Rivet analyses

title: BESIII_2022_I1989527

Cross section for $e^+e^-\to D^{+}D^{-}$ and $D^\pm D^{*\mp}$ between 4.08 and 4.6 GeV

Experiment: BESIII (BEPC)

Inspire ID: 1989527

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - JHEP 05 (2022) 155

Beams: e+ e-

Beam energies: (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); (2.2, 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

Cross section for $e^+e^-\to D^{+}D^{-}$ and $D^\pm D^{*\mp}$ between 4.08 and 4.6 GeV.

Source code:BESIII_2022_I1989527.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e+e- > D+D-, D+- D*-+ class BESIII_2022_I1989527 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I1989527);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");
  book(_nDSS, 1, 1, 3);
  book(_nDS, 2, 1, 3);
  for (const string& en : _nDS.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()] -= 1;
      --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");

  for (size_t ix = 0; ix < ufs.particles().size(); ++ix) {
    const Particle& p1 = ufs.particles()[ix];
    if (p1.abspid() != 413) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p1, nRes, ncount);
    bool matched = false;
    int sign = -p1.pid() / abs(p1.pid());
    for (unsigned int iy = 0; iy < ufs.particles().size(); ++iy) {
      if (ix == iy) continue;
      const Particle& p2 = ufs.particles()[iy];
      if (!p2.parents().empty() && p2.parents()[0].pid() == p1.pid()) {
        continue;
      }
      if (p2.pid() != sign * 413 && p2.pid() != sign * 411) continue;
      map<long, int> nRes2 = nRes;
      int ncount2 = ncount;
      findChildren(p2, nRes2, ncount2);
      if (ncount2 != 0) continue;
      matched = true;
      for (const auto& val : nRes2) {
        if (val.second != 0) {
          matched = false;
          break;
        }
      }
      if (matched) {
        sign = abs(p2.pid());
        break;
      }
    }
    if (matched) {
      if (sign == 411)
        _nDS->fill(_sqs);
      else if (sign == 413)
        _nDSS->fill(_sqs);
    }
  }
}


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

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _nDSS, _nDS;
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2022_I1989527);

} ```