Rivet analyses

title: BESII_2009_I835937

Cross sections for $e^+e^-\to K^0_SK^-K^-K^+\pi^+$, $K^0_SK^-\pi^+\eta$, $K^0_S K^- \rho^+$, $K^0_SK^-\pi^+\rho^0$ at 3.65 and 3.773 GeV

Experiment: BESII (BEPC)

Inspire ID: 835937

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Eur.Phys.J.C 64 (2009) 243-250

Beams: e+ e-

Beam energies: (1.8, 1.8); (1.9, 1.9)GeV

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

Measurement of the cross sections for $e^+e^-\to K^0_SK^-K^-K^+\pi^+$, $K^0_SK^-\pi^+\eta$, $K^0_S K^- \rho^+$, $K^0_SK^-\pi^+\rho^0$ at 3.65 and 3.773 GeV.

Source code:BESII_2009_I835937.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e+e- > light hadrons including KS0 class BESII_2009_I835937 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2009_I835937);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");

  if (isCompatibleWithSqrtS(3.65))
    _sqs = "3.65";
  else if (isCompatibleWithSqrtS(3.773)) {
    _sqs = "3.773";
    book(_sigma[1], 1, 1, 2);
  }
  raiseBeamErrorIf(_sqs.empty());
  for (size_t ix = 0; ix < 7; ++ix) {
    if (ix > 0 && ix < 5) continue;
    book(_sigma[ix], 1, 1, 1 + ix);
  }
}

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");
  // first the purely FS particles
  if (ntotal == 5 && nCount[310] == 1
      && ((nCount[-321] == 2 && nCount[321] == 1 && nCount[211] == 1)
          || (nCount[321] == 2 && nCount[-321] == 1 && nCount[-211] == 1))) {
    _sigma[0]->fill(_sqs);
  }

  // loop over unstable particles
  for (const Particle& p : ufs.particles(Cuts::pid == 221 || Cuts::pid == 113 || Cuts::abspid == 213)) {
    if (p.children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p, nRes, ncount);
    // eta /rho0
    bool matched = false;
    if (p.pid() == 221 || p.pid() == 113) {
      if (ncount == 3) {
        matched = true;
        for (const auto& val : nRes) {
          if (abs(val.first) == 310) {
            if (val.second != 1) {
              matched = false;
              break;
            }
          }
          else if (abs(val.first) == 211) {
            if (val.second != 1) {
              matched = false;
              break;
            }
          }
          else if (abs(val.first) == 321) {
            if (val.second != 1) {
              matched = false;
              break;
            }
          }
          else if (val.second != 0) {
            matched = false;
            break;
          }
        }
        if (matched) {
          if (p.pid() == 113)
            _sigma[6]->fill(_sqs);
          else if (p.pid() == 221 && _sqs == "3.773"s)
            _sigma[1]->fill(_sqs);
        }
      }
    }
    // rho+/-
    else if (p.abspid() == 213) {
      if (ncount == 2) {
        int sign = p.pid() > 0 ? -1 : 1;
        matched = true;
        for (const auto& val : nRes) {
          if (abs(val.first) == 310) {
            if (val.second != 1) {
              matched = false;
              break;
            }
          }
          else if (val.first == 321 * sign) {
            if (val.second != 1) {
              matched = false;
              break;
            }
          }
          else if (val.second != 0) {
            matched = false;
            break;
          }
        }
        if (matched) _sigma[5]->fill(_sqs);
      }
    }
    if (matched) break;
  }
}


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

/// @}


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

};

RIVET_DECLARE_PLUGIN(BESII_2009_I835937);

} ```