Rivet analyses

title: BESIII_2024_I2806455

Measurement of the cross sections for $e^+e^-\to D_s^\pm D_{s1}(2536)^\mp$ and $D_s^\pm D_{s2}^*(2573)^\mp$ for $\sqrt{s}$ from 4.6 to 4.946 GeV

Experiment: BESIII (BEPC)

Inspire ID: 2806455

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 133 (2024) 17, 171903 - arXiv: 2407.07651

Beams: e+ e-

Beam energies: (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.4, 2.4); (2.4, 2.4); (2.4, 2.4); (2.4, 2.4); (2.4, 2.4); (2.5, 2.5); (2.5, 2.5)GeV

Run details: - e+ e- > hadrons

Measurement of the cross sections for $e^+e^-\to D_s^\pm D_{s1}(2536)^\mp$ and $D_s^\pm D_{s2}^(2573)^\mp$ for $\sqrt{s}$ from 4.6 to 4.946 GeV. The product of the cross section and the branching ratios for the modes $D_{s1}(2536)^-\to \bar{D}^{0}K^-$ and $D_{s2}^*(2573)^-\to \bar{D}^0K^-$ are measured.

Source code:BESIII_2024_I2806455.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief class BESIII_2024_I2806455 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2806455);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");
  book(_sigma[0], 1, 1, 1);
  book(_sigma[1], 2, 1, 1);

  for (const string& en : _sigma[0].binning().edges<0>()) {
    const 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 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 || Cuts::abspid == 10433 || Cuts::abspid == 435);
  for (size_t ix = 0; ix < ds.size(); ++ix) {
    const Particle& p1 = ds[ix];
    int id1 = p1.abspid();
    // 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 (size_t 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;
      // particle antiparticle
      int id2 = p2.abspid();
      if (p2.pid() / id2 == sign) continue;
      if (!p2.parents().empty() && p2.parents()[0].pid() == p1.pid()) continue;
      // check not same
      if (p1.abspid() == p2.abspid()) continue;
      // at least 1 D_s
      if (p1.abspid() != 431 && p2.abspid() != 431) 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 Ds1 = id1 == 10433 ? p1 : p2;
          matched = false;
          if (Ds1.children().size() != 2) continue;
          if (Ds1.pid() == 10433
              && ((Ds1.children()[0].pid() == 423 && Ds1.children()[1].pid() == 321)
                  || (Ds1.children()[1].pid() == 423 && Ds1.children()[0].pid() == 321))) {
            matched = true;
          }
          else if (Ds1.pid() == -10433
                   && ((Ds1.children()[0].pid() == -423 && Ds1.children()[1].pid() == -321)
                       || (Ds1.children()[1].pid() == -423 && Ds1.children()[0].pid() == -321))) {
            matched = true;
          }
          if (matched) {
            _sigma[0]->fill(_sqs);
            break;
          }
        }
        else if ((id1 == 431 && id2 == 435) || (id1 == 435 && id2 == 431)) {
          Particle Ds2 = id1 == 435 ? p1 : p2;
          matched = false;
          if (Ds2.children().size() != 2) continue;
          if (Ds2.pid() == 435
              && ((Ds2.children()[0].pid() == 421 && Ds2.children()[1].pid() == 321)
                  || (Ds2.children()[1].pid() == 421 && Ds2.children()[0].pid() == 321))) {
            matched = true;
          }
          else if (Ds2.pid() == -435
                   && ((Ds2.children()[0].pid() == -421 && Ds2.children()[1].pid() == -321)
                       || (Ds2.children()[1].pid() == -421 && Ds2.children()[0].pid() == -321))) {
            matched = true;
          }
          if (matched) {
            _sigma[1]->fill(_sqs);
            break;
          }
        }
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_sigma, crossSection() / sumOfWeights() / picobarn);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _sigma[2];
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2024_I2806455); } ```