Rivet analyses

title: MARKII_1979_I143939

Measurement of $R$ and $D\bar{D}$ cross section between 3.67 and 3.872 GeV

Experiment: MARKII (SPEAR)

Inspire ID: 143939

Status: VALIDATED

Authors: - Peter Richardson

References: - Schindler, R.H. PhD Thesis, 1979

Beams: e- e+

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

Run details: - e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of $R$ and the $D\bar{D}$ cross section in $e^+e^-$ collisions between 3.67 and 3.872 GeV The individual hadronic and muonic cross sections are also outputted to the yoda file so that ratio $R$ can be recalcuated if runs are combined.

Source code:MARKII_1979_I143939.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 MARKII_1979_I143939 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(MARKII_1979_I143939);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");
  book(_c_hadrons, "/TMP/sigma_hadrons", refData<YODA::BinnedEstimate<string>>(2, 1, 1));
  book(_c_muons, "/TMP/sigma_muons", refData<YODA::BinnedEstimate<string>>(2, 1, 1));
  book(_c_DD, 3, 1, 1);
  for (const string& en : _c_hadrons.binning().edges<0>()) {
    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");
  // total hadronic and muonic cross sections
  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  if (nCount[-13] == 1 && nCount[13] == 1 && ntotal == 2 + nCount[22]) {
    // mu+mu- + photons
    _c_muons->fill(_sqs);
  }
  else
    _c_hadrons->fill(_sqs); // everything else
  // identified final state with D mesons
  const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
  for (unsigned int ix = 0; ix < ufs.particles().size(); ++ix) {
    bool matched = false;
    const Particle& p1 = ufs.particles()[ix];
    int id1 = abs(p1.pid());
    if (id1 != 411 && id1 != 421) continue;
    // check fs
    bool fs = true;
    for (const Particle& child : p1.children()) {
      if (child.pid() == p1.pid()) {
        fs = false;
        break;
      }
    }
    if (!fs) continue;
    // find the children
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p1, nRes, ncount);
    // loop over the other fs particles
    for (size_t iy = ix + 1; iy < ufs.particles().size(); ++iy) {
      const Particle& p2 = ufs.particles()[iy];
      fs = true;
      for (const Particle& child : p2.children()) {
        if (child.pid() == p2.pid()) {
          fs = false;
          break;
        }
      }
      if (!fs) continue;
      if (p2.pid() / abs(p2.pid()) == p1.pid() / abs(p1.pid())) continue;
      int id2 = abs(p2.pid());
      if (id2 != 411 && id2 != 421) continue;
      if (!p2.parents().empty() && p2.parents()[0].pid() == p1.pid()) 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) {
        _c_DD->fill(_sqs);
        break;
      }
    }
    if (matched) break;
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  double fact = crossSection() / sumOfWeights() / nanobarn;
  BinnedEstimatePtr<string> mult;
  book(mult, 2, 1, 1);
  divide(_c_hadrons, _c_muons, mult);
  scale(_c_DD, fact);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _c_hadrons, _c_muons, _c_DD;
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(MARKII_1979_I143939);

} ```