Rivet analyses

title: ARGUS_1992_I339268

$3\pi$ mass distribution in $\tau^-\to\pi^-\pi^-\pi^+\nu_\tau$ decays

Experiment: ARGUS (DORIS)

Inspire ID: 339268

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Z.Phys.C 58 (1993) 61-70

Beams: * *

Beam energies: ANY

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

Three pion mass distrubution in $\tau^-\to\pi^-\pi^-\pi^+\nu_\tau$ decays. Data take from the tables in the paper.

Source code:ARGUS_1992_I339268.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief tau -> 3 pi class ARGUS_1992_I339268 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1992_I339268);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs(Cuts::abspid == 15);
  declare(ufs, "UFS");
  DecayedParticles TAU(ufs);
  TAU.addStable(310);
  TAU.addStable(111);
  declare(TAU, "TAU");
  // histos
  book(_h_mass, 1, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  DecayedParticles TAU = apply<DecayedParticles>(event, "TAU");
  // loop over particles
  for (unsigned int ix = 0; ix < TAU.decaying().size(); ++ix) {
    int sign = TAU.decaying()[ix].pid() > 0 ? 1 : -1;
    if (!(TAU.modeMatches(ix, 4, mode) || TAU.modeMatches(ix, 4, modeCC))) {
      continue;
    }
    const Particles& pip = TAU.decayProducts()[ix].at(211 * sign);
    const Particles& pim = TAU.decayProducts()[ix].at(-211 * sign);
    double Q2 = (pip[0].mom() + pim[0].mom() + pim[1].mom()).mass2();
    _h_mass->fill(sqrt(Q2));
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h_mass, 1., false);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_mass;
const map<PdgId, unsigned int> mode = {{-211, 2}, {211, 1}, {16, 1}};
const map<PdgId, unsigned int> modeCC = {{211, 2}, {-211, 1}, {-16, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_1992_I339268);

} ```