i, 1, 1);
    // From table 82, 59.8 < pT < 94.8
    book(histEta4[centData[i]], 82 + i, 1, 1);
    // pt hists starts from table 2 on hepmc, |eta| < 2.0
    book(histpT[centData[i]], 2 + i, 1, 1);
    // keep track of sow in centrality bins.
    book(sow[centData[i]], "sow_" + toString(i));
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  if (!apply<ATLAS::MinBiasTrigger>(event, "Trigger")()) vetoEvent;
  const CentralityProjection& cent = apply<CentralityProjection>(event, "sumETFwd");
  double c = cent();
  // Find the correct centrality histograms
  auto hItr1 = histEta1.upper_bound(c);
  if (hItr1 == histEta1.end()) return;
  auto hItr2 = histEta2.upper_bound(c);
  if (hItr2 == histEta2.end()) return;
  auto hItr3 = histEta3.upper_bound(c);
  if (hItr3 == histEta3.end()) return;
  auto hItr4 = histEta4.upper_bound(c);
  if (hItr4 == histEta4.end()) return;
  auto hpTItr = histpT.upper_bound(c);
  if (hpTItr == histpT.end()) return;
  // Find the correct sow.
  auto sItr = sow.upper_bound(c);
  if (sItr == sow.end()) return;
  sItr->second->fill();

  for (const auto& p : apply<ChargedFinalState>(event, "CFS").particles()) {
    const double pT = p.pT();
    const double eta = p.abseta();
    if (pT > 1.7 && pT < 2.0)
      hItr1->second->fill(eta, 0.5);
    else if (pT > 6.7 && pT < 7.7)
      hItr2->second->fill(eta, 0.5);
    else if (pT > 19.9 && pT < 22.8)
      hItr3->second->fill(eta, 0.5);
    else if (pT > 59.8 && pT < 94.8)
      hItr4->second->fill(eta, 0.5);
    if (eta < 2) hpTItr->second->fill(pT, 1.0 / 2. / M_PI / pT / 4.);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (int i = 0, N = centData.size(); i < N; ++i) {
    histEta1[centData[i]]->scaleW(1. / sow[centData[i]]->sumW());
    histEta2[centData[i]]->scaleW(1. / sow[centData[i]]->sumW());
    histEta3[centData[i]]->scaleW(1. / sow[centData[i]]->sumW());
    histEta4[centData[i]]->scaleW(1. / sow[centData[i]]->sumW());
    histpT[centData[i]]->scaleW(1. / sow[centData[i]]->sumW() / taa[i]);
  }
}

/// @}


/// @name Histograms
/// @{
// The centrality binned histograms
map<double, Histo1DPtr> histEta1;
map<double, Histo1DPtr> histEta2;
map<double, Histo1DPtr> histEta3;
map<double, Histo1DPtr> histEta4;
map<double, Histo1DPtr> histpT;
map<double, CounterPtr> sow;


vector<double> centData;
vector<double> taa;
/// @}

};

RIVET_DECLARE_PLUGIN(ATLAS_2015_I1360290);

} ```