Rivet analyses

title: BESIII_2024_I2854046

Cross section for inclusive $J/\psi$ and $\psi(3686)$ production in $e^+e^-$ for $\sqrt{s}=3.808\to4.951$GeV

Experiment: BESIII (BEPC)

Inspire ID: 2854046

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 111 (2025) 5, 052007 - arXiv: 2411.19642

Beams: e+ e-

Beam energies: (1.9, 1.9); (1.9, 1.9); (2.0, 2.0); (2.0, 2.0); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 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); (2.5, 2.5); (2.5, 2.5)GeV

Run details: - e+e- > hadrons

Measurement of the inclusive4 cross section for inclusive $J/\psi$ and $\psi(3686)$ production in $e^+e^-$ for $\sqrt{s}=3.808\to4.951$GeV

Source code:BESIII_2024_I2854046.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e+e- -> J/psi or psi(2S) + X class BESIII_2024_I2854046 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2854046);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(Cuts::pid == 443 || Cuts::pid == 100443), "UFS");
  // book hists
  book(_h[0], 1, 1, 1);
  book(_h[1], 1, 1, 2);
  book(_h[2], 1, 1, 3);
  book(_h[3], 1, 1, 4);
  // energies
  for (const string& en : _h[0].binning().edges<0>()) {
    string en2 = en.back() == 'a' || en.back() == 'b' ? en.substr(0, en.size() - 1) : en;
    const double eval = stod(en2) * GeV;
    if (isCompatibleWithSqrtS(eval)) {
      _sqs.push_back(en);
      break;
    }
  }
  raiseBeamErrorIf(_sqs.empty());
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& ufs = apply<FinalState>(event, "UFS");
  for (const Particle& psi : ufs.particles()) {
    bool dup = false;
    for (const Particle& child : psi.children()) {
      dup |= psi.pid() == child.pid();
    }
    if (dup) continue;
    unsigned int ipsi = psi.pid() / 100000;
    for (const string& en : _sqs) {
      _h[2 * ipsi]->fill(en);
      _h[2 * ipsi + 1]->fill(en);
    }
  }
}


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

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _h[4];
vector<string> _sqs;
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2024_I2854046); } ```