Rivet analyses

title: BELLE_2019_I1762826

Cross section for $e^+e^-\to D_s^+D_{s1}(2536)^-\text{c.c.}$ between 4.52 and 5.6 GeV

Experiment: BELLE (KEKB)

Inspire ID: 1762826

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.D 100 (2019) 11, 111103

Beams: e+ e-

Beam energies: ANY

Run details: - e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to D_s^+D_{s1}(2536)^-\text{c.c.}$ times the branching ratio for $D_{s1}(2536)^-\to \bar{D}^{*0}K^-$ for centre-of-mass energies between 4.52 and 5.6 GeV by the BELLE collaboration.

Source code:BELLE_2019_I1762826.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e+e- -> Ds D_s1 class BELLE_2019_I1762826 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2019_I1762826);


/// @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_Ds, "/TMP/c_Ds");
}

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 analyse final state
  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  // unstable charm analysis
  Particles ds = apply<UnstableParticles>(event, "UFS")
                     .particles(Cuts::abspid == 431 or Cuts::abspid == 10433);
  for (unsigned int ix = 0; ix < ds.size(); ++ix) {
    const Particle& p1 = ds[ix];
    int id1 = abs(p1.pid());
    // 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;
    for (unsigned int iy = ix + 1; iy < ds.size(); ++iy) {
      const Particle& p2 = ds[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 (!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 == 431 && id2 == 10433) || (id1 == 10433 && id2 == 431)) {
          Particle Ds2 = id1 == 10433 ? p1 : p2;
          matched = false;
          if (Ds2.children().size() != 2) continue;
          if (Ds2.pid() == 10433
              && ((Ds2.children()[0].pid() == 423 && Ds2.children()[1].pid() == 321)
                  || (Ds2.children()[1].pid() == 423 && Ds2.children()[0].pid() == 321)))
            matched = true;
          else if (Ds2.pid() == -10433
                   && ((Ds2.children()[0].pid() == -423 && Ds2.children()[1].pid() == -321)
                       || (Ds2.children()[1].pid() == -423 && Ds2.children()[0].pid() == -321)))
            matched = true;
          if (matched) {
            _c_Ds->fill();
            break;
          }
        }
      }
    }
    if (matched) break;
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  double fact = crossSection() / sumOfWeights() / picobarn;
  double sigma = _c_Ds->val() * fact;
  double error = _c_Ds->err() * fact;
  Estimate1DPtr mult;
  book(mult, 1, 1, 1);
  for (auto& b : mult->bins()) {
    if (inRange(sqrtS() / GeV, b.xMin(), b.xMax())) {
      b.set(sigma, error);
    }
  }
}

/// @}


/// @name Histograms
/// @{
CounterPtr _c_Ds;
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2019_I1762826);

} ```