Rivet analyses

title: BESIII_2017_I1607253

Cross sections for $e^+e^-\to \phi\phi\phi$ and $\phi\phi\omega$ for energies between 4 and 4.6 GeV

Experiment: BESIII (BEPC)

Inspire ID: 1607253

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 774 (2017) 78-86 - arXiV:1706.07490 [hep-ex]

Beams: e+ e-

Beam energies: (2.0, 2.0); (2.1, 2.1); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3)GeV

Run details: - e+ e- to hadrons

Measurement of the cross sections for $e^+e^-\to \phi\phi\phi$ and $\phi\phi\omega$ for energies between 4 and 4.6 GeV

Source code:BESIII_2017_I1607253.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e+ e- > 2 phi + phi or omega class BESIII_2017_I1607253 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2017_I1607253);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(Cuts::pid == 223 || Cuts::pid == 333), "UFS");
  // counters
  for (size_t ix = 0; ix < 2; ++ix) {
    book(_sigma[ix], 1 + ix, 1, 1);
  }

  for (const string& en : _sigma[0].binning().edges<0>()) {
    const double eval = 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");
  Particles phi = ufs.particles(Cuts::pid == 333);
  Particles omega = ufs.particles(Cuts::pid == 223);
  if (phi.size() < 2) vetoEvent;
  bool found = false;
  // first phi
  for (unsigned int ix = 0; ix < phi.size(); ++ix) {
    const Particle& phi1 = phi[ix];
    if (phi1.children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(phi1, nRes, ncount);
    // second phi
    for (unsigned int iy = ix + 1; iy < phi.size(); ++iy) {
      const Particle& phi2 = phi[iy];
      if (phi2.children().empty()) continue;
      map<long, int> nRes2 = nRes;
      int ncount2 = ncount;
      findChildren(phi2, nRes2, ncount2);
      // search for third phi
      for (unsigned int iz = iy + 1; iz < phi.size(); ++iz) {
        const Particle& phi3 = phi[iz];
        if (phi3.children().empty()) continue;
        map<long, int> nRes3 = nRes2;
        int ncount3 = ncount2;
        findChildren(phi3, nRes3, ncount3);
        found = true;
        for (const auto& val : nRes3) {
          if (val.second != 0) {
            found = false;
            break;
          }
        }
        if (found) {
          _sigma[1]->fill(_sqs);
          break;
        }
      }
      if (found) break;
      // search for omega
      for (unsigned int iz = 0; iz < omega.size(); ++iz) {
        const Particle& omega1 = omega[iz];
        if (omega1.children().empty()) continue;
        map<long, int> nRes3 = nRes2;
        int ncount3 = ncount2;
        findChildren(omega1, nRes3, ncount3);
        found = true;
        for (const auto& val : nRes3) {
          if (val.second != 0) {
            found = false;
            break;
          }
        }
        if (found) {
          _sigma[0]->fill(_sqs);
          break;
        }
      }
      if (found) break;
    }
    if (found) break;
  }
}


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

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _sigma[2];
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2017_I1607253);

} ```