Rivet analyses

title: BESIII_2023_I2721091

$J/\psi\to \bar{p}\Sigma^+K^0_S+\mathrm{c.c.}$

Experiment: BESIII (BEPC)

Inspire ID: 2721091

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 109 (2024) 1, 012006 - arXiv: 2311.05955

Beams: * *

Beam energies: ANY

Run details: - Any process producing J/psi riginally e+e-

Measurement of the mass distributions in the decay $J/\psi\to \bar{p}\Sigma^+K^0_S+\mathrm{c.c.}$. The data were read from the plots in the paper. It is also not clear that any resolution effects have been unfolded.

Source code:BESIII_2023_I2721091.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief J/psi -> pbar Sigma+ K0S class BESIII_2023_I2721091 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2023_I2721091);


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

/// Book histograms and initialise projections before the run
void init() {
  UnstableParticles ufs = UnstableParticles(Cuts::pid == 443);
  declare(ufs, "UFS");
  DecayedParticles psi(ufs);
  psi.addStable(PID::PI0);
  psi.addStable(PID::K0S);
  psi.addStable(3222);
  psi.addStable(-3222);
  declare(psi, "psi");
  for (unsigned int iy = 0; iy < 3; ++iy) book(_h[iy], 1, 1, 1 + iy);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  DecayedParticles psi = apply<DecayedParticles>(event, "psi");
  // loop over particles
  for (unsigned int ix = 0; ix < psi.decaying().size(); ++ix) {
    int isign = 1;
    if (psi.modeMatches(ix, 3, mode1))
      isign = 1;
    else if (psi.modeMatches(ix, 3, mode2))
      isign = -1;
    else
      continue;
    const Particle& k0 = psi.decayProducts()[ix].at(310)[0];
    const Particle& sigp = psi.decayProducts()[ix].at(isign * 3222)[0];
    const Particle& prot = psi.decayProducts()[ix].at(-isign * 2212)[0];
    _h[0]->fill((prot.mom() + k0.mom()).mass());
    _h[1]->fill((sigp.mom() + k0.mom()).mass());
    _h[2]->fill((sigp.mom() + prot.mom()).mass());
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[3];
const map<PdgId, unsigned int> mode1 = {{-2212, 1}, {3222, 1}, {310, 1}};
const map<PdgId, unsigned int> mode2 = {{2212, 1}, {-3222, 1}, {310, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2023_I2721091);

} ```