Rivet analyses

title: BABAR_2012_I1125567

Mass distributions in the decay $\tau^-\to\pi^-K^0_SK^0_S$

Experiment: BABAR (PEP-II)

Inspire ID: 1125567

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 86 (2012) 092013

Beams: * *

Beam energies: ANY

Run details: - Any process producing tau leptons, originally e+e-

Measurements of mass distributions in $\tau^-\to\pi^-K^0_SK^0_S$ decays. The data were read from the plots in the paper and are not corrected, although the backgrounds given in the paper have been subtracted. The plots should therefore only be used for qualitative comparisons however the data is useful as there are not corrected distributions for this decay mode.

Source code:BABAR_2012_I1125567.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief tau -> pi- KS0 KS0 nu class BABAR_2012_I1125567 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2012_I1125567);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 15);
  declare(ufs, "UFS");
  DecayedParticles TAU(ufs);
  TAU.addStable(310);
  TAU.addStable(111);
  declare(TAU, "TAU");
  // histograms
  for (unsigned int ix = 0; ix < 3; ++ix) {
    book(_h[ix], 1, 1, 1 + ix);
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode = {{310, 2}, {-211, 1}, {16, 1}};
  static const map<PdgId, unsigned int>& modeCC = {{310, 2}, {211, 1}, {-16, 1}};
  DecayedParticles TAU = apply<DecayedParticles>(event, "TAU");
  // loop over particles
  for (unsigned int ix = 0; ix < TAU.decaying().size(); ++ix) {
    int sign = 1;
    if (TAU.decaying()[ix].pid() > 0 && TAU.modeMatches(ix, 4, mode))
      sign = 1;
    else if (TAU.decaying()[ix].pid() < 0 && TAU.modeMatches(ix, 4, modeCC))
      sign = -1;
    else
      continue;
    const Particle& pim = TAU.decayProducts()[ix].at(-211 * sign)[0];
    const Particles& K0 = TAU.decayProducts()[ix].at(310);
    _h[0]->fill((pim.momentum() + K0[0].momentum() + K0[1].momentum()).mass());
    _h[2]->fill((K0[0].momentum() + K0[1].momentum()).mass());
    for (unsigned int ix = 0; ix < 2; ++ix) {
      _h[1]->fill((pim.momentum() + K0[ix].momentum()).mass());
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 0; ix < 3; ++ix) {
    normalize(_h[ix], 1., false);
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[3];
/// @}

};

RIVET_DECLARE_PLUGIN(BABAR_2012_I1125567);

} ```