Rivet analyses

title: BABAR_2008_I765258

Cross Section for $e^+e^-\to$ $K^+K^-\eta$, $K^+K^-\pi^0$ and $K^0_SK^\pm\pi^\mp$ from threshold to 4.6 GeV

Experiment: BABAR (PEP-II)

Inspire ID: 765258

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D77 (2008) 092002, 2008

Beams: e+ e-

Beam energies: ANY

Run details: - e+e- to hadrons

Measurement of the cross section for $e^+e^-\to$ $K^+K^-\eta$, $K^+K^-\pi^0$ and $K^0_SK^\pm\pi^\mp$ via radiative return, including the identification of $\phi$ and $\eta$ mesons for energies from threshold to 4.6 GeV.

Source code:BABAR_2008_I765258.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Add a short analysis description here class BABAR_2008_I765258 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2008_I765258);


/// @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 (unsigned int ix = 1; ix < 6; ++ix) {
    stringstream ss;
    ss << "TMP/n" << ix;
    book(_nMeson[ix], ss.str());
  }
}

void findChildren(const Particle& p, map<long, int>& nRes, int& ncount) {
  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 (const Particle& p : ufs.particles(Cuts::pid == 221 or Cuts::pid == 333)) {
    if (p.children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p, nRes, ncount);

    if (p.pid() == 221) {
      bool matchedKK = false;
      if (ncount == 2) {
        matchedKK = true;
        for (const auto& val : nRes) {
          if (abs(val.first) == 321) {
            if (val.second != 1) {
              matchedKK = false;
              break;
            }
          }
          else if (val.second != 0) {
            matchedKK = false;
            break;
          }
        }
      }
      if (matchedKK) _nMeson[4]->fill();
      for (const Particle& p2 : ufs.particles()) {
        if (p2.pid() != 333) continue;
        if (p2.parents()[0].isSame(p)) continue;
        map<long, int> nResB = nRes;
        int ncountB = ncount;
        findChildren(p2, nResB, ncountB);
        if (ncountB != 0) continue;
        bool matched2 = true;
        for (const auto& val : nResB) {
          if (val.second != 0) {
            matched2 = false;
            break;
          }
        }
        if (matched2) {
          _nMeson[5]->fill();
          break;
        }
      }
    }
    else if (p.pid() == 333) {
      if (ncount != 1) continue;
      bool matched = true;
      for (const auto& val : nRes) {
        if (val.first == 111) {
          if (val.second != 1) {
            matched = false;
            break;
          }
        }
        else if (val.second != 0) {
          matched = false;
          break;
        }
      }
      if (matched) _nMeson[3]->fill();
    }
  }


  if (ntotal == 3 && nCount[310] == 1
      && ((nCount[211] == 1 && nCount[-321] == 1) || (nCount[-211] == 1 && nCount[321] == 1)))
    _nMeson[1]->fill();
  else if (ntotal == 3 && nCount[321] == 1 && nCount[-321] == 1 && nCount[111] == 1)
    _nMeson[2]->fill();
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 1; ix < 6; ++ix) {
    double sigma = _nMeson[ix]->val();
    double error = _nMeson[ix]->err();
    sigma *= crossSection() / sumOfWeights() / nanobarn;
    error *= crossSection() / sumOfWeights() / nanobarn;
    Estimate1DPtr mult;
    book(mult, ix, 1, 1);
    for (auto& b : mult->bins()) {
      if (inRange(sqrtS() / GeV, b.xMin(), b.xMax())) {
        b.set(sigma, error);
      }
    }
  }
}

/// @}


/// @name Histograms
/// @{
CounterPtr _nMeson[6];
/// @}

};

RIVET_DECLARE_PLUGIN(BABAR_2008_I765258);

} ```