Rivet analyses reference

NA22_1986_I18431

Multiplicity distributions in $pp$ , $K^+ p$ and $\pi^+ p$ at $p_{\mathrm{lab}} = 250$ GeV/c
Experiment: NA22 (SPS)
Inspire ID: 18431
Status: VALIDATED
Authors:

Christian Bierlich

References:

Z.Phys. C32 (1986) 475

Beams: p+ p+, 321 p+, 211 p+
Beam energies: (250.0, 0.0); (250.0, 0.0); (250.0, 0.0) GeV
Run details:

Fixed target events with $p$ , $K^+$ and $\pi^+$ hitting a proton target.

Charged multiplicity distributions of $pp$ , $K^+ p$ and $\pi^+ p$ fixed target collisions, $p_{\mathrm{lab}} = 250$ GeV/c or equivalently $\sqrt{s} = 21.7$ GeV/c (pp).

Source code: NA22_1986_I18431.cc

 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/Beam.hh"
 4#include "Rivet/Projections/ChargedFinalState.hh"
 5
 6namespace Rivet {
 7
 8
 9  /// NA22 min bias multiplicity distributions.
10  class NA22_1986_I18431 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(NA22_1986_I18431);
15
16
17    /// @name Analysis methods
18    /// @{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22
23      declare(ChargedFinalState(), "CFS");
24
25      // Figure out beam type
26      const ParticlePair& beam = beams();
27      int btype = 0;
28      if (beam.first.pid() == PID::PIPLUS && beam.second.pid() == PID::PROTON) {
29        btype = 1;
30        sf *= 20.94; // simga_inel(pi+ p) from DOI:10.1007/BF01550769
31      }
32      else if (beam.first.pid() == PID::KPLUS && beam.second.pid() == PID::PROTON) {
33        btype = 2;
34        sf *= 17.72; // simga_inel(K+ p) from DOI:10.1007/BF01550769
35      }
36      else if (beam.first.pid() == PID::PROTON && beam.second.pid() == PID::PROTON) {
37        btype = 3;
38        sf *= 32.40; // simga_inel(p p) from DOI:10.1007/BF01550769
39      }
40      else {
41        MSG_ERROR("Beam error: Not compatible!");
42        return;
43      }
44
45      // Book histo for appropriate beam type
46      if (btype == 3)  book(_h_mult2, btype, 1, 1);
47      else             book(_h_mult1, btype, 1, 1);
48
49    }
50
51
52    /// Perform the per-event analysis
53    void analyze(const Event& event) {
54      size_t nfs = apply<ChargedFinalState>(event, "CFS").size();
55      if (nfs >= 30)  nfs = 30;
56      if (_h_mult1) {
57        string edge = to_string(nfs)+".0";
58        if (nfs == 30)  edge = ">= 30.0";
59        _h_mult1->fill(edge);
60      }
61      if (_h_mult2)  _h_mult2->fill(nfs);
62    }
63
64
65    /// Normalise histograms etc., after the run
66    void finalize() {
67      if (_h_mult1) normalize(_h_mult1, sf); // normalize to 2 to account for bin width
68      if (_h_mult2) normalize(_h_mult2, sf); // normalize to 2 to account for bin width
69    }
70
71    /// @}
72
73
74    /// @name Histograms
75    /// @{
76    BinnedHistoPtr<string> _h_mult1;
77    BinnedHistoPtr<int> _h_mult2;
78    double sf = 2.0;
79    /// @}
80
81
82  };
83
84
85  RIVET_DECLARE_PLUGIN(NA22_1986_I18431);
86
87
88}