Rivet analyses

π⁺π⁻π⁻η mass in τ → π⁺π⁻π⁻ην_τ

Experiment: CLEOII (CESR)

Inspire ID: 444745

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 79 (1997) 2406-2410

Beams: * *

Beam energies: ANY

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

Measurement of the hadronic mass in τ → π⁺π⁻π⁻ην_τ decays, excluding the f₁ contribution. The background subtracted data were read from figure 4 in the paper.

Source code:`CLEOII_1997_I444745.cc`

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DecayedParticles.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief tau -> pi+ pi- pi- eta nu_tau
  class CLEOII_1997_I444745 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1997_I444745);


    /// @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);
      TAU.addStable(221);
      declare(TAU, "TAU");
      // histogram
      book(_h, 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, 5, mode) || TAU.modeMatches(ix, 5, modeCC))) continue;
        const Particle& pip = TAU.decayProducts()[ix].at(211 * sign)[0];
        const Particles& pim = TAU.decayProducts()[ix].at(-211 * sign);
        const Particle& eta = TAU.decayProducts()[ix].at(221)[0];
        FourMomentum phad = pip.mom() + eta.mom();
        bool hasF1 = false;
        for (unsigned int iy = 0; iy < 2; ++iy) {
          double mf1 = (phad + pim[iy].mom()).mass();
          hasF1 |= abs(mf1 - 1.2819) < 0.036;
        }
        if (hasF1) continue;
        phad += pim[0].mom() + pim[1].mom();
        _h->fill(phad.mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h, 1.0, false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h;
    const map<PdgId, unsigned int> mode = {{221, 1}, {211, 1}, {-211, 2}, {16, 1}};
    const map<PdgId, unsigned int> modeCC = {{221, 1}, {-211, 1}, {211, 2}, {-16, 1}};
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEOII_1997_I444745);

}

Rivet analyses

π+π−π−η mass in τ → π+π−π−ηντ

Source code:CLEOII_1997_I444745.cc

π⁺π⁻π⁻η mass in τ → π⁺π⁻π⁻ην_τ

Source code:`CLEOII_1997_I444745.cc`