Rivet analyses

title: BELLE_2017_I1613517

Cross Section for $e^+e^-\to D^\pm D^{\mp}$ and $D^{+}D^{*-}$ from threshold to 6 GeV

Experiment: BELLE (KEKB)

Inspire ID: 1613517

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D97 (2018) no.1, 012002

Beams: e- e+

Beam energies: ANY

Run details: - e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to D^\pm D^{\mp}$ and $D^{+}D^{*-}$ from threshold to 6 GeV.

Source code:BELLE_2017_I1613517.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief D+/- D-/+ and D+ D*- cross sections class BELLE_2017_I1613517 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2017_I1613517);


/// @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
  book(_c_DpDmS, "/TMP/sigma_DpDmS");
  book(_c_DpSDmS, "/TMP/sigma_DpSDmS");
}

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");
  // total hadronic and muonic cross sections
  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  // mu+mu- + photons
  if (nCount[-13] == 1 and nCount[13] == 1 && ntotal == 2 + nCount[22]) {
    vetoEvent;
  }
  // unstable charm analysis
  const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
  for (unsigned int ix = 0; ix < ufs.particles().size(); ++ix) {
    const Particle& p1 = ufs.particles()[ix];
    int id1 = abs(p1.pid());
    if (id1 != 411 && id1 != 413) 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);
    bool matched = false;
    int sign = p1.pid() / id1;
    // loop over the other fs particles
    for (unsigned int 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()) == sign) continue;
      int id2 = abs(p2.pid());
      if (id2 != 411 && id2 != 413) 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) {
        if (id1 == 413 && id2 == 413) {
          _c_DpSDmS->fill();
        }
        else if ((id1 == 411 && id2 == 413) || (id1 == 413 && id2 == 411)) {
          _c_DpDmS->fill();
        }
        break;
      }
    }
    if (matched) break;
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  double fact = crossSection() / sumOfWeights() / nanobarn;
  for (unsigned int iy = 1; iy < 3; ++iy) {
    double sigma = 0.0, error = 0.0;
    if (iy == 1) {
      sigma = _c_DpDmS->val() * fact;
      error = _c_DpDmS->err() * fact;
    }
    else if (iy == 2) {
      sigma = _c_DpSDmS->val() * fact;
      error = _c_DpSDmS->err() * fact;
    }
    Estimate1DPtr mult;
    book(mult, 1, 1, iy);
    for (auto& b : mult->bins()) {
      if (inRange(sqrtS() / GeV, b.xMin(), b.xMax())) {
        b.set(sigma, error);
      }
    }
  }
}
/// @}


/// @name Histograms
/// @{
CounterPtr _c_DpDmS, _c_DpSDmS;
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2017_I1613517);

} ```