Rivet analyses

title: CMD3_2022_I2108984

Cross section for $e^+e^-\to K^0_SK^\pm\pi^\mp\pi^+\pi^-$ between 1.6 and 2 GeV by CMD3

Experiment: CMD3 (VEPP-2M)

Inspire ID: 2108984

Status: VALIDATED NOHEPDATA

Authors: - Peter Richrdson

References: - arXiv: 2207.04615

Beams: e+ e-

Beam energies: ANY

Run details: - e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to K^0_SK^\pm\pi^\mp\pi^+\pi^-$, and the resonant sub-processes $f_1(1285)\pi^+\pi^-$, for energies between 1.6 and 2 GeV by the CMD3 experiment

Source code:CMD3_2022_I2108984.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e+e-> KS0 Kpi pi+pi- class CMD3_2022_I2108984 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMD3_2022_I2108984);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(Cuts::pid == 20223), "UFS");
  book(_sigma, 1, 1, 1);
  book(_res[0], "TMP/c_0", refData(2, 1, 1));
  book(_res[1], "TMP/c_1", refData(2, 1, 2));
  for (const string& en : _sigma.binning().edges<0>()) {
    const size_t idx = en.find(" to ");
    if (idx != string::npos) {
      const double emin = stod(en.substr(0, idx));
      const double emax = stod(en.substr(idx + 4, string::npos));
      if (inRange(sqrtS() / MeV, emin, emax)) {
        _sqs.push_back(en);
      }
    }
    else {
      const double eVal = stod(en) * MeV;
      if (isCompatibleWithSqrtS(eVal)) {
        _sqs.push_back(en);
      }
    }
  }
  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) {
  // find the final-state particles
  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;
  }
  // the FS cross section
  bool foundFS = false;
  if (ntotal == 5 && nCount[310] == 1
      && ((nCount[211] == 2 && nCount[-211] == 1 && nCount[-321] == 1)
          || (nCount[211] == 1 && nCount[-211] == 2 && nCount[321] == 1))) {
    foundFS = true;
    for (const string& en : _sqs) _sigma->fill(en);
  }
  // check for intermediate f_1
  for (const Particle& p : apply<FinalState>(event, "UFS").particles()) {
    if (p.children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p, nRes, ncount);
    if (ncount != 2) continue;
    bool matched = true;
    for (const auto& val : nRes) {
      if (abs(val.first) == 211) {
        if (val.second != 1) {
          matched = false;
          break;
        }
      }
      else if (val.second != 0) {
        matched = false;
        break;
      }
    }
    if (matched) {
      _res[1]->fill(sqrtS() / MeV);
      if (foundFS) _res[0]->fill(sqrtS() / MeV);
      break;
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double fact = crossSection() / nanobarn / sumOfWeights();
  scale(_sigma, fact);
  for (size_t ix = 0; ix < 2; ++ix) {
    scale(_res[ix], fact);
    Estimate1DPtr tmp;
    book(tmp, 2, 1, 1 + ix);
    barchart(_res[ix], tmp);
  }
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _sigma;
Histo1DPtr _res[2];
vector<string> _sqs;
/// @}

};

RIVET_DECLARE_PLUGIN(CMD3_2022_I2108984); } ```