Rivet analyses

title: BABAR_2007_I756323

Measurements of Semi-Leptonic Tau Decays into Three Charged Hadrons

Experiment: BaBar (PEP-II)

Inspire ID: 756323

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett.100:011801,2008 - arXiv: 0707.2981 - SLAC-R-936

Beams: * *

Beam energies: ANY

Run details: - Tau production, can be any process but original data was in $e^+ e^-$ at the $\Upsilon(4S)$ resonance, with CoM boosts of 8.0 GeV~($e^-$) and 3.5~GeV~($e^+$)

Measurement of tau decays to three charged hadrons using a data sample corresponding to an integrated luminosity of 342 fb$^{-1}$ collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy near 10.58 GeV. Can be run with any process producing tau leptons.'

Source code:BABAR_2007_I756323.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief BABAR tau lepton to three charged hadrons /// /// @author Peter Richardson class BABAR_2007_I756323 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I756323);


void init() {
  declare(UnstableParticles(), "UFS");

  book(_hist_pipipi_pipipi, 1, 1, 1);
  book(_hist_pipipi_pipi, 2, 1, 1);
  book(_hist_Kpipi_Kpipi, 3, 1, 1);
  book(_hist_Kpipi_Kpi, 4, 1, 1);
  book(_hist_Kpipi_pipi, 5, 1, 1);
  book(_hist_KpiK_KpiK, 6, 1, 1);
  book(_hist_KpiK_KK, 7, 1, 1);
  book(_hist_KpiK_piK, 8, 1, 1);
  book(_hist_KKK_KKK, 9, 1, 1);
  book(_hist_KKK_KK, 10, 1, 1);

  book(_weight_total, "/TMP/weight_total");
  book(_weight_pipipi, "/TMP/weight_pipipi");
  book(_weight_Kpipi, "/TMP/weight_Kpipi");
  book(_weight_KpiK, "/TMP/weight_KpiK");
  book(_weight_KKK, "/TMP/weight_KKK");
}


void analyze(const Event& e) {
  // Find the taus
  Particles taus;
  for (const Particle& p : apply<UnstableParticles>(e, "UFS").particles(Cuts::pid == PID::TAU)) {
    _weight_total->fill();
    Particles pip, pim, Kp, Km;
    unsigned int nstable = 0;
    // Find the decay products we want
    findDecayProducts(p, nstable, pip, pim, Kp, Km);
    if (p.pid() < 0) {
      swap(pip, pim);
      swap(Kp, Km);
    }
    if (nstable != 4) continue;
    // pipipi
    if (pim.size() == 2 && pip.size() == 1) {
      _weight_pipipi->fill();
      _hist_pipipi_pipipi->fill((pip[0].momentum() + pim[0].momentum() + pim[1].momentum()).mass());
      _hist_pipipi_pipi->fill((pip[0].momentum() + pim[0].momentum()).mass());
      _hist_pipipi_pipi->fill((pip[0].momentum() + pim[1].momentum()).mass());
    }
    else if (pim.size() == 1 && pip.size() == 1 && Km.size() == 1) {
      _weight_Kpipi->fill();
      _hist_Kpipi_Kpipi->fill((pim[0].momentum() + pip[0].momentum() + Km[0].momentum()).mass());
      _hist_Kpipi_Kpi->fill((pip[0].momentum() + Km[0].momentum()).mass());
      _hist_Kpipi_pipi->fill((pim[0].momentum() + pip[0].momentum()).mass());
    }
    else if (Kp.size() == 1 && Km.size() == 1 && pim.size() == 1) {
      _weight_KpiK->fill();
      _hist_KpiK_KpiK->fill((Kp[0].momentum() + Km[0].momentum() + pim[0].momentum()).mass());
      _hist_KpiK_KK->fill((Kp[0].momentum() + Km[0].momentum()).mass());
      _hist_KpiK_piK->fill((Kp[0].momentum() + pim[0].momentum()).mass());
    }
    else if (Kp.size() == 1 && Km.size() == 2) {
      _weight_KKK->fill();
      _hist_KKK_KKK->fill((Kp[0].momentum() + Km[0].momentum() + Km[1].momentum()).mass());
      _hist_KKK_KK->fill((Kp[0].momentum() + Km[0].momentum()).mass());
      _hist_KKK_KK->fill((Kp[0].momentum() + Km[1].momentum()).mass());
    }
  }
}


void finalize() {
  normalize(_hist_pipipi_pipipi);
  normalize(_hist_pipipi_pipi);
  normalize(_hist_Kpipi_Kpipi);
  normalize(_hist_Kpipi_Kpi);
  normalize(_hist_Kpipi_pipi);
  normalize(_hist_KpiK_KpiK);
  normalize(_hist_KpiK_KK);
  normalize(_hist_KpiK_piK);
  normalize(_hist_KKK_KKK);
  normalize(_hist_KKK_KK);
  Estimate0DPtr tmp;
  book(tmp, 11, 1, 1);
  divide(*_weight_pipipi, *_weight_total, tmp);
  scale(tmp, 100.);
  book(tmp, 12, 1, 1);
  divide(*_weight_Kpipi, *_weight_total, tmp);
  scale(tmp, 100.);
  book(tmp, 13, 1, 1);
  divide(*_weight_KpiK, *_weight_total, tmp);
  scale(tmp, 100.);
  book(tmp, 14, 1, 1);
  divide(*_weight_KKK, *_weight_total, tmp);
  scale(tmp, 100.);
}

private:

// Histograms
Histo1DPtr _hist_pipipi_pipipi, _hist_pipipi_pipi;
Histo1DPtr _hist_Kpipi_Kpipi, _hist_Kpipi_Kpi, _hist_Kpipi_pipi;
Histo1DPtr _hist_KpiK_KpiK, _hist_KpiK_KK, _hist_KpiK_piK;
Histo1DPtr _hist_KKK_KKK, _hist_KKK_KK;

// Weights counters
CounterPtr _weight_total, _weight_pipipi, _weight_Kpipi, _weight_KpiK, _weight_KKK;


void findDecayProducts(const Particle& mother,
                       unsigned int& nstable,
                       Particles& pip,
                       Particles& pim,
                       Particles& Kp,
                       Particles& Km) {
  for (const Particle& p : mother.children()) {
    long id = p.pid();
    if (id == PID::PI0)
      ++nstable;
    else if (id == PID::K0S)
      ++nstable;
    else if (id == PID::PIPLUS) {
      pip.push_back(p);
      ++nstable;
    }
    else if (id == PID::PIMINUS) {
      pim.push_back(p);
      ++nstable;
    }
    else if (id == PID::KPLUS) {
      Kp.push_back(p);
      ++nstable;
    }
    else if (id == PID::KMINUS) {
      Km.push_back(p);
      ++nstable;
    }
    else if (!p.children().empty()) {
      findDecayProducts(p, nstable, pip, pim, Kp, Km);
    }
    else
      ++nstable;
  }
}

};

RIVET_DECLARE_ALIASED_PLUGIN(BABAR_2007_I756323, BABAR_2007_S7266081);

} ```

Aliases: - BABAR_2007_S7266081