Rivet analyses

title: BELLE_2024_I2791218

Cross section for $B,\bar{B}$, $B\bar{B}^$ and $B^\bar{B}^*$ for energies between 10.653 and 10.805 GeV

Experiment: BELLE (KEKB)

Inspire ID: 2791218

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - JHEP 10 (2024) 114 - arXiv: 2405.18928

Beams: e+ e-

Beam energies: ANY

Run details: - e+ e- to hadrons

Measurement of the cross sections for $B,\bar{B}$, $B\bar{B}^$ and $B^\bar{B}^*$ by the BELLE experiment for energies between 10.653 and 10.805 GeV.

Source code:BELLE_2024_I2791218.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B() bar{B}() exclusive cross section class BELLE_2024_I2791218 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2024_I2791218);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");
  // histograms
  book(_sigma[0], 2, 1, 1);
  book(_sigma[1], 2, 1, 2);
  book(_sigma[2], 2, 1, 3);

  // Check which indices match the Ecm energy
  for (const auto& est : refData<YODA::BinnedEstimate<int>>(1, 1, 1).bins()) {
    if (abs(sqrtS() / MeV - est.val()) < est.totalErrAvg()) _sqs.push_back(est.xEdge());
  }
  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");

  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  // extract botton hadrons
  Particles bHadrons = apply<FinalState>(event, "UFS")
                           .particles(Cuts::abspid == 511 || Cuts::abspid == 513 || Cuts::abspid == 521
                                      || Cuts::abspid == 523);
  for (size_t ix = 0; ix < bHadrons.size(); ++ix) {
    long pix = bHadrons[ix].parents()[0].abspid();
    if (pix == 511 || pix == 413 || pix == 521 || pix == 523) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(bHadrons[ix], nRes, ncount);
    bool matched = false;
    for (size_t iy = ix + 1; iy < bHadrons.size(); ++iy) {
      long piy = bHadrons[ix].parents()[0].abspid();
      if (piy == 511 || piy == 413 || piy == 521 || piy == 523) continue;
      map<long, int> nRes2 = nRes;
      int ncount2 = ncount;
      findChildren(bHadrons[iy], nRes2, ncount2);
      if (ncount2 != 0) continue;
      matched = true;
      for (const auto& val : nRes2) {
        if (val.second != 0) {
          matched = false;
          break;
        }
      }
      if (matched) {
        for (const int Ecm : _sqs) {
          if (bHadrons[ix].abspid() == 511 || bHadrons[ix].abspid() == 521) {
            if (bHadrons[iy].pid() == -bHadrons[ix].pid())
              _sigma[0]->fill(Ecm);
            else
              _sigma[1]->fill(Ecm);
          }
          else if (bHadrons[ix].abspid() == 513 || bHadrons[ix].abspid() == 523) {
            if (bHadrons[iy].pid() == -bHadrons[ix].pid())
              _sigma[2]->fill(Ecm);
            else
              _sigma[1]->fill(Ecm);
          }
        }
        break;
      }
    }
    if (matched) break;
  }
}


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

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<int> _sigma[3];
vector<int> _sqs;
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2024_I2791218); } ```