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BABAR_2006_I709730

Cross section for $e^+e^-\to$ $3\pi^+3\pi^-$, $2\pi^+2\pi^-2\pi^0$, $2\pi^+2\pi^-K^+K^-$
Experiment: BABAR (PEP-II)
Inspire ID: 709730
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D73.052003
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Cross sections for $3\pi^+3\pi^-$, $2\pi^+2\pi^-2\pi^0$ and $2\pi^+2\pi^-K^+K^-$ measured by BaBar using radiative return. Useful to compare hadronization and other non-perturbative models at low energies between 1.3 and 4.5 GeV.

Source code: BABAR_2006_I709730.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5
 6namespace Rivet {
 7
 8
 9  /// @brief e+e- -> 3pi+3pi-, 2pi+pi-2pi0, 2pi+pi-K+K-
10  class BABAR_2006_I709730 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2006_I709730);
15
16
17    /// @name Analysis methods
18    /// @{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22
23      // Initialise and register projections
24      declare(FinalState(), "FS");
25      book(_num3pip3pim,      "TMP/num3pip3pim"     );
26      book(_num2pip2pim2pi0,  "TMP/num2pip2pim2pi0" );
27      book(_num2pip2pim2KpKm, "TMP/num2pip2pim2KpKm");
28    }
29
30
31    /// Perform the per-event analysis
32    void analyze(const Event& event) {
33      const FinalState& fs = apply<FinalState>(event, "FS");
34
35      map<long,int> nCount;
36      int ntotal(0);
37      for (const Particle& p : fs.particles()) {
38	nCount[p.pid()] += 1;
39	++ntotal;
40      }
41
42      if(ntotal!=6) vetoEvent;
43      if(nCount[-211]==3 && nCount[211]==3)
44	_num3pip3pim->fill();
45      else if(nCount[-211]==2 && nCount[211]==2 && nCount[111]==2)
46	_num2pip2pim2pi0->fill();
47      else if(nCount[-211]==2 && nCount[211]==2 && nCount[321]==1 && nCount[-321]==1)
48	_num2pip2pim2KpKm->fill();
49    }
50
51
52    /// Normalise histograms etc., after the run
53    void finalize() {
54
55      for(unsigned int ix=1; ix<4; ++ix) {
56        double sigma = 0., error = 0.;
57        if(ix==1) {
58          sigma = _num3pip3pim->val();
59          error = _num3pip3pim->err();
60        }
61        else if(ix==2) {
62          sigma = _num2pip2pim2pi0->val();
63          error = _num2pip2pim2pi0->err();
64        }
65        else if(ix==3) {
66          sigma = _num2pip2pim2KpKm->val();
67          error = _num2pip2pim2KpKm->err();
68        }
69        sigma *= crossSection()/ sumOfWeights() /nanobarn;
70        error *= crossSection()/ sumOfWeights() /nanobarn;
71        Estimate1DPtr mult;
72        book(mult, ix, 1, 1);
73        for (auto& b : mult->bins()) {
74          if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
75            mult->bin(1).set(sigma, error);
76          }
77        }
78      }
79    }
80
81    /// @}
82
83    // just count the number of events of the types we're looking for
84    CounterPtr _num3pip3pim,_num2pip2pim2pi0,_num2pip2pim2KpKm;
85
86  };
87
88
89  RIVET_DECLARE_PLUGIN(BABAR_2006_I709730);
90
91
92}