Rivet analyses

title: BELLE_2018_I1678261

Cross section for $e^+e^-\to\pi^+\pi^-\pi^0\chi_{b(1,2)}$ for $\sqrt{s}=10.96-11.05$ GeV

Experiment: BELLE (KEKB)

Inspire ID: 1678261

Status: VALIDATED NOHEPDATA SINGLEWEIGHT

Authors: - Peter Richardson

References: - Phys.Rev.D 98 (2018) 9, 091102

Beams: e+ e-

Beam energies: (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.4, 5.4); (5.5, 5.5); (5.5, 5.5); (5.5, 5.5); (5.5, 5.5); (5.5, 5.5); (5.5, 5.5); (5.5, 5.5); (5.5, 5.5); (5.5, 5.5); (5.5, 5.5)GeV

Run details: - e+ e- -> hadrons, KS0 and pi0 set stable

Measurement of the cross for $e^+e^-\to\pi^+\pi^-\pi^0\chi_{b(1,2)}$ for $\sqrt{s}=10.96-11.05$ GeV by BELLE.

Source code:BELLE_2018_I1678261.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e+e- -> pi+ pi- pi0 chi_b1,2 class BELLE_2018_I1678261 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2018_I1678261);


/// @name Analysis methods
/// @{

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(Cuts::pid == 20553 || Cuts::pid == 555), "UFS");
  book(_sigma, 1, 1, 1);
  for (const string& en : _sigma.binning().edges<0>()) {
    const double eval = std::stod(en) * GeV;
    if (isCompatibleWithSqrtS(eval)) {
      _sqs = en;
      break;
    }
  }
  raiseBeamErrorIf(_sqs.empty());
}

void findChildren(const Particle& p, map<long, int>& nRes, int& ncount) const {
  for (const Particle& child : p.children()) {
    if (child.children().empty()) {
      --nRes[child.pid()];
      --ncount;
    }
    else {
      findChildren(child, nRes, ncount);
    }
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& fs = apply<FinalState>(event, "FS");
  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  const FinalState& ufs = apply<FinalState>(event, "UFS");
  // loop over any chi mesons
  for (const Particle& chi : ufs.particles()) {
    bool matched = false;
    if (chi.children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(chi, nRes, ncount);
    if (ncount == 3) {
      matched = true;
      for (const auto& val : nRes) {
        if (abs(val.first) == PID::PIPLUS || val.first == PID::PI0) {
          if (val.second != 1) {
            matched = false;
            break;
          }
        }
        else if (val.second != 0) {
          matched = false;
          break;
        }
      }
      if (!matched) continue;
      _sigma->fill(_sqs);
      break;
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_sigma, crossSection() / sumOfWeights() / picobarn);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _sigma;
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2018_I1678261);

} ```