Rivet analyses

title: ARGUS_1994_I372451

$\gamma\gamma\to \phi\rho^0\ \text{and}\ \phi\omega$ between 1.5 and 3.5 GeV

Experiment: ARGUS (DORIS)

Inspire ID: 372451

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett.B 332 (1994) 451-457, 1994

Beams: 22 22

Beam energies: ANY

Run details: - gamma gamma to hadrons, K0S and pi0 mesons must be set stable

Source code:ARGUS_1994_I372451.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief gamma gamma -> phi rho or omega class ARGUS_1994_I372451 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1994_I372451);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");
  // book histos
  if (inRange(sqrtS() / GeV, 1.5, 3.5)) {
    book(_nMeson, 1, 1, 1);
    book(_avg, 2, 1, 1);
  }
  else {
    throw Error("Invalid CMS energy for ARGUS_1994_I372451");
  }
}

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");
  // find the final-state particles
  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  Particles phis = ufs.particles(Cuts::pid == 333);
  Particles rhos = ufs.particles(Cuts::pid == 113 or Cuts::pid == 223);
  for (const Particle& phi : phis) {
    bool matched = false;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(phi, nRes, ncount);
    for (const Particle& rho : rhos) {
      map<long, int> nRes2 = nRes;
      int ncount2 = ncount;
      findChildren(rho, nRes2, ncount2);
      if (ncount2 != 0) continue;
      matched = true;
      for (const auto& val : nRes2) {
        if (val.second != 0) {
          matched = false;
          break;
        }
      }
      if (matched) {
        if (rho.pid() == 113) {
          _nMeson->fill(sqrtS() / GeV);
        }
        else {
          _avg->fill("1.9 - 2.3"s);
        }
        break;
      }
    }
    if (matched) break;
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double sf = crossSection() / nanobarn / sumOfWeights();
  scale(_nMeson, sf);
  scale(_avg, sf);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _nMeson;
BinnedHistoPtr<string> _avg;
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_1994_I372451);

} ```