Rivet analyses

title: ARGUS_2000_I511512

$\gamma\gamma\to K^{0}\bar{K}^{0}\ \text{and}\ K^{+}K^{-}$ between 1.5 and 3.0 GeV

Experiment: ARGUS (DORIS)

Inspire ID: 511512

Status: VALIDATED

Authors: - Peter Richardson

References: - Eur.Phys.J.C 16 (2000) 435-444

Beams: 22 22

Beam energies: ANY

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

Measurement of the differential cross section for $\gamma\gamma\to K^{0}\bar{K}^{0}\ \text{and} K^{+}K^{-}$ for $1.5 \text{GeV} < W < 3.0 \text{GeV}$. The cross section is measured as a function of the centre-of-mass energy of the photonic collision using a range of final states.

Source code:ARGUS_2000_I511512.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief gamma gamma -> KK class ARGUS_2000_I511512 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_2000_I511512);


/// @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
  raiseBeamErrorIf(!inRange(sqrtS() / GeV, 1.5, 3.0));
  // loop over tables in paper
  book(_h["K0K0_5"], 3, 1, 1);
  book(_h["K0K0_3"], 4, 1, 1);
  book(_h["K0K0_1"], 5, 1, 1);
  book(_h["K0K0_KSKSpp"], 9, 1, 1);
  book(_h["K0K0_KSK+pp"], 6, 1, 2);
  book(_h["K0K0"], 10, 1, 1);

  book(_h["KpKm_KSK+pp"], 6, 1, 1);
  book(_h["KpKm_KSKSpp"], 8, 1, 1);
  book(_h["KpKm_K+K-pp"], 9, 1, 2);
  book(_h["K+K-"], 10, 1, 2);

  book(_h["rhoPi_5"], 3, 1, 3);
  book(_h["rhoPi_3"], 4, 1, 3);
  book(_h["rhoPi_1"], 5, 1, 3);

  book(_h["K0K+-_5"], 3, 1, 2);
  book(_h["K0K+-_3"], 4, 1, 2);
  book(_h["K0K+-_1"], 5, 1, 2);

  book(_h["K+KS-l-"], 7, 1, 1);
  book(_h["K+KS-p-"], 8, 1, 2);
  book(_h["K+K-p0"], 7, 1, 2);
  book(_h["KSKSp-p0"], 7, 1, 3);
  book(_h["KSKSp+p-"], 8, 1, 3);

  book(_h["K+K-p+p-_5"], 3, 1, 4);
  book(_h["K+K-p+p-_3"], 4, 1, 4);
  book(_h["K+K-p+p-_1"], 5, 1, 4);

  book(_h["num"], "TMP/nMeson_num", refData(11, 1, 1));
  book(_h["den"], "TMP/nMeson_den", refData(11, 1, 1));
}

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");
  // find the final-state particles
  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  if (ntotal == 4) {
    if (nCount[PID::KPLUS] == 1 && nCount[PID::KMINUS] == 1 && nCount[PID::PIPLUS] == 1
        && nCount[PID::PIMINUS] == 1) {
      _h["K+K-p+p-_5"]->fill(sqrtS() / GeV);
      _h["K+K-p+p-_3"]->fill(sqrtS() / GeV);
      _h["K+K-p+p-_1"]->fill(sqrtS() / GeV);
    }
    else if (nCount[PID::K0S] == 2 && nCount[PID::PIPLUS] == 1 && nCount[PID::PIMINUS] == 1) {
      _h["KSKSp+p-"]->fill(sqrtS() / GeV);
    }
    else if (nCount[PID::K0S] == 1 && nCount[PID::PI0] == 1
             && ((nCount[PID::KPLUS] == 1 && nCount[PID::PIMINUS] == 1)
                 || (nCount[PID::KMINUS] == 1 && nCount[PID::PIPLUS] == 1))) {
      _h["KSKSp-p0"]->fill(sqrtS() / GeV);
    }
  }
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  // find any K* mesons
  Particles Kstar = ufs.particles(Cuts::abspid == 313 or Cuts::abspid == 323);
  for (size_t ix = 0; ix < Kstar.size(); ++ix) {
    if (Kstar[ix].children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(Kstar[ix], nRes, ncount);
    int sign = Kstar[ix].pid() / Kstar[ix].abspid();
    // three body intermediate states
    if (ncount == 2) {
      // K*0 K- pi+ +ccd
      if (Kstar[ix].abspid() == 313) {
        bool matched = true;
        for (const auto& val : nRes) {
          if (val.first == sign * 211 || val.first == -sign * 321) {
            if (val.second != 1) {
              matched = false;
              break;
            }
          }
          else {
            if (val.second != 0) {
              matched = false;
              break;
            }
          }
        }
        if (matched) {
          _h["K0K+-_5"]->fill(sqrtS() / GeV);
          _h["K0K+-_3"]->fill(sqrtS() / GeV);
          _h["K0K+-_1"]->fill(sqrtS() / GeV);
        }
      }
      else {
        bool matched = false;
        // K*+ K0S pi- + cc
        for (const auto& val : nRes) {
          if (val.first == -sign * 211 || val.first == PID::K0S) {
            if (val.second != 1) {
              matched = false;
              break;
            }
          }
          else {
            if (val.second != 0) {
              matched = false;
              break;
            }
          }
        }
        if (matched) {
          _h["K+KS-l-"]->fill(sqrtS() / GeV);
          _h["K+KS-p-"]->fill(sqrtS() / GeV);
        }
        else {
          // K*+ K- pi0 +cc
          matched = false;
          for (const auto& val : nRes) {
            if (val.first == -sign * 321 || val.first == PID::PI0) {
              if (val.second != 1) {
                matched = false;
                break;
              }
            }
            else {
              if (val.second != 0) {
                matched = false;
                break;
              }
            }
          }
          if (matched) _h["K+K-p0"]->fill(sqrtS() / GeV);
        }
      }
    }

    // K*K*
    for (size_t iy = ix + 1; iy < Kstar.size(); ++iy) {
      if (Kstar[iy].children().empty()) continue;
      if (Kstar[ix].pid() != -Kstar[iy].pid()) continue;
      map<long, int> nRes2 = nRes;
      int ncount2 = ncount;
      findChildren(Kstar[iy], nRes2, ncount2);
      if (ncount2 != 0) continue;
      bool matched2 = true;
      for (const auto& val : nRes2) {
        if (val.second != 0) {
          matched2 = false;
          break;
        }
      }
      if (matched2) {
        if (Kstar[ix].abspid() == 313) {
          _h["K0K0_5"]->fill(sqrtS() / GeV);
          _h["K0K0_3"]->fill(sqrtS() / GeV);
          _h["K0K0_1"]->fill(sqrtS() / GeV);
          _h["K0K0_KSKSpp"]->fill(sqrtS() / GeV);
          _h["K0K0_KSK+pp"]->fill(sqrtS() / GeV);
          _h["K0K0"]->fill(sqrtS() / GeV);
          _h["den"]->fill(sqrtS() / GeV);
        }
        else {
          _h["KpKm_KSK+pp"]->fill(sqrtS() / GeV);
          _h["KpKm_KSKSpp"]->fill(sqrtS() / GeV);
          _h["KpKm_K+K-pp"]->fill(sqrtS() / GeV);
          _h["K+K-"]->fill(sqrtS() / GeV);
          _h["num"]->fill(sqrtS() / GeV);
        }
        break;
      }
    }
  }
  // finally the rho phi intermediate states
  for (const Particle& p1 : ufs.particles(Cuts::pid == PID::RHO0)) {
    if (p1.children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p1, nRes, ncount);
    for (const Particle& p2 : ufs.particles(Cuts::pid == PID::PHI)) {
      if (p2.children().empty()) continue;
      map<long, int> nRes2 = nRes;
      int ncount2 = ncount;
      findChildren(p2, nRes2, ncount2);
      if (ncount2 != 0) continue;
      bool matched = true;
      for (const auto& val : nRes2) {
        if (val.second != 0) {
          matched = false;
          break;
        }
      }
      if (matched) {
        _h["rhoPi_5"]->fill(sqrtS() / GeV);
        _h["rhoPi_3"]->fill(sqrtS() / GeV);
        _h["rhoPi_1"]->fill(sqrtS() / GeV);
        break;
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_h, crossSection() / nanobarn / sumOfWeights());
  // finally the ratio K*+/K*0
  Estimate1DPtr mult;
  book(mult, 11, 1, 1);
  divide(_h["num"], _h["den"], mult);
}

/// @}


/// @name Histograms
/// @{
map<string, Histo1DPtr> _h;
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_2000_I511512);

} ```