Rivet analyses

title: ATLAS_2015_I1386475

Centrality dependent of pseudorapidity distributions in p-Pb collisions $\sqrt{s_{_\text{NN}}}=5.02$ TeV.

Experiment: ATLAS (LHC)

Inspire ID: 1386475

Status: UNVALIDATED

Authors: - Leif Lonnblad - Christian Bierlich

References: - Expt page: ATLAS-HION-2012-15 - Eur.Phys.J. C76 (2016) no.4, 199 - DOI:0.1140/epjc/s10052-016-4002-3 - arXiv: 1508.00848

Beams: p+ 1000822080

Beam energies: (4000.0, 326560.0)GeV

Run details: - p-Pb minimum bias events with $c\tau > 10 cm$ stable.

The centrality dependence of the mean charged-particle multiplicity as a function of pseudorapidity in proton-lead collisions. The collision energy is asymmetric, 4000 GeV for the proton and 1570/N for the lead. The primary particle definition is $c\tau > 10 cm$ stable, and should be enforced at generator level.

Source code:ATLAS_2015_I1386475.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Analyses/AtlasCommon.hh"

namespace Rivet {

/// @brief Add a short analysis description here class ATLAS_2015_I1386475 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2015_I1386475);
/// Book histograms and initialise projections before the run
void init() {

  // The centrality projection.
  declareCentrality(ATLAS::SumET_PB_Centrality(), "ATLAS_CENT_PPB_CALIB", "SumETPb", "CENT");

  // The trigger projection.
  declare(ATLAS::MinBiasTrigger(), "Trigger");

  // The particles to be analysed.
  declare(ChargedFinalState(Cuts::eta > -2.7 && Cuts::eta < 2.7 && Cuts::pT > 0.1 * GeV), "CFS");

  // The centrality bins' upper edges.
  centralityBins = {90., 60., 40., 30., 20., 10., 5., 1.};
  for (int i = 0; i < 8; ++i) {
    book(histEta[centralityBins[i]], 2, 1, i + 1);
    book(sow[centralityBins[i]], "_sow" + to_string(i) + "Counter");
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {

  // Apply event triggers.
  if (!apply<ATLAS::MinBiasTrigger>(event, "Trigger")()) vetoEvent;

  // We must have direct acces to the centrality projection.
  const CentralityProjection& cent = apply<CentralityProjection>(event, "CENT");
  double c = cent();
  // Find the correct centrality histogram
  auto hItr = histEta.upper_bound(c);
  if (hItr == histEta.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()) hItr->second->fill(p.eta());
}

/// Finalize
void finalize() {

  // Scale by the inverse sum of event weights in each centrality
  // bin.
  for (int i = 0; i < 8; ++i) {
    histEta[centralityBins[i]]->scaleW(1. / sow[centralityBins[i]]->sumW());
  }
}

private:

/// The histograms binned in centrality.
vector<double> centralityBins;
map<double, Histo1DPtr> histEta;
map<double, CounterPtr> sow;

};

RIVET_DECLARE_PLUGIN(ATLAS_2015_I1386475);

} ```