Rivet analyses

title: BESIII_2024_I2691955

$\psi(2S)\to K^-\Lambda^0\bar\Xi^++\mathrm{c.c.}$

Experiment: BESIII (BEPC)

Inspire ID: 2691955

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 109 (2024) 7, 072008 - arXiv: 2308.15206

Beams: * *

Beam energies: ANY

Run details: - Any process producing psi(2S) originally e+e-

Measurement of the mass distributions in the decay $\psi(2S)\to K^-\Lambda^0\bar\Xi^++\mathrm{c.c.}$. 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_2024_I2691955.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief psi(2S) -> K- Lambda9 Xibar+ class BESIII_2024_I2691955 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2691955);


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

/// Book histograms and initialise projections before the run
void init() {
  UnstableParticles ufs = UnstableParticles(Cuts::pid == 100443);
  declare(ufs, "UFS");
  DecayedParticles psi(ufs);
  psi.addStable(PID::PI0);
  psi.addStable(3122);
  psi.addStable(-3122);
  psi.addStable(3312);
  psi.addStable(-3312);
  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 isgn = 1;
    if (psi.modeMatches(ix, 3, mode1))
      isgn = 1;
    else if (psi.modeMatches(ix, 3, mode2))
      isgn = -1;
    else
      continue;
    const Particle& Km = psi.decayProducts()[ix].at(-isgn * 321)[0];
    const Particle& lam = psi.decayProducts()[ix].at(isgn * 3122)[0];
    const Particle& xi = psi.decayProducts()[ix].at(-isgn * 3312)[0];
    _h[0]->fill((Km.mom() + xi.mom()).mass());
    _h[1]->fill((lam.mom() + xi.mom()).mass());
    _h[2]->fill((Km.mom() + lam.mom()).mass());
  }
}


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

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[3];
const map<PdgId, unsigned int> mode1 = {{-321, 1}, {3122, 1}, {-3312, 1}};
const map<PdgId, unsigned int> mode2 = {{321, 1}, {-3122, 1}, {3312, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2024_I2691955);

} ```