Rivet analyses

title: BESIII_2023_I2670262

Mass distributions in $J/\psi\to \bar\Lambda^0\pi^+\Sigma^-$, $\bar\Lambda^0\pi^-\Sigma^+$ decays

Experiment: BESIII (BEPC)

Inspire ID: 2670262

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 108 (2023) 11, 112012 - arXiv: 2306.10319

Beams: * *

Beam energies: ANY

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

Mass distributions in $J/\psi\to \bar\Lambda^0\pi^+\Sigma^-$, $\bar\Lambda^0\pi^-\Sigma^+$ decays and charge conjugate decays. The data were read from the figures in the paper and the backgrounds given subtracted.

Source code:BESIII_2023_I2670262.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief class BESIII_2023_I2670262 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2023_I2670262);

/// @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(3122);
  psi.addStable(-3122);
  psi.addStable(3112);
  psi.addStable(-3112);
  psi.addStable(3222);
  psi.addStable(-3222);
  declare(psi, "psi");
  for (unsigned int ix = 0; ix < 4; ++ix) {
    for (unsigned int iy = 0; iy < 3; ++iy) book(_h[ix][iy], 1 + ix, 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, ipi, isig = 3112, imode;
    if (psi.modeMatches(ix, 3, mode1)) {
      isgn = -1;
      ipi = 1;
      imode = 0;
    }
    else if (psi.modeMatches(ix, 3, mode2)) {
      isgn = 1;
      ipi = -1;
      imode = 1;
    }
    else if (psi.modeMatches(ix, 3, mode3)) {
      isgn = -1;
      ipi = -1;
      isig = 3222;
      imode = 2;
    }
    else if (psi.modeMatches(ix, 3, mode4)) {
      isgn = 1;
      ipi = 1;
      isig = 3222;
      imode = 3;
    }
    else
      continue;
    const Particle& lam = psi.decayProducts()[ix].at(isgn * 3122)[0];
    const Particle& sig = psi.decayProducts()[ix].at(-isgn * isig)[0];
    const Particle& pi = psi.decayProducts()[ix].at(ipi * 211)[0];
    _h[imode][0]->fill((lam.mom() + pi.mom()).mass());
    _h[imode][1]->fill((sig.mom() + pi.mom()).mass());
    _h[imode][2]->fill((lam.mom() + sig.mom()).mass());
  }
}


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

/// @}

/// @name Histograms
/// @{
Histo1DPtr _h[4][3];
const map<PdgId, unsigned int> mode1 = {{-3122, 1}, {3112, 1}, {211, 1}};
const map<PdgId, unsigned int> mode2 = {{3122, 1}, {-3112, 1}, {-211, 1}};
const map<PdgId, unsigned int> mode3 = {{-3122, 1}, {3222, 1}, {-211, 1}};
const map<PdgId, unsigned int> mode4 = {{3122, 1}, {-3222, 1}, {211, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2023_I2670262);

} ```