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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 Lönnblad
  • Christian Bierlich
References:
  • 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
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Tools/AtlasCommon.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief Add a short analysis description here
 9  class ATLAS_2015_I1386475 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2015_I1386475);
14 /// Book histograms and initialise projections before the run
15  void init() {
16
17    // The centrality projection.
18    declareCentrality(ATLAS::SumET_PB_Centrality(),
19                      "ATLAS_pPb_Calib", "SumETPb", "CENT");
20
21    // The trigger projection.
22    declare(ATLAS::MinBiasTrigger(), "Trigger");
23
24    // The particles to be analysed.
25    declare(ChargedFinalState(Cuts::eta > -2.7 && Cuts::eta < 2.7 &&
26                              Cuts::pT > 0.1*GeV), "CFS");
27    
28    // The centrality bins' upper edges.
29    centralityBins = {90., 60., 40., 30., 20., 10., 5., 1.};
30    for (int i = 0; i < 8; ++i) {
31      book(histEta[centralityBins[i]], 2, 1, i + 1);
32      book(sow[centralityBins[i]], "_sow"+to_string(i) + "Counter");
33    }
34  }
35
36  /// Perform the per-event analysis
37  void analyze(const Event& event) {
38    
39    // Apply event triggers.
40    if ( !apply<ATLAS::MinBiasTrigger>(event, "Trigger")() ) vetoEvent;
41
42    // We must have direct acces to the centrality projection.
43    const CentralityProjection& cent = 
44      apply<CentralityProjection>(event,"CENT");
45    double c = cent();
46    // Find the correct centrality histogram
47    auto hItr = histEta.upper_bound(c);
48    if (hItr == histEta.end()) return;
49    // Find the correct sow.
50    auto sItr = sow.upper_bound(c);
51    if (sItr == sow.end()) return;
52    sItr->second->fill();
53    for ( const auto &p : apply<ChargedFinalState>(event,"CFS").particles() )
54      hItr->second->fill(p.eta());
55  }
56    
57  /// Finalize
58  void finalize() {
59
60    // Scale by the inverse sum of event weights in each centrality
61    // bin.
62    for (int i = 0; i < 8; ++i)
63      histEta[centralityBins[i]]->scaleW(1./sow[centralityBins[i]]->sumW());
64
65  }
66
67private:
68
69  /// The histograms binned in centrality.
70  vector<double> centralityBins;
71  map<double,Histo1DPtr> histEta;
72  map<double, CounterPtr> sow;
73
74
75
76
77
78  };
79
80
81  // The hook for the plugin system
82  RIVET_DECLARE_PLUGIN(ATLAS_2015_I1386475);
83
84
85}