Rivet analyses

Mass distributions in τ⁻ → π⁻π⁻π⁺π⁰ν_τ

Experiment: CLEOII (CESR)

Inspire ID: 501487

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 61 (2000) 052002

Beams: * *

Beam energies: ANY

Run details: none listed

Mass distributions in τ⁻ → π⁻π⁻π⁺π⁰ν_τ. The data were read from figures 2 and 3 in the paper and may not be fully corrected..

Source code:`CLEOII_1999_I501487.cc`

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

namespace Rivet {


  /// @brief tau -> pi- pi- pi+ pi0
  class CLEOII_1999_I501487 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1999_I501487);


    /// @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");
      // histograms
      for (unsigned int ix = 0; ix < 3; ++ix) {
        book(_h_2pi[ix], 1, 1, 1 + ix);
        if (ix == 2) continue;
        book(_h_4pi[ix], 2, 1, 1 + ix);
      }
    }


    /// 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& pi0 = TAU.decayProducts()[ix].at(111)[0];
        const Particles& pim = TAU.decayProducts()[ix].at(-211 * sign);
        const Particle& pip = TAU.decayProducts()[ix].at(211 * sign)[0];
        Particle omega;
        int iomega = -1;
        for (unsigned int ix = 0; ix < 2; ++ix) {
          Particle parent = pim[ix];
          while (!parent.parents().empty()) {
            parent = parent.parents()[0];
            if (parent.pid() == 223) break;
          }
          if (parent.pid() == 223) {
            omega = parent;
            iomega = ix;
          }
        }
        FourMomentum phad = pim[0].mom() + pim[1].mom() + pip.mom() + pi0.mom();
        const double q = phad.mass();
        if (iomega > 0) {
          _h_4pi[0]->fill(q);
        }
        else {
          _h_4pi[1]->fill(q);
          _h_2pi[0]->fill((pi0.mom() + pip.mom()).mass());
          for (unsigned int iy = 0; iy < 2; ++iy) {
            _h_2pi[1]->fill((pim[iy].mom() + pi0.mom()).mass());
            _h_2pi[2]->fill((pim[iy].mom() + pip.mom()).mass());
          }
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_2pi, 1.0, false);
      normalize(_h_4pi, 1.0, false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_2pi[3], _h_4pi[2];
    const map<PdgId, unsigned int> mode = {{111, 1}, {-211, 2}, {211, 1}, {16, 1}};
    const map<PdgId, unsigned int> modeCC = {{111, 1}, {211, 2}, {-211, 1}, {-16, 1}};
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEOII_1999_I501487);

}

Rivet analyses

Mass distributions in τ− → π−π−π+π0ντ

Source code:CLEOII_1999_I501487.cc

Mass distributions in τ⁻ → π⁻π⁻π⁺π⁰ν_τ

Source code:`CLEOII_1999_I501487.cc`