Rivet analyses

title: CLEO_1995_I396711

Mass spectrum in hadronic $\tau$ decays

Experiment: CLEO (CESR)

Inspire ID: 396711

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 356 (1995) 580-588

Beams: * *

Beam energies: ANY

Run details: - Tau production, can be any process but original data was in $e^+ e^-$ at the $\Upsilon(4S)$ resonance

Measurement of the mass spectrum in hadronic $\tau$ decays. The decay were read from figure 1 in the paper which is fully corrected.

Source code:CLEO_1995_I396711.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brieftau -> hadrons class CLEO_1995_I396711 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_1995_I396711);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(Cuts::abspid == PID::TAU), "UFS");
  book(_h, 1, 1, 1);
}


void findDecayProducts(const Particle& mother, Particles& hadrons) {
  for (const Particle& p : mother.children()) {
    long id = p.abspid();
    if (id == PID::PI0 || id == 311 || id == 310 || id == 130) {
      hadrons.push_back(p);
    }
    else if (!p.children().empty()) {
      findDecayProducts(p, hadrons);
    }
    else if (id > 16) {
      hadrons.push_back(p);
    }
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::abspid == PID::TAU)) {
    Particles hadrons;
    // find the decay products we want
    findDecayProducts(p, hadrons);
    if (hadrons.size() <= 1) continue;
    FourMomentum ptotal;
    for (const Particle& p2 : hadrons) ptotal += p2.momentum();
    _h->fill(ptotal.mass2());
  }
}


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

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEO_1995_I396711);

} ```