Rivet analyses

title: BESIII_2021_I1929314

Cross sections for $e^+e^-\to$ $K^+K^-\pi^+\pi^-(\pi^0)$, $K^+K^-K^+K^-(\pi^0)$, $\pi^+\pi^-\pi^+\pi^-(\pi^0)$ and $p\bar{p}\pi^+\pi^-(\pi^0)$ between 3.773 and 4.6 GeV

Experiment: BESIII (BEPC)

Inspire ID: 1929314

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.D 104 (2021) 11, 112009

Beams: e+ e-

Beam energies: (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (2.0, 2.0); (2.0, 2.0); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3)GeV

Run details: - e+e- to hadrons

Measurement of the dressed cross sections for $e^+e^-\to$ $K^+K^-\pi^+\pi^-(\pi^0)$, $K^+K^-K^+K^-(\pi^0)$, $\pi^+\pi^-\pi^+\pi^-(\pi^0)$ and $p\bar{p}\pi^+\pi^-(\pi^0)$ between 3.773 and 4.6 GeV by the BESIII collaboration. There were three duplicate energy points in the data, for these points the one with higher statistics was retained.

Source code:BESIII_2021_I1929314.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+e- -> 4 charged particles (+pi0) cross sections class BESIII_2021_I1929314 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1929314);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(FinalState(), "FS");
  for (size_t ix = 0; ix < 8; ++ix) {
    book(_nCharged[ix], 1, 1, ix + 1);
  }

  for (const string& en : _nCharged[0].binning().edges<0>()) {
    const double eval = stod(en) * GeV;
    if (isCompatibleWithSqrtS(eval)) {
      _sqs = en;
      break;
    }
  }
  raiseBeamErrorIf(_sqs.empty());
}


/// 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;
  }
  if (ntotal == 4) {
    if (nCount[211] == 1 && nCount[-211] == 1) {
      if (nCount[321] == 1 && nCount[-321] == 1)
        _nCharged[0]->fill(_sqs);
      else if (nCount[2212] == 1 && nCount[-2212] == 1)
        _nCharged[3]->fill(_sqs);
    }
    else if (nCount[321] == 2 && nCount[-321] == 2)
      _nCharged[1]->fill(_sqs);
    else if (nCount[211] == 2 && nCount[-211] == 2)
      _nCharged[2]->fill(_sqs);
  }
  else if (ntotal == 5 && nCount[111] == 1) {
    if (nCount[211] == 1 && nCount[-211] == 1) {
      if (nCount[321] == 1 && nCount[-321] == 1)
        _nCharged[4]->fill(_sqs);
      else if (nCount[2212] == 1 && nCount[-2212] == 1)
        _nCharged[7]->fill(_sqs);
    }
    else if (nCount[321] == 2 && nCount[-321] == 2)
      _nCharged[5]->fill(_sqs);
    else if (nCount[211] == 2 && nCount[-211] == 2)
      _nCharged[6]->fill(_sqs);
  }
}


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


/// @name Histograms
/// @{
BinnedHistoPtr<string> _nCharged[8];
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2021_I1929314);

} ```