Rivet analyses

title: BESII_2007_I762901

Cross-sections for light hadrons at 3.650 and 3.773 GeV

Experiment: BESII (BEPC)

Inspire ID: 762901

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B656 (2007) 30-37, 2007

Beams: e+ e-

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

Run details: - e+e- to hadrons

Cross section for $e^+e^-\to 2\pi^+2\pi^-K^+K^-$, $\pi^+\pi^-2K^+2K^-$, $2\pi^+2\pi^-p\bar{p}$, $3\pi^+3\pi^-$, $2\pi^+2\pi^-K^+K^-\pi^0$, $\rho^0\pi^+\pi^-$, $\rho^0K^+K^-$, $\rho^0p\bar{p}$, $K^{*0}K^-\pi^++\text{c.c.}$ at 3.650 and 3.773 GeV.

Source code:BESII_2007_I762901.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Cross-sections for light hadrons at 3.650 and 3.773 GeV class BESII_2007_I762901 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2007_I762901);


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

/// Book histograms and initialise projections before the run
void init() {

  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");

  // Book histograms
  for (size_t ix = 1; ix < 11; ++ix) {
    if (ix == 6) continue;
    book(_nMeson[ix], 1, 1, ix);
  }
  for (const string& en : _nMeson[1].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;
  }
  if (ntotal == 6) {
    if (nCount[211] == 2 && nCount[-211] == 2 && nCount[321] == 1 && nCount[-321] == 1)
      _nMeson[1]->fill(_sqs);
    else if (nCount[211] == 1 && nCount[-211] == 1 && nCount[321] == 2 && nCount[-321] == 2) {
      if (_sqs == "3.773") _nMeson[2]->fill(_sqs);
    }
    else if (nCount[211] == 2 && nCount[-211] == 2 && nCount[2212] == 1 && nCount[-2212] == 1)
      _nMeson[3]->fill(_sqs);
    else if (nCount[211] == 3 && nCount[-211] == 3)
      _nMeson[4]->fill(_sqs);
  }
  else if (ntotal == 7) {
    if (nCount[211] == 2 && nCount[-211] == 2 && nCount[321] == 1 && nCount[-321] == 1
        && nCount[111] == 1)
      _nMeson[5]->fill(_sqs);
  }
  const FinalState& ufs = apply<FinalState>(event, "UFS");
  for (const Particle& p : ufs.particles()) {
    if (p.children().empty()) continue;
    if (p.pid() != 113 && p.abspid() != 313) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p, nRes, ncount);
    if (p.pid() == 113) {
      if (ncount != 2) continue;
      unsigned int nPi(0), nK(0), nProt(0);
      bool matched = true;
      for (const auto& val : nRes) {
        if (abs(val.first) == 211 && val.second == 1) {
          nPi += 1;
        }
        else if (abs(val.first) == 321 && val.second == 1) {
          nK += 1;
        }
        else if (abs(val.first) == 2212 && val.second == 1) {
          nProt += 1;
        }
        else if (val.second != 0) {
          matched = false;
          break;
        }
      }
      if (matched) {
        if (nProt == 2 && nPi == 0 && nK == 0)
          _nMeson[9]->fill(_sqs);
        else if (nProt == 0 && nPi == 2 && nK == 0)
          _nMeson[7]->fill(_sqs);
        else if (nProt == 0 && nPi == 0 && nK == 2)
          _nMeson[8]->fill(_sqs);
      }
    }
    else if (p.abspid() == 313) {
      if (ncount != 2) continue;
      unsigned int npi(0), nK(0);
      bool matched = true;
      int ipi = p.pid() == 313 ? 211 : -211;
      int iK = p.pid() == 313 ? -321 : 321;
      for (const auto& val : nRes) {
        if (abs(val.first) == ipi && val.second == 1) {
          npi += 1;
        }
        else if (abs(val.first) == iK && val.second == 1) {
          nK += 1;
        }
        else if (val.second != 0) {
          matched = false;
          break;
        }
      }
      if (matched) {
        if (npi == 1 && nK == 1) _nMeson[10]->fill(_sqs);
      }
    }
  }
}


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

/// @}


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

};

RIVET_DECLARE_PLUGIN(BESII_2007_I762901);

} ```