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Rivet analyses reference

TASSO_1982_I168232

$\pi^0$ spectrum in $e^+e^-$ at 14 and 34 GeV
Experiment: TASSO (TASSO)
Inspire ID: 168232
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B108 (1982) 71-76, 1982
Beams: e+ e-
Beam energies: (7.0, 7.0); (17.0, 17.0) GeV
Run details:
  • e+ e- to hadrons. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Measurement of the $\pi^0$ spectrum in $e^+e^-$ collisions for centre-of-mass energies of 14 and 34 GeV by the TASSO experiment at Petra. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Source code: TASSO_1982_I168232.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4#include "Rivet/Projections/Beam.hh"
 5
 6namespace Rivet {
 7
 8
 9  /// @brief pi0 spectrum at 14 and 34 GeV
10  class TASSO_1982_I168232 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1982_I168232);
15
16
17    /// @name Analysis methods
18    //@{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22
23
24      declare(Beam(), "Beams");
25      declare(UnstableParticles(), "UFS");
26      
27      // Book histograms
28      sqs = 1.0;
29      if(isCompatibleWithSqrtS(14.)) {
30	book(_h_E, 2,1,1);
31	book(_h_p, 2,2,2);
32	book(_h_x, 2,3,3);
33	sqs = 14.0;
34      }
35      else if (isCompatibleWithSqrtS(34.)) {
36	book(_h_E, 3,1,1);
37	book(_h_p, 3,2,2);
38	book(_h_x, 3,3,3);
39	sqs = 34.0;
40      }
41      else
42        MSG_ERROR("Not compatible with energy " << sqrtS() << "GeV.");
43    }
44
45
46    /// Perform the per-event analysis
47    void analyze(const Event& event) {
48      // Get beams and average beam momentum
49      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
50      const double meanBeamMom = ( beams.first.p3().mod() +
51                                   beams.second.p3().mod() ) / 2.0;
52      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
53
54      for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::PI0)) {
55	if(!p.parents().empty() && p.parents()[0].pid()==PID::K0S)
56	  continue;
57	double xE = p.E()/meanBeamMom;
58	double beta = p.p3().mod()/p.E();
59	_h_E->fill(p.E()       );
60	_h_p->fill(p.p3().mod());
61	_h_x->fill(xE,1./beta);
62      }
63
64    }
65
66
67    /// Normalise histograms etc., after the run
68    void finalize() {
69
70      scale(_h_E, crossSection()/nanobarn/sumOfWeights());
71      scale(_h_p, crossSection()/nanobarn/sumOfWeights());
72      scale(_h_x, sqr(sqs)*crossSection()/microbarn/sumOfWeights());
73
74    }
75
76    //@}
77
78
79    /// @name Histograms
80    //@{
81    Histo1DPtr _h_E,_h_p,_h_x;
82    double sqs;
83    //@}
84
85  };
86
87  // The hook for the plugin system
88  RIVET_DECLARE_PLUGIN(TASSO_1982_I168232);
89
90}